150027811 - GE CRITICAL POWER

225814fc

LTC2258-14

LTC2257-14/LTC2256-14

For more information www.linear.com/LTC2258-14For more information www.linear.com/LTC2258-14

Typical applicaTion

FeaTures

applicaTions

DescripTion

14-Bit, 65/40/25Msps

Ultralow Power 1.8V ADCs

n Communications

n Cellular Base Stations

n Software Defined Radios

n Portable Medical Imaging

n Multi-Channel Data Acquisition

n Nondestructive Testing L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear

Technology Corporation. All other trademarks are the property of their respective owners.

n 74dB SNR

n 88dB SFDR

n Low Power: 81mW/49mW/35mW

n Single 1.8V Supply

n CMOS, DDR CMOS or DDR LVDS Outputs

n Selectable Input Ranges: 1V

P-P

to 2V

P-P

n 800MHz Full-Power Bandwidth S/H

n Optional Data Output Randomizer

n Optional Clock Duty Cycle Stabilizer

n Shutdown and Nap Modes

n Serial SPI Port for Configuration

n Pin Compatible 14-Bit and 12-Bit Versions

n 40-Pin (6mm × 6mm) QFN Package

The LTC

2258-14/LTC2257-14/LTC2256-14 are sam-

pling 14-bit A/D converters designed for digitizing high

frequency, wide dynamic range signals. They are perfect

for demanding communications applications with AC

performance that includes 74dB SNR and 88dB spurious

free dynamic range (SFDR). Ultralow jitter of 0.17psRMS

allows undersampling of IF frequencies with excellent

noise performance.

DC specs include ±1LSB INL (typical), ±0.3LSB DNL (typi-

cal) and no missing codes over temperature. The transition

noise is a low 1.13LSBRMS.

The digital outputs can be either full rate CMOS, double

data rate CMOS, or double data rate LVDS. A separate

output power supply allows the CMOS output swing to

range from 1.2V to 1.8V.

The ENC+ and ENC– inputs may be driven differentially

or single ended with a sine wave, PECL, LVDS, TTL or

CMOS inputs. An optional clock duty cycle stabilizer al-

lows high performance at full speed for a wide range of

clock duty cycles.

LTC2258-14 2-Tone FFT,

fIN = 68MHz and 69MHz

–

INPUT

S/H

CORRECTION

LOGIC OUTPUT

DRIVERS

14-BIT

PIPELINED

ADC CORE

CLOCK/DUTY

CYCLE

CONTROL

D13

•

65MHz

CLOCK

ANALOG

INPUT

225814 TA01a

CMOS

LVDS

1.2V

TO 1.8V

1.8V

VDD

OVDD

OGND

GND FREQUENCY (MHz)

–100

–110

–120

–70

–60

–80

–90

AMPLITUDE (dBFS)

–50

–30

–40

–20

–10

10 20 30

225814 TA01b

LTC2258-14

LTC2257-14/LTC2256-14

225814fc

For more information www.linear.com/LTC2258-14For more information www.linear.com/LTC2258-14

absoluTe MaxiMuM raTings

Supply Voltages (VDD, OVDD) ....................... –0.3V to 2V

Analog Input Voltage (AIN+, AIN–,

PAR/SER, SENSE) (Note 3) .......... –0.3V to (VDD + 0.2V)

Digital Input Voltage (ENC+, ENC–, CS,

SDI, SCK) (Note 4) .................................... –0.3V to 3.9V

SDO (Note 4) ............................................. –0.3V to 3.9V

(Notes 1, 2)

3940 38 37 36 35 34 33 32 31

11 20

12 13 14 15

FULL-RATE CMOS OUTPUT MODE

TOP VIEW

UJ PACKAGE

40-LEAD (6mm × 6mm) PLASTIC QFN

16 17 18 19

AIN+

AIN–

GND

REFH

REFL

PAR/SER

VDD

CLKOUT+

CLKOUT–

OVDD

OGND

VDD

SENSE

VREF

VCM

DNC

D13

D12

D11

D10

ENC+

ENC–

SCK

SDI

SDO

TJMAX = 150°C, θJA = 32°C/W

EXPOSED PAD (PIN 41) IS GND, MUST BE SOLDERED TO PCB

3940 38 37 36 35 34 33 32 31

11 20

12 13 14 15

DOUBLE DATA RATE CMOS OUTPUT MODE

TOP VIEW

UJ PACKAGE

40-LEAD (6mm × 6mm) PLASTIC QFN

16 17 18 19

AIN+

AIN–

GND

REFH

REFL

PAR/SER

VDD

D8_9

DNC

CLKOUT+

CLKOUT–

OVDD

OGND

D6_7

DNC

D4_5

DNC

VDD

SENSE

VREF

VCM

DNC

D12_13

DNC

D10_11

DNC

ENC+

ENC–

SCK

SDI

SDO

DNC

D0_1

DNC

D2_3

TJMAX = 150°C, θJA = 32°C/W

EXPOSED PAD (PIN 41) IS GND, MUST BE SOLDERED TO PCB

3940 38 37 36 35 34 33 32 31

11 20

12 13 14 15

DOUBLE DATA RATE LVDS OUTPUT MODE

TOP VIEW

UJ PACKAGE

40-LEAD (6mm × 6mm) PLASTIC QFN

16 17 18 19

AIN+

AIN–

GND

REFH

REFL

PAR/SER

VDD

D8_9+

D8_9–

CLKOUT+

CLKOUT–

OVDD

OGND

D6_7+

D6_7–

D4_5+

D4_5–

VDD

SENSE

VREF

VCM

OF+

OF–

D12_13+

D12_13–

D10_11+

D10_11–

ENC+

ENC–

SCK

SDI

SDO

D0_1–

D0_1+

D2_3–

D2_3+

TJMAX = 150°C, θJA = 32°C/W

EXPOSED PAD (PIN 41) IS GND, MUST BE SOLDERED TO PCB

pin conFiguraTions

Digital Output Voltage ................ –0.3V to (OVDD + 0.3V)

Operating Temperature Range:

LTC2258C, LTC2257C, LTC2256C ............ 0°C to 70°C

LTC2258I, LTC2257I, LTC2256I ...........–40°C to 85°C

Storage Temperature Range .................. –65°C to 150°C

225814fc

LTC2258-14

LTC2257-14/LTC2256-14

For more information www.linear.com/LTC2258-14For more information www.linear.com/LTC2258-14

converTer characTerisTics

The l denotes the specifications which apply over the full operating

temperature range, otherwise specifications are at TA = 25°C. (Note 5)

PARAMETER CONDITIONS

LTC2258-14 LTC2257-14 LTC2256-14

UNITSMIN TYP MAX MIN TYP MAX MIN TYP MAX

Resolution (No Missing Codes) l14 14 14 Bits

Integral Linearity Error Differential Analog Input (Note 6) l–3 ±1 3 –2.5 ±1 2.5 –2.5 ±1 2.5 LSB

Differential Linearity Error Differential Analog Input l–0.8 ±0.3 0.8 –0.8 ±0.3 0.8 –0.8 ±0.3 0.8 LSB

Offset Error (Note 7) l–9 ±1.5 9 –9 ±1.5 9 –9 ±1.5 9 mV

Gain Error Internal Reference

External Reference

–1.5

±1.5

±0.4

1.5

–1.5

±1.5

±0.4

1.5

–1.5

±1.5

±0.4

1.5

%FS

Offset Drift ±20 ±20 ±20 µV/°C

Full-Scale Drift Internal Reference

External Reference

±30

±10

±30

±10

±30

±10

ppm/°C

Transition Noise External Reference 1.13 1.13 1.13 LSBRMS

orDer inForMaTion

LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE

LTC2258CUJ-14#PBF LTC2258CUJ-14#TRPBF LTC2258UJ-14 40-Lead (6mm × 6mm) Plastic QFN 0°C to 70°C

LTC2258IUJ-14#PBF LTC2258IUJ-14#TRPBF LTC2258UJ-14 40-Lead (6mm × 6mm) Plastic QFN –40°C to 85°C

LTC2257CUJ-14#PBF LTC2257CUJ-14#TRPBF LTC2257UJ-14 40-Lead (6mm × 6mm) Plastic QFN 0°C to 70°C

LTC2257IUJ-14#PBF LTC2257IUJ-14#TRPBF LTC2257UJ-14 40-Lead (6mm × 6mm) Plastic QFN –40°C to 85°C

LTC2256CUJ-14#PBF LTC2256CUJ-14#TRPBF LTC2256UJ-14 40-Lead (6mm × 6mm) Plastic QFN 0°C to 70°C

LTC2256IUJ-14#PBF LTC2256IUJ-14#TRPBF LTC2256UJ-14 40-Lead (6mm × 6mm) Plastic QFN –40°C to 85°C

Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.

Consult LTC Marketing for information on non-standard lead based finish parts.

For more information on lead free part marking, go to: http://www.linear.com/leadfree/

For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/

LTC2258-14

LTC2257-14/LTC2256-14

225814fc

For more information www.linear.com/LTC2258-14For more information www.linear.com/LTC2258-14

analog inpuT

The l denotes the specifications which apply over the full operating temperature range, otherwise

specifications are at TA = 25°C. (Note 5)

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

VIN Analog Input Range (AIN+ – AIN–) 1.7V < VDD < 1.9V l1 to 2 VP-P

VIN(CM) Analog Input Common Mode (AIN+ + AIN–)/2 Differential Analog Input (Note 8) lVCM – 100mV VCM VCM + 100mV V

VSENSE External Voltage Reference Applied to SENSE External Reference Mode l0.625 1.250 1.300 V

IINCM Analog Input Common Mode Current Per Pin, 65Msps

Per Pin, 40Msps

Per Pin, 25Msps

µA

IIN1 Analog Input Leakage Current 0 < AIN+, AIN– < VDD, No Encode l–1 1 µA

IIN2 PAR/SER Input Leakage Current 0 < PAR/SER < VDD l–3 3 µA

IIN3 SENSE Input Leakage Current 0.625 < SENSE < 1.3V l–6 6 µA

tAP Sample-and-Hold Acquisition Delay Time 0 ns

tJITTER Sample-and-Hold Acquisition Delay Jitter 0.17 psRMS

CMRR Analog Input Common Mode Rejection Ratio 80 dB

BW-3B Full-Power Bandwidth Figure 6 Test Circuit 800 MHz

DynaMic accuracy

The l denotes the specifications which apply over the full operating temperature range,

otherwise specifications are at TA = 25°C. AIN = –1dBFS. (Note 5)

SYMBOL PARAMETER CONDITIONS

LTC2258-14 LTC2257-14 LTC2256-14

UNITSMIN TYP MAX MIN TYP MAX MIN TYP MAX

SNR Signal-to-Noise Ratio 5MHz Input

30MHz Input

70MHz Input

140MHz Input

72.4

73.8

73.7

71.9

73.4

73.2

73.1

72.6

71.2

72.9

72.8

72.1

71.8

SFDR Spurious Free Dynamic Range

2nd or 3rd Harmonic

5MHz Input

30MHz Input

70MHz Input

140MHz Input

Spurious Free Dynamic Range

4th Harmonic or Higher

5MHz Input

30MHz Input

70MHz Input

140MHz Input

S/(N+D) Signal-to-Noise Plus

Distortion Ratio

5MHz Input

30MHz Input

70MHz Input

140MHz Input

71.5

73.8

73.7

73.6

72.5

71.5

73.2

73.1

72.3

70.7

72.8

72.7

71.2

inTernal reFerence characTerisTics

The l denotes the specifications which apply over the

full operating temperature range, otherwise specifications are at TA = 25°C. (Note 5)

PARAMETER CONDITIONS MIN TYP MAX UNITS

VCM Output Voltage IOUT = 0 0.5 • VDD – 25mV 0.5 • VDD 0.5 • VDD + 25mV V

VCM Output Temperature Drift ±25 ppm/°C

VCM Output Resistance –600µA < IOUT < 1mA 4 Ω

VREF Output Voltage IOUT = 0 1.225 1.250 1.275 V

VREF Output Temperature Drift ±25 ppm/°C

VREF Output Resistance –400µA < IOUT < 1mA 7 Ω

VREF Line Regulation 1.7V < VDD < 1.9V 0.6 mV/V

225814fc

LTC2258-14

LTC2257-14/LTC2256-14

For more information www.linear.com/LTC2258-14For more information www.linear.com/LTC2258-14

DigiTal inpuTs anD ouTpuTs

The l denotes the specifications which apply over the full operating

temperature range, otherwise specifications are at TA = 25°C. (Note 5)

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

ENCODE INPUTS (ENC+, ENC– )

Differential Encode Mode (ENC– Not Tied to GND)

VID Differential Input Voltage (Note 8) l0.2 V

VICM Common Mode Input Voltage Internally Set

Externally Set (Note 8)

1.1

1.2

1.6

VIN Input Voltage Range ENC+, ENC– to GND l0.2 3.6 V

RIN Input Resistance (See Figure 10) 10 kΩ

CIN Input Capacitance (Note 8) 3.5 pF

Single-Ended Encode Mode (ENC– Tied to GND)

VIH High Level Input Voltage VDD = 1.8V l1.2 V

VIL Low Level Input Voltage VDD = 1.8V l0.6 V

VIN Input Voltage Range ENC+ to GND l0 3.6 V

RIN Input Resistance (See Figure 11) 30 kΩ

CIN Input Capacitance (Note 8) 3.5 pF

DIGITAL INPUTS (CS, SDI, SCK)

VIH High Level Input Voltage VDD = 1.8V l1.3 V

VIL Low Level Input Voltage VDD = 1.8V l0.6 V

IIN Input Current VIN = 0V to 3.6V l–10 10 µA

CIN Input Capacitance (Note 8) 3 pF

SDO OUTPUT (Open-Drain Output. Requires 2k Pull-Up Resistor if SDO is Used)

ROL Logic Low Output Resistance to GND VDD = 1.8V, SDO = 0V 200 Ω

IOH Logic High Output Leakage Current SDO = 0V to 3.6V l–10 10 µA

COUT Output Capacitance (Note 8) 4 pF

DIGITAL DATA OUTPUTS (CMOS MODES: FULL D ATA RATE AND DOUBLE DATA RATE)

OVDD = 1.8V

VOH High Level Output Voltage IO = –500µA l1.750 1.790 V

VOL Low Level Output Voltage IO = 500µA l0.010 0.050 V

OVDD = 1.5V

VOH High Level Output Voltage IO = –500µA 1.488 V

VOL Low Level Output Voltage IO = 500µA 0.010 V

OVDD = 1.2V

VOH High Level Output Voltage IO = –500µA 1.185 V

VOL Low Level Output Voltage IO = 500µA 0.010 V

DIGITAL DATA OUTPUTS (LVDS MODE)

VOD Differential Output Voltage 100Ω Differential Load, 3.5mA Mode

100Ω Differential Load, 1.75mA Mode

l247 350

175

454 mV

VOS Common Mode Output Voltage 100Ω Differential Load, 3.5mA Mode

100Ω Differential Load, 1.75mA Mode

l1.125 1.250

1.250

1.375 V

RTERM On-Chip Termination Resistance Termination Enabled, OVDD = 1.8V 100 Ω

LTC2258-14

LTC2257-14/LTC2256-14

225814fc

For more information www.linear.com/LTC2258-14For more information www.linear.com/LTC2258-14

power requireMenTs

The l denotes the specifications which apply over the full operating temperature

range, otherwise specifications are at TA = 25°C. (Note 9)

SYMBOL PARAMETER CONDITIONS

LTC2258-14 LTC2257-14 LTC2256-14

UNITSMIN TYP MAX MIN TYP MAX MIN TYP MAX

CMOS Output Modes: Full Data Rate and Double Data Rate

VDD Analog Supply Voltage (Note 10) l1.7 1.8 1.9 1.7 1.8 1.9 1.7 1.8 1.9 V

OVDD Output Supply Voltage (Note 10) l1.1 1.9 1.1 1.9 1.1 1.9 V

IVDD Analog Supply Current DC Input

Sine Wave Input

l44.7

45.3

49.5 27

27.9

30 19.5

19.9

22 mA

IOVDD Digital Supply Current Sine Wave Input, OVDD=1.2V 2.6 1.6 1.1 mA

PDISS Power Dissipation DC Input

Sine Wave Input, OVDD=1.2V

l80.5

84.7

90 48.6

52.1

54 35.1

37.1

40 mW

LVDS Output Mode

VDD Analog Supply Voltage (Note 10) l1.7 1.8 1.9 1.7 1.8 1.9 1.7 1.8 1.9 V

OVDD Output Supply Voltage (Note 10) l1.7 1.9 1.7 1.9 1.7 1.9 V

IVDD Analog Supply Current Sine Wave Input l48.9 54 31.4 35 23.5 26 mA

IOVDD Digital Supply Current

(0VDD = 1.8V)

Sine Input, 1.75mA Mode

Sine Input, 3.5mA Mode

20.7

40.5

20.7

40.5

20.7

40.5

PDISS Power Dissipation Sine Input, 1.75mA Mode

Sine Input, 3.5mA Mode

125.3

160.9

139

177

93.8

129.4

105

143

79.6

115.2

126

All Output Modes

PSLEEP Sleep Mode Power 0.5 0.5 0.5 mW

PNAP Nap Mode Power 9 9 9 mW

PDIFFCLK Power Increase with Differential Encode Mode Enabled

(No increase for Nap or Sleep Modes)

10 10 10 mW

TiMing characTerisTics

The l denotes the specifications which apply over the full operating temperature

range, otherwise specifications are at TA = 25°C. (Note 5)

SYMBOL PARAMETER CONDITIONS

LTC2258-14 LTC2257-14 LTC2256-14

UNITSMIN TYP MAX MIN TYP MAX MIN TYP MAX

fSSampling Frequency (Note 10) l1 65 1 40 1 25 MHz

tLENC Low Time (Note 8) Duty Cycle Stabilizer Off

Duty Cycle Stabilizer On

7.3

2.0

7.69

500

11.88

2.00

12.5

500

2.00

500

tHENC High Time (Note 8) Duty Cycle Stabilizer Off

Duty Cycle Stabilizer On

7.3

2.0

7.69

500

11.88

2.00

12.5

500

2.00

500

tAP Sample-and-Hold

Acquisition Delay Time

0 0 0 ns

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

Digital Data Outputs (CMOS Modes: Full Data Rate and Double Data Rate)

tDENC to Data Delay CL = 5pF (Note 8) l1.1 1.7 3.1 ns

tCENC to CLKOUT Delay CL = 5pF (Note 8) l1 1.4 2.6 ns

tSKEW DATA to CLKOUT Skew tD – tC (Note 8) l0 0.3 0.6 ns

Pipeline Latency Full Data Rate Mode

Double Data Rate Mode

5.0

5.5

Cycles

225814fc

LTC2258-14

LTC2257-14/LTC2256-14

For more information www.linear.com/LTC2258-14For more information www.linear.com/LTC2258-14

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

Digital Data Outputs (LVDS Mode)

tDENC to Data Delay CL = 5pF (Note 8) l1.1 1.8 3.2 ns

tCENC to CLKOUT Delay CL = 5pF (Note 8) l1 1.5 2.7 ns

tSKEW DATA to CLKOUT Skew tD – tC (Note 8) l0 0.3 0.6 ns

Pipeline Latency 5.5 Cycles

SPI Port Timing (Note 8)

tSCK SCK Period Write Mode

Readback Mode, CSDO = 20pF, RPULLUP = 2k

250

tSCS to SCK Setup Time l5 ns

tHSCK to CS Setup Time l5 ns

tDS SDI Setup Time l5 ns

tDH SDI Hold Time l5 ns

tDO SCK Falling to SDO Valid Readback Mode, CSDO = 20pF, RPULLUP = 2k l125 ns

TiMing characTerisTics

The l denotes the specifications which apply over the full operating temperature

range, otherwise specifications are at TA = 25°C. (Note 5)

Note 1: Stresses beyond those listed under Absolute Maximum Ratings

may cause permanent damage to the device. Exposure to any Absolute

Maximum Rating condition for extended periods may affect device

reliability and lifetime.

Note 2: All voltage values are with respect to GND with GND and OGND

shorted (unless otherwise noted).

Note 3: When these pin voltages are taken below GND or above VDD, they

will be clamped by internal diodes. This product can handle input currents

of greater than 100mA below GND or above VDD without latchup.

Note 4: When these pin voltages are taken below GND they will be

clamped by internal diodes. When these pin voltages are taken above VDD

they will not be clamped by internal diodes. This product can handle input

currents of greater than 100mA below GND without latchup.

Note 5: V

= OV

= 1.8V, f

SAMPLE

= 65MHz (LTC2258),

40MHz (LTC2257), or 25MHz (LTC2256), LVDS outputs with internal

termination disabled, differential ENC+/ENC– = 2V

P-P

sine wave, input

range = 2V

P-P

with differential drive, unless otherwise noted.

Note 6: Integral nonlinearity is defined as the deviation of a code from a

best fit straight line to the transfer curve. The deviation is measured from

the center of the quantization band.

Note 7: Offset error is the offset voltage measured from –0.5 LSB when

the output code flickers between 00 0000 0000 0000 and 11 1111 1111

1111 in 2’s complement output mode.

Note 8: Guaranteed by design, not subject to test.

Note 9: V

= 1.8V, f

SAMPLE

= 65MHz (LTC2258), 40MHz (LTC2257), or

25MHz (LTC2256), ENC+ = single-ended 1.8V square wave, ENC– = 0V,

input range = 2V

P-P

with differential drive, 5pF load on each digital output

unless otherwise noted.

Note 10: Recommended operating conditions.

LTC2258-14

LTC2257-14/LTC2256-14

225814fc

For more information www.linear.com/LTC2258-14For more information www.linear.com/LTC2258-14

Double Data Rate CMOS Output Mode Timing

All Outputs Are Single-Ended and Have CMOS Levels

•

tCtC

OFN-5 OFN-4 OFN-3 OFN-2

D0N-5 D1N-5 D0N-4 D1N-4 D0N-3 D1N-3 D0N-2 D1N-2

D12N-5 D13N-5 D12N-4 D13N-4 D12N-3 D13N-3 D12N-2 D13N-2

tAP

N + 1

N + 2 N + 4

N + 3

ANALOG

INPUT

ENC–

ENC+

D0_1

D12_13

CLKOUT+

CLKOUT–

225814 TD02

TiMing DiagraMs

Full-Rate CMOS Output Mode Timing

All Outputs Are Single-Ended and Have CMOS Levels

N – 5 N – 4 N – 3 N – 2 N – 1

tAP

N + 1

N + 2 N + 4

N + 3

ANALOG

INPUT

ENC–

ENC+

CLKOUT+

CLKOUT–

D0-D13, OF

225814 TD01

225814fc

LTC2258-14

LTC2257-14/LTC2256-14

For more information www.linear.com/LTC2258-14For more information www.linear.com/LTC2258-14

TiMing DiagraMs

Double Data Rate LVDS Output Mode Timing

All Outputs Are Differential and Have LVDS Levels

tDtD

tCtC

OFN-5 OFN-4 OFN-3 OFN-3

D0N-5 D1N-5 D0N-4 D1N-4 D0N-3 D1N-3 D0N-2 D1N-2

D12N-5 D13N-5 D12N-4 D13N-4 D12N-3 D13N-3 D12N-2 D13N-2

tAP

N + 1

N + 2 N + 4

N + 3

ANALOG

INPUT

ENC–

ENC+

D0_1+

D0_1–

D12_13+

D12_13–

CLKOUT+

CLKOUT–

OF+

OF–

225814 TD03

•

tStDS

A5 A4 A3 A2 A1 A0 XX

D7 D6 D5 D4 D3 D2 D1 D0

XX XX XX XX XX XX XX

SCK

SDI R/W

SDO HIGH IMPEDANCE

SPI Port Timing (Readback Mode)

SPI Port Timing (Write Mode)

tDH

tDO

tSCK tH

A6 A5 A4 A3 A2 A1 A0 D7 D6 D5 D4 D3 D2 D1 D0

225814 TD04

SCK

SDI R/W

SDO HIGH IMPEDANCE

LTC2258-14

LTC2257-14/LTC2256-14

225814fc

For more information www.linear.com/LTC2258-14For more information www.linear.com/LTC2258-14

Typical perForMance characTerisTics

LTC2258-14: Integral

Nonlinearity (INL)

LTC2258-14: Differential

Nonlinearity (DNL)

LTC2258-14: 8k Point FFT,

fIN = 5MHz, –1dBFS, 65Msps

OUTPUT CODE

–2.0

–0.5

–1.0

–1.5

INL ERROR (LSB)

0.5

1.0

1.5

2.0

4096 8192 12288 16384

225814 G01

OUTPUT CODE

–1.0

–0.4

–0.2

–0.6

–0.8

DNL ERROR (LSB)

0.4

0.2

0.6

0.8

1.0

4096 8192 12288 16384

225814 G02

FREQUENCY (MHz)

–100

–110

–120

–70

–60

–80

–90

AMPLITUDE (dBFS)

–50

–30

–40

–20

–10

225814 G03

010 20 30

LTC2258-14: 8k Point FFT,

fIN = 30MHz, –1dBFS, 65Msps

LTC2258-14: 8k Point FFT,

fIN = 70MHz, –1dBFS, 65Msps

LTC2258-14: 8k Point FFT,

fIN = 140MHz, –1dBFS, 65Msps

LTC2258-14: 8k Point 2-Tone FFT,

fIN = 68MHz, 69MHz, –1dBFS,

65Msps

LTC2258-14: Shorted Input

Histogram

FREQUENCY (MHz)

–100

–110

–120

–70

–60

–80

–90

AMPLITUDE (dBFS)

–50

–30

–40

–20

–10

225814 G04

10 20 30

FREQUENCY (MHz)

–100

–110

–120

–70

–60

–80

–90

AMPLITUDE (dBFS)

–50

–30

–40

–20

–10

10 20 30

225814 G05

FREQUENCY (MHz)

–100

–110

–120

–70

–60

–80

–90

AMPLITUDE (dBFS)

–50

–30

–40

–20

–10

10 20 30

225814 G06

FREQUENCY (MHz)

–100

–110

–120

–70

–60

–80

–90

AMPLITUDE (dBFS)

–50

–30

–40

–20

–10

10 20 30

225814 G07

OUTPUT CODE

8197

1000

3000

2000

COUNT

4000

5000

6000

8199 8201 8203 8205

225814 G08

INPUT FREQUENCY (MHz)

SNR (dBFS)

50 100 150 200 250 300 350

225814 G09

LTC2258-14: SNR vs Input

Frequency, –1dB, 2V Range,

65Msps

225814fc

LTC2258-14

LTC2257-14/LTC2256-14

For more information www.linear.com/LTC2258-14For more information www.linear.com/LTC2258-14

Typical perForMance characTerisTics

LTC2258-14: SFDR vs Input Level,

fIN = 70MHz, 2V Range, 65Msps

LTC2258-14: IVDD vs Sample Rate,

5MHz Sine Wave Input, –1dB

INPUT LEVEL (dBFS)

–80

SFDR (dBc AND dBFS)

100

110

–70 –60 –50 –40 –30 –20 –10 0

225814 G12

dBFS

dBc

SAMPLE RATE (Msps)

IVDD (mA)

20 40 60

225814 G13

LVDS OUTPUTS

CMOS OUTPUTS

INPUT FREQUENCY (MHz)

SFDR (dBFS)

50 100 150 200 250 300 350

225814 G10

LTC2258-14: SFDR vs Input

Frequency, –1dB, 2V Range,

65Msps

LTC2258-14: IOVDD vs Sample

Rate, 5MHz Sine Wave Input,

–1dB, 5pF on Each Data Output

LTC2258-14: SNR vs SENSE,

fIN = 5MHz, –1dB

LTC2257-14: Integral Nonlinearity

(INL)

LTC2257-14: Differential

Nonlinearity (DNL)

LTC2257-14: 8k Point FFT,

fIN = 5MHz, –1dBFS, 40Msps

LTC2257-14: 8k Point FFT,

fIN = 29MHz, –1dBFS, 40Msps

SAMPLE RATE (Msps)

IOVDD (mA)

20 40 60

225814 G14

1.75mA LVDS

1.8V CMOS 1.2V CMOS

3.5mA LVDS

SENSE PIN (V)

0.6

SNR (dBFS)

0.7 0.8 0.9 1.1 1.2 1.31

225814 G15

OUTPUT CODE

–2.0

–0.5

–1.0

–1.5

INL ERROR (LSB)

0.5

1.0

1.5

2.0

4096 8192 12288 16384

225814 G21

OUTPUT CODE

–1.0

–0.4

–0.2

–0.6

–0.8

DNL ERROR (LSB)

0.4

0.2

0.6

0.8

1.0

4096 8192 12288 16384

225814 G22

FREQUENCY (MHz)

–100

–110

–120

–70

–60

–80

–90

AMPLITUDE (dBFS)

–50

–30

–40

–20

–10

10 20

225814 G23

FREQUENCY (MHz)

–100

–110

–120

–70

–60

–80

–90

AMPLITUDE (dBFS)

–50

–30

–40

–20

–10

10 20

225814 G24

LTC2258-14

LTC2257-14/LTC2256-14

225814fc

For more information www.linear.com/LTC2258-14For more information www.linear.com/LTC2258-14

Typical perForMance characTerisTics

LTC2257-14: 8k Point FFT,

fIN = 69MHz, –1dBFS, 40Msps

LTC2257-14: 8k Point FFT,

fIN = 139MHz, –1dBFS, 40Msps

FREQUENCY (MHz)

–100

–110

–120

–70

–60

–80

–90

AMPLITUDE (dBFS)

–50

–30

–40

–20

–10

10 20

225814 G25

FREQUENCY (MHz)

–100

–110

–120

–70

–60

–80

–90

AMPLITUDE (dBFS)

–50

–30

–40

–20

–10

10 20

225814 G26

LTC2257-14: 8k Point 2-Tone FFT,

fIN = 68MHz, 69MHz, –1dBFS,

40Msps

FREQUENCY (MHz)

–100

–110

–120

–70

–60

–80

–90

AMPLITUDE (dBFS)

–50

–30

–40

–20

–10

225814 G27

LTC2257-14: IVDD vs Sample Rate,

5MHz Sine Wave Input, –1dB

LTC2257-14: IOVDD vs Sample

Rate, 5MHz Sine Wave Input,

–1dB, 5pF on Each Data Output

LTC2257-14: Shorted Input

Histogram

LTC2257-14: SFDR vs Input Level,

fIN = 70MHz, 2V Range, 40Msps

OUTPUT CODE

8198

1000

3000

2000

COUNT

4000

5000

6000

8200 8202 8204 8206

225814 G28

SAMPLE RATE (Msps)

IVDD (mA)

20 40

225814 G33

LVDS OUTPUTS

CMOS OUTPUTS

SAMPLE RATE (Msps)

OVDD

(mA)

225814 G34

1.75mA LVDS

1.8V CMOS 1.2V CMOS

3.5mA LVDS

0 20 40

INPUT LEVEL (dBFS)

–80

SFDR (dBc AND dBFS)

100

110

–70 –60 –50 –40 –30 –20 –10 0

225814 G32

dBFS

dBc

INPUT FREQUENCY (MHz)

SNR (dBFS)

50 100 150 200 250 300 350

225814 G29

INPUT FREQUENCY (MHz)

SFDR (dBFS)

50 100 150 200 250 300 350

225814 G30

LTC2257-14: SNR vs Input

Frequency, –1dB, 2V Range,

40Msps

LTC2257-14: SFDR vs Input

Frequency, –1dB, 2V Range,

40Msps

225814fc

LTC2258-14

LTC2257-14/LTC2256-14

For more information www.linear.com/LTC2258-14For more information www.linear.com/LTC2258-14

LTC2257-14: SNR vs SENSE,

fIN = 5MHz, –1dB

Typical perForMance characTerisTics

LTC2256-14: Integral Nonlinearity

(INL)

LTC2256-14: Differential

Nonlinearity (DNL)

SENSE PIN (V)

0.6

SNR (dBFS)

0.7 0.8 0.9 1.1 1.2 1.31

225814 G35

OUTPUT CODE

–2.0

–0.5

–1.0

–1.5

INL ERROR (LSB)

0.5

1.0

1.5

2.0

4096 8192 12288 16384

225814 G41

OUTPUT CODE

–1.0

–0.4

–0.2

–0.6

–0.8

DNL ERROR (LSB)

0.4

0.2

0.6

0.8

1.0

4096 8192 12288 16384

225814 G42

LTC2256-14: 8k Point 2-Tone FFT,

fIN = 68MHz, 69MHz, –1dBFS,

25Msps

LTC2256-14: Shorted Input

Histogram

LTC2256-14: 8k Point FFT,

fIN = 30MHz, –1dBFS, 25Msps

LTC2256-14: 8k Point FFT,

fIN = 70MHz, –1dBFS, 25Msps

LTC2256-14: 8k Point FFT,

fIN = 140MHz, –1dBFS, 25Msps

LTC2256-14: 8k Point FFT,

fIN = 5MHz, –1dBFS, 25Msps

FREQUENCY (MHz)

–100

–110

–120

–70

–60

–80

–90

AMPLITUDE (dBFS)

–50

–30

–40

–20

–10

510

225814 G43

FREQUENCY (MHz)

–100

–110

–120

–70

–60

–80

–90

AMPLITUDE (dBFS)

–50

–30

–40

–20

–10

510

225814 G44

FREQUENCY (MHz)

–100

–110

–120

–70

–60

–80

–90

AMPLITUDE (dBFS)

–50

–30

–40

–20

–10

510

225814 G45

FREQUENCY (MHz)

–100

–110

–120

–70

–60

–80

–90

AMPLITUDE (dBFS)

–50

–30

–40

–20

–10

510

225814 G46

FREQUENCY (MHz)

–100

–110

–120

–70

–60

–80

–90

AMPLITUDE (dBFS)

–50

–30

–40

–20

–10

510

225814 G47

OUTPUT CODE

8198

1000

3000

2000

COUNT

4000

5000

6000

8200 8202 8204 8206

225814 G48

LTC2258-14

LTC2257-14/LTC2256-14

225814fc

For more information www.linear.com/LTC2258-14For more information www.linear.com/LTC2258-14

Typical perForMance characTerisTics

LTC2256-14: SFDR vs Input Level,

fIN = 70MHz, 2V Range, 25Msps

INPUT LEVEL (dBFS)

–80

SFDR (dBc AND dBFS)

100

110

–70 –60 –50 –40 –30 –20 –10 0

225814 G52

dBFS

dBc

INPUT FREQUENCY (MHz)

SNR (dBFS)

50 100 150 200 250 300 350

225814 G49

INPUT FREQUENCY (MHz)

SFDR (dBFS)

50 100 150 200 250 300 350

225814 G50

LTC2256-14: SNR vs Input

Frequency, –1dB, 2V Range,

25Msps

LTC2256-14: SFDR vs Input

Frequency, –1dB, 2V Range,

25Msps

LTC2256-14: IVDD vs Sample Rate,

5MHz Sine Wave Input, –1dB

LTC2256-14: IOVDD vs Sample Rate,

5MHz Sine Wave Input, –1dB, 5pF

on Each Data Output

LTC2256-14: SNR vs SENSE,

fIN = 5MHz, –1dB

SAMPLE RATE (Msps)

IOVDD (mA)

10 20

225814 G54

1.75mA LVDS

1.8V CMOS 1.2V CMOS

3.5mA LVDS

SAMPLE RATE (Msps)

IVDD (mA)

10 20

225814 G53

LVDS OUTPUTS

CMOS OUTPUTS

SENSE PIN (V)

0.6

SNR (dBFS)

0.7 0.8 0.9 1.1 1.2 1.31

225814 G55

225814fc

LTC2258-14

LTC2257-14/LTC2256-14

For more information www.linear.com/LTC2258-14For more information www.linear.com/LTC2258-14

pin FuncTions

PINS THAT ARE THE SAME FOR ALL DIGITAL OUTPUT

MODES

AIN+ (Pin 1): Positive Differential Analog Input.

AIN– (Pin 2): Negative Differential Analog Input.

GND (Pin 3): ADC Power Ground.

REFH (Pins 4, 5): ADC High Reference. Bypass to Pins

6, 7 with a 2.2µF ceramic capacitor and to ground with a

0.1µF ceramic capacitor.

REFL (Pins 6, 7): ADC Low Reference. Bypass to Pins

4, 5 with a 2.2µF ceramic capacitor and to ground with a

0.1µF ceramic capacitor.

PAR/SER (Pin 8): Programming Mode Selection Pin. Con-

nect to ground to enable the serial programming mode.

CS, SCK, SDI, SDO become a serial interface that control

the A/D operating modes. Connect to VDD to enable the

parallel programming mode where CS, SCK, SDI become

parallel logic inputs that control a reduced set of the A/D

operating modes. PAR/SER should be connected directly

to ground or the VDD of the part and not be driven by a

logic signal.

VDD (Pins 9, 10, 40): 1.8V Analog Power Supply. Bypass

to ground with 0.1µF ceramic capacitors. Pins 9 and 10

can share a bypass capacitor.

ENC+ (Pin 11): Encode Input. Conversion starts on the

rising edge.

ENC– (Pin 12): Encode Complement Input. Conversion

starts on the falling edge.

CS (Pin 13): In serial programming mode, (PAR/SER =

0V), CS is the serial interface chip select input. When

CS is low, SCK is enabled for shifting data on SDI into

the mode control registers. In the parallel programming

mode (PAR/SER = VDD), CS controls the clock duty cycle

stabilizer. When CS is low, the clock duty cycle stabilizer is

turned off. When CS is high, the clock duty cycle stabilizer

is turned on. CS can be driven with 1.8V to 3.3V logic.

SCK (Pin 14): In serial programming mode, (PAR/SER

= 0V), SCK is the serial interface clock input. In the

parallel programming mode (PAR/SER = VDD), SCK

controls the digital output mode. When SCK is low,

the full-rate CMOS output mode is enabled. When SCK

is high, the double data rate LVDS output mode (with

3.5mA output current) is enabled. SCK can be driven

with 1.8V to 3.3V logic.

SDI (Pin 15): In serial programming mode, (PAR/SER =

0V), SDI is the serial interface data input. Data on SDI is

clocked into the mode control registers on the rising edge

of SCK. In the parallel programming mode (PAR/SER =

VDD), SDI can be used to power down the part. When SDI

is low, the part operates normally. When SDI is high, the

part enters sleep mode. SDI can be driven with 1.8V to

3.3V logic.

SDO (Pin 16): In serial programming mode, (PAR/SER

= 0V), SDO is the optional serial interface data output.

Data on SDO is read back from the mode control registers

and can be latched on the falling edge of SCK. SDO is an

open-drain NMOS output that requires an external 2k

pull-up resistor to 1.8V-3.3V. If read back from the mode

control registers is not needed, the pull-up resistor is not

necessary and SDO can be left unconnected. In the parallel

programming mode (PAR/SER = VDD), SDO is not used

and should not be connected.

OGND (Pin 25): Output Driver Ground.

OVDD (Pin 26): Output Driver Supply. Bypass to ground

with a 0.1µF ceramic capacitor.

VCM (Pin 37): Common Mode Bias Output, Nominally

Equal to VDD/2. VCM should be used to bias the common

mode of the analog inputs. Bypass to ground with a 0.1µF

ceramic capacitor.

VREF (Pin 38): Reference Voltage Output, Nominally 1.25V.

Bypass to ground with a 1µF ceramic capacitor.

SENSE (Pin 39): Reference Programming Pin. Connecting

SENSE to VDD selects the internal reference and a ±1V input

range. Connecting SENSE to ground selects the internal

reference and a ±0.5V input range. An external reference

between 0.625V and 1.3V applied to SENSE selects an

input range of ±0.8 • VSENSE.

LTC2258-14

LTC2257-14/LTC2256-14

225814fc

For more information www.linear.com/LTC2258-14For more information www.linear.com/LTC2258-14

pin FuncTions

FULL-RATE CMOS OUTPUT MODE

All Pins Below Have CMOS Output Levels (OGND to

OVDD)

D0 to D13 (Pins 17-24, 29-34): Digital Outputs. D13 is

the MSB.

CLKOUT– (Pin 27): Inverted version of CLKOUT+.

CLKOUT+ (Pin 28): Data Output Clock. The digital outputs

normally transition at the same time as the falling edge

of CLKOUT+. The phase of CLKOUT+ can also be delayed

relative to the digital outputs by programming the mode

control registers.

DNC (Pin 35): Do not connect this pin.

OF (Pin 36): Over/Under Flow Digital Output. OF is high

when an overflow or underflow has occurred.

DOUBLE DATA RATE CMOS OUTPUT MODE

All Pins Below Have CMOS Output Levels (OGND to

OVDD)

D0_1 to D12_13 (Pins 18, 20, 22, 24, 30, 32, 34): Double

Data Rate Digital Outputs. Tw o data bits are multiplexed onto

each output pin. The even data bits (D0, D2, D4, D6, D8, D10,

D12) appear when CLKOUT+ is low. The odd data bits (D1,

D3, D5, D7, D9, D11, D13) appear when CLKOUT+ is high.

CLKOUT– (Pin 27): Inverted version of CLKOUT+.

CLKOUT+ (Pin 28): Data Output Clock. The digital outputs

normally transition at the same time as the falling and ris-

ing edges of CLKOUT+. The phase of CLKOUT+ can also

be delayed relative to the digital outputs by programming

the mode control registers.

DNC (Pins 17, 19, 21, 23, 29, 31, 33, 35): Do not con-

nect these pins.

OF (Pin 36): Over/Under Flow Digital Output. OF is high

when an overflow or underflow has occurred.

DOUBLE DATA RATE LVDS OUTPUT MODE

All Pins Below Have LVDS Output Levels. The Output

Current Level is Programmable. There is an Optional

Internal 100Ω Termination Resistor Between the Pins

of Each LVDS Output Pair.

D0_1–/D0_1+ to D12_13–/D12_13+ (Pins 17/18, 19/20,

21/22, 23/24, 29/30, 31/32, 33/34): Double Data Rate

Digital Outputs. Tw o data bits are multiplexed onto each

differential output pair. The even data bits (D0, D2, D4,

D6, D8, D10, D12) appear when CLKOUT+ is low. The odd

data bits (D1, D3, D5, D7, D9, D11, D13) appear when

CLKOUT+ is high.

CLKOUT–/CLKOUT+ (Pins 27/28): Data Output Clock.

The digital outputs normally transition at the same time

as the falling and rising edges of CLKOUT+. The phase of

CLKOUT+ can also be delayed relative to the digital outputs

by programming the mode control registers.

OF–/OF+ (Pins 35/36): Over/Under Flow Digital Output.

OF+ is high when an overflow or underflow has occurred.

225814fc

LTC2258-14

LTC2257-14/LTC2256-14

For more information www.linear.com/LTC2258-14For more information www.linear.com/LTC2258-14

FuncTional block DiagraM

Figure 1. Functional Block Diagram

DIFF

REF

AMP

REF

BUF

2.2µF

0.1µF 0.1µF

0.1µF

INTERNAL CLOCK SIGNALSREFH

REFH

REFL

CLOCK/DUTY

CYCLE

CONTROL

RANGE

SELECT

1.25V

REFERENCE

FIRST PIPELINED

ADC STAGE

FIFTH PIPELINED

ADC STAGE

FOURTH PIPELINED

ADC STAGE

SECOND PIPELINED

ADC STAGE

ENC+ENC–

SHIFT REGISTER

AND CORRECTION

SDOCS

OGND

OVDD

D13

CLKOUT–

CLKOUT+

225814 F01

INPUT

S/H

SENSE

VREF

AIN–

AIN+

1µF

VCM

0.1µF

VDD/2

THIRD PIPELINED

ADC STAGE

OUTPUT

DRIVERS

MODE

CONTROL

REGISTERS

SCKPAR/SER SDI

•

VDD

GND

LTC2258-14

LTC2257-14/LTC2256-14

225814fc

For more information www.linear.com/LTC2258-14For more information www.linear.com/LTC2258-14

CONVERTER OPERATION

The LTC2258-14/LTC2257-14/LTC2256-14 are low power

14-bit 65Msps/40Msps/25Msps A/D converters that are

be driven differentially. The encode input can be driven

differentially, or single ended for lower power consump-

tion. The digital outputs can be CMOS, double data rate

CMOS (to halve the number of output lines), or double

data rate LVDS (to reduce digital noise in the system.)

Many additional features can be chosen by programming

the mode control registers through a serial SPI port. See

the Serial Programming Mode section.

ANALOG INPUT

The analog input is a differential CMOS sample-and-hold

circuit (Figure 2). The inputs should be driven differentially

around a common mode voltage set by the VCM output

pin, which is nominally VDD/2. For the 2V input range,

the inputs should swing from VCM – 0.5V to VCM + 0.5V.

There should be 180° phase difference between the inputs.

CSAMPLE

3.5pF

RON

25Ω

RON

25Ω

VDD

LTC2258-14

AIN+

225814 F02

CSAMPLE

3.5pF

VDD

AIN–

ENC–

ENC+

1.2V

10k

1.2V

10k

CPARASITIC

1.8pF

CPARASITIC

1.8pF

10Ω

10Ω

Figure 2. Equivalent Input Circuit

applicaTions inForMaTion

225814fc

LTC2258-14

LTC2257-14/LTC2256-14

For more information www.linear.com/LTC2258-14For more information www.linear.com/LTC2258-14

applicaTions inForMaTion

Figure 5. Recommended Front-End Circuit for Input

Frequencies from 170MHz to 270MHz

Figure 6. Recommended Front-End Circuit for Input

Frequencies Above 270MHz

INPUT DRIVE CIRCUITS

Input filtering

If possible, there should be an RC lowpass filter right at

the analog inputs. This lowpass filter isolates the drive

circuitry from the A/D sample-and-hold switching, and

also limits wideband noise from the drive circuitry. Figure 3

shows an example of an input RC filter. The RC component

values should be chosen based on the application’s input

frequency.

Figure 4. Recommended Front-End Circuit for Input

Frequencies from 70MHz to 170MHz

Transformer Coupled Circuits

Figure 3 shows the analog input being driven by an RF

transformer with a center-tapped secondary. The center

tap is biased with VCM, setting the A/D input at its optimal

DC level. At higher input frequencies a transmission line

balun transformer (Figures 4 to 6) has better balance,

resulting in lower A/D distortion.

25Ω

50Ω

0.1µF

AIN+

AIN–

4.7pF

0.1µF

VCM

ANALOG

INPUT

0.1µF

T1: MA/COM MABA-007159-000000

T2: MA/COM MABAES0060

RESISTORS, CAPACITORS ARE 0402 PACKAGE SIZE

225814 F04

LTC2258-14

25Ω

50Ω

0.1µF

AIN+

AIN–

1.8pF

0.1µF

VCM

ANALOG

INPUT

0.1µF

T1: MA/COM MABA-007159-000000

T2: COILCRAFT WBC1-1LB

RESISTORS, CAPACITORS ARE 0402 PACKAGE SIZE

225814 F05

LTC2258-14

25Ω

50Ω

0.1µF

2.7nH

AIN+

AIN–

0.1µF

VCM

ANALOG

INPUT

0.1µF

T1: MA/COM ETC1-1-13

RESISTORS, CAPACITORS

ARE 0402 PACKAGE SIZE

225814 F06

LTC2258-14

25Ω

25Ω 25Ω

25Ω

50Ω

0.1µF

AIN+

AIN–

12pF

0.1µF

VCM

LTC2258-14

ANALOG

INPUT

0.1µF T1

1:1

T1: MA/COM MABAES0060

RESISTORS, CAPACITORS

ARE 0402 PACKAGE SIZE

225814 F03

Figure 3. Analog Input Circuit Using a Transformer.

Recommended for Input Frequencies from 5MHz to 70MHz

LTC2258-14

LTC2257-14/LTC2256-14

225814fc

For more information www.linear.com/LTC2258-14For more information www.linear.com/LTC2258-14

applicaTions inForMaTion

25Ω

200Ω

0.1µF AIN+

AIN–

12pF

0.1µF

VCM

LTC2258-14

225814 F07

––

ANALOG

INPUT

HIGH SPEED

DIFFERENTIAL

AMPLIFIER

0.1µF

Figure 7. Front-End Circuit Using a High Speed

Differential Amplifier

Amplifier Circuits

Figure 7 shows the analog input being driven by a high

speed differential amplifier. The output of the amplifier is

AC coupled to the A/D so the amplifier’s output common

mode voltage can be optimally set to minimize distortion.

At very high frequencies an RF gain block will often have

lower distortion than a differential amplifier. If the gain

block is single-ended, then a transformer circuit (Figures 4

to 6) should convert the signal to differential before driv-

ing the A/D.

Reference

The LTC2258-14/2257-14/2256-14 has an internal 1.25V

voltage reference. For a 2V input range using the internal

reference, connect SENSE to VDD. For a 1V input range

using the internal reference, connect SENSE to ground.

For a 2V input range with an external reference, apply a

1.25V reference voltage to SENSE (Figure 9.)

The input range can be adjusted by applying a voltage to

SENSE that is between 0.625V and 1.30V. The input range

will then be 1.6 • VSENSE.

The VREF

, REFH and REFL pins should be bypassed as

shown in Figure 8. The 0.1µF capacitor between REFH

and REFL should be as close to the pins as possible (not

on the back side of the circuit board).

VREF

REFH

SENSE

TIE TO VDD FOR 2V RANGE;

TIE TO GND FOR 1V RANGE;

RANGE = 1.6 • VSENSE FOR

0.65V < VSENSE < 1.300V

1.25V

REFL

0.1µF2.2µF

INTERNAL ADC

HIGH REFERENCE

BUFFER

5Ω

0.8x

DIFF AMP

INTERNAL ADC

LOW REFERENCE

1.25V BANDGAP

REFERENCE

0.625V

RANGE

DETECT

AND

CONTROL

1µF

0.1µF

225814 F08

LTC2258-14

Figure 8. Reference Circuit

SENSE

1.25V

EXTERNAL

REFERENCE

1µF

VREF

225814 F09

LTC2258-14

Figure 9. Using an External 1.25V Reference

225814fc

LTC2258-14

LTC2257-14/LTC2256-14

For more information www.linear.com/LTC2258-14For more information www.linear.com/LTC2258-14

applicaTions inForMaTion

Encode Input

The signal quality of the encode inputs strongly affects

the A/D noise performance. The encode inputs should

be treated as analog signals—do not route them next to

digital traces on the circuit board. There are two modes

of operation for the encode inputs: the differential encode

mode (Figure 10) and the single-ended encode mode

(Figure 11).

The differential encode mode is recommended for sinu-

soidal, PECL or LVDS encode inputs (Figures 12, 13). The

encode inputs are internally biased to 1.2V through 10k

equivalent resistance. The encode inputs can be taken

above VDD (up to 3.6V), and the common mode range

is from 1.1V to 1.6V. In the differential encode mode,

ENC– should stay at least 200mV above ground to avoid

falsely triggering the single-ended encode mode. For good

jitter performance ENC+ and ENC– should have fast rise

and fall times.

The single-ended encode mode should be used with CMOS

encode inputs. To select this mode, ENC– is connected

to ground and ENC+ is driven with a square wave encode

input. ENC+ can be taken above VDD (up to 3.6V) so 1.8V

to 3.3V CMOS logic levels can be used. The ENC+ threshold

is 0.9V. For good jitter performance ENC+ should have fast

rise and fall times.

Clock Duty Cycle Stabilizer

For good performance the encode signal should have a

50%(±5%) duty cycle. If the optional clock duty cycle

stabilizer circuit is enabled, the encode duty cycle can

vary from 30% to 70% and the duty cycle stabilizer will

maintain a constant 50% internal duty cycle. If the encode

signal changes frequency or is turned off, the duty cycle

stabilizer circuit requires one hundred clock cycles to lock

onto the input clock. The duty cycle stabilizer is enabled

VDD

LTC2258-14

225814 F10

ENC–

ENC+

15k

VDD

DIFFERENTIAL

COMPARATOR

30k

Figure 10. Equivalent Encode Input Circuit

for Differential Encode Mode

30k

ENC+

ENC–

225814 F11

1.8V TO 3.3V

LTC2258-14

CMOS LOGIC

BUFFER

Figure 11. Equivalent Encode Input Circuit

for Single-Ended Encode Mode

100Ω

25Ω

ENC+

ENC–

0.1µF

T1: COILCRAFT WBC4 - 1WL

D1: AVAGO HSMS - 2822

RESISTORS, CAPACITORS ARE 0402 PACKAGE SIZE

225814 F12

LTC2258-14

1:4

Figure 12. Sinusoidal Encode Drive

ENC+

ENC–

PECL OR

LVDS

CLOCK

0.1µF

225814 F13

LTC2258-14

Figure 13. PECL or LVDS Encode Drive

LTC2258-14

LTC2257-14/LTC2256-14

225814fc

For more information www.linear.com/LTC2258-14For more information www.linear.com/LTC2258-14

applicaTions inForMaTion

by mode control register A2 (serial programming mode),

or by CS (parallel programming mode).

For applications where the sample rate needs to be changed

quickly, the clock duty cycle stabilizer can be disabled. If

the duty cycle stabilizer is disabled, care should be taken

to make the sampling clock have a 50%(±5%) duty cycle.

The duty cycle stabilizer should not be used below 5Msps.

DIGITAL OUTPUTS

Digital Output Modes

The LTC2258-14/LTC2257-14/LTC2256-14 can operate in

three digital output modes: full rate CMOS, double data

rate CMOS (to halve the number of output lines), or double

data rate LVDS (to reduce digital noise in the system). The

output mode is set by mode control register A3 (serial

programming mode), or by SCK (parallel programming

mode). Note that double data rate CMOS cannot be selected

in the parallel programming mode.

Full-Rate CMOS Mode

In full-rate CMOS mode the 14 digital outputs (D0-D13),

overflow (OF), and the data output clocks (CLKOUT+,

CLKOUT–) have CMOS output levels. The outputs are

A/D core power and ground. OVDD can range from 1.1V

to 1.9V, allowing 1.2V through 1.8V CMOS logic outputs.

For good performance, the digital outputs should drive

minimal capacitive loads. If the load capacitance is larger

than 10pF a digital buffer should be used.

Double Data Rate CMOS Mode

In double data rate CMOS mode, two data bits are

multiplexed and output on each data pin. This reduces the

number of data lines by seven, simplifying board routing

and reducing the number of input pins needed to receive

the data. The 7 digital outputs (D0_1, D2_3, D4_5, D6_7,

D8_9, D10_11, D12_13), overflow (OF), and the data

output clocks (CLKOUT+, CLKOUT–) have CMOS output

levels. The outputs are powered by OVDD and OGND which

are isolated from the A/D core power and ground. OVDD

can range from 1.1V to 1.9V, allowing 1.2V through 1.8V

CMOS logic outputs.

For good performance the digital outputs should drive

minimal capacitive loads. If the load capacitance is larger

than 10pF a digital buffer should be used.

Double Data Rate LVDS Mode

In double data rate LVDS mode, two data bits are

multiplexed and output on each differential output pair.

There are 7 LVDS output pairs (D0_1+/D0_1– through

D12_13+/D12_13–) for the digital output data. Overflow

(OF+/OF–) and the data output clock (CLKOUT+/CLKOUT–)

each have an LVDS output pair.

By default the outputs are standard LVDS levels: 3.5mA

output current and a 1.25V output common mode volt-

age. An external 100Ω differential termination resistor

is required for each LVDS output pair. The termination

resistors should be located as close as possible to the

LVDS receiver.

The outputs are powered by OVDD and OGND which are

isolated from the A/D core power and ground. In LVDS

mode, OVDD must be 1.8V.

Programmable LVDS Output Current

In LVDS mode, the default output driver current is 3.5mA.

This current can be adjusted by serially programming mode

control register A3. Available current levels are 1.75mA,

2.1mA, 2.5mA, 3mA, 3.5mA, 4mA and 4.5mA.

Optional LVDS Driver Internal Termination

In most cases using just an external 100Ω termination

resistor will give excellent LVDS signal integrity. In addi-

tion, an optional internal 100Ω termination resistor can

be enabled by serially programming mode control register

A3. The internal termination helps absorb any reflections

caused by imperfect termination at the receiver. When the

internal termination is enabled, the output driver current

is increased by 1.6x to maintain about the same output

voltage swing.

Overflow Bit

The overflow output bit (OF) outputs a logic high when

the analog input is either overranged or underranged. The

overflow bit has the same pipeline latency as the data bits.

225814fc

LTC2258-14

LTC2257-14/LTC2256-14

For more information www.linear.com/LTC2258-14For more information www.linear.com/LTC2258-14

Phase Shifting the Output Clock

In full-rate CMOS mode the data output bits normally

change at the same time as the falling edge of CLKOUT+,

so the rising edge of CLKOUT+ can be used to latch the

output data. In double data rate CMOS and LVDS modes

the data output bits normally change at the same time as

the falling and rising edges of CLKOUT+. To allow adequate

setup-and-hold time when latching the data, the CLKOUT+

signal may need to be phase shifted relative to the data

output bits. Most FPGAs have this feature; this is generally

the best place to adjust the timing.

The LTC2258-14/LTC2257-14/LTC2256-14 can also phase

shift the CLKOUT+/CLKOUT– signals by serially program-

ming mode control register A2. The output clock can be

shifted by 0°, 45°, 90° or 135°. To use the phase shifting

feature the clock duty cycle stabilizer must be turned

on. Another control register bit can invert the polarity of

CLKOUT+ and CLKOUT–, independently of the phase shift.

The combination of these two features enables phase shifts

of 45° up to 315° (Figure 14).

DATA FORMAT

Table 1 shows the relationship between the analog input

voltage, the digital data output bits and the overflow bit.

By default the output data format is offset binary. The 2’s

complement format can be selected by serially program-

ming mode control register A4.

Table 1. Output Codes vs Input Voltage

AIN+ – AIN–

(2V Range)

D13-D0

(OFFSET BINARY)

D13-D0

(2’s COMPLEMENT)

>1.000000V

+0.999878V

+0.999756V

11 1111 1111 1111

11 1111 1111 1110

01 1111 1111 1111

01 1111 1111 1110

+0.000122V

+0.000000V

–0.000122V

–0.000244V

10 0000 0000 0001

10 0000 0000 0000

01 1111 1111 1111

01 1111 1111 1110

00 0000 0000 0001

00 0000 0000 0000

11 1111 1111 1111

11 1111 1111 1110

–0.999878V

–1.000000V

≤–1.000000V

00 0000 0000 0001

00 0000 0000 0000

10 0000 0000 0001

10 0000 0000 0000

applicaTions inForMaTion

CLKOUT+

D0-D13, OF

PHASE

SHIFT

0°

45°

90°

135°

180°

225°

270°

315°

CLKINV

CLKPHASE1

MODE CONTROL BITS

CLKPHASE0

225814 F14

ENC+

Figure 14. Phase Shifting CLKOUT

LTC2258-14

LTC2257-14/LTC2256-14

225814fc

For more information www.linear.com/LTC2258-14For more information www.linear.com/LTC2258-14

Digital Output Randomizer

Interference from the A/D digital outputs is sometimes

unavoidable. Digital interference may be from capacitive or

inductive coupling or coupling through the ground plane.

Even a tiny coupling factor can cause unwanted tones

in the ADC output spectrum. By randomizing the digital

output before it is transmitted off chip, these unwanted

tones can be randomized which reduces the unwanted

tone amplitude.

The digital output is “randomized” by applying an

exclusive-OR logic operation between the LSB and all

other data output bits. To decode, the reverse opera-

tion is applied—an exclusive-OR operation is applied

between the LSB and all other bits. The LSB, OF and

CLKOUT outputs are not affected. The output random-

izer is enabled by serially programming mode control

Alternate Bit Polarity

Another feature that reduces digital feedback on the circuit

board is the alternate bit polarity mode. When this mode

is enabled, all of the odd bits (D1, D3, D5, D7, D9, D11,

D13) are inverted before the output buffers. The even bits

(D0, D2, D4, D6, D8, D10, D12), OF and CLKOUT are not

affected. This can reduce digital currents in the circuit

board ground plane and reduce digital noise, particularly

for very small analog input signals.

When there is a very small signal at the input of the A/D

that is centered around mid-scale, the digital outputs toggle

between mostly 1s and mostly 0s. This simultaneous

switching of most of the bits will cause large currents in the

ground plane. By inverting every other bit, the alternate bit

polarity mode makes half of the bits transition high while

half of the bits transition low. To first order, this cancels

current flow in the ground plane, reducing the digital noise.

applicaTions inForMaTion

CLKOUT CLKOUT

D13/D0

D12/D0

•

D2/D0

D1/D0

225814 F15

D13

D12

RANDOMIZER

D13

FPGA

PC BOARD

D12

•

225814 F16

D1/D0

D2/D0

D12/D0

D13/D0

CLKOUT

LTC2258-14

Figure 15. Functional Equivalent of Digital Output Randomizer Figure 16. Unrandomizing a Randomized Digital

Output Signal

225814fc

LTC2258-14

LTC2257-14/LTC2256-14

For more information www.linear.com/LTC2258-14For more information www.linear.com/LTC2258-14

The digital output is decoded at the receiver by invert-

ing the odd bits (D1, D3, D5, D7, D9, D11, D13.) The

alternate bit polarity mode is independent of the digital

output randomizer—either, both or neither function

can be on at the same time. When alternate bit polarity

mode is on, the data format is offset binary and the 2’s

complement control bit has no effect. The alternate bit

polarity mode is enabled by serially programming mode

control register A4.

Digital Output Test Patterns

To allow in-circuit testing of the digital interface to the

A/D, there are several test modes that force the A/D data

outputs (OF, D13-D0) to known values:

All 1s: All outputs are 1

All 0s: All outputs are 0

Alternating: Outputs change from all 1s to all 0s on

alternating samples

Checkerboard: Outputs change from 101010101010101

to 010101010101010 on alternating samples

The digital output test patterns are enabled by serially

programming mode control register A4. When enabled,

the test patterns override all other formatting modes: 2’s

complement, randomizer, alternate-bit-polarity.

Output Disable

The digital outputs may be disabled by serially program-

ming mode control register A3. All digital outputs including

OF and CLKOUT are disabled. The high impedance disabled

state is intended for long periods of inactivity—it is too

slow to multiplex a data bus between multiple converters

at full speed.

Sleep and Nap Modes

The A/D may be placed in sleep or nap modes to conserve

power. In sleep mode the entire A/D converter is powered

down, resulting in 0.5mW power consumption. Sleep mode

is enabled by mode control register A1 (serial program-

ming mode), or by SDI (parallel programming mode).

The amount of time required to recover from sleep mode

depends on the size of the bypass capacitors on VREF

REFH, and REFL. For the suggested values in Figure 8,

the A/D will stabilize after 2ms.

In nap mode the A/D core is powered down while the

internal reference circuits stay active, allowing faster

wake-up than from sleep mode. Recovering from nap

mode requires at least 100 clock cycles. If the applica-

tion demands very accurate DC settling then an additional

50µs should be allowed so the on-chip references can

settle from the slight temperature shift caused by the

change in supply current as the A/D leaves nap mode.

Nap mode is enabled by mode control register A1 in the

serial programming mode.

DEVICE PROGRAMMING MODES

The operating modes of the LTC2258-14/LTC2257-14/

LTC2256-14 can be programmed by either a parallel

interface or a simple serial interface. The serial interface

has more flexibility and can program all available modes.

The parallel interface is more limited and can only program

some of the more commonly used modes.

Parallel Programming Mode

To use the parallel programming mode, PAR/SER should

be tied to VDD. The CS, SCK and SDI pins are binary logic

inputs that set certain operating modes. These pins can

be tied to VDD or ground, or driven by 1.8V, 2.5V or 3.3V

CMOS logic. Table 2 shows the modes set by CS, SCK

and SDI.

Table 2. Parallel Programming Mode Control Bits (PAR/SER = VDD)

PIN DESCRIPTION

CS Clock Duty Cycle Stabilizer Control Bit

0 = Clock Duty Cycle Stabilizer Off

1 = Clock Duty Cycle Stabilizer On

SCK Digital Output Mode Control Bit

0 = Full-Rate CMOS Output Mode

1 = Double Data Rate LVDS Output Mode

(3.5mA LVDS Current, Internal Termination Off)

SDI Power Down Control Bit

0 = Normal Operation

1 = Sleep Mode

applicaTions inForMaTion

LTC2258-14

LTC2257-14/LTC2256-14

225814fc

For more information www.linear.com/LTC2258-14For more information www.linear.com/LTC2258-14

applicaTions inForMaTion

Serial Programming Mode

To use the serial programming mode, PAR/SER should be

tied to ground. The CS, SCK, SDI and SDO pins become a

serial interface that program the A/D mode control registers.

Data is written to a register with a 16-bit serial word. Data

can also be read back from a register to verify its contents.

Serial data transfer starts when CS is taken low. The data

on the SDI pin is latched at the first 16 rising edges of

SCK. Any SCK rising edges after the first 16 are ignored.

The data transfer ends when CS is taken high again.

The first bit of the 16-bit input word is the R/W bit. The

next seven bits are the address of the register (A6:A0).

The final eight bits are the register data (D7:D0).

If the R/W bit is low, the serial data (D7:D0) will be writ-

ten to the register set by the address bits (A6:A0). If the

R/W bit is high, data in the register set by the address bits

(A6:A0) will be read back on the SDO pin (see the timing

diagrams). During a read back command the register is

not updated and data on SDI is ignored.

The SDO pin is an open-drain output that pulls to ground

with a 200Ω impedance. If register data is read back

through SDO, an external 2k pull-up resistor is required. If

serial data is only written and read back is not needed, then

SDO can be left floating and no pull-up resistor is needed.

Table 3 shows a map of the mode control registers.

Software Reset

If serial programming is used, the mode control registers

should be programmed as soon as possible after the power

supplies turn on and are stable. The first serial command

must be a software reset which will reset all register data

bits to logic 0. To perform a software reset, bit D7 in the

reset register is written with a logic 1. After the reset SPI

write command is complete, bit D7 is automatically set

back to zero.

Table 3. Serial Programming Mode Register Map

D7 D6 D5 D4 D3 D2 D1 D0

RESET X X X X X X X

Bit 7 RESET Software Reset Bit

0 = Not Used

1 = Software Reset. All Mode Control Registers are Reset to 00h. This Bit is Automatically Set Back to Zero at the end of the SPI

Write Command.

The Reset Register is Write Only.

Bits 6-0 Unused, Don’t Care Bits.

D7 D6 D5 D4 D3 D2 D1 D0

X X X X X X PWROFF1 PWROFF0

Bits 7-2 Unused, Don’t Care Bits.

Bits 1-0 PWROFF1:PWROFF0 Power Down Control Bits

00 = Normal Operation

01 = Nap Mode

10 = Not Used

11 = Sleep Mode

225814fc

LTC2258-14

LTC2257-14/LTC2256-14

For more information www.linear.com/LTC2258-14For more information www.linear.com/LTC2258-14

D7 D6 D5 D4 D3 D2 D1 D0

X X X X CLKINV CLKPHASE1 CLKPHASE0 DCS

Bits 7-4 Unused, Don’t Care Bits.

Bit 3 CLKINV Output Clock Invert Bit

0 = Normal CLKOUT Polarity (As Shown in the Timing Diagrams)

1 = Inverted CLKOUT Polarity

Bits 2-1 CLKPHASE1:CLKPHASE0 Output Clock Phase Delay Bits

00 = No CLKOUT Delay (As Shown in the Timing Diagrams)

01 = CLKOUT+/CLKOUT– Delayed by 45° (Clock Period • 1/8)

10 = CLKOUT+/CLKOUT– Delayed by 90° (Clock Period • 1/4)

11 = CLKOUT+/CLKOUT– Delayed by 135° (Clock Period • 3/8)

Note: If the CLKOUT Phase Delay Feature is Used, the Clock Duty Cycle Stabilizer Must Also be Turned On

Bit 0 DCS Clock Duty Cycle Stabilizer Bit

0 = Clock Duty Cycle Stabilizer Off

1 = Clock Duty Cycle Stabilizer On

D7 D6 D5 D4 D3 D2 D1 D0

X ILVDS2 ILVDS1 ILVDS0 TERMON OUTOFF OUTMODE1 OUTMODE0

Bit 7 Unused, Don’t Care Bit.

Bits 6-4 ILVDS2:ILVDS0 LVDS Output Current Bits

000 = 3.5mA LVDS Output Driver Current

001 = 4.0mA LVDS Output Driver Current

010 = 4.5mA LVDS Output Driver Current

011 = Not Used

100 = 3.0mA LVDS Output Driver Current

101 = 2.5mA LVDS Output Driver Current

110 = 2.1mA LVDS Output Driver Current

111 = 1.75mA LVDS Output Driver Current

Bit 3 TERMON LVDS Internal Termination Bit

0 = Internal Termination Off

1 = Internal Termination On. LVDS Output Driver Current is 1.6× the Current Set by ILVDS2:ILVDS0

Bit 2 OUTOFF Output Disable Bit

0 = Digital Outputs are Enabled

1 = Digital Outputs are Disabled and Have High Output Impedance

Bits 1-0 OUTMODE1:OUTMODE0 Digital Output Mode Control Bits

00 = Full-Rate CMOS Output Mode

01 = Double Data Rate LVDS Output Mode

10 = Double Data Rate CMOS Output Mode

11 = Not Used

applicaTions inForMaTion

LTC2258-14

LTC2257-14/LTC2256-14

225814fc

For more information www.linear.com/LTC2258-14For more information www.linear.com/LTC2258-14

applicaTions inForMaTion

D7 D6 D5 D4 D3 D2 D1 D0

X X OUTTEST2 OUTTEST1 OUTTEST0 ABP RAND TWOSCOMP

Bit 7-6 Unused, Don’t Care Bits.

Bits 5-3 OUTTEST2:OUTTEST0 Digital Output Test Pattern Bits

000 = Digital Output Test Patterns Off

001 = All Digital Outputs = 0

011 = All Digital Outputs = 1

101 = Checkerboard Output Pattern. OF, D13-D0 Alternate Between 101 0101 0101 0101 and 010 1010 1010 1010

111 = Alternating Output Pattern. OF, D13-D0 Alternate Between 000 0000 0000 0000 and 111 1111 1111 1111

Note: Other Bit Combinations are not Used

Bit 2 ABP Alternate Bit Polarity Mode Control Bit

0 = Alternate Bit Polarity Mode Off

1 = Alternate Bit Polarity Mode On

Bit 1 RAND Data Output Randomizer Mode Control Bit

0 = Data Output Randomizer Mode Off

1 = Data Output Randomizer Mode On

Bit 0 TWOSCOMP Tw o ’s Complement Mode Control Bit

0 = Offset Binary Data Format

1 = Tw o ’s Complement Data Format

Note: ABP = 1 Forces the Output Format to be Offset Binary

GROUNDING AND BYPASSING

The LTC2258-14/LTC2257-14/LTC2256-14 requires a

printed circuit board with a clean unbroken ground plane.

A multilayer board with an internal ground plane is rec-

ommended. Layout for the printed circuit board should

ensure that digital and analog signal lines are separated as

much as possible. In particular, care should be taken not

to run any digital track alongside an analog signal track

or underneath the ADC.

High quality ceramic bypass capacitors should be used at

the VDD, OVDD, VCM, VREF, REFH and REFL pins. Bypass

capacitors must be located as close to the pins as possible.

Of particular importance is the 0.1µF capacitor between

REFH and REFL. This capacitor should be on the same

side of the circuit board as the A/D, and as close to the

device as possible (1.5mm or less). Size 0402 ceramic

capacitors are recommended. The larger 2.2µF capacitor

between REFH and REFL can be somewhat further away.

The VCM capacitor should be located as close to the pin

as possible. To make space for this the capacitor on VREF

can be further away or on the back of the PC board. The

traces connecting the pins and bypass capacitors must

be kept short and should be made as wide as possible.

The analog inputs, encode signals, and digital outputs

should not be routed next to each other. Ground fill and

grounded vias should be used as barriers to isolate these

signals from each other.

HEAT TRANSFER

Most of the heat generated by the ADC is transferred from

the die through the bottom-side exposed pad and package

leads onto the printed circuit board. For good electrical and

thermal performance, the exposed pad must be soldered

to a large grounded pad on the PC board.

225814fc

LTC2258-14

LTC2257-14/LTC2256-14

For more information www.linear.com/LTC2258-14For more information www.linear.com/LTC2258-14

Typical applicaTions

AIN+

AIN–

GND

REFH

REFL

PAR/SER

VDD

CLKOUT+

CLKOUT–

OVDD

OGND

R13

100Ω

ENCODE CLOCK

SPI BUS

225814 TA02

C20

2.2µF

C15

0.1µF

PAR/SER

R27 10Ω

R16

100Ω

R28 10Ω

C21

0.1µF

GND ENC+ENC–CS SCK SDI SDO D0 D1 D2 D3

20191817161514131211

31323334353637383940

VDD SENSE VREF VCM OF+OF–D13 D12 D11 D10

0VDD

C37

0.1µF

LTC2258CUJ

C23

1µF

SENSE

C17

1µF

C13

1µF

C51

4.7pF

R14

R39

33.2Ω

R40

33.2Ω

C12

0.1µF

R15 100Ω

R10 10Ω

R9 10Ω

ANALOG INPUT

MABAES0060

• •

C19

0.1µF

DIGITAL

OUTPUTS

DIGITAL

OUTPUTS

VDD

C18

0.1µF

VDD

LTC2258 Schematic

LTC2258-14

LTC2257-14/LTC2256-14

225814fc

For more information www.linear.com/LTC2258-14For more information www.linear.com/LTC2258-14

Typical applicaTions

Silkscreen Top Top Side

Inner Layer 2 GND Inner Layer 3

225814 TA04

225814 TA04 225814 TA06

225814 TA03

225814fc

LTC2258-14

LTC2257-14/LTC2256-14

For more information www.linear.com/LTC2258-14For more information www.linear.com/LTC2258-14

Typical applicaTions

Inner Layer 4 Inner Layer 5 Power

Bottom Side

225814 TA07 225814 TA08

225814 TA09

LTC2258-14

LTC2257-14/LTC2256-14

225814fc

For more information www.linear.com/LTC2258-14For more information www.linear.com/LTC2258-14

package DescripTion

UJ Package

40-Lead Plastic QFN (6mm × 6mm)

(Reference LTC DWG # 05-08-1728 Rev Ø)

6.00 ± 0.10

(4 SIDES)

NOTE:

1. DRAWING IS A JEDEC PACKAGE OUTLINE VARIATION OF (WJJD-2)

2. DRAWING NOT TO SCALE

3. ALL DIMENSIONS ARE IN MILLIMETERS

4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE

MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.20mm ON ANY SIDE, IF PRESENT

5. EXPOSED PAD SHALL BE SOLDER PLATED

6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE TOP AND BOTTOM OF PACKAGE

PIN 1 TOP MARK

(SEE NOTE 6)

PIN 1 NOTCH

R = 0.45 OR

0.35 × 45°

CHAMFER

0.40 ± 0.10

4039

BOTTOM VIEW—EXPOSED PAD

4.50 REF

(4-SIDES)

4.42 ±0.10

4.42 ±0.05

0.75 ± 0.05 R = 0.115

TYP

0.25 ± 0.05

0.50 BSC

0.200 REF

0.00 – 0.05

(UJ40) QFN REV Ø 0406

RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS

APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED

0.70 ±0.05

4.50 ±0.05

(4 SIDES)

5.10 ±0.05

6.50 ±0.05

0.25 ±0.05

0.50 BSC

PACKAGE OUTLINE

R = 0.10

TYP

Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings.

225814fc

LTC2258-14

LTC2257-14/LTC2256-14

For more information www.linear.com/LTC2258-14For more information www.linear.com/LTC2258-14

Information furnished by Linear Technology Corporation is believed to be accurate and reliable.

However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa-

tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.

revision hisTory

REV DATE DESCRIPTION PAGE NUMBER

B 08/12 Corrected IOVDD to IOVDD 11, 12, 14

Corrected RESET REGISTER A0, D7 description 26

Attached VDD to pins 9, 10 and 40 on schematic 29

C 1/14 Corrected "external reference” to "internal reference” for 1V input range. 20

(Revision history begins at Rev B)

LTC2258-14

LTC2257-14/LTC2256-14

225814fc

For more information www.linear.com/LTC2258-14For more information www.linear.com/LTC2258-14

Linear Technology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

(408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com

LT 0114 REV C • PRINTED IN USA

relaTeD parTs

PART NUMBER DESCRIPTION COMMENTS

LT1993-2 High Speed Differential Op Amp 800MHz BW, 70dBc Distortion at 70MHz, 6dB Gain

LT1994 Low Noise, Low Distortion Fully Differential Input/

Output Amplifier/Driver

Low Distortion: –94dBc at 1MHz

LTC2202 16-Bit, 10Msps, 3.3V ADC, Lowest Noise 140mW, 81.6dB SNR, 100dB SFDR, 48-Pin QFN

LTC2203 16-Bit, 25Msps, 3.3V ADC, Lowest Noise 220mW, 81.6dB SNR, 100dB SFDR, 48-Pin QFN

LTC2204 16-Bit, 40Msps, 3.3V ADC 480mW, 79dB SNR, 100dB SFDR, 48-Pin QFN

LTC2205 16-Bit, 65Msps, 3.3V ADC 590mW, 79dB SNR, 100dB SFDR, 48-Pin QFN

LTC2206 16-Bit, 80Msps, 3.3V ADC 725mW, 77.9dB SNR, 100dB SFDR, 48-Pin QFN

LTC2207 16-Bit, 105Msps, 3.3V ADC 900mW, 77.9dB SNR, 100dB SFDR, 48-Pin QFN

LTC2208 16-Bit, 130Msps, 3.3V ADC, LVDS Outputs 1250mW, 77.7dB SNR, 100dB SFDR, 64-Pin QFN

LTC2209 16-Bit, 160Msps, 3.3V ADC, LVDS Outputs 1450mW, 77.1dB SNR, 100dB SFDR, 64-Pin QFN

LTC2220 12-Bit, 170Msps ADC 890mW, 67.5dB SNR, 9mm × 9mm QFN Package

LTC2220-1 12-Bit, 185Msps, 3.3V ADC, LVDS Outputs 910mW, 67.7dB SNR, 80dB SFDR, 64-Pin QFN

LTC2224 12-Bit, 135Msps, 3.3V ADC, High IF Sampling 630mW, 67.6dB SNR, 84dB SFDR, 48-Pin QFN

LTC2249 14-Bit, 80Msps ADC 230mW, 73dB SNR, 5mm × 5mm QFN Package

LTC2250 10-Bit, 105Msps ADC 320mW, 61.6dB SNR, 5mm × 5mm QFN Package

LTC2251 10-Bit, 125Msps ADC 395mW, 61.6dB SNR, 5mm × 5mm QFN Package

LTC2252 12-Bit, 105Msps ADC 320mW, 70.2dB SNR, 5mm × 5mm QFN Package

LTC2253 12-Bit, 125Msps ADC 395mW, 70.2dB SNR, 5mm × 5mm QFN Package

LTC2254 14-Bit, 105Msps ADC 320mW, 72.5dB SNR, 5mm × 5mm QFN Package

LTC2255 14-Bit, 125Msps, 3V ADC, Lowest Power 395mW, 72.5dB SNR, 88dB SFDR, 32-Pin QFN

LTC2256-12/

LTC2257-12/

LTC2258-12

12-Bit, 25/40/65Msps 1.8V ADCs, Ultralow Power 34mW/47mW/79mW, 71.1dB SNR, 88dB SFDR, DDR LVDS/DDR CMOS/

CMOS Outputs, 6mm × 6mm QFN Package

LTC2259-12/

LTC2260-12/

LTC2261-12

12-Bit, 80/105/125Msps 1.8V ADCs, Ultralow

Power

87mW/103mW/124mW, 70.8dB SNR, 85dB SFDR, DDR LVDS/DDR CMOS/

CMOS Outputs, 6mm × 6mm QFN Package

LTC2259-14/

LTC2260-14/

LTC2261-14

14-Bit, 80/105/125Msps 1.8V ADCs, Ultralow

Power

89mW/106mW/127mW, 73.4dB SNR, 85dB SFDR, DDR LVDS/DDR CMOS/

CMOS Outputs, 6mm × 6mm QFN Package

LTC2284 14-Bit, Dual, 105Msps, 3V ADC, Low Crosstalk 540mW, 72.4dB SNR, 88dB SFDR, 64-Pin QFN

LTC2299 Dual 14-Bit, 80Msps ADC 230mW, 71.6dB SNR, 5mm x 5mm QFN Package

LT5517 40MHz to 900MHz Direct Conversion Quadrature

Demodulator

High IIP3: 21dBm at 800MHz, Integrated LO Quadrature Generator

LT5527 400MHz to 3.7GHz High Linearity Downconverting

Mixer

24.5dBm IIP3 at 900MHz, 23.5dBm IIP3 at 3.5GHz, NF = 12.5dB,

50Ω Single-Ended RF and LO Ports

LT5557 400MHz to 3.8GHz High Linearity Downconverting

Mixer

23.7dBm IIP3 at 2.6GHz, 23.5dBm IIP3 at 3.5GHz, NF = 13.2dB,

3.3V Supply Operation, Integrated T

ransformer

LT5575 800MHz to 2.7GHz Direct Conversion Quadrature

Demodulator

High IIP3: 28dBm at 900MHz, Integrated LO Quadrature Generator

Integrated RF and LO T

ransformer

LTC6400-20 1.8GHz Low Noise, Low Distortion Differential ADC

Driver for 300MHz IF

Fixed Gain 10V/V, 2.1nV√Hz Total Input Noise, 3mm × 3mm QFN-16 Package

LT6604-2.5/

LT6604-5/

LT6604-10/

LT6604-15

Dual Matched 2.5MHz, 5MHz, 10MHz, 15MHz Filter

with ADC Driver

Dual Matched 4th Order LP Filters with Differential Drivers. Low Noise, Low

Distortion Amplifiers