LT6656BILS8-1.25#PBF - LINEAR TECHNOLOGY

LT6656

6656fc

For more information www.linear.com/LT6656

TYPICAL APPLICATION

Output Voltage Temperature Drift

TEMPERATURE (°C)

–40

2.498

2.499

OUT

(V)

2.500

2.501

2.502

2.503

–20 0 20 40

6652 TA01b

60 80

38 TYPICAL UNITS

LT6656-2.5

Basic Connection

DESCRIPTION

1µA Precision Series

Voltage Reference

The LT

6656 is a tiny precision voltage reference that

draws less than 1µA of supply current and can operate

with a supply voltage within 10mV of the output voltage.

The LT6656 offers an initial accuracy of 0.05% and tem-

perature drift of 10ppm/°C. The combined low power and

precision characteristics are ideal for portable and battery

powered instrumentation.

The LT6656 can supply up to 5mA of output drive with

65ppm/mA of load regulation, allowing it to be used as

the supply voltage and the reference input to a low power

ADC. The LT6656 can accept a supply voltage up to 18V

and withstand the reversal of the input connections.

The LT6656 output is stable with 1µF or larger output

capacitance and operates with a wide range of output

capacitor ESR.

This reference is fully speciﬁed for operation from –40°C

to 85°C, and is functional over the extreme temperature

range of –55°C to 125°C. Low hysteresis and a consistent

temperature drift are obtained through advanced design,

processing and packaging techniques.

The LT6656 is offered in the 6-lead SOT-23, (2mm ×

2mm) DFN, and 8-lead LS8 Packages. The LS8 is a 5mm

× 5mm surface mount hermetic package that provides

outstanding stability.

FEATURES

APPLICATIONS

n Ultralow Supply Current: 850nA

n Low Drift

A Grade: 10 ppm/°C Max

B Grade: 20 ppm/°C Max

n High Accuracy

A Grade: 0.05% Max

B Grade: 0.1% Max

n Long-Term Drift: 15ppm/√kHr (LS8 Package)

n No Humidity Sensitivity (LS8 Package)

n High Output Drive Current: 5mA Min

n Low Dropout Voltage: 10mV Max

n Fully Speciﬁed from –40°C to 85°C

n Operational from –55°C to 125°C

n Wide Supply Range to 18V

n Reverse Input/Output Protection

n Available Output Voltage Options:

1.25V, 2.048V, 2.5V, 3V, 3.3V, 4.096V and 5V

n Available in Low Proﬁle (1mm) ThinSOT™,

(2mm × 2mm) DFN and High Stability Hermetic

(5mm × 5mm) LS8 Packages

n Precision A/D and D/A Converters

n Portable Gas Monitors

n Battery- or Solar-Powered Systems

n Precision Regulators

n Low Voltage Signal Processing

n Micropower Remote Sensing

2.51V ≤ V

IN ≤ 18V

0.1µF 1µF

OUT

2.5V

6656 TA01a

LT6656-2.5

VIN VOUT

GND

L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and

ThinSOT is a trademark of Linear Technology Corporation. All other trademarks are the property

of their respective owners.

LT6656

6656fc

For more information www.linear.com/LT6656

ABSOLUTE MAXIMUM RATINGS

Input Voltage ........................................................... ±20V

Output Voltage ........................................... –0.3V to 20V

Output Voltage Above Input Voltage .........................20V

Speciﬁed Temperature Range (Note 2)

Commercial ............................................. 0°C to 70°C

Industrial .............................................–40°C to 85°C

(Note 1)

ORDER INFORMATION

TAPE AND REEL (MINI) TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION SPECIFIED TEMPERATURE RANGE

LT6656ACS6-1.25#TRMPBF LT6656ACS6-1.25#TRPBF LTFNK 6-Lead Plastic TSOT-23 0°C to 70°C

LT6656BCS6-1.25#TRMPBF LT6656BCS6-1.25#TRPBF LTFNK 6-Lead Plastic TSOT-23 0°C to 70°C

LT6656AIS6-1.25#TRMPBF LT6656AIS6-1.25#TRPBF LTFNK 6-Lead Plastic TSOT-23 –40°C to 85°C

LT6656BIS6-1.25#TRMPBF LT6656BIS6-1.25#TRPBF LTFNK 6-Lead Plastic TSOT-23 –40°C to 85°C

LT6656ACS6-2.048#TRMPBF LT6656ACS6-2.048#TRPBF LTFNN 6-Lead Plastic TSOT-23 0°C to 70°C

LT6656BCS6-2.048#TRMPBF LT6656BCS6-2.048#TRPBF LTFNN 6-Lead Plastic TSOT-23 0°C to 70°C

LT6656AIS6-2.048#TRMPBF LT6656AIS6-2.048#TRPBF LTFNN 6-Lead Plastic TSOT-23 –40°C to 85°C

LT6656BIS6-2.048#TRMPBF LT6656BIS6-2.048#TRPBF LTFNN 6-Lead Plastic TSOT-23 –40°C to 85°C

LT6656ACS6-2.5#TRMPBF LT6656ACS6-2.5#TRPBF LTFGW 6-Lead Plastic TSOT-23 0°C to 70°C

LT6656BCS6-2.5#TRMPBF LT6656BCS6-2.5#TRPBF LTFGW 6-Lead Plastic TSOT-23 0°C to 70°C

LT6656AIS6-2.5#TRMPBF LT6656AIS6-2.5#TRPBF LTFGW 6-Lead Plastic TSOT-23 –40°C to 85°C

LT6656BIS6-2.5#TRMPBF LT6656BIS6-2.5#TRPBF LTFGW 6-Lead Plastic TSOT-23 –40°C to 85°C

LT6656ACS6-3#TRMPBF LT6656ACS6-3#TRPBF LTFNQ 6-Lead Plastic TSOT-23 0°C to 70°C

LT6656BCS6-3#TRMPBF LT6656BCS6-3#TRPBF LTFNQ 6-Lead Plastic TSOT-23 0°C to 70°C

LT6656AIS6-3#TRMPBF LT6656AIS6-3#TRPBF LTFNQ 6-Lead Plastic TSOT-23 –40°C to 85°C

LT6656BIS6-3#TRMPBF LT6656BIS6-3#TRPBF LTFNQ 6-Lead Plastic TSOT-23 –40°C to 85°C

LT6656ACS6-3.3#TRMPBF LT6656ACS6-3.3#TRPBF LTFNS 6-Lead Plastic TSOT-23 0°C to 70°C

LT6656BCS6-3.3#TRMPBF LT6656BCS6-3.3#TRPBF LTFNS 6-Lead Plastic TSOT-23 0°C to 70°C

LT6656AIS6-3.3#TRMPBF LT6656AIS6-3.3#TRPBF LTFNS 6-Lead Plastic TSOT-23 –40°C to 85°C

LT6656BIS6-3.3#TRMPBF LT6656BIS6-3.3#TRPBF LTFNS 6-Lead Plastic TSOT-23 –40°C to 85°C

Operating Temperature Range (Note 2).. –55°C to 125°C

Output Short Circuit Duration ......................... Indeﬁnite

Junction Temperature .......................................... 150°C

Storage Temperature Range (Note 3) ..... –65°C to 150°C

Lead Temperature (Soldering, 10 sec.)

TSOT-23 (Note 4) ..............................................300°C

GND* 1

GND 2

NC 3

6 V

OUT

5 NC

4 VIN

TOP VIEW

S6 PACKAGE

6-LEAD PLASTIC TSOT-23

TJMAX = 150°C, θJA = 230°C/W

*CONNECT PIN TO DEVICE GND (PIN 2)

TOP VIEW

VIN

VOUT

GND

GND*

DC PACKAGE

6-LEAD (2mm × 2mm) PLASTIC DFN

GND*

TJMAX = 125°C, θJA = 102°C/W

EXPOSED PAD (PIN 7) MUST BE CONNECTED TO GND

GND*

VOUT

GND

VIN

TOP VIEW

LS8 PACKAGE

8-PIN LEADLESS CHIP CARRIER (5mm × 5mm)

TJMAX = 150°C, θJA = 125°C/W

*CONNECT PIN TO DEVICE GND (PIN 4)

PIN CONFIGURATION

LEAD FREE FINISH

LT6656

6656fc

For more information www.linear.com/LT6656

ORDER INFORMATION

LEAD FREE FINISH

TAPE AND REEL (MINI) TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION SPECIFIED TEMPERATURE RANGE

LT6656ACS6-4.096#TRMPBF LT6656ACS6-4.096#TRPBF LTFNV 6-Lead Plastic TSOT-23 0°C to 70°C

LT6656BCS6-4.096#TRMPBF LT6656BCS6-4.096#TRPBF LTFNV 6-Lead Plastic TSOT-23 0°C to 70°C

LT6656AIS6-4.096#TRMPBF LT6656AIS6-4.096#TRPBF LTFNV 6-Lead Plastic TSOT-23 –40°C to 85°C

LT6656BIS6-4.096#TRMPBF LT6656BIS6-4.096#TRPBF LTFNV 6-Lead Plastic TSOT-23 –40°C to 85°C

LT6656ACS6-5#TRMPBF LT6656ACS6-5#TRPBF LTFNX 6-Lead Plastic TSOT-23 0°C to 70°C

LT6656BCS6-5#TRMPBF LT6656BCS6-5#TRPBF LTFNX 6-Lead Plastic TSOT-23 0°C to 70°C

LT6656AIS6-5#TRMPBF LT6656AIS6-5#TRPBF LTFNX 6-Lead Plastic TSOT-23 –40°C to 85°C

LT6656BIS6-5#TRMPBF LT6656BIS6-5#TRPBF LTFNX 6-Lead Plastic TSOT-23 –40°C to 85°C

LT6656ACDC-1.25#TRMPBF LT6656ACDC-1.25#TRPBF LFNM 6-Lead (2mm × 2mm) Plastic DFN 0°C to 70°C

LT6656BCDC-1.25#TRMPBF LT6656BCDC-1.25#TRPBF LFNM 6-Lead (2mm × 2mm) Plastic DFN 0°C to 70°C

LT6656AIDC-1.25#TRMPBF LT6656AIDC-1.25#TRPBF LFNM 6-Lead (2mm × 2mm) Plastic DFN –40°C to 85°C

LT6656BIDC-1.25#TRMPBF LT6656BIDC-1.25#TRPBF LFNM 6-Lead (2mm × 2mm) Plastic DFN –40°C to 85°C

LT6656ACDC-2.048#TRMPBF LT6656ACDC-2.048#TRPBF LFNP 6-Lead (2mm × 2mm) Plastic DFN 0°C to 70°C

LT6656BCDC-2.048#TRMPBF LT6656BCDC-2.048#TRPBF LFNP 6-Lead (2mm × 2mm) Plastic DFN 0°C to 70°C

LT6656AIDC-2.048#TRMPBF LT6656AIDC-2.048#TRPBF LFNP 6-Lead (2mm × 2mm) Plastic DFN –40°C to 85°C

LT6656BIDC-2.048#TRMPBF LT6656BIDC-2.048#TRPBF LFNP 6-Lead (2mm × 2mm) Plastic DFN –40°C to 85°C

LT6656ACDC-2.5#TRMPBF LT6656ACDC-2.5#TRPBF LFGX 6-Lead (2mm × 2mm) Plastic DFN 0°C to 70°C

LT6656BCDC-2.5#TRMPBF LT6656BCDC-2.5#TRPBF LFGX 6-Lead (2mm × 2mm) Plastic DFN 0°C to 70°C

LT6656AIDC-2.5#TRMPBF LT6656AIDC-2.5#TRPBF LFGX 6-Lead (2mm × 2mm) Plastic DFN –40°C to 85°C

LT6656BIDC-2.5#TRMPBF LT6656BIDC-2.5#TRPBF LFGX 6-Lead (2mm × 2mm) Plastic DFN –40°C to 85°C

LT6656ACDC-3#TRMPBF LT6656ACDC-3#TRPBF LFNR 6-Lead (2mm × 2mm) Plastic DFN 0°C to 70°C

LT6656BCDC-3#TRMPBF LT6656BCDC-3#TRPBF LFNR 6-Lead (2mm × 2mm) Plastic DFN 0°C to 70°C

LT6656AIDC-3#TRMPBF LT6656AIDC-3#TRPBF LFNR 6-Lead (2mm × 2mm) Plastic DFN –40°C to 85°C

LT6656BIDC-3#TRMPBF LT6656BIDC-3#TRPBF LFNR 6-Lead (2mm × 2mm) Plastic DFN –40°C to 85°C

LT6656ACDC-3.3#TRMPBF LT6656ACDC-3.3#TRPBF LFNT 6-Lead (2mm × 2mm) Plastic DFN 0°C to 70°C

LT6656BCDC-3.3#TRMPBF LT6656BCDC-3.3#TRPBF LFNT 6-Lead (2mm × 2mm) Plastic DFN 0°C to 70°C

LT6656AIDC-3.3#TRMPBF LT6656AIDC-3.3#TRPBF LFNT 6-Lead (2mm × 2mm) Plastic DFN –40°C to 85°C

LT6656BIDC-3.3#TRMPBF LT6656BIDC-3.3#TRPBF LFNT 6-Lead (2mm × 2mm) Plastic DFN –40°C to 85°C

LT6656ACDC-4.096#TRMPBF LT6656ACDC-4.096#TRPBF LFNW 6-Lead (2mm × 2mm) Plastic DFN 0°C to 70°C

LT6656BCDC-4.096#TRMPBF LT6656BCDC-4.096#TRPBF LFNW 6-Lead (2mm × 2mm) Plastic DFN 0°C to 70°C

LT6656AIDC-4.096#TRMPBF LT6656AIDC-4.096#TRPBF LFNW 6-Lead (2mm × 2mm) Plastic DFN –40°C to 85°C

LT6656BIDC-4.096#TRMPBF LT6656BIDC-4.096#TRPBF LFNW 6-Lead (2mm × 2mm) Plastic DFN –40°C to 85°C

LT6656ACDC-5#TRMPBF LT6656ACDC-5#TRPBF LFNY 6-Lead (2mm × 2mm) Plastic DFN 0°C to 70°C

LT6656BCDC-5#TRMPBF LT6656BCDC-5#TRPBF LFNY 6-Lead (2mm × 2mm) Plastic DFN 0°C to 70°C

LT6656AIDC-5#TRMPBF LT6656AIDC-5#TRPBF LFNY 6-Lead (2mm × 2mm) Plastic DFN –40°C to 85°C

LT6656BIDC-5#TRMPBF LT6656BIDC-5#TRPBF LFNY 6-Lead (2mm × 2mm) Plastic DFN –40°C to 85°C

LEAD FREE FINISH PART MARKING* PACKAGE DESCRIPTION SPECIFIED TEMPERATURE RANGE

LT6656AILS8-1.25#PBF†656125 8-Lead (5mm × 5mm) Ceramic LCC –40°C to 85°C

LT6656BILS8-1.25#PBF†656125 8-Lead (5mm × 5mm) Ceramic LCC –40°C to 85°C

TRM = 500 pieces. *Temperature grades are identiﬁed by a label on the shipping container.

Consult LTC Marketing for parts speciﬁed with wider operating temperature ranges.

Consult LTC Marketing for information on 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/

†This product is only offered in trays. For more information go to: http://www.linear.com/packaging/

LT6656

6656fc

For more information www.linear.com/LT6656

AVAILABLE OPTIONS

OUTPUT VOLTAGE INITIAL ACCURACY

TEMPERATURE

COEFFICIENT

SPECIFIED TEMPERATURE RANGE

0°C TO 70°C –40°C TO 85°C

ORDER PART NUMBER* ORDER PART NUMBER*

1.250V 0.05% 10ppm/°C LT6656ACS6-1.25 LT6656AIS6-1.25

0.05% 10ppm/°C N/A LT6656AILS8-1.25

0.10% 20ppm/°C LT6656BCS6-1.25 LT6656BIS6-1.25

0.10% 10ppm/°C LT6656ACDC-1.25 LT6656AIDC-1.25

0.10% 15ppm/°C N/A LT6656BILS8-1.25

0.20% 20ppm/°C LT6656BCDC-1.25 LT6656BIDC-1.25

2.048V 0.05% 10ppm/°C LT6656ACS6-2.048 LT6656AIS6-2.048

0.10% 20ppm/°C LT6656BCS6-2.048 LT6656BIS6-2.048

0.10% 10ppm/°C LT6656ACDC-2.048 LT6656AIDC-2.048

0.20% 20ppm/°C LT6656BCDC-2.048 LT6656BIDC-2.048

2.500V 0.05% 10ppm/°C LT6656ACS6-2.5 LT6656AIS6-2.5

0.10% 20ppm/°C LT6656BCS6-2.5 LT6656BIS6-2.5

0.10% 10ppm/°C LT6656ACDC-2.5 LT6656AIDC-2.5

0.20% 20ppm/°C LT6656BCDC-2.5 LT6656BIDC-2.5

3.000V 0.05% 10ppm/°C LT6656ACS6-3 LT6656AIS6-3

0.10% 20ppm/°C LT6656BCS6-3 LT6656BIS6-3

0.10% 10ppm/°C LT6656ACDC-3 LT6656AIDC-3

0.20% 20ppm/°C LT6656BCDC-3 LT6656BIDC-3

3.300V 0.05% 10ppm/°C LT6656ACS6-3.3 LT6656AIS6-3.3

0.10% 20ppm/°C LT6656BCS6-3.3 LT6656BIS6-3.3

0.10% 10ppm/°C LT6656ACDC-3.3 LT6656AIDC-3.3

0.20% 20ppm/°C LT6656BCDC-3.3 LT6656BIDC-3.3

4.096V 0.05% 10ppm/°C LT6656ACS6-4.096 LT6656AIS6-4.096

0.10% 20ppm/°C LT6656BCS6-4.096 LT6656BIS6-4.096

0.10% 10ppm/°C LT6656ACDC-4.096 LT6656AIDC-4.096

0.20% 20ppm/°C LT6656BCDC-4.096 LT6656BIDC-4.096

5.000V 0.05% 10ppm/°C LT6656ACS6-5 LT6656AIS6-5

0.10% 20ppm/°C LT6656BCS6-5 LT6656BIS6-5

0.10% 10ppm/°C LT6656ACDC-5 LT6656AIDC-5

0.20% 20ppm/°C LT6656BCDC-5 LT6656BIDC-5

*See Order Information section for complete part number listing.

LT6656

6656fc

For more information www.linear.com/LT6656

ELECTRICAL CHARACTERISTICS

The l denotes the speciﬁcations which apply over the speciﬁed

temperature range, otherwise speciﬁcations are at TA = 25°C. VIN = VOUT + 0.5V (for LT6656-1.25, VIN = 2.2V), CL = 1μF, IL = 0,unless

otherwise noted.

PARAMETER CONDITIONS MIN TYP MAX UNITS

Output Voltage Error LT6656ACS6, LT6656AIS6, LT6656AILS8

LT6656BCS6, LT6656BIS6, LT6656BILS8

LT6656ACDC, LT6656AIDC

LT6656BCDC, LT6656BIDC

–0.05

–0.1

–0.2

0.05

0.1

0.2

Output Voltage Temperature Coefﬁcient (Note 5) LT6656A

LT6656B

ppm/°C

Line Regulation VIN = (VOUT + 0.5V) to 18V

LT6656-2.048, LT6656-2.5, LT6656-3,

LT6656-3.3, LT6656-4.096, LT6656-5

2 25

ppm/V

VIN = 2.2V to 18V

LT6656-1.25

2 25

ppm/V

Load Regulation (Note 6) IL = 5mA, Sourcing

LT6656-2.048, LT6656-2.5, LT6656-3,

LT6656-3.3, LT6656-4.096, LT6656-5

65 150

375

ppm/mA

IL = 5mA, Sourcing

LT6656S6-1.25, LT6656DC-1.25

80 175

425

ppm/mA

IL = 5mA, Sourcing

LT6656LS8-1.25

135 250

500

ppm/mA

Dropout Voltage (Note 7) VIN – VOUT, ∆VOUT Error ≤ 0.1%

IL = 0

LT6656-2.048, LT6656-2.5, LT6656-3,

LT6656-3.3, LT6656-4.096, LT6656-5

IL = 5mA, Sourcing

LT6656-2.048, LT6656-2.5, LT6656-3,

LT6656-3.3, LT6656-4.096, LT6656-5

250 370

500

Minimum Input Voltage IL = 0, ∆VOUT Error ≤ 0.1%

LT6656-1.25

0°C ≤ TA ≤ 70°C

–40°C ≤ TA ≤ 85°C

1.35

1.5

1.6

1.8

Supply Current

0.85 1.0

1.5

µA

Output Short Circuit Current Short VOUT to GND

Short VOUT to VIN

Input Reverse Leakage Current VIN = –18V, VOUT = GND 80 µA

Reverse Output Current VIN = GND, VOUT = 18V 30 µA

Output Voltage Noise (Note 8) 0.1Hz to 10Hz

10Hz to 1kHz, LT6656-1.25

10Hz to 1kHz, LT6656-2.5

10Hz to 1kHz, LT6656-5

140

ppmP-P

µVRMS

Turn-On Time LT6656-1.25, 0.1% Settling

LT6656-2.5, 0.1% Settling

LT6656-5, 0.1% Settling

Long Term Drift of Output Voltage (Note 9) LT6656S6, LT6656DC

LT6656LS8

ppm/√kHr

Hysteresis (Note 10) LT6656S6, LT6656DC

∆T = 0°C to 70°C

∆T = –40°C to 85°C

ppm

LT6656LS8

∆T = 0°C to 70°C

∆T = –40°C to 85°C

ppm

LT6656

6656fc

For more information www.linear.com/LT6656

ELECTRICAL CHARACTERISTICS

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: The LT6656C is guaranteed to meet speciﬁed performance from

0°C to 70°C. The LT6656C is designed, characterized and expected to

meet speciﬁed performance from –40°C to 85°C but is not tested or

QA sampled at these temperatures. The LT6656I is guaranteed to meet

speciﬁed performance from –40°C to 85°C. By design, the LT6656 is

guaranteed functional over the operating temperature range of –55°C to

125°C.

Note 3: If the LT6656 is stored outside of the speciﬁed temperature range,

the output may shift due to hysteresis.

Note 4: The stated temperature is typical for soldering of the leads during

manual rework. For detailed IR reﬂow recommendations, refer to the

Applications section.

Note 5: Temperature coefﬁcient is measured by dividing the maximum

change in output voltage by the speciﬁed temperature range.

Note 6: Load regulation is measured with a pulse from no load to the

speciﬁed load current. Output changes due to die temperature change

must be taken into account separately.

Note 7: Excludes load regulation errors.

Note 8: Peak-to-peak noise is measured with a 3-pole highpass ﬁlter at

0.1Hz and a 4-pole lowpass ﬁlter at 10Hz. The unit is enclosed in a still-air

environment to eliminate thermocouple effects on the leads. The test

time is 10 seconds. RMS noise is measured on a spectrum analyzer in a

shielded environment.

Note 9: Long term stability typically has a logarithmic characteristic and

therefore, changes after 1000 hours tend to be much smaller than before

that time. Total drift in the second thousand hours is normally less than

one third that of the ﬁrst thousand hours with a continuing trend toward

reduced drift with time. Long-term stability will also be affected by

differential stresses between the IC and the board material created during

board assembly.

Note 10: Hysteresis in output voltage is created by mechanical stress

that differs depending on whether the IC was previously at a higher or

lower temperature. Output voltage is always measured at 25°C, but

the IC is cycled to the hot or cold temperature limit before successive

measurements. For instruments that are stored at well controlled

temperatures (within 20 or 30 degrees of operational temperature)

hysteresis is usually not a dominant error source. Typical hysteresis is the

worst-case of 25°C to cold to 25°C or 25°C to hot to 25°C, preconditioned

by one thermal cycle.

TYPICAL PERFORMANCE CHARACTERISTICS

Output Voltage Temperature Drift Typical VOUT Distribution Supply Current vs Input Voltage

100

0.1

INPUT VOLTAGE (V)

SUPPLY CURRENT (µA)

10 186 14

6656 G17

8 164 122

TA = 125°C

TA = 85°C

TA = 25°C

TA = –40°C

TA = –55°C

1.25V OPTION

TEMPERATURE (°C)

–60 –40

–1000

1000

2000

CHANGE IN OUTPUT VOLTAGE (ppm)

3000

5000

6000

7000

8000

9000

4000

10000

–20 0 20 40

6652 G01

60 12010080

ALL OPTIONS

25 TYPICAL UNITS

NORMALIZED AT 25°C

CL = 1µF

IL = 0

OUTPUT VOLTAGE ERROR (%)

–0.10

0.10

NUMBER OF UNITS

200

180

140

100

160

120

6656 G02

–0.02–0.06 0.060.020

ALL OPTIONS

CL = 1µF

IL = 0

TA = 25°C

LT6656

6656fc

For more information www.linear.com/LT6656

TYPICAL PERFORMANCE CHARACTERISTICS

Power Supply Rejection Ratio

vs Frequency

Dropout Voltage vs Load Current

Load Regulation (Sourcing) Load Regulation (Sinking)

Line Regulation

Supply Current vs Input Voltage

100

0.1

INPUT VOLTAGE (V)

SUPPLY CURRENT (µA)

10 186 14

6656 G03

8 164 122

TA = 125°C

TA = 85°C

TA = 25°C

TA = –55°C

2.048V TO 5V OPTIONS

2.5V OPTION SHOWN

VON MOVES WITH VOLTAGE OPTION

VON

0.1µ 1µ 1m

10m

100µ10µ

1000

100

LOAD CURRENT (A)

DROPOUT VOLTAGE (mV)

6656 G04

TA = 125°C

TA = 85°C

TA = 25°C

TA = –55°C

2.048V TO 5V OPTIONS

VIN – VOUT

INITIAL VIN = VOUT + 0.5V

∆VOUT = 0.1%

750

500

250

–750

–500

–250

OUTPUT VOLTAGE CHANGE (ppm)

6656 G05

TA = 125°C

TA = 85°C

TA = 25°C

TA = –55°C

2.048V TO 5V OPTIONS

VIN = VOUT + 0.5V

CL = 1µF

0.1µ 1µ 1m

10m

100µ10µ

LOAD CURRENT (A)

10µ

100µ

5.0

2.0

1.5

3.0

2.5

4.0

3.5

4.5

1.0

0.5

–0.5

LOAD CURRENT (A)

OUTPUT VOLTAGE CHANGE (%)

6656 G06

TA = 85°C, 125°C

TA = 25°C

TA = –40°C

TA = –55°C

ALL OPTIONS

VIN = VOUT + 0.5V

CL = 1µF

1000

900

800

700

600

500

400

300

200

100

–200

–100

INPUT VOLTAGE (V)

OUTPUT VOLTAGE CHANGE (ppm)

10 186 14

6656 G08

8 164 122

TA = 125°C

TA = 85°C

TA = 25°C

TA = –55°C

ALL OPTIONS

IL = 0

CL = 1µF

2.5V OPTION SHOWN

VON MOVES WITH

VOLTAGE OPTION

VON

FREQUENCY (Hz)

POWER SUPPLY REJECTION RATIO (dB)

6656 G09

010 1k

10k

100

VIN = VOUT + 0.5V

CL = 1µF

IL = 0

1.25V OPTION

2.5V OPTION

5V OPTION

Minimum Supply Voltage

vs Load Current

2.0

1.8

1.6

1.4

1.2

0.8

1.0

MINIMUM SUPPLY VOLTAGE (V)

6656 G18

1.25V OPTION

INITIAL VIN = 2.2V

∆VOUT = 0.1%

TA = 125°C

TA = 85°C

TA = 25°C

TA = –40°C

TA = –55°C

0.1µ 1µ 1m

10m

100µ10µ

LOAD CURRENT (A)

Load Regulation (Sourcing)

500

250

–1000

–750

–500

–250

OUTPUT VOLTAGE CHANGE (ppm)

6656 G19

TA = 125°C

TA = 85°C

TA = 25°C

TA = –40°C

TA = –55°C

1.25V OPTION

VIN = 1.75V

CL = 1µF

0.1µ 1µ 1m

10m

100µ10µ

LOAD CURRENT (A)

Power Supply Rejection Ratio

vs Frequency

FREQUENCY (Hz)

POWER SUPPLY REJECTION RATIO (dB)

6656 G20

–10

10 1k

10k

100

2.5V OPTION

VIN = 3V

IL = 0, CL = 1µF

IL = 0, CL = 10µF

IL = 1mA, CL = 1µF

IL = 1mA, CL = 10µF

LT6656

6656fc

For more information www.linear.com/LT6656

Output Impedance vs Frequency

FREQUENCY (Hz)

OUTPUT IMPEDANCE (Ω)

6656 G21

10k

100

110 1k

10k

100

VIN = VOUT + 0.5V

CL = 1µF

IL = 0

1.25V OPTION

2.5V OPTION

5V OPTION

TYPICAL PERFORMANCE CHARACTERISTICS

Reverse Output Current

Reverse Input Current

0 15

105

100

OUTPUT VOLTAGE (V)

REVERSE OUTPUT CURRENT (µA)

6656 G12

TA = 125°C

TA = 85°C

TA = 25°C

TA = –55°C

ALL OPTIONS

VIN = GND

INPUT VOLTAGE (V)

REVERSE INPUT CURRENT (µA)

6656 G11

1000

100

00 –2 –4 –6 –8

–20

–18–16–14–12–10

TA = 125°C

TA = 85°C

TA = 25°C

TA = –55°C

ALL OPTIONS

VOUT = GND

Output Noise Voltage Spectrum

vs Load Capacitance

FREQUENCY (Hz)

NOISE VOLTAGE (µV/√Hz)

6656 G15

01 100

2.5V OPTION

VIN = 3V

IL = 0 CL = 47µF

CL = 4.7µF

CL = 0.47µF

Output Noise 0.1Hz to 10Hz

Output Voltage Noise Spectrum

vs Load Current

OUTPUT NOISE (20ppm/DIV)

TIME (1s/DIV)

6656 G13

ALL OPTIONS

VIN = VOUT + 0.5V

CL = 1µF

IL = 0

FREQUENCY (Hz)

NOISE VOLTAGE (µV/√Hz)

6656 G14

010 1k

10k

100

2.5V OPTION

VIN = 3V

CL = 1µF

IL = 0

IL = 10µA

IL = 250µA

IL = 1mA

Ground Current vs Load Current

LOAD CURRENT (A)

GROUND CURRENT (µA)

6656 G07

1000

100

10µ 1m

10m

100µ

TA = 125°C

TA = 85°C

TA = 25°C

TA = –55°C

ALL OPTIONS

VIN = VOUT + 0.5V

CL = 1µF

Output Impedance vs Frequency

FREQUENCY (Hz)

OUTPUT IMPEDANCE (Ω)

6656 G22

10k

100

110 1k

10k

100

2.5V OPTION

VIN = 3V

IL = 0, CL = 1µF

IL = 0, CL = 10µF

IL = 100µA, CL = 1µF

IL = 100µA, CL = 10µF

Output Voltage Noise Spectrum

FREQUENCY (Hz)

NOISE VOLTAGE (µV

RMS

/√Hz)

6656 G24

010 1k

10k

100

VIN = VOUT + 5V

CL = 1µF

IL = 0

1.25V OPTION

2.5V OPTION

5V OPTION

LT6656

6656fc

For more information www.linear.com/LT6656

TYPICAL PERFORMANCE CHARACTERISTICS

Long-Term Drift Long-Term Drift (LS8)

HOURS

LONG TERM DRIFT (ppm)

200

150

–50

–150

100

–100

–200 500 900300 700

6656 G16

1000

400 800200 600100

ALL OPTIONS

CL = 1µF

IL = 0

5 TYPICAL PARTS

SOLDERED ONTO PCB

Integrated 10Hz to 1kHz Noise

vs Load Current

0.1µ 1µ 1m

10m

100µ10µ

250

150

200

100

LOAD CURRENT (A)

INTEGRATED NOISE (µV

RMS

)

6656 G23

CL = 0.47µF

CL = 1µF

CL = 10µF

CL = 47µF

2.5V OPTION

Integrated 10Hz to 1kHz Noise

vs Load Current

0.1µ 1µ 1m

10m

100µ10µ

500

400

200

100

300

LOAD CURRENT (A)

INTEGRATED NOISE (µV

RMS

)

6656 G25

VIN = VOUT + 0.5V

CL = 1µF

1.25V OPTION

2.5V OPTION

5V OPTION

TIME (HOURS)

OUTPUT VOLTAGE CHANGE (ppm)

100

900800

6656 G26

–50

–100

–200 200 400 600

100 1000

300 500 700

–150

200 1.25V OPTION

VIN = 2V

CLOAD =1µF

ILOAD = 0

150

35 TYPICAL PARTS

SOLDERED ONTO PCB

LT6656

6656fc

For more information www.linear.com/LT6656

PIN FUNCTIONS

(TSOT-23/DFN)

GND* (Pin 1/Pin 3): Internal Function. This pin must be

tied to ground.

GND (Pin 2/Pin 2): Device Ground.

NC (Pins 3, 5/Pins 1, 5): Not Internally Connected. May

be tied to VIN, VOUT, GND or ﬂoated.

VIN (Pin 4/Pin 6): Power Supply. The minimum supply

varies with output load and voltage option, see the Dropout

Voltage speciﬁcation in the Electrical Characteristics table

for further details. The maximum input voltage is 18V.

Bypass VIN with a 0.1µF capacitor to ground.

VOUT (Pin 6/Pin 4): Output Voltage. A minimum output

capacitor of 1µF is required for stable operation.

GND*(Exposed Pad Pin 7, DFN Only): This pin must be

tied to ground.

(LS8)

NC (Pins 1, 2, 7): Not Internally Connected. May be tied

to VIN, VOUT, GND or ﬂoated.

GND* (Pin 3): Internal Function. This pin must be tied

to ground.

GND (Pin 4): Device Ground.

VOUT (Pin 5): Output Voltage. A minimum output capacitor

of 1µF is required for stable operation.

VOUT (Pin 6): Output Voltage. Tie to pin 5 for best load

regulation.

VIN (Pin 8): Power Supply. Bypass VIN with a 0.1µF

capacitor to ground.

BLOCK DIAGRAM

6656 BD

BANDGAP ERROR

AMP

GND

VIN

TSOT-23/DFN

GND*

VOUT

6656 BD (LS8)

BANDGAP ERROR

AMP

GND

VIN

LS8

GND*

VOUT

3 4

LT6656

6656fc

For more information www.linear.com/LT6656

APPLICATIONS INFORMATION

Long Battery Life

Series references have a large advantage over shunt style

references. Shunt references require a resistor from the

power supply to operate. This resistor must be chosen

to supply the maximum current that can be demanded by

the load. When the load is not operating at this maximum

current, the shunt reference must always sink this current,

resulting in high dissipation and shortened battery life.

The LT6656 series reference does not require a current

setting resistor and is speciﬁed to operate with any supply

from 1.5V to 18V, depending on the output voltage option,

load current and operating temperature (see Dropout

Voltage and Minimum Input Voltage in the Typical Perfor-

mance Characteristics). When the load does not demand

current, the LT6656 reduces its dissipation and battery life

is extended. If the reference is not delivering load current,

it dissipates only a few µW, yet the same connection can

deliver 5mA of load current when required.

Start-Up

To ensure proper start-up, the output voltage should be

between –0.3V and the rated output voltage. If the output

load may be driven more than 0.3V below ground, a low

forward voltage schottky diode from the output to ground

is required. The turn-on characteristics can be seen in

Figure 1.

Figure 1. LT6656-2.5 Turn-On Characteristics, CL = 1µF

Figure 2. Transient Load Test Circuit

2N7000

CIN

0.1µF CL

1µF

VGEN

6656 F02

LT6656-2.5

1V/DIV

VIN

VOUT

1ms/DIV 6656 F01

Output Voltage Options

The performance of the LT6656 is consistent for the 2.048V

to 5V options. The 1.25V option has slightly reduced load

regulation, and unlike the higher voltage options, the

minimum operating supply voltage is limited by internal

circuitry rather than the output voltage.

Parameters that are based on changes in the output voltage,

such as load regulation and hysteresis, remain proportional

to the output voltage and are speciﬁed in relative units,

for example, parts per million (ppm). Parameters that

are not based on changes in the output voltage, such as

supply current and reverse input current, are the same

for all options.

The bandwidth of the LT6656 decreases with higher output

voltage. This causes parameters that are affected by both

bandwidth and output voltage, such as wideband noise

and output impedance, to increase less with higher output

voltage.

Bypass and Load Capacitance

The LT6656 voltage reference needs a 0.1μF input bypass

capacitor placed within an inch of the input pin. An ad-

ditional 2.2μF capacitor should be used when the source

impedance of the input supply is high or when driving

heavy loads. The bypassing of other local devices may

serve as the required components. The output of the

LT6656 requires a capacitance of 1µF or larger. The LT6656

is stable with a wide variety of capacitor types including

ceramic, tantalum and electrolytic due to its low sensitivity

to ESR (5Ω or less).

The test circuit in Figure 2 was used to test the response

and stability of the LT6656 to various load currents. The

resultant transient responses can be seen in Figure 3 and

Figure 4. The large scale output response to a 500mV input

step is shown in Figure 5 with a more detailed photo and

description in the Output Settling section.

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6656fc

For more information www.linear.com/LT6656

Output Settling

The output of the LT6656 is primarily designed to source

current into a load, but is capable of sinking current to

aid in output transient recovery. The output stage uses a

class B architecture to minimize quiescent current and

has a crossover dead band as the output transitions from

sourcing to sinking current.

APPLICATIONS INFORMATION

Figure 5. Output Response to 0.5VP-P Step on VIN, CL = 1µF, IL = 0

The settling time is typically less than 8ms for output loads

up to 5mA, however the time required to settle when the

load is turned off or in response to an input transient can be

signiﬁcantly longer due to the dead band (shown in Figure

7). During this interval the output stage is neither sourcing

nor sinking current so the settling time is dominated by

the ability of the application circuit to discharge the output

capacitor to the voltage at which the sourcing circuitry

in the output stage reactivates. Larger load currents will

decrease the settling time and higher output capacitance

will increase the settling time.

In application circuits where the LT6656 is experiencing

a load step greater than 5µA, such as an ADC reference

and supply implementation, the settling time will typically

remain less than 8ms, regardless of the output settling

from a previous load step.

The settling time can be estimated by the following

equation:

Settling time≈

2(Deadband)(C

)

+(VOUT )(0.8ms/V)

The deadband is ≈7mV for the 2.5V option, is proportional

to the voltage option (i.e., ≈14mV for the 5V option) and

can double due to variations in processing.

The graph in Figure 6 shows the settling time versus load

step with no load and with a constant 2µA load applied.

Note the settling time can be longer with load steps that

are not large enough to activate the sinking side of the

output stage.

2.7V

2.5V

OUT

2.3V

3.25V

VIN

2.75V

5ms/DIV 6656 F05

Figure 6. Output Settling Time to 0.05% vs Load Step

LOAD STEP (mA)

OUTPUT SETTLING TIME (ms)

6656 F06

0.001 1

0.10.01

2.5V OPTION

VIN = 3V

CL = 1µF

∆IL = LOAD

STEP TO 2µA

∆IL = LOAD

STEP TO ZERO

∆IL = ZERO TO

LOAD STEP

2.52V

2.50V

OUT

2.48V

1mA

IOUT

2mA

5ms/DIV 6656 F04

2.52V

2.50V

OUT

2.48V

0µA

IOUT

100µA

5ms/DIV 6656 F03

Figure 3. Transient Response, 0µA to 100µA Load Step

(R2 = 24.9k, R1 = Open)

Figure 4. Transient Response, 1mA to 2mA Load Step

(R1 = R2 = 2.49k)

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IL = 0

VOUT

10mV/DIV

IL = 5µA

3.25V

VIN 2.75V

5ms/DIV 6656 F07

Figure 7. Detailed Output Response to a 0.5V Input Step,

CIN = CL = 1µF

APPLICATIONS INFORMATION

The photo in Figure 7 shows the output response to a 0.5V

input step in both a no-load and 5µA load condition. In

the no-load condition only the bias current of the internal

bandgap reference (about 400nA) is available to discharge

the output capacitor.

Output Noise

Low frequency noise is proportional to the output voltage

and is insensitive to output current and moderate levels

of output capacitance.

Wideband noise increases less with higher output voltage

and is proportional to the bandwidth of the output stage,

increasing with higher load current and lower output

capacitance.

Peaking in the noise response is another factor contribut-

ing to the output noise level for a given frequency range.

Noise peaking can be reduced by increasing the size of the

output capacitor when driving heavier loads, or conversely,

reducing the size of the output capacitor when driving

lighter loads. Noise plots in the Typical Performance Curves

section show noise spectrum with various load currents

and output capacitances.

Internal Protection

The LT6656 incorporates several internal protection

features that make it ideal for use in battery powered

systems. Reverse input protection limits the input cur-

rent to typically less than 40µA when either the LT6656

or the battery is installed backwards. In systems where

the output can be held up by a backup battery with the

input pulled to ground, the reverse output protection of

the LT6656 limits the output current to typically less than

30µA. The current versus reverse voltage is shown in the

Typical Performance Characteristics section.

Long-Term Drift

Long-term drift cannot be extrapolated from accelerated

high temperature testing. This erroneous technique gives

drift numbers that are wildly optimistic. A more realistic

way to determine long-term drift is to measure it over the

time interval of interest. The LT6656 drift data was taken

over 100 parts that were soldered onto PC boards in a

typical application conﬁguration. The boards were then

placed into a constant temperature oven with TA = 30°C,

their outputs scanned regularly and measured with an

8.5 digit DVM. The parts chosen in the Long Term Drift

curves in the Typical Performance Characteristics section

represent high, low and typical units.

Hysteresis

Hysteresis on the LT6656 is measured in two steps, for

example, from 25°C to –40°C to 25°C, then from 25°C to

85°C to 25°C, for the industrial temperature range. After

preconditioning by one thermal cycle, this two-step cycle

is repeated several times and the maximum hysteresis

from all the partial cycles is noted.

Results over both commercial and industrial temperature

ranges are shown in Figure 8 and Figure 9. The parts cycled

over the higher temperature range have a higher hysteresis

than those cycled over the lower range.

Power Dissipation

The LT6656 will not exceed the maximum junction tem-

perature when operating within its speciﬁed temperature

range of –40°C to 85°C, maximum input voltage of 18V

and speciﬁed load current of 5mA.

IR Reﬂow Shift

The different expansion and contraction rates of the mate-

rials that make up the LT6656 package may induce small

stresses on the die that can cause the output to shift during

LT6656

6656fc

For more information www.linear.com/LT6656

APPLICATIONS INFORMATION

Figure 12. Lead Free Reﬂow Proﬁle Due to IR Reﬂow

Figure 9. LT6656 S6, DC –40°C to 85°C Hysteresis

Figure 11. LT6656 LS8 –40°C to 85°C Hysteresis

Figure 10. LT6656 LS8 0°C to 70°C Hysteresis

HYSTERESIS (ppm)

–160 –120 –40–80

NUMBER OF UNITS

6656 F09

160

12040 800

–40°C TO 25°C

85°C TO 25°C

2.5V OPTION

VIN = 3V

CL = 1µF

IL = 0

Figure 8. LT6656 S6, DC 0°C to 70°C Hysteresis

HYSTERESIS (ppm)

–60 –40 –20

NUMBER OF UNITS

6656 F08

6040200

2.5V OPTION

VIN = 3V

CL = 1µF

IL = 0

0°C TO 25°C

70°C TO 25°C

IR reﬂow. Common lead free IR reﬂow proﬁles reach over

250°C, considerably more than lead solder proﬁles. The

higher reﬂow temperature of the lead free parts exacerbates

the issue of thermal expansion and contraction causing

the output shift to generally be greater than with a leaded

reﬂow process.

The lead free IR reﬂow proﬁle used to experimentally

measure the output voltage shift in the LT6656-2.5 is

shown in Figure 12. Similar results can be expected us-

ing a convection reﬂow oven. Figures 13 and 14 show the

change in output voltage that was measured for parts that

were run through the reﬂow process for 1 cycle and also 3

cycles. Additional drift of the LT6656 after IR reﬂow does

not vary signiﬁcantly.

HYSTERESIS (ppm)

–60 –40 –20

NUMBER OF UNITS

6656 F10

6040200

1.25V OPTION

VIN = 2V

CL = 1µF

IL = 0

0°C TO 25°C

70°C TO 25°C

HYSTERESIS (ppm)

–160 –120 –40–80

NUMBER OF UNITS

6656 F11

16012040 800

–40°C TO 25°C

85°C TO 25°C

1.25V OPTION

VIN = 2V

CL = 1µF

IL = 0

0246

MINUTES

150

225

300

6656 F12

120s

40s

30s

TP = 260°C

RAMP

DOWN

RAMP TO

150°C

TS = 190°C

T = 150°C

130s

TL = 217°C

TS(MAX) = 200°C

380s

LT6656

6656fc

For more information www.linear.com/LT6656

Figure 13. ∆VOUT Due to IR Reﬂow,

Peak Temperature = 260°C, SOT-23

Figure 14. ∆VOUT Due to IR Reﬂow,

Peak Temperature = 260°C, DFN

APPLICATIONS INFORMATION

short as possible to minimize the voltage drops caused

by load and ground currents. Excessive trace resistance

directly impacts load regulation.

Humidity Sensitivity

Plastic mold compounds absorb water. With changes in

relative humidity, plastic packaging materials change the

amount of pressure they apply to the die inside, which

can cause slight changes in the output of a voltage refer-

ence, usually on the order of 100ppm. The LS8 package is

hermetic, so it is not affected by humidity, and is therefore

more stable in environments where humidity may be a

concern. However

, PC board material may absorb water

and apply mechanical stress to the LT6656LS8. Proper

board materials and layout are essential.

For best stability, the PC board layout is critical. Change

in temperature and position of the PC board, as well as

aging, can alter the mechanical stress applied to compo-

nents soldered to the board. FR4 and similar materials also

absorb water, causing the board to swell. Even conformal

coating or potting of the board does not always eliminate

this effect, though it may delay the symptoms by reduc-

ing the rate of absorption. Removing power and ground

planes in the PC board under the voltage reference can

improve the stability signiﬁcantly.

Figure 15a shows a tab cut through the PC board on three

sides of an LT6656, which signiﬁcantly reduces stress

on the IC, as described in Application Note 82. For even

better performance, Figure 15b shows slots cut through

the PC board on all four sides. The slots should be as

long as possible, and the corners just large enough to

accommodate routing of traces. It has been shown that

for PC boards designed in this way, humidity sensitivity

can be reduced to less than 35ppm for a change in relative

humidity of approximately 60%. Mounting the reference

near the center of the board, with slots on four sides, can

further reduce the sensitivity to less than 10ppm.

An additional advantage of slotting the PC board is that the

LT6656 is thermally isolated from surrounding circuitry.

This can help reduce thermocouple effects and improve

accuracy.

CHANGE IN OUTPUT VOLTAGE (ppm)

0 6020

NUMBER OF UNITS

6656 F13

220180140100

SOT-23

3 CYCLES

1 CYCLE

2.5V OPTION

VIN = 3V

CL = 1µF

IL = 0

CHANGE IN OUTPUT VOLTAGE (ppm)

–160

NUMBER OF UNITS

160

6656 F14

0–80 080 240

DFN

3 CYCLES

1 CYCLE

2.5V OPTION

VIN = 3V

CL = 1µF

IL = 0

PC Board Layout

The mechanical stress of soldering a surface mount volt-

age reference to a PC board can cause the output voltage

to shift and temperature coefﬁcient to change.

To reduce the effects of stress-related shifts, position

the reference near the short edge of the PC board or in a

corner. In addition, slots can be cut into the board on two

sides of the device. See Application Note AN82 for more

information. http://www.linear.com

The input and output capacitors should be mounted close

to the package. The GND and VOUT traces should be as

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APPLICATIONS INFORMATION

LS8

6656 F15a

Figure 15a. 3-Sided PCB Cutout

Figure 15b. 4-Sided PCB Cutout

LS8

6656 F12b

LT6656

6656fc

For more information www.linear.com/LT6656

TYPICAL APPLICATIONS

Regulator Reference

The robust input and output of the LT6656 along with its

high output current make it an excellent precision low

power regulator as well as a reference. The LT6656 would

be a good match with a small, low power microcontroller.

Using the LT6656 as a regulator reduces power consump-

tion, decreases solution size and increases the accuracy

of the microcontroller’s on board ADC.

Low Power ADC Reference

Low power ADCs draw only a few µAs during their idle

period and well over 100µA during conversions. Despite

these surges of current, the ADC in reality can have very

low power consumption. Figure 17 shows the LTC2480,

a low power delta sigma ADC. When the ADC is disabled

its quiescent current (IQ) is roughly 1µA, during conver-

sion the IQ jumps up to 160µA. In reality, the power con-

sumption is not only based on the IQ during conversion,

but the real power consumption of the ADC is set by the

conversion time and the sample rate. The LTC2480 shown

in Figure 17 has a conversion time of 160ms which sets

the maximum sample rate of 6 samples per second. The

maximum sample rate also sets the maximum current

consumption to 160µA, but at slower sample rates the

ADC will have signiﬁcantly lower average current draw.

If the ADC is sampled at 1 sample per second the aver-

age current drawn by the ADC during a 1 second interval

would only be 26.4µA. When taking into consideration the

current drawn by the reference, the total current draw is

only 27.4µA. This system is greatly simpliﬁed because

the precision reference does not need to be cycled on and

off to save power. Furthermore, leaving the reference on

continuously eliminates concern for turn-on settling time.

0.1µF 10µF

LT6656-2.5

3V ≤ VIN ≤ 18V

6656 F16

PB0/AIN0/AREF/MOSI

MCU

PB1/INT0/AIN1/MISO/OC1A 6

PB2/ADC1/SCK/T0/INT0 7

PB3/ADC2 2

PB4/ADC3 3

PB5/RESET/ADC0 1

VCC/VREF

GND

OUTIN

0.1µF

5.1V ≤ VIN ≤ 18V

4.7µF

6656 F17

DIFFERENTIAL INPUT

±VREF • 0.5 (±2.5V)

AT 1sps, IQ = 27.4µA

LT6656-5

IN OUT

SDOIN–

SCK

IN+

LTC2480

VCC

REF

Figure 16. Microcontroller Reference and Regulator

Figure 17. Low Power ADC Reference

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TYPICAL APPLICATIONS

Micropower Regulator, IQ = 2µA, Sink Up to 8mA

0.1µF

3V ≤ V

≤ 18V

2.5V

1µF

6656 TA06

LT6656-2.5

IN OUT

–

LT6003

Boosted Output Current Reference

1µF

220Ω

6656 TA04

10µF

3.6V ≤ V

≤ 18V

VOUT

40mA MAX

2N2905

OUT

LT6656-2.5

0.1µF

Extended Supply Range Reference

UP TO 160V

OUT

2.2µF 1µF

MMBT5551

6656 TA03

0.1µF

330k

BZX584C12

OUT

LT6656-2.5

ADC Reference and Bridge Excitation Supply

0.1µF

3.8V

≤ VIN ≤ 18V

1µF

0.1µF

10µF

LT6656-3.3

IN OUT

0.1µF

0.1µF CS

SCK

SDO

IN–

IN+

VREF VCC

LTC2452

10k10k

10k

3.3V ≤ V

≤ 5.5V

LT6656

6656fc

For more information www.linear.com/LT6656

TYPICAL APPLICATIONS

Low Power Precision High Voltage Supply Monitor, IQ = 1.4µA, High Voltage Supply Load = 10µA

0.1µF

6.5V ≤ VCC ≤ 10V

VCC

1µF

LT6656-5

IN OUT

OVERVOLTAGE FLAG

6656 TA08

–

LTC1540

1, 2

100V

105V OVERVOLTAGE THRESHOLD

9.53M

475k

2-Terminal Current Source

0.1µF

1µF

LT6656-1.25

GND

IN OUT

6656 TA09

–

LT6003

–

VREF

OUT

REF











Precision Current and Boosted Reference, IQ = 5.5µA

0.1µF 1µF

LT6656-2.5

IN OUT

2.75V

3V ≤ VCC ≤ 16V

6656 TA10

–

LT6004

–

LT6004

200k

249k

2.5V

1µA OUT

VCC

2N5086

LT6656

6656fc

For more information www.linear.com/LT6656

PACKAGE DESCRIPTION

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

1.50 – 1.75

(NOTE 4)

2.80 BSC

0.30 – 0.45

6 PLCS (NOTE 3)

DATUM ‘A’

0.09 – 0.20

(NOTE 3) S6 TSOT-23 0302

2.90 BSC

(NOTE 4)

0.95 BSC

1.90 BSC

0.80 – 0.90

1.00 MAX 0.01 – 0.10

0.20 BSC

0.30 – 0.50 REF

PIN ONE ID

NOTE:

1. DIMENSIONS ARE IN MILLIMETERS

2. DRAWING NOT TO SCALE

3. DIMENSIONS ARE INCLUSIVE OF PLATING

4. DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR

5. MOLD FLASH SHALL NOT EXCEED 0.254mm

6. JEDEC PACKAGE REFERENCE IS MO-193

3.85 MAX

0.62

MAX

0.95

REF

RECOMMENDED SOLDER PAD LAYOUT

PER IPC CALCULATOR

1.4 MIN

2.62 REF

1.22 REF

S6 Package

6-Lead Plastic TSOT-23

(Reference LTC DWG # 05-08-1636)

LT6656

6656fc

For more information www.linear.com/LT6656

PACKAGE DESCRIPTION

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

2.00 ±0.10

(4 SIDES)

NOTE:

1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (WCCD-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 0.15mm ON ANY SIDE

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

0.40 ±0.10

BOTTOM VIEW—EXPOSED PAD

0.56 ±0.05

(2 SIDES)

0.75 ±0.05

R = 0.125

TYP

R = 0.05

TYP

1.37 ±0.05

(2 SIDES)

PIN 1 BAR

TOP MARK

(SEE NOTE 6)

0.200 REF

0.00 – 0.05

(DC6) DFN REV B 1309

0.25 ±0.05

0.50 BSC

0.25 ±0.05

1.42 ±0.05

(2 SIDES)

RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS

0.61 ±0.05

(2 SIDES)

1.15 ±0.05

0.70 ±0.05

2.55 ±0.05

PACKAGE

OUTLINE

0.50 BSC

PIN 1 NOTCH

R = 0.20 OR

0.25 × 45°

CHAMFER

DC6 Package

6-Lead Plastic DFN (2mm × 2mm)

(Reference LTC DWG # 05-08-1703 Rev B)

LT6656

6656fc

For more information www.linear.com/LT6656

PACKAGE DESCRIPTION

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

2.00 REF

R0.20 REF

4.20 ±0.10

4.20 SQ ±0.10

2.54 ±0.15

1.00 × 7 TYP

0.64 × 8 TYP

LS8 0113 REV B

R0.20 REF

0.95 ±0.10

1.45 ±0.10

0.10 TYP0.70 TYP

1.4

0.5

1.50 ±0.15

2.50 ±0.15

2.54 ±0.15

0.70 ±0.05 × 8

PACKAGE OUTLINE

0.5

5.00 SQ ±0.15

5.80 SQ ±0.15

APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED

NOTE:

1. ALL DIMENSIONS ARE IN MILLIMETERS

2. DRAWING NOT TO SCALE

3. DIMENSIONS PACKAGE DO NOT INCLUDE PLATING BURRS

PLATING BURRS, IF PRESENT, SHALL NOT EXCEED 0.30mm ON ANY SIDE

4. PLATING—ELECTO NICKEL MIN 1.25UM, ELECTRO GOLD MIN 0.30UM

5. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE

TOP AND BOTTOM OF PACKAGE

PIN 1

TOP MARK

(SEE NOTE 5)

LS8 Package

8-Pin Leadless Chip Carrier (5mm × 5mm)

(Reference LTC DWG # 05-08-1852 Rev B)

ABCDEF

XYY ZZ

Q12345

TRAY PIN 1

BEVEL PACKAGE IN TRAY LOADING ORIENTATION

COMPONENT

PIN “A1”

1.4

LT6656

6656fc

For more information www.linear.com/LT6656

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

A 7/10 Voltage options added (1.25, 2.048, 3, 3.3), reﬂected throughout the data sheet 1 to 18

B 5/11 Added 6-lead DFN package reﬂected throughout the data sheet 1 to 20

C 11/13 Addition of 1.25V option in the LS8 package

Note 10 updated with additional explanation of hysteresis

Pin Functions updated to show pin numbers and LS8 package

Block Diagram updated to show pin numbers and LS8 package

Hysteresis section updated with additional explanation

Hysteresis graphs updated for SOT23 and LS8 packages

New section added for Humidity Sensitivity

1 to 4

15, 16

LT6656

6656fc

For more information www.linear.com/LT6656

 LINEAR TECHNOLOGY CORPORATION 2010

LT 1113 REV C • PRINTED IN USA

Linear Technology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

(408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com/LT6656

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LT1460 Micropower Series Reference 0.075% Max, 10ppm/°C Max Drift, 2.5V, 5V and 10V Versions,MSOP, PDIP, SO-8,

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LTC1540 Nanopower Comparator with Reference 600nA Max Supply Current, 2% 1.182V Reference, MSOP and SO-8 Packages

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Reference

0.05% Max, 10ppm/°C Max Drift, 1.25V, 2.5V, 4.096V, 5V, 10µA Maximum Supply

Current

LT1790 Micropower Precision Series Reference 0.05% Max, 10ppm/°C Max, 60µA Supply, SOT23 Package

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LT6003 1.6V, 1µA Precision Rail-to-Rail Op Amp 1µA Max Supply Current, 1.6V Minimum Operating Voltage, SOT-23 and DFN Packages

LT6650 Micropower Reference with Buffer Ampliﬁer 0.05% Max, 5.6µA Supply, SOT-23 Package

LT6660 Tiny Micropower Series Reference 0.2% Max, 20ppm/°C Max, 20mA Output Current, 2mm × 2mm DFN

LT6700 Micropower, Low Voltage Dual Comparator

with 40mV Reference

6.5µA Supply Current, 1.4V Minimum Operating Voltage

TYPICAL APPLICATION

Reference Regulator for Micropower DAC, Total IQ = 4.8µA

0.1µF

5.1V ≤ V

IN ≤ 18V

10µF

VREF VCC

GND

SCK

SDI

LTC1662

DAC A

DAC B

LT6656-5

IN OUT 5V

0V TO 5V OUTPUT

6656 TA07