1
LT1398/LT1399/LT1399HV
sn13989 13989fas
Low Cost Dual and Triple
300MHz Current Feedback
Amplifiers with Shutdown
3-Input Video MUX Cable Driver
The LT
®
1399 and LT1399HV contain three independent
300MHz current feedback amplifiers, each with a shut-
down pin. The LT1399HV is a higher voltage version of the
LT1399. The LT1398 is a two amplifier version of the
LT1399.
The LT1398/LT1399 operate on all supplies from a single
4V to ±6V. The LT1399HV operates on all supplies from 4V
to ±7.5V.
Each amplifier draws 4.6mA when active. When disabled
each amplifier draws zero supply current and its output be-
comes high impedance. The amplifiers turn on in only 30ns
and turn off in 40ns, making them ideal in spread spectrum
and portable equipment applications.
The LT1398/LT1399/LT1399HV are manufactured on Lin-
ear Technology’s proprietary complementary bipolar pro-
cess. The LT1399/LT1399HV are pin-for-pin upgrades to
the LT1260 optimized for use on ±5V/±7.5V supplies.
■
300MHz Bandwidth on ±5V (A
V
= 1, 2 and –1)
■
0.1dB Gain Flatness: 150MHz (A
V
= 1, 2 and –1)
■
Completely Off in Shutdown, 0µA Supply Current
■
High Slew Rate: 800V/µs
■
Wide Supply Range:
±2V(4V) to ±6V(12V) (LT1398/LT1399)
±2V (4V) to ±7.5V (15V) (LT1399HV)
■
80mA Output Current
■
Low Supply Current: 4.6mA/Amplifier
■
Fast Turn-On Time: 30ns
■
Fast Turn-Off Time: 40ns
■
16-Pin Narrow SO/Narrow SSOP Packages
■
RGB Cable Drivers
■
LCD Drivers
■
Spread Spectrum Amplifiers
■
MUX Amplifiers
■
Composite Video Cable Drivers
■
Portable Equipment
, LTC and LT are registered trademarks of Linear Technology Corporation.
Square Wave Response
OUTPUT
200mV/DIV
TIME (10ns/DIV)
1398/99 TA02
R
L
= 100Ω
R
F
= R
G
= 324Ω
f = 10MHz
FEATURES
DESCRIPTIO
U
APPLICATIO S
U
TYPICAL APPLICATIO
U
–
+
1/3 LT1399
R
G
200Ω
R
F
324Ω
A
EN A
V
IN A
–
+
1/3 LT1399
R
G
200Ω
R
F
324Ω
EN B
V
IN B
BC
CHANNEL
SELECT
97.6Ω
97.6Ω
–
+
1/3 LT1399
R
G
200Ω
R
F
324Ω
EN C
V
IN C
97.6Ω
75Ω
V
OUT
75Ω
CABLE
1399 TA01
2
LT1398/LT1399/LT1399HV
sn13989 13989fas
The ● denotes specifications which apply over the specified operating temperature range, otherwise specifications are at TA = 25°C.
For each amplifier: VCM = 0V, VS = ±5V, EN = 0V, pulse tested, unless otherwise noted. (Note 4)
A
U
G
W
A
W
U
W
ARBSOLUTEXI T
IS
(Note 1)
Total Supply Voltage (V
+
to V
–
)
LT1398/LT1399 ................................................ 12.6V
LT1399HV ....................................................... 15.5V
Input Current (Note 2) ....................................... ±10mA
Output Current................................................. ±100mA
Differential Input Voltage (Note 2) ........................... ±5V
Output Short-Circuit Duration (Note 3)........ Continuous
Operating Temperature Range (Note 9)... –40°C to 85°C
Specified Temperature Range (Note 4).. –40°C to 85°C
Storage Temperature Range ................ –65°C to 150°C
Junction Temperature (Note 5)............................ 150°C
Lead Temperature (Soldering, 10 sec)................. 300°C
WU
U
PACKAGE/ORDER I FOR ATIO
ORDER PART
NUMBER
LT1399CGN
LT1399CS
LT1399HVCS
LT1399IGN
LT1399IS
T
JMAX
= 150°C, θ
JA
= 120°C/W (GN)
T
JMAX
= 150°C, θ
JA
= 100°C/W (S)
*Ground pins are not internally connected. For best channel isolation, connect to ground. Consult factory for parts specified with wider operating
temperature ranges.
ORDER PART
NUMBER
LT1398CS
T
JMAX
= 150°C, θ
JA
= 100°C/W
1
2
3
4
5
6
7
8
TOP VIEW
16
15
14
13
12
11
10
9
–IN A
+IN A
*GND
*GND
*GND
*GND
+IN B
–IN B
EN A
OUT A
V+
GND*
GND*
V–
OUT B
EN B
A
S PACKAGE
16-LEAD PLASTIC SO
B
ELECTRICAL C CHARA TERISTICS
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
OS
Input Offset Voltage 1.5 10 mV
●12 mV
∆V
OS
/∆T Input Offset Voltage Drift ●15 µV/°C
I
IN+
Noninverting Input Current 10 25 µA
●30 µA
I
IN–
Inverting Input Current 10 50 µA
●60 µA
e
n
Input Noise Voltage Density f = 1kHz, R
F
= 1k, R
G
= 10Ω, R
S
= 0Ω4.5 nV/√Hz
+i
n
Noninverting Input Noise Current Density f = 1kHz 6 pA/√Hz
–i
n
Inverting Input Noise Current Density f = 1kHz 25 pA/√Hz
R
IN
Input Resistance V
IN
= ±3.5V ●0.3 1 MΩ
C
IN
Input Capacitance Amplifier Enabled 2.0 pF
Amplifier Disabled 2.5 pF
C
OUT
Output Capacitance Amplifier Disabled 8.5 pF
V
INH
Input Voltage Range, High V
S
= ±5V ● 3.5 4.0 V
V
S
= 5V, 0V 4.0 V
1
2
3
4
5
6
7
8
TOP VIEW
16
15
14
13
12
11
10
9
–IN R
+IN R
*GND
–IN G
+IN G
*GND
+IN B
–IN B
EN R
OUT R
V
+
EN G
OUT G
V
–
OUT B
EN B
R
G
S PACKAGE
16-LEAD PLASTIC SO
GN PACKAGE
16-LEAD PLASTIC SSOP
B
GN PART MARKING
1399
1399I
(LT1398/LT1399)
3
LT1398/LT1399/LT1399HV
sn13989 13989fas
ELECTRICAL C CHARA TERISTICS
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
INL
Input Voltage Range, Low V
S
= ±5V ● –3.5 –4.0 V
V
S
= 5V, 0V 1.0 V
V
OUTH
Maximum Output Voltage Swing, High V
S
= ±5V, R
L
= 100k 3.9 4.2 V
V
S
= ±5V, R
L
= 100k ●3.7 V
V
S
= 5V, 0V; R
L
= 100k 4.2 V
V
OUTL
Maximum Output Voltage Swing, Low V
S
= ±5V, R
L
= 100k –3.9 –4.2 V
V
S
= ±5V, R
L
= 100k ●–3.7 V
V
S
= 5V, 0V; R
L
= 100k 0.8 V
V
OUTH
Maximum Output Voltage Swing, High V
S
= ±5V, R
L
= 150Ω3.4 3.6 V
V
S
= ±5V, R
L
= 150Ω●3.2 V
V
S
= 5V, 0V; R
L
= 150Ω3.6 V
V
OUTL
Maximum Output Voltage Swing, Low V
S
= ±5V, R
L
= 150Ω–3.4 –3.6 V
V
S
= ±5V, R
L
= 150Ω●–3.2 V
V
S
= 5V, 0V; R
L
= 150Ω0.6 V
CMRR Common Mode Rejection Ratio V
CM
= ±3.5V ●42 52 dB
–I
CMRR
Inverting Input Current V
CM
= ±3.5V 10 16 µA/V
Common Mode Rejection V
CM
= ±3.5V ●22 µA/V
PSRR Power Supply Rejection Ratio V
S
= ±2V to ±5V, EN = V
–
●56 70 dB
+I
PSRR
Noninverting Input Current V
S
= ±2V to ±5V, EN = V
–
12 µA/V
Power Supply Rejection ●3µA/V
–I
PSRR
Inverting Input Current V
S
= ±2V to ±5V, EN = V
–
●27 µA/V
Power Supply Rejection
A
V
Large-Signal Voltage Gain V
OUT
= ±2V, R
L
= 150Ω50 65 dB
R
OL
Transimpedance, ∆V
OUT
/∆I
IN
–
V
OUT
= ±2V, R
L
= 150Ω40 100 kΩ
I
OUT
Maximum Output Current R
L
= 0Ω●80 mA
I
S
Supply Current per Amplifier V
OUT
= 0V ●4.6 6.5 mA
Disable Supply Current per Amplifier EN Pin Voltage = 4.5V, R
L
= 150Ω●0.1 100 µA
I
EN
Enable Pin Current 30 110 µA
●200 µA
SR Slew Rate (Note 6) A
V
= 10, R
L
= 150Ω500 800 V/µs
t
ON
Turn-On Delay Time (Note 7) R
F
= R
G
= 324Ω, R
L
= 100Ω30 75 ns
t
OFF
Turn-Off Delay Time (Note 7) R
F
= R
G
= 324Ω, R
L
= 100Ω40 100 ns
t
r
, t
f
Small-Signal Rise and Fall Time R
F
= R
G
= 324Ω, R
L
= 100Ω, V
OUT
= 1V
P-P
1.3 ns
t
PD
Propagation Delay R
F
= R
G
= 324Ω, R
L
= 100Ω, V
OUT
= 1V
P-P
2.5 ns
os Small-Signal Overshoot R
F
= R
G
= 324Ω, R
L
= 100Ω, V
OUT
= 1V
P-P
10 %
t
S
Settling Time 0.1%, A
V
= –1, R
F
= R
G
= 309Ω, R
L
= 150Ω25 ns
dG Differential Gain (Note 8) R
F
= R
G
= 324Ω, R
L
= 150Ω0.13 %
dP Differential Phase (Note 8) R
F
= R
G
= 324Ω, R
L
= 150Ω0.10 DEG
The ● denotes specifications which apply over the specified operating temperature range, otherwise specifications are at TA = 25°C.
For each amplifier: VCM = 0V, VS = ±5V, EN = 0V, pulse tested, unless otherwise noted. (Note 4)
(LT1398/LT1399)
4
LT1398/LT1399/LT1399HV
sn13989 13989fas
The ● denotes specifications which apply over the specified operating temperature range, otherwise specifications are at TA = 25°C.
For each amplifier: VCM = 0V, VS = ±7.5V, EN = 0V, pulse tested, unless otherwise noted. (Note 4)
ELECTRICAL C CHARA TERISTICS
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
OS
Input Offset Voltage 1.5 10 mV
●12 mV
∆V
OS
/∆T Input Offset Voltage Drift ●15 µV/°C
I
IN+
Noninverting Input Current 10 25 µA
●30 µA
I
IN–
Inverting Input Current 10 50 µA
●60 µA
e
n
Input Noise Voltage Density f = 1kHz, R
F
= 1k, R
G
= 10Ω, R
S
= 0Ω, V
S
= ±5V 4.5 nV/√Hz
+i
n
Noninverting Input Noise Current Density f = 1kHz, V
S
= ±5V 6 pA/√Hz
–i
n
Inverting Input Noise Current Density f = 1kHz, V
S
= ±5V 25 pA/√Hz
R
IN
Input Resistance V
IN
= ±6V ●0.3 1 MΩ
C
IN
Input Capacitance Amplifier Enabled 2.0 pF
Amplifier Disabled 2.5 pF
C
OUT
Output Capacitance Amplifier Disabled 8.5 pF
V
INH
Input Voltage Range, High V
S
= ±7.5V ● 6 6.5 V
V
S
= 7.5V, 0V 6.5 V
V
INL
Input Voltage Range, Low V
S
= ±7.5V ● –6 –6.5 V
V
S
= 7.5V, 0V 1.0 V
V
OUTH
Maximum Output Voltage Swing, High V
S
= ±7.5V, R
L
= 100k 6.4 6.7 V
V
S
= ±7.5V, R
L
= 100k ●6.1 V
V
S
= 7.5V, 0V; R
L
= 100k 6.7 V
V
OUTL
Maximum Output Voltage Swing, Low V
S
= ±7.5V, R
L
= 100k –6.4 –6.7 V
V
S
= ±7.5V, R
L
= 100k ●–6.1 V
V
S
= 7.5V, 0V; R
L
= 100k 0.8 V
V
OUTH
Maximum Output Voltage Swing, High V
S
= ±7.5V, R
L
= 150Ω5.4 5.8 V
V
S
= ±7.5V, R
L
= 150Ω●5.1 V
V
S
= 7.5V, 0V; R
L
= 150Ω5.8 V
V
OUTL
Maximum Output Voltage Swing, Low V
S
= ±7.5V, R
L
= 150Ω–5.4 –5.8 V
V
S
= ±7.5V, R
L
= 150Ω●–5.1 V
V
S
= 7.5V, 0V; R
L
= 150Ω0.6 V
CMRR Common Mode Rejection Ratio V
CM
= ±6V ●42 52 dB
–I
CMRR
Inverting Input Current V
CM
= ±6V 10 16 µA/V
Common Mode Rejection V
CM
= ±6V ●22 µA/V
PSRR Power Supply Rejection Ratio V
S
= ±2V to ±7.5V, EN = V
–
●56 70 dB
+I
PSRR
Noninverting Input Current V
S
= ±2V to ±7.5V, EN = V
–
12 µA/V
Power Supply Rejection ●3µA/V
–I
PSRR
Inverting Input Current V
S
= ±2V to ±7.5V, EN = V
–
●27 µA/V
Power Supply Rejection
A
V
Large-Signal Voltage Gain V
OUT
= ±4.5V, R
L
= 150Ω50 65 dB
R
OL
Transimpedance, ∆V
OUT
/∆I
IN
–
V
OUT
= ±4.5V, R
L
= 150Ω40 100 kΩ
I
OUT
Maximum Output Current R
L
= 0Ω●80 mA
I
S
Supply Current per Amplifier V
OUT
= 0V ●4.6 7 mA
Disable Supply Current per Amplifier EN Pin Voltage = 7V, R
L
= 150Ω●0.1 100 µA
I
EN
Enable Pin Current 30 110 µA
●200 µA
(LT1399HV)
5
LT1398/LT1399/LT1399HV
sn13989 13989fas
The ● denotes specifications which apply over the specified operating temperature range, otherwise specifications are at TA = 25°C.
For each amplifier: VCM = 0V, VS = ±7.5V, EN = 0V, pulse tested, unless otherwise noted. (Note 4)
ELECTRICAL C CHARA TERISTICS
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
SR Slew Rate (Note 6) A
V
= 10, R
L
= 150Ω, V
S
= ±5V 500 800 V/µs
t
ON
Turn-On Delay Time (Note 7) R
F
= R
G
= 324Ω, R
L
= 100Ω, V
S
= ±5V 30 75 ns
t
OFF
Turn-Off Delay Time (Note 7) R
F
= R
G
= 324Ω, R
L
= 100Ω, V
S
= ±5V 40 100 ns
t
r
, t
f
Small-Signal Rise and Fall Time R
F
= R
G
= 324Ω, R
L
= 100Ω, V
OUT
= 1V
P-P
, 1.3 ns
V
S
= ±5V
t
PD
Propagation Delay R
F
= R
G
= 324Ω, R
L
= 100Ω, V
OUT
= 1V
P-P
, 2.5 ns
V
S
= ±5V
os Small-Signal Overshoot R
F
= R
G
= 324Ω, R
L
= 100Ω, V
OUT
= 1V
P-P
,10%
V
S
= ±5V
t
S
Settling Time 0.1%, A
V
= –1V, R
F
= R
G
= 309Ω, R
L
= 150Ω,25ns
V
S
= ±5V
dG Differential Gain (Note 8) R
F
= R
G
= 324Ω, R
L
= 150Ω, V
S
= ±5V 0.13 %
dP Differential Phase (Note 8) R
F
= R
G
= 324Ω, R
L
= 150Ω, V
S
= ±5V 0.10 DEG
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: This parameter is guaranteed to meet specified performance
through design and characterization. It has not been tested.
Note 3: A heat sink may be required depending on the power supply
voltage and how many amplifiers have their outputs short circuited.
Note 4: The LT1398C/LT1399C/LT1399HVC are guaranteed to meet
specified performance from 0°C to 70°C and are designed, characterized
and expected to meet these extended temperature limits, but are not tested
or QA sampled at –40°C and 85°C. The LT1399I is guaranteed to meet
specified performance from –40°C to 85°C.
Note 5: TJ is calculated from the ambient temperature TA and the
power dissipation PD according to the following formula:
LT1398CS, LT1399CS, LT1399IS, LT1399HVCS:
TJ = TA + (PD • 100°C/W)
LT1399CGN, LT1399IGN: TJ = TA + (PD • 120°C/W)
Note 6: Slew rate is measured at ±2V on a ±3V output signal.
Note 7: Turn-on delay time (tON) is measured from control input to
appearance of 1V at the output, for VIN = 1V. Likewise, turn-off delay
time (tOFF) is measured from control input to appearance of 0.5V on
the output for VIN = 0.5V. This specification is guaranteed by design
and characterization.
Note 8: Differential gain and phase are measured using a Tektronix
TSG120YC/NTSC signal generator and a Tektronix 1780R Video
Measurement Set. The resolution of this equipment is 0.1% and 0.1°.
Ten identical amplifier stages were cascaded giving an effective
resolution of 0.01% and 0.01°.
Note 9: The LT1398C, LT1398I, LT1399C, LT1399I, LT1399HVC and
LT1399HVI are guaranteed functional over the operating temperature
range of –40°C to 85°C.
SMALL SIGNAL SMALL SIGNAL SMALL SIGNAL
V
S
(V) A
V
R
L
(Ω)R
F
(Ω)R
G
(Ω) –3dB BW (MHz) 0.1dB BW (MHz) PEAKING (dB)
±5 1 100 365 – 300 150 0.05
±5 2 100 324 324 300 150 0
±5 –1 100 309 309 300 150 0
TYPICAL AC PERFOR A CE
WU
(LT1399HV)
6
LT1398/LT1399/LT1399HV
sn13989 13989fas
Closed-Loop Gain vs Frequency
(AV = 1)
4
2
0
–2
–4
GAIN (dB)
1M 10M 1G100M
FREQUENCY (Hz)
V
S
= ±5V
V
IN
= –10dBm
R
F
= 365Ω
R
L
= 100Ω
1398/99 G01
Closed-Loop Gain vs Frequency
(AV = –1)
V
S
= ±5V
V
IN
= –10dBm
R
F
= R
G
= 309Ω
R
L
= 100Ω
1398/99 G03
4
2
0
–2
–4
GAIN (dB)
1M 10M 1G100M
FREQUENCY (Hz)
Closed-Loop Gain vs Frequency
(AV = 2)
V
S
= ±5V
V
IN
= –10dBm
R
F
= R
G
= 324Ω
R
L
= 100Ω
10
8
6
4
2
GAIN (dB)
1M 10M 1G100M
FREQUENCY (Hz) 1398/99 G02
Large-Signal Transient Response
(AV = –1)
OUTPUT (1V/DIV)
TIME (5ns/DIV)V
S
= ±5V
V
IN
= ±2.5V
R
F
= R
G
= 309Ω
R
L
= 100Ω
1398/99 G06
Large-Signal Transient Response
(AV = 2)
OUTPUT (1V/DIV)
TIME (5ns/DIV)V
S
= ±5V
V
IN
= ±1.25V
R
F
= R
G
= 324Ω
R
L
= 100Ω
1398/99 G05
Large-Signal Transient Response
(AV = 1)
OUTPUT (1V/DIV)
TIME (5ns/DIV)V
S
= ±5V
V
IN
= ±2.5V
R
F
= 365Ω
R
L
= 100Ω
1398/99 G04
CCHARA TERISTICS
UW
ATYPICALPER
FORCE
PSRR vs Frequency
Maximum Undistorted Output
Voltage vs Frequency
2nd and 3rd Harmonic Distortion
vs Frequency
FREQUENCY (kHz)
90
DISTORTION (dB)
80
60
40
30
1 100 1000 100000
1398/1399 G07
100
10 10000
50
70
110
HD2
HD3
T
A
= 25°C
R
F
= R
G
= 324Ω
R
L
= 100Ω
V
S
= ±5V
V
OUT
= 2VPP
FREQUENCY (MHz)
1
2
OUTPUT VOLTAGE (V
P-P
)
3
4
5
6
8
10 100
1398/1399 G08
7A
V
= +1 A
V
= +2
T
A
= 25°C
R
F
= 324Ω
R
L
= 100Ω
V
S
= ±5V
FREQUENCY (Hz)
20
PSRR (dB)
40
50
70
80
10k 1M 10M 100M
1398/1399 G09
0100k
60
30
10
+PSRR
–PSRR
T
A
= 25°C
R
F
= R
G
= 324Ω
R
L
= 100Ω
A
V
= +2
7
LT1398/LT1399/LT1399HV
sn13989 13989fas
CCHARA TERISTICS
UW
ATYPICALPER
FORCE
Input Voltage Noise and Current
Noise vs Frequency
FREQUENCY (Hz)
10
INPUT NOISE (nV/√Hz OR pA/√Hz)
10
100
1000
30 100 300 1k 3k 10k 30k 100k
1398/1399 G10
1
–IN
+IN
EN
FREQUENCY (Hz)
10k
0.01
OUTPUT IMPEDANCE (Ω)
1
100
1M 10M100k 100M
1398/1399 G11
0.1
10
R
F
= R
G
= 324Ω
R
L
= 50Ω
A
V
= +2
V
S
= ±5V
FREQUENCY (Hz)
100k
100
OUTPUT IMPEDANCE (DISABLED) (Ω)
1k
10k
100k
1M 10M 100M
1398/1399 G12
R
F
= 365Ω
A
V
= +1
V
S
= ±5V
Output Impedance vs Frequency Output Impedance (Disabled)
vs Frequency
Maximum Capacitive Load
vs Feedback Resistor Capacitive Load
vs Output Series Resistor Supply Current vs Supply Voltage
FEEDBACK RESISTANCE (Ω)
300
1
CAPACITIVE LOAD (pF)
10
100
1000
900 1500 2100 2700 3300
1398/1399 G13
RF = RG
AV = +2
VS = ±5V
PEAKING ≤ 5dB
CAPACITIVE LOAD (pF)
10
0
OUTPUT SERIES RESISTANCE (Ω)
10
20
40
100 1000
1398/1399 G14
30
RF = RG = 324Ω
VS = ±5V
OVERSHOOT < 2%
SUPPLY VOLTAGE (±V)
0
0
SUPPLY CURRENT (mA)
1
3
4
5
2459
1398/1399 G15
2
13 678
6
EN = V
–
EN = 0V
Output Voltage Swing
vs Temperature Enable Pin Current
vs Temperature Positive Supply Current per
Amplifier vs Temperature
AMBIENT TEMPERATURE (°C)
–50
–5
OUTPUT VOLTAGE SWING (V)
–4
–2
–1
0
5
2
050 75
1398/1399 G16
–3
3
4
1
–25 25 100 125
R
L
= 150ΩR
L
= 100k
R
L
= 150ΩR
L
= 100k
AMBIENT TEMPERATURE (°C)
–50
–40
–30
–10
25 75
1398/1399 G17
–50
–60
–25 0 50 100 125
–70
–80
–20
ENABLE PIN CURRENT (µA)
V
S
= ±5V
EN = 0V
EN = –5V
AMBIENT TEMPERATURE (°C)
–50
POSITIVE SUPPLY CURRENT PER AMPLIFIER (mA)
4.75
25
1398/1399 G18
4.00
3.50
–25 0 50
3.25
3.00
5.00
4.50
4.25
3.75
75 100 125
EN = –5V
EN = 0
V
S
= ±5V
8
LT1398/LT1399/LT1399HV
sn13989 13989fas
CCHARA TERISTICS
UW
ATYPICALPER
FORCE
Input Offset Voltage
vs Temperature Input Bias Currents
vs Temperature
All Hostile Crosstalk
Propagation Delay Rise Time and Overshoot
All Hostile Crosstalk (Disabled)
AMBIENT TEMPERATURE (°C)
–50
INPUT OFFSET VOLTAGE (mV)
2.5
25
1398/1399 G19
1.0
0
–25 0 50
–0.5
–1.0
3.0
2.0
1.5
0.5
75 100 125
V
S
= ±5V
AMBIENT TEMPERATURE (°C)
–50
6
9
I
B+
I
B–
15
25 75
1398/99 G20
3
0
–25 0 50 100 125
–3
–6
12
INPUT BIAS CURRENT (µA)
V
S
= ±5V
FREQUENCY (Hz)
–70
ALL HOSTILE CROSSTALK (dB)
–10
0
–80
–90
–20
–50
–30
–40
–60
100k 10M 100M 500M
1398/1399 G21
–100 1M
R
F
= R
G
= 324Ω
R
L
= 100Ω
A
V
= +2
R
G
B
INPUT
100mV/DIV
OUTPUT
200mV/DIV
t
PD
= 2.5ns
TIME (500ps/DIV)A
V
= +2
R
L
= 100Ω
R
F
= R
G
= 324Ω
V
OUT
200mV/DIV
OS = 10%
t
r
= 1.3ns
TIME (500ps/DIV)A
V
= +2
R
L
= 100Ω
R
F
= R
G
= 324Ω
FREQUENCY (Hz)
–70
ALL HOSTILE CROSSTALK (dB)
–10
–80
–90
–20
–50
–30
–40
–60
100k 10M 100M 500M
1398/1399 G24
–100
–110 1M
R
F
= R
G
= 324Ω
R
L
= 100Ω
A
V
= +2
R
G
B
1398/1399 G22 1398/1399 G23
9
LT1398/LT1399/LT1399HV
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PIN FUNCTIONS
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LT1399, LT1399HV
–IN R (Pin 1): Inverting Input of R Channel Amplifier.
+IN R (Pin 2): Noninverting Input of R Channel Amplifier.
GND (Pin 3): Ground. Not connected internally.
–IN G (Pin 4): Inverting Input of G Channel Amplifier.
+IN G (Pin 5): Noninverting Input of G Channel Amplifier.
GND (Pin 6): Ground. Not connected internally.
+IN B (Pin 7): Noninverting Input of B Channel Amplifier.
–IN B (Pin 8): Inverting Input of B Channel Amplifier.
EN B (Pin 9): B Channel Enable Pin. Logic low to enable.
OUT B (Pin 10): B Channel Output.
V
–
(Pin 11): Negative Supply Voltage, Usually –5V.
OUT G (Pin 12): G Channel Output.
EN G (Pin 13): G Channel Enable Pin. Logic low to enable.
V
+
(Pin 14): Positive Supply Voltage, Usually 5V.
OUT R (Pin 15): R Channel Output.
EN R (Pin 16): R Channel Enable Pin. Logic low to enable.
Take care to minimize the stray capacitance between the
output and the inverting input. Capacitance on the invert-
ing input to ground will cause peaking in the frequency
response (and overshoot in the transient response).
Capacitive Loads
The LT1398/LT1399/LT1399HV can drive many capaci-
tive loads directly when the proper value of feedback
resistor is used. The required value for the feedback
resistor will increase as load capacitance increases and as
closed-loop gain decreases. Alternatively, a small resistor
(5Ω to 35Ω) can be put in series with the output to isolate
the capacitive load from the amplifier output. This has the
advantage that the amplifier bandwidth is only reduced
when the capacitive load is present. The disadvantage is
that the gain is a function of the load resistance.
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Feedback Resistor Selection
The small-signal bandwidth of the LT1398/LT1399/
LT1399HV is set by the external feedback resistors and the
internal junction capacitors. As a result, the bandwidth is
a function of the supply voltage, the value of the feedback
resistor, the closed-loop gain and the load resistor. The
LT1398/LT1399 have been optimized for ±5V supply
operation and have a –3dB bandwidth of 300MHz at a gain
of 2. The LT1399HV provides performance similar to the
LT1399. Please refer to the resistor selection guide in the
Typical AC Performance table.
Capacitance on the Inverting Input
Current feedback amplifiers require resistive feedback
from the output to the inverting input for stable operation.
LT1398
–IN A (Pin 1): Inverting Input of A Channel Amplifier.
+IN A (Pin 2): Noninverting Input of A Channel Amplifier.
GND (Pins 3, 4, 5, 6): Ground. Not connected internally.
+IN B (Pin 7): Noninverting Input of B Channel Amplifier.
–IN B (Pin 8): Inverting Input of B Channel Amplifier.
EN B (Pin 9): B Channel Enable Pin. Logic low to enable.
OUT B (Pin 10): B Channel Output.
V
–
(Pin 11): Negative Supply Voltage, Usually –5V.
GND (Pins 12, 13): Ground. Not connected internally.
V
+
(Pin 14): Positive Supply Voltage, Usually 5V.
OUT A (Pin 15): A Channel Output.
EN A (Pin 16): A Channel Enable Pin. Logic low to enable.
10
LT1398/LT1399/LT1399HV
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Power Supplies
The LT1398/LT1399 will operate from single or split
supplies from ±2V (4V total) to ±6V (12V total). The
LT1399HV will operate from single or split supplies from
±2V (4V total) to ±7.5V (15V total). It is not necessary to
use equal value split supplies, however the offset voltage
and inverting input bias current will change. The offset
voltage changes about 600µV per volt of supply mis-
match. The inverting bias current will typically change
about 2µA per volt of supply mismatch.
Slew Rate
Unlike a traditional voltage feedback op amp, the slew rate
of a current feedback amplifier is not independent of the
amplifier gain configuration. In a current feedback ampli-
fier, both the input stage and the output stage have slew rate
limitations. In the inverting mode, and for gains of 2 or more
in the noninverting mode, the signal amplitude between the
input pins is small and the overall slew rate is that of the
output stage. For gains less than 2 in the noninverting mode,
the overall slew rate is limited by the input stage.
The input slew rate of the LT1398/LT1399/LT1399HV is
approximately 600V/µs and is set by internal currents and
capacitances. The output slew rate is set by the value of the
feedback resistor and internal capacitance. At a gain of 2
with 324Ω feedback and gain resistors and ±5V supplies,
the output slew rate is typically 800V/µs. Larger feedback
resistors will reduce the slew rate as will lower supply
voltages.
Enable/ Disable
Each amplifier of the LT1398/LT1399/LT1399HV has a
unique high impedance, zero supply current mode which
is controlled by its own EN pin. These amplifiers are
designed to operate with CMOS logic; the amplifiers draw
zero current when these pins are high. To activate each
amplifier, its EN pin is normally pulled to a logic low.
However, supply current will vary as the voltage between
the V+ supply and EN is varied. As seen in Figure 1, +IS
does vary with (V+ – VEN), particularly when the voltage
difference is less than 3V. For normal operation, it is
important to keep the EN pin at least 3V below the V+
supply. If a V+ of less than 3V is desired, and the amplifier
will remain enabled at all times, then the EN pin should be
tied to the V– supply. The enable pin current is approxi-
mately 30µA when activated. If using CMOS open-drain
logic, an external 1k pull-up resistor is recommended to
ensure that the LT1399 remains disabled in spite of any
CMOS drain-leakage currents.
Figure 1. +IS vs (V+ – VEN)
V
+
– V
EN
(V)
0
0
+I
S
(mA)
0.5
1.5
2.0
2.5
5.0
3.5
245
1398/99 F01
1.0
4.0
4.5
3.0
1367
T
A
= 25°C
V
+
= 5V
V
–
= –5V
V
–
= 0V
Figure 2. Amplifier Enable Time, AV = 2
V
S
= ±5V
V
IN
= 1V R
F
= 324Ω
R
G
= 324ΩR
L
= 100Ω1398/99 F02
OUTPUT
EN
Figure 3. Amplifier Disable Time, AV = 2
V
S
= ±5V
V
IN
= 1V R
F
= 324Ω
R
G
= 324ΩR
L
= 100Ω1398/99 F03
OUTPUT
EN
11
LT1398/LT1399/LT1399HV
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The enable/disable times are very fast when driven from
standard 5V CMOS logic. Each amplifier enables in about
30ns (50% point to 50% point) while operating on ±5V
supplies (Figure 2). Likewise, the disable time is approxi-
mately 40ns (50% point to 50% point) (Figure 3).
Differential Input Signal Swing
To avoid any breakdown condition on the input transis-
tors, the differential input swing must be limited to ±5V. In
normal operation, the differential voltage between the
input pins is small, so the ±5V limit is not an issue. In the
disabled mode however, the differential swing can be the
same as the input swing, and there is a risk of device
breakdown if input voltage range has not been properly
considered.
3-Input Video MUX Cable Driver
The application on the first page of this data sheet shows
a low cost, 3-input video MUX cable driver. The scope
photo below (Figure 4) displays the cable output of a
30MHz square wave driving 150
Ω
. In this circuit the
active amplifier is loaded by the sum of R
F
and R
G
of each
disabled amplifier. Resistor values have been chosen to
keep the total back termination at 75Ω while maintaining
a gain of 1 at the 75Ω load. The switching time between
any two channels is approximately 32ns when both
enable pins are driven.
When building the board, care was taken to minimize
trace lengths at the inverting input. The ground plane was
also pulled away from R
F
and R
G
on both sides of the
board to minimize stray capacitance.
Figure 5. 3-Input Video MUX Switching Response (AV = 2)
V
S
= ±5V 20ns/DIV
V
INA
= V
INB
= 2V
P-P
at 3.58MHz
1398/99 F05
EN A
EN B
OUTPUT
Using the LT1399 to Drive LCD Displays
Driving the current crop of XGA and UXGA LCD displays
can be a difficult problem because they require drive
voltages of up to 12V, are usually a capacitive load of over
300pF, and require fast settling. The LT1399HV is par-
ticularly well suited for driving these LCD displays be-
cause it is capable of swinging more than ±6V on ±7.5V
supplies, and it can drive large capacitive loads with a
small series resistor at the output, minimizing settling
time. As seen in Figures 6 and 7, at a gain of +3 with a
16.9Ω output series resistor and a 330pF load, the
LT1399HV is capable of settling to 0.1% in 30ns for a 6V
step. Similarly, a 12V output step settles in 70ns.
Figure 6. LT1399/LT1399HV Large-Signal Pulse Response
V
IN
V
OUT
V
S
= ±5V 20ns/DIV
R
F
= 324Ω
R
G
= 162Ω
R
S
= 16.9Ω
C
L
= 330pF
1398/99 AI06
Figure 4. Square Wave Response
OUTPUT
200mV/DIV
5ns/DIV
1398/99 F04
R
L
= 150Ω
R
F
= R
G
= 324Ω
f = 10MHz
12
LT1398/LT1399/LT1399HV
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Buffered RGB to Color-Difference Matrix
Two LT1398s can be used to create buffered color-
difference signals from RGB inputs (Figure 8). In this
application, the R input arrives via 75Ω coax. It is routed
to the noninverting input of LT1398 amplifier A1 and to
a 1082Ω resistor R8. There is also an 80.6Ω termination
–
+
A2
1/2 LT1398
–
+
B1
1/2 LT1398
–
+
A1
1/2 LT1398
R7
324Ω
R6
162ΩR5
324Ω
R10
2940Ω
R9
549Ω
R11
80.6Ω
R
G
B
R12
86.6Ω
R13
76.8Ω
ALL RESISTORS 1%
V
S
= ±5V
R8
1082Ω
75Ω
SOURCES
R1
324Ω
R2
324Ω
R4
324Ω
R3
324Ω
B-Y
Y
R-Y
1398/99 F08
–
+
B2
1/2 LT1398
resistor R11, which yields a 75Ω input impedance at the
R input when considered in parallel with R8. R8 connects
to the inverting input of a second LT1398 amplifier (A2),
which also sums the weighted G and B inputs to create a
–0.5 • Y output. LT1398 amplifier B1 then takes the
–0.5 • Y output and amplifies it by a gain of –2, resulting
in the Y output. Amplifier A1 is configured in a noninvert-
ing gain of 2 with the bottom of the gain resistor R2 tied
to the Y output. The output of amplifier A1 thus results in
the color-difference output R-Y.
The B input is similar to the R input. It arrives via 75Ω
coax, and is routed to the noninverting input of LT1398
amplifier B2, and to a 2940Ω resistor R10. There is also
a 76.8Ω termination resistor R13, which yields a 75Ω
input impedance when considered in parallel with R10.
R10 also connects to the inverting input of amplifier A2,
adding the B contribution to the Y signal as discussed
above. Amplifier B2 is configured in a noninverting gain
of 2 configuration with the bottom of the gain resistor R4
tied to the Y output. The output of amplifier B2 thus
results in the color-difference output B-Y.
Figure 7. LT1399HV Output Voltage Swing
V
IN
V
OUT
V
S
= ±7.5V 50ns/DIV
R
F
= 324Ω
R
G
= 162Ω
R
S
= 16.9Ω
C
L
= 330pF
1398/99 F07
Figure 8. Buffered RGB to Color-Difference Matrix
13
LT1398/LT1399/LT1399HV
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The G input also arrives via 75Ω coax and adds its
contribution to the Y signal via a 549Ω resistor R9, which
is tied to the inverting input of amplifier A2. There is also
an 86.6Ω termination resistor R12, which yields a 75Ω
termination when considered in parallel with R9. Using
superposition, it is straightforward to determine the
output of amplifier A2. Although inverted, it sums the R,
G and B signals in the standard proportions of 0.3R,
0.59G and 0.11B that are used to create the Y signal.
Amplifier B1 then inverts and amplifies the signal by 2,
resulting in the Y output.
Buffered Color-Difference to RGB Matrix
The LT1399 can be used to create buffered RGB outputs
from color-difference signals (Figure 9). The R output is
a back-terminated 75Ω signal created using resistor R5
and LT1399 amplifier A1 configured for a gain of +2 via
324Ω resistors R3 and R4. The noninverting input of
amplifier A1 is connected via 1k resistors R1 and R2 to
the Y and R-Y inputs respectively, resulting in cancella-
tion of the Y signal at the amplifier input. The remaining
R signal is then amplified by A1.
The B output is also a back-terminated 75Ω signal
created using resistor R16 and amplifier A3 configured
for a gain of +2 via 324Ω resistors R14 and R15. The
noninverting input of amplifier A3 is connected via 1k
resistors R12 and R13 to the Y and B-Y inputs respec-
tively, resulting in cancellation of the Y signal at the
amplifier input. The remaining B signal is then amplified
by A3.
The G output is the most complicated of the three. It is a
weighted sum of the Y, R-Y and B-Y inputs. The Y input
is attenuated via resistors R6 and R7 such that amplifier
A2’s noninverting input sees 0.83Y. Using superposition,
we can calculate the positive gain of A2 by assuming that
R8 and R9 are grounded. This results in a gain of 2.41 and
a contribution at the output of A2 of 2Y. The R-Y input is
amplified by A2 with the gain set by resistors R8 and R10,
giving an amplification of –1.02. This results in a contri-
bution at the output of A2 of 1.02Y – 1.02R. The B-Y input
is amplified by A2 with the gain set by resistors R9 and
R10, giving an amplification of –0.37. This results in a
contribution at the output of A2 of 0.37Y – 0.37B.
If we now sum the three contributions at the output of A2,
we get:
A2
OUT
= 3.40Y – 1.02R – 0.37B
It is important to remember though that Y is a weighted
sum of R, G and B such that:
Y = 0.3R + 0.59G + 0.11B
If we substitute for Y at the output of A2 we then get:
A2
OUT
= (1.02R – 1.02R) + 2G + (0.37B – 0.37B)
= 2G
The back-termination resistor R11 then halves the output
of A2 resulting in the G output.
–
+
A2
1/3 LT1399
R7
1k
B-Y
R-Y
Y
R10
324Ω
R11
75Ω
R6
205Ω
R2
1k
R1
1k
R8
316Ω
R9
845Ω
–
+
A3
1/3 LT1399
R14
324Ω
B
G
R16
75Ω
R12
1k
R13
1k
R15
324Ω
ALL RESISTORS 1%
VS = ±5V
–
+
A1
1/3 LT1399
R3
324Ω
R
R5
75Ω
R4
324Ω
1398/99 F09
Figure 9. Buffered Color-Difference to RGB Matrix
14
LT1398/LT1399/LT1399HV
sn13989 13989fas
SI PLIFIED SCHE ATIC
WW
, each amplifier
EN
+IN –IN OUT
V
+
V
–
1398/99 SS
15
LT1398/LT1399/LT1399HV
sn13989 13989fas
S Package
16-Lead Plastic Small Outline (Narrow 0.150)
(LTC DWG # 05-08-1610)
Dimensions in inches (millimeters) unless otherwise noted.
PACKAGE DESCRIPTIO
U
GN Package
16-Lead Plastic SSOP (Narrow 0.150)
(LTC DWG # 05-08-1641)
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 represen-
tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
GN16 (SSOP) 0398
* DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
** DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD
FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
12
345678
0.229 – 0.244
(5.817 – 6.198)
0.150 – 0.157**
(3.810 – 3.988)
16 15 14 13
0.189 – 0.196*
(4.801 – 4.978)
12 11 10 9
0.016 – 0.050
(0.406 – 1.270)
0.015 ± 0.004
(0.38 ± 0.10) × 45°
0° – 8° TYP
0.007 – 0.0098
(0.178 – 0.249)
0.053 – 0.068
(1.351 – 1.727)
0.008 – 0.012
(0.203 – 0.305)
0.004 – 0.0098
(0.102 – 0.249)
0.025
(0.635)
BSC
0.009
(0.229)
REF
0.016 – 0.050
0.406 – 1.270
0.010 – 0.020
(0.254 – 0.508)× 45°
0° – 8° TYP
0.008 – 0.010
(0.203 – 0.254)
12345678
0.150 – 0.157**
(3.810 – 3.988)
16 15 14 13
0.386 – 0.394*
(9.804 – 10.008)
0.228 – 0.244
(5.791 – 6.197)
12 11 10 9
S16 0695
0.053 – 0.069
(1.346 – 1.752)
0.014 – 0.019
(0.355 – 0.483)
0.004 – 0.010
(0.101 – 0.254)
0.050
(1.270)
TYP
DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD
FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
*
**
16
LT1398/LT1399/LT1399HV
sn13989 13989fas
PART NUMBER DESCRIPTION COMMENTS
LT1203/LT1205 150MHz Video Multiplexers 2:1 and Dual 2:1 MUXs with 25ns Switch Time
LT1204 4-Input Video MUX with Current Feedback Amplifier Cascadable Enable 64:1 Multiplexing
LT1227 140MHz Current Feedback Amplifier 1100V/µs Slew Rate, Shutdown Mode
LT1252/LT1253/LT1254 Low Cost Video Amplifiers Single, Dual and Quad Current Feedback Amplifiers
LT1259/LT1260 Dual/Triple Current Feedback Amplifier 130MHz Bandwidth, 0.1dB Flatness >30MHz
LT1395/LT1396/LT1397 Single/Dual/Quad Current Feedback Amplifiers 400MHz Bandwidth, 0.1dB Flatness >100MHz
LT1675/LT1675-1 Triple/Single 2:1 Buffered Video Mulitplexer 2.5ns Switching Time, 250MHz Bandwidth
LT1806/LT1807 Single/Dual 325MHz Rail-to-Rail In/Out Op Amp Low Distortion, Low Noise
LT1809/LT1810 Single/Dual 180MHz Rail-to-Rail In/Out Op Amp 350V/µs, Low Distortion
LINEAR TECHNOLOGY CORPORATION 1998
LT/TP 0501 2K REV A • PRINTED IN USA
U
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PPLICATITYPICAL
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900
●
FAX: (408) 434-0507
●
www.linear-tech.com
RELATED PARTS
Single Supply RGB Video Amplifier
The LT1399 can be used with a single supply voltage of
6V or more to drive ground-referenced RGB video. In
Figure 10, two 1N4148 diodes D1 and D2 have been
placed in series with the output of the LT1399 amplifier
A1 but within the feedback loop formed by resistor R8.
These diodes effectively level-shift A1’s output down-
ward by 2 diodes, allowing the circuit output to swing to
ground.
Amplifier A1 is used in a positive gain configuration. The
feedback resistor R8 is 324Ω. The gain resistor is created
from the parallel combination of R6 and R7, giving a
Thevenin equivalent 80.4Ω connected to 3.75V. This
gives an AC gain of +5 from the noninverting input of
amplifier A1 to the cathode of D2. However, the video
input is also attenuated before arriving at A1’s positive
input. Assuming a 75Ω source impedance for the signal
driving V
IN
, the Thevenin equivalent signal arriving at
A1’s positive input is 3V + 0.4V
IN
, with a source imped-
ance of 714Ω. The combination of these two inputs gives
an output at the cathode of D2 of 2 • V
IN
with no additional
DC offset. The 75Ω back termination resistor R9 halves
the signal again such that V
OUT
equals a buffered version
of V
IN
.
It is important to note that the 4.7µF capacitor C1 has
been added to provide enough current to maintain the
voltage drop across diodes D1 and D2 when the circuit
output drops low enough that the diodes might otherwise
reverse bias. This means that this circuit works fine for
continuous video input, but will require that C1 charge up
after a period of inactivity at the input.
–
+
A1
1/3 LT1399
D1
1N4148
C1
4.7µF
D2
1N4148 R9
75Ω
R8
324Ω
V
S
6V TO 12V
R7
324Ω
R5
2.32Ω
R4
75Ω
V
IN
R2
1300Ω
R1
1000Ω
5V
R6
107Ω
R3
160Ω
V
OUT
1398/99 F10
VIDEO
SOURCE
75Ω
Figure 10. Single Supply RGB Video Amplifier (1 of 3 Channels)
