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LT1187CS8 [Linear]

Low Power Video Difference Amplifier; 低功耗视频差分放大器器
LT1187CS8
型号： LT1187CS8
厂家： Linear    Linear
描述：

Low Power Video Difference Amplifier
低功耗视频差分放大器器

放大器 光电二极管
文件： 总12页 (文件大小：386K)
中文：  中文翻译
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LT1187  
Low Power  
Video Difference Amplifier  
U
DESCRIPTIO  
EATURE  
S
F
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The LT1187 is a difference amplifier optimized for opera-  
tion on ±5V, or a single 5V supply, and gain ≥2. This  
versatile amplifier features uncommitted high input im-  
pedance (+) and (–) inputs, and can be used in differential  
or single-ended configurations. Additionally, a second set  
of inputs give gain adjustment and DC control to the  
difference amplifier.  
Differential or Single-Ended Gain Block (Adjustable)  
–3dB Bandwidth, AV = ±2  
Slew Rate  
Low Supply Current  
Output Current  
CMRR at 10MHz  
LT1193 Pin Compatible  
Low Cost  
Single 5V Operation  
Drives Cables Directly  
Output Shutdown  
50MHz  
165V/µs  
13mA  
±20mA  
40dB  
The LT1187’s high slew rate, 165V/µs, wide bandwidth,  
50MHz, and ±20mA output current require only 13mA of  
supply current. The shutdown feature reduces the power  
dissipation to a mere 15mW, and allows multiple amplifi-  
ers to drive the same cable.  
O U  
PPLICATI  
S
A
The LT1187 is a low power version of the popular LT1193,  
and is available in 8-pin miniDIPs and SO packages. For  
applications with gains of 10 or more, see the LT1189  
data sheet.  
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Line Receivers  
Video Signal Processing  
Cable Drivers  
Tape and Disc Drive Systems  
U
O
TYPICAL APPLICATI  
Cable Sense Amplifier for Loop Through Connections  
with DC Adjust  
Closed-Loop Gain vs Frequency  
40  
V
IN  
V
= ±5V  
= 1k  
S
L
R
30  
20  
5V  
3
2
+
–
7
CABLE  
6
V
LT1187  
OUT  
1
8
V
+
–
DC  
4
10  
–5V  
1k  
0
1k  
–10  
0.1  
1
10  
100  
FREQUENCY (MHz)  
LT1187 • TA01  
LT1187 • TA02  
1
LT1187  
W W W  
U
/O  
ABSOLUTE AXI U RATI GS  
PACKAGE RDER I FOR ATIO  
Total Supply Voltage (V + to V –) ............................. 18V  
Differential Input Voltage ........................................ ±6V  
Input Voltage .......................................................... ±VS  
Output Short Circuit Duration (Note 1) ........ Continuous  
Operating Temperature Range  
LT1187M..................................... – 55°C to 150°C  
LT1187C............................................. 0°C to 70°C  
Junction Temperature (Note 2)  
Plastic Package (CN8,CS8) ......................... 150°C  
Ceramic Package (CJ8,MJ8) ....................... 175°C  
Storage Temperature Range ................ – 65°C to 150°C  
Lead Temperature (Soldering, 10 sec.)................ 300°C  
TOP VIEW  
ORDER PART  
+/REF  
–IN  
1
2
3
4
8
7
6
5
–/FB  
NUMBER  
+
V
LT1187MJ8  
LT1187CJ8  
LT1187CN8  
LT1187CS8  
+IN  
OUT  
S/D  
–
V
J8 PACKAGE  
N8 PACKAGE  
8-LEAD HERMETIC DIP 8-LEAD PLASTIC DIP  
S8 PACKAGE  
8-LEAD PLASTIC SOIC  
LT1187 • POI01  
S8 PART MARKING  
1187  
TJMAX = 175°C, θJA = 100°C/W (J8)  
TJMAX = 150°C, θJA = 100°C/W (N8)  
JMAX = 150°C, θJA = 150°C/W (S8)  
T
Consult factory for Industrial grade parts.  
+
5V LECTR AL CHARACTERIST  
E
IC  
ICS TA = 25°C, (Note 3)  
–
VS = ±5V, VREF = 0V, RFB1 = 900Ω from pins 6 to 8, RFB2 = 100Ω from pin 8 to ground, RL = RFB1 + RFB2 = 1k, CL ≤ 10pF, pin 5 open.  
LT1187M/C  
SYMBOL  
PARAMETER  
CONDITIONS  
MIN  
TYP  
MAX  
UNITS  
V
OS  
Input Offset Voltage  
Either Input, (Note 4)  
SOIC Package  
2.0  
2.0  
10  
11  
mV  
mV  
I
I
Input Offset Current  
Input Bias Current  
Either Input  
Either Input  
0.2  
1.0  
µA  
µA  
OS  
±0.5 ±2.0  
65  
B
e
Input Noise Voltage  
Input Noise Current  
Input Resistance  
f = 10kHz  
O
nV/√Hz  
pA/√Hz  
kΩ  
n
i
f = 10kHz  
O
1.5  
n
R
Differential  
Either Input  
(Note 5)  
100  
IN  
C
V
Input Capacitance  
2.0  
pF  
IN  
Input Voltage Limit  
±380  
3.5  
mV  
IN LIM  
Input Voltage Range  
Common-Mode Rejection Ratio  
Power Supply Rejection Ratio  
Output Voltage Swing  
–2.5  
70  
V
CMRR  
PSRR  
V
CM  
= –2.5V to 3.5V  
100  
dB  
V = ±2.375V to ±8V  
S
70  
85  
dB  
V
V = ±5V, R = 1k, A = 50  
S
±3.8  
±6.7  
±6.4  
±4.0  
±7.0  
±6.8  
V
OUT  
L
V
V = ±8V, R = 1k, A = 50  
S
L
V
V = ±8V, R = 300Ω, A = 50, (Note 3)  
S
L
V
G
Gain Error  
V = ±1V, A = 10, R = 1k  
0.2  
165  
53  
1.0  
%
V/µs  
MHz  
MHz  
ns  
E
O
V
L
SR  
Slew Rate  
(Note 6, 10)  
V = 1V , (Note 7)  
100  
150  
FPBW  
BW  
Full Power Bandwidth  
Small Signal Bandwidth  
Rise Time, Fall Time  
Propagation Delay  
Overshoot  
O
P-P  
A = 10  
V
5.7  
230  
26  
t , t  
r
A = 50, V = ±1.5V, 20% to 80% (Note 10)  
325  
f
V
O
t
R = 1k, V = ±125mV, 50% to 50%  
ns  
PD  
L
O
V = ±50mV  
O
0
%
t
Settling Time  
3V Step, 0.1%, (Note 8)  
100  
0.6  
0.8  
13  
ns  
s
Diff A  
Differential Gain  
Differential Phase  
Supply Current  
R = 1k, A = 4, (Note 9)  
%
V
L
V
Diff Ph  
R = 1k, A = 4, (Note 9)  
DEG  
P-P  
L
V
I
16  
mA  
mA  
S
–
Shutdown Supply Current  
Pin 5 at V  
0.8  
1.5  
2
LT1187  
+
5V LECTR AL CHARACTERIST  
E
IC  
ICS TA = 25°C, (Note 3)  
–
VS = ±5V, VREF = 0V, RFB1 = 900Ω from pins 6 to 8, RFB2 = 100Ω from pin 8 to ground, RL = RFB1 + RFB2 = 1k, CL ≤ 10pF, pin 5 open.  
LT1187M/C  
SYMBOL  
PARAMETER  
CONDITIONS  
MIN  
TYP  
MAX  
UNITS  
µA  
–
I
t
t
Shutdown Pin Current  
Turn On Time  
Pin 5 at V  
5
25  
S/D  
ON  
–
Pin 5 from V to Ground, R = 1k  
500  
600  
ns  
L
–
Turn Off Time  
Pin 5 from Ground to V , R = 1k  
ns  
OFF  
L
5V LECTR AL CHARACTERIST  
ICS  
open.  
TA = 25°C, (Note 3)  
E
IC  
–
VS+ = 5V, VS = 0V, VREF = 2.5V, RFB1 = 900Ω from pins 6 to 8, RFB2 = 100Ω from pin 8 to VREF, RL = RFB1 + RFB2 = 1k, CL ≤ 10pF, pin 5  
LT1187M/C  
SYMBOL  
PARAMETER  
CONDITIONS  
MIN  
TYP  
MAX  
UNITS  
V
OS  
Input Offset Voltage  
Either Input, (Note 4)  
SOIC Package  
2.0  
2.0  
10  
12  
mV  
mV  
I
I
Input Offset Current  
Either Input  
Either Input  
0.2  
1.0  
±2.0  
3.5  
µA  
µA  
V
OS  
Input Bias Current  
±0.5  
B
Input Voltage Range  
Common-Mode Rejection Ratio  
Output Voltage Swing  
2.0  
70  
CMRR  
V
CM  
= 2.0V to 3.5V  
100  
4.0  
0.15  
130  
5.3  
12  
dB  
V
V
R = 300Ω to Ground  
V
V
High  
Low  
3.6  
OUT  
L
OUT  
OUT  
(Note 3)  
0.4  
SR  
Slew Rate  
V = 1.5V to 3.5V  
O
V/µs  
MHz  
mA  
BW  
Small-Signal Bandwidth  
Supply Current  
A = 10  
V
I
I
15  
1.5  
25  
S
–
–
Shutdown Supply Current  
Shutdown Pin Current  
Pin 5 at V  
Pin 5 at V  
0.8  
5
mA  
µA  
S/D  
+
5V LECTR AL CHARACTERIST  
E
IC  
ICS –55°C ≤ TA ≤ 125°C, (Note 3)  
–
VS = ±5V, VREF = 0V, RFB1 = 900Ω from pins 6 to 8, RFB2 = 100Ω from pin 8 to ground, RL = RFB1 + RFB2 = 1k, CL ≤ 10pF, pin 5 open.  
LT1187M  
SYMBOL  
PARAMETER  
CONDITIONS  
MIN  
TYP  
MAX  
UNITS  
mV  
µV/°C  
µA  
V
OS  
Input Offset Voltage  
Either Input, (Note 4)  
2.0  
15  
∆V /∆T  
OS  
Input V Drift  
8.0  
OS  
I
I
Input Offset Current  
Either Input  
Either Input  
0.2  
1.5  
±3.5  
3.5  
OS  
B
Input Bias Current  
±0.5  
µA  
Input Voltage Range  
–2.5  
70  
V
CMRR  
PSRR  
Common-Mode Rejection Ratio  
Power Supply Rejection Ratio  
Output Voltage Swing  
V
CM  
= –2.5V to 3.5V  
100  
85  
dB  
V = ±2.375V to ±8V  
S
60  
dB  
V
OUT  
V = ±5V, R = 1k, A = 50  
±3.7  
±6.6  
±6.4  
±4.0  
±7.0  
±6.8  
0.2  
13  
V
S
L
V
V = ±8V, R = 1k, A = 50  
S
L
V
V = ±8V, R = 300Ω, A = 50, (Note 3)  
S
L
V
G
E
Gain Error  
V = ±1V, A = 10, R = 1k  
1.2  
17  
%
mA  
mA  
µA  
O
V
L
I
Supply Current  
S
–
Shutdown Supply Current  
Shutdown Pin Current  
Pin 5 at V , (Note 11)  
0.8  
1.5  
25  
–
I
Pin 5 at V  
5
S/D  
3
LT1187  
+
5V LECTR AL CHARACTERIST  
E
IC  
ICS 0°C ≤ TA ≤ 70°C, (Note 3)  
–
VS = ±5V, VREF = 0V, RFB1 = 900Ω from pins 6 to 8, RFB2 = 100Ω from pin 8 to ground, RL = RFB1 + RFB2 = 1k, CL ≤ 10pF, pin 5 open.  
LT1187C  
SYMBOL  
PARAMETER  
CONDITIONS  
MIN  
TYP  
MAX  
UNITS  
mV  
µV/°C  
µA  
V
OS  
Input Offset Voltage  
Either Input, (Note 4)  
2.0  
12  
∆V /∆T  
OS  
Input V Drift  
9.0  
OS  
I
I
Input Offset Current  
Either Input  
Either Input  
0.2  
1.5  
±3.5  
3.5  
OS  
B
Input Bias Current  
±0.5  
µA  
Input Voltage Range  
–2.5  
70  
V
CMRR  
PSRR  
Common-Mode Rejection Ratio  
Power Supply Rejection Ratio  
Output Voltage Swing  
V
CM  
= –2.5V to 3.5V  
100  
85  
dB  
V = ±2.375V to ±8V  
S
65  
dB  
V
OUT  
V = ±5V, R = 1k, A = 50  
±3.7  
±6.6  
±6.4  
±4.0  
±7.0  
±6.8  
0.2  
13  
V
S
L
V
V = ±8V, R = 1k, A = 50  
S
L
V
V = ±8V, R = 300Ω, A = 50, (Note 3)  
S
L
V
G
E
Gain Error  
V = ±1V, A = 10, R = 1k  
1.0  
17  
%
mA  
mA  
µA  
O
V
L
I
Supply Current  
S
–
Shutdown Supply Current  
Shutdown Pin Current  
Pin 5 at V , (Note 11)  
0.8  
5
1.5  
25  
–
I
Pin 5 at V  
S/D  
ELECTRICAL CHARACTERISTICS  
5V  
0°C ≤ TA ≤ 70°C, (Note 3)  
VS+ = 5V, VS– = 0V, VREF = 2.5V, RFB1 = 900Ω from pins 6 to 8, RFB2 = 100Ω from pin 8 to VREF, RL = RFB1 + RFB2 = 1k, CL ≤ 10pF, pin 5 open.  
LT1187C  
TYP  
SYMBOL  
PARAMETER  
CONDITIONS  
MIN  
MAX  
UNITS  
V
OS  
Input Offset Voltage  
Either Input, (Note 4)  
SOIC Package  
2.0  
2.0  
12.0  
13.0  
mV  
mV  
∆V /∆T  
Input V Drift  
9.0  
0.2  
µV/°C  
µA  
µA  
V
OS  
OS  
I
I
Input Offset Current  
Either Input  
Either Input  
1.5  
±3.5  
3.5  
OS  
B
Input Bias Current  
±0.5  
Input Voltage Range  
Common-Mode Rejection Ratio  
Output Voltage Swing  
2.0  
70  
CMRR  
V
CM  
= 2.0V to 3.5V  
100  
4.0  
0.15  
12  
dB  
V
V
OUT  
R = 300Ω to Ground  
L
V
V
High  
Low  
3.5  
OUT  
OUT  
(Note 3)  
0.4  
16  
I
I
Supply Current  
mA  
mA  
µA  
S
–
Shutdown Supply Current  
Shutdown Pin Current  
Pin 5 at V , (Note 11)  
0.8  
5
1.5  
25  
–
Pin 5 at V  
S/D  
Note 1: A heat sink may be required to keep the junction temperature below  
absolute maximum when the output is shorted continuously.  
Note 6: Slew rate is measured between ±0.5V on the output, with a V step  
IN  
of ±0.75V, A = 3 and R = 1k.  
V L  
Note 2: T is calculated from the ambient temperature T and power dissipation  
Note 7: Full power bandwidth is calculated from the slew rate measurement:  
FPBW = SR/2πVp.  
Note 8: Settling time measurement techniques are shown in “Take the  
Guesswork Out of Settling Time Measurements,” EDN, September 19, 1985.  
J
A
P
D
according to the following formulas:  
LT1187MJ8,LT1187CJ8: T = T + (P × 100°C/W)  
J
A
D
LT1187CN8:  
LT1187CS8:  
T = T + (P × 100°C/W)  
J A D  
T = T + (P × 150°C/W)  
J
A
D
Note 9: NTSC (3.58MHz).  
Note 3: When R = 1k is specified, the load resistor is R + R , but when  
L
FB1  
FB2  
Note 10: AC parameters are 100% tested on the ceramic and plastic DIP  
packaged parts (J8 and N8 suffix) and are sample tested on every lot of the SO  
packaged parts (S8 suffix).  
R = 300Ω is specified, then an additional 430Ω is added to the output such  
L
that (R + R ) in parallel with 430Ω is R = 300Ω.  
FB1  
FB2  
L
Note 4: V measured at the output (pin 6) is the contribution from both input  
OS  
Note 11: See Application section for shutdown at elevated temperatures. Do  
pair, and is input referred.  
not operate shutdown above T > 125°C.  
J
Note 5: V  
is the maximum voltage between –V and +V (pin 2 and  
IN LIM  
IN IN  
pin 3) for which the output can respond.  
4
LT1187  
U W  
TYPICAL PERFOR A CE CHARACTERISTICS  
Input Bias Current vs  
Common-Mode Voltage vs  
Temperature  
Common-Mode Voltage  
Input Bias Current vs Temperature  
+
100  
0
V
3.0  
2.5  
V
= ±5V  
S
+
–0.5  
–1.0  
–1.5  
–2.0  
V
= 1.8V TO 9V  
+I  
B
2.0  
1.5  
1.0  
0.5  
–100  
–200  
–300  
–400  
–I  
B
I
OS  
–55°C  
2.0  
1.5  
1.0  
0.5  
25°C  
+
V
= –1.8V TO –9V  
0
125°C  
–
–0.5  
V
–5 –4 –3 –2 –1  
0
1
2
3
4
5
–50 –25  
0
25  
50  
75  
100 125  
–50 –25  
0
25  
50  
75 100 125  
TEMPERATURE (°C)  
TEMPERATURE (°C)  
COMMON-MODE VOLTAGE (V)  
LT1187 • TPC02  
LT1187 • TPC03  
LT1187 • TPC01  
Equivalent Input Noise Voltage vs  
Frequency  
Equivalent Input Noise Current vs  
Frequency  
Supply Current vs Supply Voltage  
600  
500  
400  
300  
200  
100  
0
12  
10  
8
16  
14  
12  
10  
8
V
= ±5V  
= 25°C  
= 0Ω  
V
= ±5V  
= 25°C  
= 100k  
S
A
S
S
A
S
T
T
R
R
–55°C  
25°C  
6
125°C  
4
2
0
10  
100  
1k  
10k  
100k  
10  
100  
1k  
10k  
100k  
0
2
4
6
8
10  
FREQUENCY (Hz)  
FREQUENCY (Hz)  
±SUPPLY VOLTAGE (V)  
LT1187 • TPC04  
LT1187 • TPC05  
LT1187 • TPC06  
Shutdown Supply Current vs  
Temperature  
Gain Error vs Temperature  
Open-Loop Gain vs Temperature  
8
6
4
2
0
6
5
4
3
2
1
0
0
–0.05  
–0.10  
–0.15  
V
S
= ±5V  
= ±2V  
= 10  
= 1k  
V
= ±5V  
V
S
V
O
= ±5V  
= ±3V  
S
V
OUT  
V
R
R
L
= 1k  
A
L
V
= –V + 0.6V  
EE  
S/D  
V
S/D  
= –V + 0.4V  
EE  
R
L
= 500Ω  
V
S/D  
= –V + 0.2V  
EE  
V
S/D  
= –V  
EE  
–0.20  
–50 –25  
0
25  
50  
75 100 125  
–50 –25  
0
25  
50  
75 100 125  
–50 –25  
0
25  
50  
75 100 125  
TEMPERATURE (°C)  
TEMPERATURE (°C)  
TEMPERATURE (°C)  
LT1187 • TPC09  
LT1187 • TPC07  
LT1187 • TPC08  
5
LT1187  
U W  
TYPICAL PERFOR A CE CHARACTERISTICS  
Open-Loop Voltage Gain vs  
Gain Bandwidth Product vs  
Supply Voltage  
Gain, Phase vs Frequency  
Load Resistance  
100  
80  
60  
40  
20  
0
100  
80  
16k  
12k  
8k  
60  
50  
V
T
= ±5V  
= 25°C  
= 1k  
S
T
= –55°C  
A
= 20dB  
A
T
V
V
V
= ±5V  
= ±3V  
= +25˚C  
S
O
A
A
PHASE  
R
L
= 25°C  
A
T
60  
T
A
= 125˚C  
40  
20  
0
GAIN  
40  
30  
4k  
–20  
–20  
0
100k  
1M  
10M  
100M  
100  
1k  
LOAD RESISTANCE (Ω)  
10k  
0
2
4
6
8
10  
FREQUENCY (Hz)  
±SUPPLY VOLTAGE (V)  
LT1187 • TPC11  
LT1187 • TPC12  
Gain Bandwidth Product and  
Unity Gain Phase Margin vs  
Temperature  
Common-Mode Rejection Ratio  
vs Frequency  
Output Impedance vs Frequency  
65  
55  
45  
35  
100  
10  
80  
70  
60  
60  
50  
40  
30  
V
T
= ±5V  
= 25°C  
V
= ±5V  
= 1k  
S
A
S
L
V
= ±5V  
= 25°C  
= 1k  
S
A
L
R
T
R
GAIN BANDWIDTH  
PRODUCT  
50  
40  
30  
A
= 10  
= 2  
V
UNITY GAIN  
PHASE MARGIN  
1.0  
0.1  
A
V
1k  
10k  
100k  
1M  
10M  
100M  
–50 –25  
0
25  
50  
75 100 125  
100k  
1M  
10M  
100M  
TEMPERATURE (°C)  
FREQUENCY (Hz)  
FREQUENCY (Hz)  
LT1187 • TPC13  
LT1187 • TPC14  
LT1187 • TPC15  
Power Supply Rejection Ratio vs  
Frequency  
Output Short Circuit Current vs  
Temperature  
+
± Output Swing vs Supply Voltage  
V
36  
35  
–0.7  
–0.8  
–0.9  
–1.0  
–1.1  
80  
60  
40  
20  
0
V
= ±5V  
V
= ±5V  
S
A
S
T
= 25°C  
125°C  
V
= ±300mV  
RIPPLE  
25°C  
34  
33  
32  
31  
30  
+PSRR  
–PSRR  
–55°C  
R
L
= 1k  
±1.8V ≤ V ≤ ±9V  
S
125°C  
25°C  
0.5  
0.4  
0.3  
–55°C  
0.2  
0.1  
–20  
–
–50 –25  
0
25  
50  
75  
100 125  
0
2
4
6
8
10  
1k  
10k  
100k  
1M  
10M  
100M  
V
TEMPERATURE (°C)  
FREQUENCY (Hz)  
±SUPPLY VOLTAGE (V)  
LT1187 • TPC17  
LT1187 • TPC18  
LT1187 • TPC16  
6
LT1187  
U W  
TYPICAL PERFOR A CE CHARACTERISTICS  
Output Voltage Swing vs  
Load Resistance  
Output Voltage Step vs  
Settling Time, AV = 2  
Slew Rate vs Temperature  
250  
200  
150  
5
3
4
2
V
S
L
= ±5V  
= 1k  
= ±0.5V  
= 2  
V
= ±5V  
= 25°C  
= 1k  
V
= ±5V  
S
A
L
S
R
V
T
R
T
A
= –55°C  
O
V
10mV  
A
T
= 25°C  
= 25°C  
A
–SLEW RATE  
+SLEW RATE  
T
= 125°C  
A
1
0
–1  
–3  
–5  
T
A
–2  
–4  
10mV  
T
= –55°C  
A
T
A
= 125°C  
–50 –25  
0
25  
50  
75 100 125  
TEMPERATURE (°C)  
10  
100  
LOAD RESISTANCE (Ω)  
1000  
40  
50  
60  
70  
80  
90  
100  
SETTLING TIME (ns)  
LT1187 • TPC20  
LT1187 • TPC19  
LT1187 • TPC21  
Harmonic Distortion vs  
Output Voltage  
Large-Signal Transient Response  
–30  
–35  
–40  
–45  
–50  
–55  
–60  
V
= ±5V  
= 25°C  
= 1k  
S
A
L
T
R
f = 1MHz  
= 10  
HD  
3
A
V
HD  
2
4
6
7
0
1
2
3
5
OUTPUT VOLTAGE (V  
)
P-P  
INPUT IN LIMITING, AV = 3, SR = 180V/µs  
LT1187 • TPC22  
LT1187 • TPC23  
Small-Signal Transient Response  
Small-Signal Transient Response  
AV = 2, RFB = 1k, OVERSHOOT = 25%  
AV = 2, RFB = 1k, OVERSHOOT = 25%  
LT1187 • TPC24  
LT1187 • TPC25  
7
LT1187  
APPLICATIO S I FOR ATIO  
U
U U  
W
The primary use of the LT1187 is in converting high speed  
differential signals to a single-ended output. The LT1187  
videodifferenceamplifierhastwouncommittedhighinput  
impedance (+) and (–) inputs. The amplifier has another  
set of inputs which can be used for reference and feed-  
back. Additionally, this set of inputs give gain adjust and  
DC control to the difference amplifier. The voltage gain of  
the LT1187issetlikeaconventionaloperationalamplifier.  
Feedback is applied to pin 8, and it is optimized for gains  
of2orgreater. Theamplifiercanbeoperatedsingle-ended  
by connecting either the (+) or (–) inputs to the +/REF (pin  
1). The voltage gain is set by the resistors: (RFB + RG)/RG.  
Power Supply Bypassing  
The LT1187 is quite tolerant of power supply bypassing.  
In some applications a 0.1µF ceramic disc capacitor  
placed 1/2 inch from the amplifier is all that is required. In  
applications requiringgood settling time, it isimportant to  
use multiple bypass capacitors. A 0.1µF ceramic disc in  
parallel with a 4.7µF tantalum is recommended.  
Calculating the Output Offset Voltage  
Both input stages contribute to the output offset voltage at  
pin 6. The feedback correction forces balance in the input  
stages by introducing an Input VOS at pin 8. The complete  
expression for the output offset voltage is:  
Like the single-ended case, the differential voltage gain is  
setbytheexternalresistors:(RFB +RG)/RG. Themaximum  
input differential signal for which the output will respond  
is approximately ±0.38V.  
VOUT =(VOS +IOS(RS)+IB(RREF)) ×(RFB+RG)/RG +IB(RFB)  
RS represents the input source resistance, typically 75Ω,  
and RREF represents the finite source impedance from the  
DC reference voltage, for VREF grounded, RREF = 0Ω. The  
IOS is normally a small contributor and the expression  
simplifies to:  
S/D  
S/D  
+
+
V
V
5
5
3
2
3
2
7
7
V
+
+
IN  
V
–
–
IN  
6
6
LT1187  
LT1187  
V
V
OUT  
1
8
1
8
OUT  
+/REF  
–/FB  
+/REF  
–/FB  
VOUT = VOS(RFB+RG)/RG + IB(RFB)  
4
4
–
–
V
V
If RFB is limited to 1k the last term of the equation  
contributes only 2mV, since IB is less than 2µA.  
R
R
FB  
FB  
R
+
+
R
G
FB  
R
R
G
FB  
A
= +  
V
R
G
A
V
= –  
R
G
+
7
V
R
G
R
G
6
S/D  
S/D  
+
+
V
V
5
5
3
2
3
2
7
7
+
–
+
R
FB  
V
V
IN DIFF  
IN DIFF  
–
8
Q1  
Q2  
Q3  
Q4  
6
6
LT1187  
+/REF  
–/FB  
LT1187  
V
V
OUT  
1
8
1
8
OUT  
V
+/REF  
–/FB  
IN  
R
G
R
G
V
+
3
2
1
REF  
+
IN  
R
–
+
4
4
–
R
R
E
1.1k  
E
1.1k  
–
V
R
V
R
R
S
R
S
R
REF  
FB  
FB  
345µA  
350µA  
R
FB  
R
+R  
G
R
G
FB  
FB  
–
4
V
V
= (V  
IN DIFF  
+ V  
)
V
O
=
V
–
V
IN  
O
IN  
IN DIFF  
(
(
(
(
R
ILT1187 • AI02  
G
R
R
R
G
G
G
LT1187 • AI01  
Figure 1. Simplified Input Stage Schematic  
8
LT1187  
U
U U  
W
APPLICATIO S I FOR ATIO  
Operating with Low Closed-Loop Gains  
Small-Signal Transient Response  
The LT1187 has been optimized for closed-loop gains of  
2 or greater. For a closed-loop gain of 2 the response  
peaks about 2dB. Peaking can be eliminated by placing a  
capacitor across the feedback resistor, (feedback zero).  
This peaking shows up as time domain overshoot of  
about 25%.  
Closed-Loop Voltage Gain vs Frequency  
9
8
C
= 0pF  
FB  
7
6
5
AV = 2, WITH 8pF FEEDBACK CAPACITOR  
LT1187 • AI05  
C
= 5pF  
FB  
4
3
2
Extending the Input Range  
C
= 10pF  
FB  
V
= ±5V  
= 25°C  
= 2  
= 900Ω  
= 900Ω  
S
A
V
FB  
G
T
Figure 1 shows a simplified schematic of the LT1187. In  
normal operation the REF pin 1 is grounded or taken to a  
DC offset control voltage and differential signals are ap-  
plied between pins 2 and 3. The input responds linearly  
until all of the 345µA current flows through the 1.1k  
resistor and Q1 (or Q2) turns off. Therefore the maximum  
inputswingis380mVP or760mVP-P. Theseconddifferen-  
tial pair, Q3 and Q4, is running at slightly larger current so  
that when the first input stage limits, the second stage  
remains biased to maintain the feedback.  
A
R
R
1
0
–1  
100k  
1M  
10M  
100M  
FREQUENCY (Hz)  
LT1187 • AI03  
Small-Signal Transient Response  
Occasionally it is necessary to handle signals larger than  
760mVP-P at the input. The LT1187 input stage can be  
tricked to handle up to 1.5VP-P. To do this, it is necessary  
to ground pin 3 and apply the differential input signal  
between pin 1 and 2. The input signal is now applied  
across two 1.1k resistors in series. Since the input signal  
is applied to both input pairs, the first pair will run out of  
bias current before the second pair, causing the amplifier  
to go open-loop. The results of this technique are shown  
in the following scope photo.  
AV = 2, OVERSHOOT = 25%, RFB = RG = 1k  
LT1187 • AI04  
9
LT1187  
U
U U  
W
APPLICATIO S I FOR ATIO  
LT1187 in Unity Gain  
Performance Characteristics section. At very high el-  
evated temperature it is important to hold the shutdown  
pin close to the negative supply to keep the supply current  
from increasing.  
A
B
Send Color Video Over Twisted-Pair  
With an LT1187 it is possible to send and receive color  
compositevideosignalsmorethan1000feetonalowcost  
twisted-pair. A bidirectional “video bus” consists of the  
LT1195opampandtheLT1187videodifferenceamplifier.  
A pair of LT1195s at TRANSMIT 1, is used to generate  
differential signals to drive the line which is back-termi-  
natedinitscharacteristicimpedance.TheLT1187,twisted-  
pair receiver, converts signals from differential to single-  
ended. Topology of the LT1187 provides for cable com-  
pensation at the amplifier’s feedback node as shown. In  
this case, 1000 feet of twisted-pair is compensated with  
1000pF and 50Ω to boost the 3dB bandwidth of the  
systemfrom750kHzto4MHz. Thisbandwidthisadequate  
to pass a 3.58MHz chroma subcarrier, and the 4.5MHz  
soundsubcarrier.Attenuationinthecablecanbecompen-  
sated by lowering the gain set resistor RG. At TRANSMIT  
2, another pair of LT1195s serve the dual function to  
provide cable termination via low output impedance, and  
generatedifferentialsignalsforTRANSMIT2. Cabletermi-  
nation is made up of a 15Ω and 33Ω attenuator to reduce  
the differentialinput signalto the LT1187. Maximuminput  
C
(A) STANDARD INPUTS, PINS 2 TO 3, VIN = 1.0VP-P  
(B) EXTENDED INPUTS, PINS 2 TO 2, VIN = 1.0VP-P  
(C) EXTENDED INPUTS, PINS 1 TO 2, VIN = 2.0VP-P  
LT1187 • AI06  
Using the Shutdown Feature  
The LT1187 has a unique feature that allows the amplifier  
to be shutdown for conserving power, or for multiplexing  
severalamplifiersontoa commoncable. The amplifierwill  
shutdown by taking pin 5 to V–. In shutdown, the amplifier  
dissipates15mWwhilemaintainingatruehighimpedance  
output state of 20k in parallel with the feedback resistors.  
For MUX applications, the amplifiers may be configured  
inverting, noninverting, or differential. When the output is  
loaded with as little 1k from the amplifier’s feedback  
resistors, theamplifiershutsoffin600ns. Thisshutoffcan  
be under the control of HC CMOS operating between 0V  
and –5V.  
signal for the LT1187 is 760mVP-P  
.
The ability to maintain shutoff is shown on the curve  
Shutdown Supply Current vs Temperature in the Typical  
1.5MHz Square Wave Input and Unequalized Response Through  
1000 Feet of Twisted-Pair  
1MHz Sine Wave Gated Off with Shutdown Pin  
SHUTDOWN  
VOUT  
AV = 2, RFB = RG = 1k  
LT1187 • AI08  
LT1187 • AI07  
10  
LT1187  
U
U U  
W
APPLICATIO S I FOR ATIO  
1.5MHz Square Wave Input and Equalized Response  
Through 1000 Feet of Twisted-Pair  
Multiburst Pattern Passed Through  
1000 Feet of Twisted-Pair  
LT1187 • AI10  
LT1187 • AI09  
Bidirectional Video Bus  
TRANSMIT 1  
TRANSMIT 2  
3
3
+
+
6
6
1k  
1k  
LT1195  
1k  
LT1195  
75Ω  
75Ω  
2
2
–
–
1k  
1k  
1k  
1k  
1k  
2
3
2
3
–
+
–
+
6
6
LT1195  
LT1195  
33Ω  
15Ω  
33Ω  
15Ω  
33Ω  
15Ω  
33Ω  
S/D  
5
S/D  
5
3
2
1
8
3
+
–
+
–
+
–
+
15Ω  
2
1
8
75Ω  
75Ω  
6
6
LT1187  
LT1187  
1000 FEET  
TWISTED-PAIR  
–
R
R
FB  
300Ω  
FB  
300Ω  
1000pF  
1000pF  
50Ω  
R
R
300Ω  
G
G
50Ω  
300Ω  
LT1187 • AI11  
RECEIVE 2  
RECEIVE 1  
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-  
tationthattheinterconnectionofitscircuitsasdescribedhereinwillnotinfringeonexistingpatentrights.  
11  
LT1187  
W
W
SI PLIFIED SCHE ATIC  
+
V
7
V
BIAS  
V
BIAS  
C
M
+
–
3
2
C
FF  
V
6
+V  
+V  
OUT  
*
–
V
4
5
S/D  
1
+/REF  
8
–/FB  
* SUBSTRATE DIODE, DO NOT FORWARD BIAS  
LT1187 • SS  
U
PACKAGE DESCRIPTIO Dimensions in inches (millimeters) unless otherwise noted.  
0.405  
(10.287)  
MAX  
0.005  
(0.127)  
MIN  
0.200  
(5.080)  
MAX  
0.290 – 0.320  
(7.366 – 8.128)  
CORNER LEADS OPTION  
(4 PLCS)  
6
5
8
7
0.015 – 0.060  
(0.381 – 1.524)  
0.023 – 0.045  
0.025  
0.220 – 0.310  
(0.58 – 1.14)  
HALF LEAD  
OPTION  
J8 Package  
8-Lead Hermetic DIP  
(0.635)  
RAD TYP  
(5.588 – 7.874)  
0.008 – 0.018  
(0.203 – 0.460)  
0° – 15°  
0.045 – 0.065  
(1.14 – 1.65)  
FULL LEAD  
OPTION  
1
2
3
4
0.045 – 0.065  
(1.14 – 1.65)  
0.385 ± 0.025  
(9.779 ± 0.635)  
0.125  
3.175  
MIN  
0.100 ± 0.010  
0.014 – 0.026  
(2.540 ± 0.254)  
(0.360 – 0.660)  
0.400  
(10.160)  
MAX  
0.130 ± 0.005  
(3.302 ± 0.127)  
0.300 – 0.320  
(7.620 – 8.128)  
0.045 – 0.065  
(1.143 – 1.651)  
8
7
6
5
4
0.065  
(1.651)  
TYP  
0.250 ± 0.010  
(6.350 ± 0.254)  
N8 Package  
8-Lead Plastic DIP  
0.009 – 0.015  
(0.229 – 0.381)  
0.125  
(3.175)  
MIN  
0.020  
(0.508)  
MIN  
+0.025  
–0.015  
1
2
3
0.045 ± 0.015  
(1.143 ± 0.381)  
0.100 ± 0.010  
(2.540 ± 0.254)  
0.325  
+0.635  
8.255  
(
)
–0.381  
0.018 ± 0.003  
(0.457 ± 0.076)  
0.189 – 0.197  
(4.801 – 5.004)  
0.010 – 0.020  
(0.254 – 0.508)  
7
5
8
6
× 45°  
0.053 – 0.069  
(1.346 – 1.752)  
0.004 – 0.010  
(0.101 – 0.254)  
0.008 – 0.010  
(0.203 – 0.254)  
S8 Package  
8-Lead Plastic SOIC  
0.228 – 0.244  
(5.791 – 6.197)  
0.150 – 0.157  
(3.810 – 3.988)  
0.016 – 0.050  
0.406 – 1.270  
0.050  
(1.270)  
BSC  
0.014 – 0.019  
(0.355 – 0.483)  
0°– 8° TYP  
1
2
3
4
BA/LT/GP 0293 10K REV0  
Linear Technology Corporation  
1630 McCarthy Blvd., Milpitas, CA 95035-7487  
12  
●
●
(408) 432-1900 FAX: (408) 434-0507 TELEX: 499-3977  
LINEAR TECHNOLOGY CORPORATION 1993  

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