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December 1994 |
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LM194/LM394 Supermatch Pair |
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General Description |
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The LM194 and LM394 are junction isolated ultra well- |
matched transistor pair. In many cases, trimming can be |
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matched monolithic NPN transistor pairs with an order of |
eliminated entirely, improving reliability and decreasing |
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magnitude improvement in matching over conventional tran- |
costs. Additionally, the low noise and high gain make this |
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sistor pairs. This was accomplished by advanced linear pro- |
device attractive even where matching is not critical. |
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cessing and a unique new device structure. |
The LM194 and LM394/LM394B/LM394C are available in |
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Electrical characteristics of these devices such as drift ver- |
an isolated header 6-lead TO-5 metal can package. The |
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sus initial offset voltage, noise, and the exponential relation- |
LM394/LM394B/LM394C are available in an 8-pin plastic |
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ship of base-emitter voltage to collector current closely ap- |
dual-in-line package. The LM194 is identical to the LM394 |
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proach those of a theoretical transistor. Extrinsic emitter |
except for tighter electrical specifications and wider temper- |
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and base resistances are much lower than presently avail- |
ature range. |
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able pairs, either monolithic or discrete, giving extremely low |
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noise and theoretical operation over a wide current range. |
Features |
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Most parameters are guaranteed over a current range of |
Y Emitter-base voltage matched to 50 mV |
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1 mA to 1 mA and 0V up to 40V collector-base voltage, |
Y Offset voltage drift less than 0.1 mV/§C |
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ensuring superior performance in nearly all applications. |
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Y Current gain (hFE) matched to 2% |
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To guarantee long term stability of matching parameters, |
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Y Common-mode rejection ratio greater than 120 dB |
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internal clamp diodes have been added across the emitter- |
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Y Parameters guaranteed over 1 mA to 1 mA collector |
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base junction of each transistor. These prevent degradation |
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current |
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due to reverse biased emitter currentÐthe most common |
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Y Extremely low noise |
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cause of field failures in matched devices. The parasitic iso- |
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Y Superior logging characteristics compared to |
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lation junction formed by the diodes also clamps the sub- |
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conventional pairs |
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strate region to the most negative emitter to ensure com- |
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plete isolation between devices. |
Y Plug-in replacement for presently available devices |
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The LM194 and LM394 will provide a considerable improve- |
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ment in performance in most applications requiring a closely |
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Typical Applications |
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Low Cost Accurate Square Root Circuit |
Low Cost Accurate Squaring Circuit |
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IOUT e 10b5. 0 |
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IOUT e 10b6 (VIN)2 |
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10 VIN |
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TL/H/9241 ± 2
TL/H/9241 ± 1
*Trim for full scale accuracy
Pair Supermatch LM194/LM394
C1995 National Semiconductor Corporation |
TL/H/9241 |
RRD-B30M115/Printed in U. S. A. |
Absolute Maximum Ratings
If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/Distributors for availability and specifications.
(Note 4)
Collector Current |
20 mA |
Collector-Emitter Voltage |
VMAX |
Collector-Emitter Voltage |
35V |
LM394C |
20V |
Collector-Base Voltage |
35V |
LM394C |
20V |
Collector-Substrate Voltage |
35V |
LM394C |
20V |
Collector-Collector Voltage |
35V |
LM394C |
20V |
Base-Emitter Current |
g10 mA |
Power Dissipation |
500 mW |
Junction Temperature |
b55§C to a125§C |
LM194 |
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LM394/LM394B/LM394C |
b25§C to a85§C |
Storage Temperature Range |
b65§C to a150§C |
Soldering Information |
260§C |
Metal Can Package (10 sec.) |
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Dual-In-Line Package (10 sec.) |
260§C |
Small Outline Package |
215§C |
Vapor Phase (60 sec.) |
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Infrared (15 sec.) |
220§C |
See AN-450 ``Surface Mounting and their Effects on Product Reliability'' for other methods of soldering surface mount devices.
Electrical Characteristics (TJ e 25§C)
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Parameter |
Conditions |
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LM194 |
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LM394 |
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LM394B/394C |
Units |
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Min |
Typ |
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Max |
Min |
Typ |
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Max |
Min |
Typ |
Max |
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Current Gain (hFE) |
VCB e 0V to VMAX (Note 1) |
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IC e 1 mA |
350 |
700 |
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300 |
700 |
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225 |
500 |
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IC e 100 mA |
350 |
550 |
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250 |
550 |
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200 |
400 |
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IC e 10 mA |
300 |
450 |
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200 |
450 |
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150 |
300 |
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IC e 1 mA |
200 |
300 |
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150 |
300 |
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100 |
200 |
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Current Gain Match, |
VCB e 0V to VMAX |
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(hFE Match) |
IC e 10 mA to 1 mA |
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0.5 |
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2 |
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0.5 |
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4 |
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1.0 |
5 |
% |
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e |
100 [DIB] [hFE(MIN)] |
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IC e 1 mA |
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1.0 |
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1.0 |
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2.0 |
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% |
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IC |
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Emitter-Base Offset |
VCB e 0 |
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25 |
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100 |
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25 |
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150 |
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50 |
200 |
mV |
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Voltage |
IC e 1 mA to 1 mA |
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Change in Emitter-Base |
(Note 1) |
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Offset Voltage vs |
IC e 1 mA to 1 mA, |
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10 |
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25 |
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10 |
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50 |
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10 |
100 |
mV |
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Collector-Base Voltage |
VCB e 0V to VMAX |
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(CMRR) |
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Change in Emitter-Base |
VCB e 0V, |
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5 |
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25 |
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5 |
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50 |
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5 |
50 |
mV |
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Offset Voltage vs |
IC e 1 mA to 0.3 mA |
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Collector Current |
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Emitter-Base Offset |
IC e 10 mA to 1 mA (Note 2) |
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0.08 |
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0.3 |
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0.08 |
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1.0 |
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0.2 |
1.5 |
mV/§C |
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Voltage Temperature |
IC1 e IC2 |
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Drift |
VOS Trimmed to 0 at 25§C |
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0.03 |
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0.1 |
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0.03 |
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0.3 |
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0.03 |
0.5 |
mV/§C |
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Logging Conformity |
IC e 3 nA to 300 mA, |
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150 |
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150 |
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150 |
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mV |
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VCB e 0, (Note 3) |
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Collector-Base Leakage |
VCB e VMAX |
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0.05 |
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0.25 |
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0.05 |
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0.5 |
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0.05 |
0.5 |
nA |
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Collector-Collector |
VCC e VMAX |
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0.1 |
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2.0 |
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0.1 |
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5.0 |
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0.1 |
5.0 |
nA |
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Leakage |
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Input Voltage Noise |
IC e 100 mA, VCB e 0V, |
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1.8 |
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1.8 |
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1.8 |
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nV/0 |
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Hz |
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f e 100 Hz to 100 kHz |
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Collector to Emitter |
IC e 1 mA, IB e 10 mA |
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0.2 |
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0.2 |
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0.2 |
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V |
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Saturation Voltage |
IC e 1 mA, IB e 100 mA |
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0.1 |
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0.1 |
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0.1 |
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V |
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Note 1: Collector-base voltage is swept from 0 to VMAX at a collector current of 1 mA, 10 mA, 100 mA, and 1 mA.
Note 2: Offset voltage drift with VOS e 0 at TA e 25§C is valid only when the ratio of IC1 to IC2 is adjusted to give the initial zero offset. This ratio must be held to within 0.003% over the entire temperature range. Measurements taken at a25§C and temperature extremes.
Note 3: Logging conformity is measured by computing the best fit to a true exponential and expressing the error as a base-emitter voltage deviation.
Note 4: Refer to RETS194X drawing of military LM194H version for specifications.
2
Typical Applications (Continued)
Fast, Accurate Logging Amplifier, VIN e 10V to 0.1 mV or IIN e 1 mA to 10 nA
VOUT e b log10 # VIN J
VREF
TL/H/9241 ± 3
*1 kX (g1%) at 25§C, a3500 ppm/§C.
Available from Vishay Ultronix,
Grand Junction, CO, Q81 Series.
Voltage Controlled Variable Gain Amplifier
TL/H/9241 ± 4
*R8±R10 and D2 provide a temperature |
Distortion k 0.1% |
independent gain control. |
Bandwidth l 1 MHz |
G e b336 V1 (dB) |
100 dB gain range |
3
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