NSC LM194MDS Datasheet
TL/H/9241
LM194/LM394 Supermatch Pair
December 1994
LM194/LM394 Supermatch Pair
General Description
The LM194 and LM394 are junction isolated ultra wellmatched monolithic NPN transistor pairs with an order of
magnitude improvement in matching over conventional transistor pairs. This was accomplished by advanced linear processing and a unique new device structure.
Electrical characteristics of these devices such as drift versus initial offset voltage, noise, and the exponential relationship of base-emitter voltage to collector current closely approach those of a theoretical transistor. Extrinsic emitter
and base resistances are much lower than presently available pairs, either monolithic or discrete, giving extremely low
noise and theoretical operation over a wide current range.
Most parameters are guaranteed over a current range of
1 mA to 1 mA and 0V up to 40V collector-base voltage,
ensuring superior performance in nearly all applications.
To guarantee long term stability of matching parameters,
internal clamp diodes have been added across the emitterbase junction of each transistor. These prevent degradation
due to reverse biased emitter currentÐthe most common
cause of field failures in matched devices. The parasitic isolation junction formed by the diodes also clamps the substrate region to the most negative emitter to ensure complete isolation between devices.
The LM194 and LM394 will provide a considerable improvement in performance in most applications requiring a closely
matched transistor pair. In many cases, trimming can be
eliminated entirely, improving reliability and decreasing
costs. Additionally, the low noise and high gain make this
device attractive even where matching is not critical.
The LM194 and LM394/LM394B/LM394C are available in
an isolated header 6-lead TO-5 metal can package. The
LM394/LM394B/LM394C are available in an 8-pin plastic
dual-in-line package. The LM194 is identical to the LM394
except for tighter electrical specifications and wider temperature range.
Features
Y
Emitter-base voltage matched to 50 mV
Y
Offset voltage drift less than 0.1 mV/§C
Y
Current gain (hFE) matched to 2%
Y
Common-mode rejection ratio greater than 120 dB
Y
Parameters guaranteed over 1 mA to 1 mA collector
current
Y
Extremely low noise
Y
Superior logging characteristics compared to
conventional pairs
Y
Plug-in replacement for presently available devices
Typical Applications
Low Cost Accurate Square Root Circuit
I
OUT
e
10
b
5
.010 V
IN
TL/H/9241– 1
Low Cost Accurate Squaring Circuit
I
OUT
e
10
b
6
(VIN)
2
TL/H/9241– 2
*Trim for full scale accuracy
C
1995 National Semiconductor Corporation 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 V
MAX
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
g
10 mA
Power Dissipation 500 mW
Junction Temperature
LM194
b
55§Ctoa125§C
LM394/LM394B/LM394C
b
25§Ctoa85§C
Storage Temperature Range
b
65§Ctoa150§C
Soldering Information
Metal Can Package (10 sec.) 260
§
C
Dual-In-Line Package (10 sec.) 260
§
C
Small Outline Package
Vapor Phase (60 sec.) 215
§
C
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 (T
J
e
25§C)
Parameter Conditions
LM194 LM394 LM394B/394C
Units
Min Typ Max Min Typ Max Min Typ Max
Current Gain (hFE)V
CB
e
0V to V
MAX
(Note 1)
I
C
e
1 mA 350 700 300 700 225 500
I
C
e
100 mA 350 550 250 550 200 400
I
C
e
10 mA 300 450 200 450 150 300
I
C
e
1 mA 200 300 150 300 100 200
Current Gain Match, V
CB
e
0V to V
MAX
(hFEMatch) I
C
e
10 mA to 1 mA 0.5 2 0.5 4 1.0 5 %
e
100[DI
B
][
h
FE(MIN)
]
I
C
I
C
e
1 mA 1.0 1.0 2.0 %
Emitter-Base Offset V
CB
e
0
25 100 25 150 50 200 mV
Voltage I
C
e
1 mAto1mA
Change in Emitter-Base (Note 1)
Offset Voltage vs I
C
e
1 mAto1mA,
10 25 10 50 10 100 mV
Collector-Base Voltage V
CB
e
0V to V
MAX
(CMRR)
Change in Emitter-Base V
CB
e
0V,
525 550 550 mV
Offset Voltage vs I
C
e
1 mA to 0.3 mA
Collector Current
Emitter-Base Offset I
C
e
10 mA to 1 mA (Note 2)
0.08 0.3 0.08 1.0 0.2 1.5 mV/
§
C
Voltage Temperature I
C1
e
I
C2
Drift VOSTrimmed to 0 at 25§C 0.03 0.1 0.03 0.3 0.03 0.5 mV/§C
Logging Conformity I
C
e
3nAto300mA,
150 150 150 mV
V
CB
e
0, (Note 3)
Collector-Base Leakage V
CB
e
V
MAX
0.05 0.25 0.05 0.5 0.05 0.5 nA
Collector-Collector V
CC
e
V
MAX
0.1 2.0 0.1 5.0 0.1 5.0 nA
Leakage
Input Voltage Noise I
C
e
100 mA, V
CB
e
0V,
1.8 1.8 1.8 nV/
0
Hz
f
e
100 Hz to 100 kHz
Collector to Emitter I
C
e
1 mA, I
B
e
10 mA 0.2 0.2 0.2 V
Saturation Voltage I
C
e
1 mA, I
B
e
100 mA 0.1 0.1 0.1 V
Note 1: Collector-base voltage is swept from 0 to V
MAX
at a collector current of 1 mA, 10 mA, 100 mA, and 1 mA.
Note 2: Offset voltage drift with V
OS
e
0atT
A
e
25§C is valid only when the ratio of IC1to IC2is adjusted to give the initial zero offset. This ratio must be held to
within 0.003% over the entire temperature range. Measurements taken at
a
25§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, V
IN
e
10V to 0.1 mV or I
IN
e
1mAto10nA
TL/H/9241– 3
*1kX(g1%) at 25§C,a3500 ppm/§C.
Available from Vishay Ultronix,
Grand Junction, CO, Q81 Series.
V
OUT
eb
log
10
#
V
IN
V
REF
J
Voltage Controlled Variable Gain Amplifier
TL/H/9241– 4
*R8– R10 and D2 provide a temperature Distortionk0.1%
independent gain control. Bandwidth
l
1 MHz
G
eb
336 V1 (dB) 100 dB gain range
3
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