LM195/LM395
Ultra Reliable Power Transistors
General Description
The LM195/LM395 are fast, monolithic power transistors
with complete overload protection. These devices, which act
as high gain power transistors, have included on the chip,
current limiting, power limiting, and thermal overload protec-
tion making them virtually impossible to destroy from any
type of overload. In the standard TO-3 transistor power pack-
age, the LM195 will deliver load currents in excess of 1.0A
and can switch 40V in 500 ns.
The inclusion of thermal limiting, a feature not easily avail-
able in discrete designs, provides virtually absolute protec-
tion against overload. Excessive power dissipation or inad-
equate heat sinking causes the thermal limiting circuitry to
turn off the device preventing excessive heating.
The LM195 offers a significant increase in reliability as well
as simplifying power circuitry. In some applications, where
protection is unusually difficult, such as switching regulators,
lamp or solenoid drivers where normal power dissipation is
low, the LM195 is especially advantageous.
The LM195 is easy to use and only a few precautions need
be observed. Excessive collector to emitter voltage can de-
stroy the LM195 as with any power transistor. When the de-
vice is used as an emitter follower with low source imped-
ance, it is necessary to insert a 5.0k resistor in series with
the base lead to prevent possible emitter follower oscilla-
tions. Although the device is usually stable as an emitter fol-
lower, the resistor eliminates the possibility of trouble without
degrading performance. Finally, since it has good high fre-
quency response, supply bypassing is recommended.
For low-power applications (under 100 mA), refer to the
LP395 Ultra Reliable Power Transistor.
The LM195/LM395 are available in standard TO-3 power
packages and solid Kovar TO-5. The LM195 is rated for op-
eration from -55C to +150C and the LM395 from 0C to
+125C.
Features
n
Internal thermal limiting
n
Greater than 1.0A output current
n
3.0 A typical base current
n
500 ns switching time
n
2.0V saturation
n
Base can be driven up to 40V without damage
n
Directly interfaces with CMOS or TTL
n
100% electrical burn-in
Simplified Circuit
DS006009-1
June 1999
LM195/LM395
Ultra
Reliable
Power
T
ransistors
1999 National Semiconductor Corporation
DS006009
www.national.com
Absolute Maximum Ratings
(Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Collector to Emitter Voltage
LM195
42V
LM395
36V
Collector to Base Voltage
LM195
42V
LM395
36V
Base to Emitter Voltage (Forward)
LM195
LM395
42V
36V
Base to Emitter Voltage (Reverse)
20V
Collector Current
Internally Limited
Power Dissipation
Internally Limited
Operating Temperature Range
LM195
-55C to +150C
LM395
0C to +125C
Storage Temperature Range
-65C to +150C
Lead Temperature
(Soldering, 10 sec.)
260C
Preconditioning
100% Burn-In In Thermal Limit
Electrical Characteristics
(Note 2)
Parameter
Conditions
LM195
LM395
Units
Min
Typ
Max
Min
Typ
Max
Collector-Emitter Operating Voltage
I
Q
I
C
I
MAX
42
36
V
(Note 4)
Base to Emitter Breakdown Voltage
0
V
CE
V
CEMAX
42
36
60
V
Collector Current
TO-3, TO-220
V
CE
15V
1.2
2.2
1.0
2.2
A
TO-5
V
CE
7.0V
1.2
1.8
1.0
1.8
A
Saturation Voltage
I
C
1.0A, T
A
= 25C
1.8
2.0
1.8
2.2
V
Base Current
0
I
C
I
MAX
3.0
5.0
3.0
10
A
0
V
CE
V
CEMAX
Quiescent Current (I
Q
)
V
be
= 0
2.0
5.0
2.0
10
mA
0
V
CE
V
CEMAX
Base to Emitter Voltage
I
C
= 1.0A, T
A
= +25C
0.9
0.9
V
Switching Time
V
CE
= 36V, R
L
= 36
,
500
500
ns
T
A
= 25C
Thermal Resistance Junction to
TO-3 Package (K)
2.3
3.0
2.3
3.0
C/W
Case (Note 3)
TO-5 Package (H)
12
15
12
15
C/W
TO-220 Package (T)
4
6
C/W
Note 1: "Absolute Maximum Ratings" indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is
functional, but do not guarantee specific performance limits.
Note 2: Unless otherwise specified, these specifications apply for -55C
T
j
+150C for the LM195 and 0C
+125C for the LM395.
Note 3: Without a heat sink, the thermal resistance of the TO-5 package is about +150C/W, while that of the TO-3 package is +35C/W.
Note 4: Selected devices with higher breakdown available.
Note 5: Refer to RETS195H and RETS195K drawings of military LM195H and LM195K versions for specifications.
www.national.com
3
PDF 
ZIP
