LP395
Ultra Reliable Power Transistor
General Description
The LP395 is a fast monolithic transistor with complete over-
load protection. This very high gain transistor has included
on the chip, current limiting, power limiting, and thermal
overload protection, making it difficult to destroy from almost
any type of overload. Available in an epoxy TO-92 transistor
package this device is guaranteed to deliver 100 mA.
Thermal limiting at the chip level, a feature not available in
discrete designs, provides comprehensive protection against
overload. Excessive power dissipation or inadequate heat
sinking causes the thermal limiting circuitry to turn off the de-
vice preventing excessive die temperature.
The LP395 offers a significant increase in reliability while
simplifying protection circuitry. It is especially attractive as a
small incandescent lamp or solenoid driver because of its
low drive requirements and blowout-proof design.
The LP395 is easy to use and only a few precautions need
be observed. Excessive collector to emitter voltage can de-
stroy the LP395 as with any transistor. When the device is
used as an emitter follower with a low source impedance, it
is necessary to insert a 4.7 k
resistor in series with the
base lead to prevent possible emitter follower oscillations.
Also since it has good high frequency response, supply
by-passing is recommended.
Areas where the LP395 differs from a standard NPN transis-
tor are in saturation voltage, leakage (quiescent) current and
in base current. Since the internal protection circuitry re-
quires voltage and current to function, the minimum voltage
across the device in the on condition (saturated) is typically
1.6 Volts, while in the off condition the quiescent (leakage)
current is typically 200 A. Base current in this device flows
out of the base lead, rather than into the base as is the case
with conventional NPN transistors. Also the base can be
driven positive up to 36 Volts without damage, but will draw
current if driven negative more than 0.6 Volts. Additionally, if
the base lead is left open, the LP395 will turn on.
The LP395 is a low-power version of the 1-Amp LM195/
LM295/LM395 Ultra Reliable Power Transistor.
The LP395 is rated for operation over a -40C to +125C
range.
Features
n
Internal thermal limiting
n
Internal current and power limiting
n
Guaranteed 100 mA output current
n
0.5 A typical base current
n
Directly interfaces with TTL or CMOS
n
+36 Volts on base causes no damage
n
2 s switching time
Connection Diagram
Typical Applications
TO-92 Package
DS005525-1
Order Number LP395Z
See NS Package Z03A
Fully Protected Lamp Driver
DS005525-3
April 1998
LP395
Ultra
Reliable
Power
T
ransistor
1999 National Semiconductor Corporation
DS005525
www.national.com
Absolute Maximum Ratings
(Note 1)
Collector to Emitter Voltage
36V
Collector to Base Voltage
36V
Base to Emitter Voltage (Forward)
36V
Base to Emitter Voltage (Reverse)
10V
Base to Emitter Current (Reverse)
20 mA
Collector Current Limit
Internally Limited
Power Dissipation
Internally Limited
Operating Temperature Range
-40C to +125C
Storage Temperature Range
-65C to +150C
Lead Temp. (Soldering, 10 seconds)
260C
Electrical Characteristics
Tested
Design
Units
Symbol
Parameter
Conditions
Typical
Limit
Limit
(Limit)
(Note 3)
(Note 4)
V
CE
Collector to Emitter
0.5 mA
I
C
100 mA
36
36
V(Max)
Operating Voltage
(Note 2)
I
CL
Collector Current Limit
V
BE
= 2V, V
CE
= 36V
45
25
20
mA(Min)
(Note 5)
V
BE
= 2V, V
CE
= 15V
90
60
50
mA(Min)
V
BE
= 2V, 2V
V
CE
6V
130
100
100
mA(Min)
I
B
Base Current
0
I
C
100 mA
-0.3
-2.0
-2.5
A(Max)
I
Q
Quiescent Current
V
BE
= 0V, 0
V
CE
36V
0.24
0.50
0.60
mA(Max)
V
CE(SAT)
Saturation Voltage
V
BE
= 2V, I
C
= 100 mA
1.82
2.00
2.10
V(Max)
BV
BE
Base to Emitter Break-
0
V
CE
36V, I
B
= 2 A
36
36
V(Min)
down Voltage (Note 5)
V
BE
Base to Emitter Voltage
I
C
= 5 mA
0.69
0.79
0.90
V(Max)
(Note 6)
I
C
= 100 mA (Note 5)
1.02
1.40
V (Max)
t
S
Switching Time
V
CE
= 20V, R
L
= 200
2
s
V
BE
= 0V, +2V, 0V
JA
Thermal Resistance
0.4" leads soldered to
150
180
C/W
Junction to Ambient
printed circuit board
(Max)
0.125" leads soldered to
130
160
C/W
printed circuit board
(Max)
Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is func-
tional, but do not guarantee specific performance limits.
Note 2: Parameters identified with boldface type apply at temp. extremes. All other numbers, unless noted apply at +25C.
Note 3: Guaranteed and 100% production tested.
Note 4: Guaranteed (but not 100% production tested) over the operating temperature and supply voltage ranges. These limits are not used to calculate outgoing
quality levels.
Note 5: These numbers apply for pulse testing with a low duty cycle.
Note 6: Base positive with respect to emitter.
Simplified Circuit
Applications Information
One failure mode incandescent lamps may experience is
one in which the filament resistance drops to a very low
value before it actually blows out. This is especially rough on
most solid-state lamp drivers and in most cases a lamp fail-
ure of this type will also cause the lamp driver to fail. Be-
cause of its high gain and blowout-proof design, the LP395 is
an ideal candidate for reliably driving small incandescent
lamps. Additionally, the current limiting characteristics of the
LP395 are advantageous as it serves to limit the cold fila-
ment inrush current, thus increasing lamp life.
DS005525-5
www.national.com
2
Typical Performance Characteristics
5 Volt Transfer Function
DS005525-10
36 Volt Transfer Function
DS005525-11
Collector Characteristics
DS005525-12
Available Collector Current
DS005525-13
Quiescent Collector Current
DS005525-14
Saturation Voltage
DS005525-15
Collector Current Threshold
DS005525-9
www.national.com
3
Typical Applications
Lamp Flasher
(Short Circuit Proof)
DS005525-6
Optically Isolated
Switch
DS005525-7
Two Terminal
Current Limiter
DS005525-8
Composite PNP
DS005525-2
www.national.com
4
Physical Dimensions
inches (millimeters) unless otherwise noted
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www.national.com
Order Number LP395Z
NS Package Z03A
LP395
Ultra
Reliable
Power
T
ransistor
National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications.
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