NSC LP395Z Datasheet

LP395
Ultra Reliable Power Transistor

General Description

The LP395 is a fast monolithic transistor with complete over­load 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, providescomprehensiveprotection against
overload. Excessive power dissipation or inadequate heat
sinking causes the thermal limiting circuitry to turn off the de­vice 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 de­stroy 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 kΩ 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 transis­tor are in saturation voltage, leakage (quiescent) current and

in base current. Since the internal protection circuitry re­quires 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 µA. 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 −40˚C to +125˚C
range.

Features

n Internal thermal limiting
n Internal current and power limiting
n Guaranteed 100 mA output current
n 0.5 µA typical base current
n Directly interfaces with TTL or CMOS
n +36 Volts on base causes no damage
n 2 µs switching time

LP395 Ultra Reliable Power Transistor

April 1998

Connection Diagram Typical Applications

TO-92 Package

DS005525-1

Order Number LP395Z
See NS Package Z03A

© 1999 National Semiconductor Corporation DS005525 www.national.com

Fully Protected Lamp Driver

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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

Collector Current Limit Internally Limited
Power Dissipation Internally Limited
Operating Temperature Range −40˚C to +125˚C
Storage Temperature Range −65˚C to +150˚C
Lead Temp. (Soldering, 10 seconds) 260˚C

Base to Emitter Current (Reverse) 20 mA

Electrical Characteristics

Tested Design Units

Symbol Parameter Conditions Typical Limit Limit (Limit)

(Note 3) (Note 4)

V

CE

I

CL

I

B

I

Q

V

CE(SAT)

BV

BE

V

BE

t

S

θ

JA

Note 1: AbsoluteMaximum 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: Parameters identified with boldface type apply at temp. extremes. All other numbers, unless noted apply at +25˚C.
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.

Collector to Emitter 0.5 mA ≤ IC≤ 100 mA 36 36 V(Max)
Operating Voltage (Note 2)
Collector Current Limit V
(Note 5) V

=

BE

=

BE

=

V

BE

2V, V

CE

2V, V

CE

2V, 2V ≤ V

=

36V 45 25 20 mA(Min)

=

15V 90 60 50 mA(Min)

≤ 6V 130 100 100 mA(Min)

CE

Base Current 0 ≤ IC≤ 100 mA −0.3 −2.0 −2.5 µA(Max)
Quiescent Current V
Saturation Voltage V
Base to Emitter Break- 0 ≤ VCE≤ 36V, I

BE
BE

=

0V, 0 ≤ V

=

2V, I

≤ 36V 0.24 0.50 0.60 mA(Max)

CE

=

100 mA 1.82 2.00 2.10 V(Max)

C

=

2µA 36 36 V(Min)

B

down Voltage (Note 5)
Base to Emitter Voltage I
(Note 6) I
Switching Time V

=

5 mA 0.69 0.79 0.90 V(Max)

C

=

100 mA (Note 5) 1.02 1.40 V (Max)

C

=

CE

=

V

BE

=

20V, R

L

0V, +2V, 0V

200Ω 2µs

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)

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 fail­ure of this type will also cause the lamp driver to fail. Be­cause 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 fila­ment inrush current, thus increasing lamp life.

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