1FEATURES

2• Internal Thermal Limiting

• Internal Current and Power Limiting

• Specified 100 mA Output Current

• 0.5 μA Typical Base Current

• Directly Interfaces with TTL or CMOS

• +36 Volts On Base Causes No Damage

• 2 μs Switching Time

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 specified 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 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.