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.