LM2925

Low Dropout Regulator with Delayed Reset

General Description

The LM2925 features a low dropout, high current regulator.

Also included on-chip is a reset function with an externally

set delay time. Upon power up, or after the detection of any

error in the regulated output, the reset pin remains in the ac-

tive low state for the duration of the delay. Types of errors de-

tected include any that cause the output to become unregu-

lated: low input voltage, thermal shutdown, short circuit,

input transients, etc. No external pull-up resistor is neces-

sary. The current charging the delay capacitor is very low, al-

lowing long delay times.

Designed primarily for automotive applications, the LM2925

and all regulated circuitry are protected from reverse battery

installations or two-battery jumps. During line transients,

such as a load dump (60V) when the input voltage to the

regulator can momentarily exceed the specified maximum

operating voltage, the 0.75A regulator will automatically shut

down to protect both internal circuits and the load. The

LM2925 cannot be harmed by temporary mirror-image inser-

tion. Familiar regulator features such as short circuit and

thermal overload protection are also provided.

Features

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5V, 750 mA output

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Externally set delay for reset

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Input-output differential less than 0.6V at 0.5A

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Reverse battery protection

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60V load dump protection

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−50V reverse transient protection

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Short circuit protection

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Internal thermal overload protection

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Available in plastic TO-220

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Long delay times available

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P

Typical Application Circuit

Connection Diagram

DS005268-1

without bound to maintain regulation during transients. Locate as close as

possible to the regulator. This capacitor must be rated over the same

operating temperature range as the regulator. The equivalent series

resistance (ESR) of this capacitor is critical; see curve.

FIGURE 1. Test and Application Circuit

TO-220 5-Lead

DS005268-2

Order Number LM2925T

See NS Package Number T05A

April 1998

© 1998 National Semiconductor Corporation

DS005268

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