LM2925 National Semiconductor, LM2925 Datasheet



Manufacturer Part Number
Low Dropout Regulator with Delayed Reset
National Semiconductor
© 1998 National Semiconductor Corporation
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
Typical Application Circuit
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.
Required if regulator is located far from power supply filter.
must be at least 10 µF to maintain stability. May be increased
FIGURE 1. Test and Application Circuit
LM2925 cannot be harmed by temporary mirror-image inser-
tion. Familiar regulator features such as short circuit and
thermal overload protection are also provided.
n 5V, 750 mA output
n Externally set delay for reset
n Input-output differential less than 0.6V at 0.5A
n Reverse battery protection
n 60V load dump protection
n −50V reverse transient protection
n Short circuit protection
n Internal thermal overload protection
n Available in plastic TO-220
n Long delay times available
n P
Connection Diagram
Product Enhancement tested
See NS Package Number T05A
Order Number LM2925T
TO-220 5-Lead
April 1998

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