LM2926 National Semiconductor, LM2926 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 LM2926 is a 5V, 500 mA, low dropout regulator with de-
layed reset. The microprocessor reset flag is set low by ther-
mal shutdown, short circuits, overvoltage conditions, drop-
out, and power-up. After the fault condition is corrected, the
reset flag remains low for a delay time determined by the de-
lay capacitor. Hysteresis is included in the reset circuit to
prevent oscillations, and a reset output is guaranteed down
to 3.2V supply input. A latching comparator is used to dis-
charge the delay capacitor, which guarantees a full reset
pulse even when triggered by a relatively short fault condi-
tion. A patented quiescent current reduction circuit drops the
ground pin current to 8 mA at full load when the input-output
differential is 3V or more.
Familiar PNP regulator features such as reverse battery pro-
tection, transient protection, and overvoltage shutdown are
included in the LM2926 making it suitable for use in automo-
tive and battery operated equipment.
The LM2927 is electrically identical to the LM2926 but has a
different pin-out. The LM2927 is pin-for-pin compatible with
the L4947 and TLE4260 alternatives. The LM2926 is
pin-for-pin compatible with the LM2925.
Typical Application
the regulator. This capacitor msut be rated over the same operating temperature range as the regulator. The equivalent series resistance (ESR) of this
capacitor is critical; see curve under Typical Performance Characteristics.
Connection Diagrams and Ordering Information
Required if regulator is located far (
must be at least 10 µF to maintain stability. May be increased without bound to maintain regulation during transients. Locate as close as possible to
See NS Package Number TO5A
Order Number LM2926T
5–Lead TO-220
Front View
2") from power supply filter.
n 5% output accuracy over entire operating range
n Dropout voltage typically 350 mV at 500 mA output
n Externally programmed reset delay
n Short circuit proof
n Reverse battery proof
n Thermally protected
n LM2926 is pin-for-pin compatible with the LM2925
n P
n Battery operated equipment
n Microprocessor-based systems
n Portable instruments
Product Enhancement tested
See NS Package Number TO5A
Order Number LM2927T
5-Lead TO-220
Front View
April 1998

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