LM2927T National Semiconductor, LM2927T Datasheet



Manufacturer Part Number
National Semiconductor

Specifications of LM2927T

Regulator Topology
Positive Fixed
Voltage - Output
Voltage - Input
Up to 26V
Voltage - Dropout (typical)
0.35V @ 500mA
Number Of Regulators
Current - Output
Operating Temperature
-40°C ~ 125°C
Mounting Type
Through Hole
Package / Case
Lead Free Status / RoHS Status
Contains lead / RoHS non-compliant
Current - Limit (min)
Other names
© 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

Related parts for LM2927T

LM2927T Summary of contents

Page 1

... Short circuit proof n Reverse battery proof n Thermally protected n LM2926 is pin-for-pin compatible with the LM2925 + n P Product Enhancement tested Applications n Battery operated equipment n Microprocessor-based systems n Portable instruments DS010759-1 5-Lead TO-220 DS010759-2 Front View Order Number LM2927T See NS Package Number TO5A April 1998 DS010759-14 www.national.com ...

Page 2

... Absolute Maximum Ratings If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Input Voltage Survival t = 100 Continuous Reset Output Sink Current ESD Susceptibility (Note 2) Electrical Characteristics = 14.4V µF, −40˚ Parameter REGULATOR OUTPUT ...

Page 3

Electrical Characteristics = 14.4V µF, −40˚ 125˚C, unless otherwise specified Parameter REGULATOR OUTPUT Maximum Operational Input Continuous Voltage Peak Transient Input Voltage V 7V Reverse DC Input Voltage V −0.6V, ...

Page 4

Typical Performance Characteristics Supply Current DS010759-17 Dropout Voltage DS010759-20 Ripple Rejection DS010759-23 Line Transient Response DS010759-26 www.national.com (Continued) Quiescent Current DS010759-18 Output Current Limit DS010759-21 Ripple Rejection DS010759-24 Load Transient Response DS010759-27 4 Quiescent Current DS010759-19 Output Capacitor ESR DS010759-22 ...

Page 5

Typical Performance Characteristics Reset Delay DS010759-29 Typical Circuit Waveforms Applications Information EXTERNAL CAPACITORS The LM2926/7 output capacitor is required for stability. With- out it, the regulator output will oscillate at amplitudes as high as several volts peak-to-peak at frequencies up ...

Page 6

Applications Information lay capacitor. When the capacitor voltage increases 3.75V ( V ) from its discharged value, the reset output is DELAY again set HIGH. The delay time is calculated by: 6 ± The constant, 1 has ...

Page 7

Applications Information (Continued) the LM 2926/7 may fail to bring the processor under control. The LM2926/7 reset output may be more efficiently em- ployed in certain applications as a means of defeating memory WRITE lines, clocks, or external loads, rather ...

Page 8

Typical Applications (Continued) Using the Reset to De-Activate Power Loads. The LM1921 is a Fully Protected 1 Amp High-Side Driver. Using the Reset to Ensure an Accurate Display www.national.com Generating an Active High Reset Signal DS010759-12 on Power-Up or Power-Down ...

Page 9

9 ...

Page 10

... National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications. 5-Lead TO-220 Outline Drawing Order Number LM2926T or LM2927T NS Package Number T05A 2 ...

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