National LM1578A LM2578A LM3578A User Manual
Summary
The reliable LM1578A family of switching regulators is an essential component for versatile DC-to-DC voltage conversion circuits, supporting buck, boost, and inverting modes. Operating from 2V to 40V with up to 750 mA output current, it features a unique comparator stage and integrated 1.0V reference, simplifying power management design. This technical manual provides engineers and designers with comprehensive details, including absolute maximum ratings, detailed functional diagrams, electrical specifications, and operational guidelines required for building high-reliability power solutions.
Page 1 Text Content
LM 1578A /LM 2578A /LM 3578A itching egulator
April
LM1578A/LM2578A/LM3578A Switching Regulator General Description Features
The LM1578A is switching regulator which can easily be Inverting and non-inverting feedback inputs
set up for such DC-to-DC voltage conversion circuits as the 1.0V reference at inputs buck, boost, and inverting configurations. The LM1578A fea- Operates from supply voltages of 2V to 40V tures unique comparator input stage which not only has Output current up to m A, saturation less than 0.9V separate pins for both the inverting and non-inverting inputs,
Current limit and thermal shut down
but also provides an internal 1.0V reference to each input,
Duty cycle up to 90%
thereby simplifying circuit design and p.c. board layout. The output can switch up to m A and has output pins for its
collector and emitter to promote design flexibility. An external Applications
current limit terminal may be referenced to either the ground Switching regulators in buck, boost, inverting, and or the Vin terminal, depending upon the application. In addi- single-ended transformer configurations tion, the LM1578A has an on board oscillator, which sets the Motor speed control
switching frequency with single external capacitor from <1
Lamp flasher
Hz to k Hz (typical). The LM1578A is an improved version of the LM1578, offer- ing higher maximum ratings for the total supply voltage and output transistor emitter and collector voltages.
Functional Diagram
DS008711-1
National Semiconductor Corporation DS008711 www.national.com
Page Summary Contents For National LM1578A LM2578A LM3578A User Manual
Manual Details
| Brand | National |
|---|---|
| Pages | 18 |
| File Size | 1.10 MB |
| Published | May 27, 2026 |
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Frequently Asked Questions
What is the operating supply voltage range for the regulator?
The device can operate from a total supply voltage of 2V to 40V.
Can this regulator be used in different topologies?
Yes, it supports buck, boost, and inverting configurations, as well as single-ended transformer applications.
What are the maximum output current and saturation characteristics?
The output can switch up to 750 mA, with a collector saturation voltage of less than 0.9V.
How is the switching frequency determined for motor control?
The on board oscillator sets the switching frequency using a single external capacitor, ranging from Lamp flasher Hz to 100 kHz.