LM3578AM linear and digital integrated circuits Integrated Circuit Chip Switching Regulator

LM2578A/LM3578A

Switching Regulator

General Description

The LM2578A is a switching regulator which can easily be set up for such DC-to-DC voltage conversion circuits as the buck, boost, and inverting configurations. The LM2578A features a unique comparator input stage which not only has separate pins for both the inverting and non-inverting inputs, but also provides an internal 1.0V reference to each input, thereby simplifying circuit design and p.c. board layout. The output can switch up to 750 mA and has output pins for its collector and emitter to promote design flexibility. An external current limit terminal may be referenced to either the ground or the Vin terminal, depending upon the application. In addition, the LM2578A has an on board oscillator, which sets the switching frequency with a single external capacitor from <1 Hz to 100 kHz (typical).

The LM2578A is an improved version of the LM2578, offering higher maximum ratings for the total supply voltage and output transistor emitter and collector voltages.

Features

• Inverting and non-inverting feedback inputs
• 1.0V reference at inputs
• Operates from supply voltages of 2V to 40V
• Output current up to 750 mA, saturation less than 0.9V
• Current limit and thermal shut down n Duty cycle up to 90%

Applications

• Switching regulators in buck, boost, inverting, and single-ended transformer configurations
• Motor speed control
• Lamp flasher

Absolute Maximum Ratings (Note 1)

If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications.

Total Supply Voltage                                                     50V

Collector Output to Ground                                          −0.3V to +50V

Emitter Output to Ground (Note 2)                               −1V to +50V

Power Dissipation (Note 3)                                           Internally limited

Output Current                                                             750 mA

Storage Temperature                                                  −65˚C to +150˚C

Lead Temperature (soldering, 10 seconds)                 260˚C

Maximum Junction Temperature                                   150˚C

ESD Tolerance (Note 4)                                                2 kV

Operating Ratings

Ambient Temperature Range

    LM2578A                                                                −40˚C ≤ T_A ≤+85˚C

    LM3578A                                                                0˚C ≤ T_A ≤+70˚C

Junction Temperature Range

    LM2578A                                                               −40˚C ≤ T_J ≤+125˚C

    LM3578A                                                                0˚C ≤ T_J ≤+125˚C

Connection Diagram and Ordering Information

Functional Diagram

Stock Offer (Hot Sell)