LM5035A datasheet(5/30 Pages) NSC

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TSSOP 20 PIN

LM5035A

LLP PIN

LM5035A

TSSOP 28 PIN

LM5035A-1

Name

Description

Application Information

Oscillator Frequency

Control and Sync Clock

Input

Normally biased at 2V. An external

resistor connected between RT

and AGND sets the internal

oscillator frequency. The internal

oscillator can be synchronized to

an external clock with a frequency

higher than the free running

frequency set by the RT resistor.

AGND

Analog Ground

Connect directly to Power Ground.

Current Sense input for

current limit

If CS exceeds 0.25V, the output

pulse will be terminated, entering

cycle-by-cycle current limit. An

internal switch holds CS low for

50ns after HO or LO switches high

to blank leading edge transients.

Soft-start Input

An internal 110µA current source

charges an external capacitor to

set the soft-start rate. During a

current limit restart sequence, the

internal current source is reduced

to 1.2µA to increase the delay

before retry.

DLY

Timing programming pin

for the LO and HO to SR1

and SR2 outputs.

An external resistor to ground sets

the timing for the non-overlap time

of HO to SR1 and LO to SR2.

RES

Restart Timer

If cycle-by-cycle current limit is

exceeded during any cycle, a 22 µA

current is sourced to the RES pin

capacitor.If the RES capacitor

voltage reaches 2.5V, the soft-start

capacitor will be fully discharged

and then released with a pull-up

current of 1.2µA. After the first

output pulse at LO (when SS

>COMP offset, typically 1V), the SS

pin charging current will revert to

110µA.

Boost voltage for the HO

driver

An external diode is required from

VCC to HB and an external

capacitor is required from HS to HB

to power the HO gate driver.

Switch node

Connection common to the

transformer and both power

switches. Provides a return path for

the HO gate driver.

High side gate drive

output.

Output of the high side PWM gate

driver. Capable of sinking 2A peak

current

Low side gate dfrive

output.

Output of the low side PWM gate

driver. Capable of sinking 2A peak

current.

PGND

Power Ground

Connect directly to Analog Ground.

LM5035A Datasheet(PDF) 5 Page - National Semiconductor (TI)

LM5035A Datasheet(HTML) 5 Page - National Semiconductor (TI)

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