LM5035 datasheet(4/28 Pages) NSC

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Pin Descriptions (Continued)

TSSOP

LLP

Name

Description

Application Information

RES

Restart Timer

If cycle-by-cycle current limit is exceeded during any cycle, a

22µA 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

55µA.

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 drive output.

Output of the low side PWM gate driver. Capable of sinking 2A

peak current.

PGND

Power Ground

Connect directly to Analog Ground.

VCC

Output of the high voltage

start-up regulator. The VCC

voltage is regulated to 7.6V.

If an auxiliary winding raises the voltage on this pin above the

regulation setpoint, the Start-up Regulator will shutdown, thus

reducing the internal power dissipation.

SR2

Synchronous rectifier driver

output.

Control output of the synchronous FET gate. Capable of 0.5A

peak current.

SR1

Synchronous rectifier driver

output.

Control output of the synchronous FET gate. Capable of 0.5A

peak current.

REF

Output of 5V Reference

Maximum output current is 20mA. Locally decoupled with a

0.1µF capacitor.

VIN

Input voltage source

Input to the Start-up Regulator. Operating input range is 13V to

100V with transient capability to 105V. For power sources

outside of this range, the LM5035 can be biased directly at

VCC by an external regulator.

Exposed Pad, underside of

package

No electrical contact. Connect to system ground plane for

reduced thermal resistance.

No connection

No electrical contact.

No connection

No electrical contact.

No connection

No electrical contact.

No connection

No electrical contact.

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