SSL1750_1

© NXP B.V. 2008. All rights reserved.

Product data sheet

Rev. 01 — 15 September 2008

8 of 29

NXP Semiconductors

SSL1750

SMPS control IC for LED drivers

7.1.2 Supply management

All internal reference voltages are derived from a temperature compensated and trimmed

on-chip band gap circuit. Internal reference currents are derived from a temperature

compensated and trimmed on-chip current reference circuit.

7.1.3 Latch input

The pin LATCH is a general purpose input pin, which can be used to switch off both

Switching of both converters is stopped as soon as the voltage on this pin drops below

1.25 V.

At initial start-up switching is inhibited until the voltage on pin LATCH is above

1.35 V (typ). No internal filtering is done on this pin. An internal Zener clamp of 2.7 V (typ)

protects this pin from excessive voltages.

Fig 5.

Start-up sequence, normal operation, and restart sequence

LATCH

PROTECTION

PFCSENSE

PFCDRIVER

FBSENSE

FBDRIVER

FBCTRL

VOSENSE

CHARGING VCC

CAPACITOR

STARTING

CONVERTERS

NORMAL

OPERATION

PROTECTION

RESTART

soft start

soft start

VINSENSE

014aaa060