SSL1750 datasheet(7/29 Pages) NXP

7 / 29 page

SSL1750_1

Product data sheet

Rev. 01 — 15 September 2008

7 of 29

NXP Semiconductors

SSL1750

SMPS control IC for LED drivers

As soon as the ﬂyback converter is started, the voltage on pin FBCTRL is monitored. If the

output voltage of the ﬂyback converter does not reach its intended regulation level in a

predeﬁned time, the voltage on pin FBCTRL reaches the Vto(FBCTRL) level and an error is

assumed. The SSL1750 then initiates a safe restart.

When one of the protection functions is activated, both converters stop switching and the

VCC voltage drops to Vth(UVLO). A latched protection recharges the VCC capacitor via pin

HV, but does not restart the converters. For a safe restart protection, the capacitor is

recharged via pin HV and the device restarts (see Figure 1).

In the event of an overvoltage protection of the PFC circuit

(VI on pin VOSENSE > Vovp(VOSENSE)), only the PFC controller stops switching until the

voltage on pin VOSENSE drops below Vovp(VOSENSE) again. Also, if a mains undervoltage

is detected (VI on pin VINSENSE < Vstop(VINSENSE)), only the PFC controller stops

switching until VI on pin VINSENSE > Vstart(VINSENSE) again.

When the voltage on pin VCC drops below the undervoltage lockout level, both controllers

stop switching and reenter the safe restart mode. In the safe restart mode the driver

outputs are disabled and pin VCC voltage is recharged via pin HV.

SSL1750 数据表(PDF) 7 Page - NXP Semiconductors