SSL2103T NXP [NXP Semiconductors], SSL2103T Datasheet - Page 7

• Manufacturer Part Number: SSL2103T
• Description: SMPS controller IC for dimmable LED lighting
• Manufacturer: NXP [NXP Semiconductors]

NXP Semiconductors
SSL2103
Product data sheet
8.5 Valley switching
The SB_DRV output is activated when the maximum voltage on pin HVDET is below the
V
on pin ISENSE exceeds the V
output is deactivated when the ISENSE voltage drops below the V
(250 mV typically). The WB_DRV output is also deactivated when the strong bleeder
switch is switched on. See
A new cycle is started when the primary switch is switched on (see
determined by the oscillator voltage, RC and the internal regulation level, the switch is
turned off and the secondary stroke starts. The internal regulation level is determined by
the voltage on pin PWMLIMIT.
After the secondary stroke, the drain voltage shows an oscillation with a frequency of
approximately:
where:
As soon as the oscillator voltage is high again and the secondary stroke has ended, the
circuit waits for a low drain voltage before starting a new primary stroke.
Figure 6
secondary stroke and the RC voltage.
The primary stroke starts some time before the actual valley at low ringing frequencies,
and some time after the actual valley at high ringing frequencies.
--------------------------------------------- -
2
Fig 5.
th(SBLEED)

L
C
p

p
= primary self inductance
= parasitic capacitance on drain node

1

shows the drain voltage together with the valley signal, the signal indicating the
Bleeder circuit
L
p
level (52 V typically). The WB_DRV output is activated as soon as the voltage

WB_DRV
C
All information provided in this document is subject to legal disclaimers.
p

Rev. 2 — 25 November 2010
ISENSE
−0.25 V
−0.1 V
Figure
th(high)(ISENSE)
5.
S
Q
R
SMPS controller IC for dimmable LED lighting
B1
LOW V DETECT
level (100 mV typically). The WB_DRV
GND
OR
HVDET
INTEGRATED
th(low)(ISENSE)
Figure
SB_DRV
001aam658
SSL2103
© NXP B.V. 2010. All rights reserved.
6). After a time
level
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