SSL4101T View Datasheet(PDF) - NXP Semiconductors.
Part Name
Description
MFG CO.
'SSL4101T' PDF : 29 Pages View PDF
NXP Semiconductors
SSL4101T
GreenChip III+ SMPS control IC
S2
RSS2
CSS2
RSENSE2
Istart(soft)fb ≤ 60 μA
SOFT START
CONTROL
10
FBSENSE
OCP
+
0.5 V
Fig 12. Soft start-up of flyback
014aaa020
7.3.7 Maximum on-time
The flyback controller limits the ‘on-time’ of the external MOSFET to 40 μs (typical). When
the ‘on-time’ is longer than 40 μs, the IC stops switching and enters the safe restart mode.
7.3.8 Overvoltage protection (FBAUX pin)
An output overvoltage protection is implemented in the GreenChip III+ series. This works
for the SSL4101T by sensing the auxiliary voltage via the current flowing into pin FBAUX
during the secondary stroke. The auxiliary winding voltage is a well-defined replica of the
output voltage. Voltage spikes are averaged by an internal filter.
If the output voltage exceeds the OVP trip level, an internal counter starts counting
subsequent OVP events. The counter has been added to prevent incorrect OVP detection
which might occur during ESD or lightning events. If the output voltage exceeds the OVP
trip level a few times and not again in a subsequent cycle, the internal counter counts
down at twice the speed it uses when counting up.
However, when typically eight cycles of subsequent OVP events are detected, the IC
assumes a true OVP and the OVP circuit switches the power MOSFET off. As the
protection is latched, the converter only restarts after the internal latch is reset. In a typical
application the mains should be interrupted to reset the internal latch.
The output voltage Vo(OVP) at which the OVP function trips, can be set by the
demagnetization resistor, RFBAUX :
VO(ovp)
=
---N----s----
Naux
(
Io
vp
(F
B
AU
X)
×
RFBAUX
+
Vclamp(FBAUX))
where Ns is the number of secondary turns and Naux is the number of auxiliary turns of the
transformer. Current Iovp(FBAUX) is internally trimmed.
The value of RFBAUX can be adjusted to the turns ratio of the transformer, thus making an
accurate OVP detection possible.
SSL4101T
Product data sheet
All information provided in this document is subject to legal disclaimers.
Rev. 1 — 21 April 2011
© NXP B.V. 2011. All rights reserved.
16 of 29
Share Link: 
