TEA1532 Philips Semiconductors, TEA1532 Datasheet - Page 11

• Manufacturer Part Number: TEA1532
• Description: GreenChip SMPS control IC
• Manufacturer: Philips Semiconductors

Philips Semiconductors
9397 750 13113
Preliminary data sheet
7.15 OverTemperature Protection (OTP)
7.16 Soft start-up (pin SENSE)
When pin DEM is grounded (CCM), the brown-out protection is disabled. In this case the
duty cycle is limited to 0.7, so at low mains voltage the on-time is limited and therefore the
dissipation in the FET is limited.
The IC provides accurate temperature protection. The IC will stop switching when the
junction temperature exceeds the thermal shutdown temperature. When V
V
restart. Subsequently, V
Operation only recommences when V
when V
To prevent transformer rattle at start-up or during hiccup, the transformer peak current is
slowly increased by the soft start function. This can be achieved by inserting a resistor
and a capacitor between pin SENSE (pin 6) and sense resistor R
source charges the capacitor to V
The start level and the time constant of the increasing primary current level can be
adjusted externally by changing the values of R
The charging current I
below approximately 0.5 V. If the voltage on pin SENSE exceeds 0.5 V, the soft start
current source will start limiting current I
switched off; see
Since the soft start current I
current during start-up.
I
primary(max)
Fig 9. Soft start-up.
UVLO
=
R
, capacitor C
ss
mains
C
ss
=
is disconnected for a short period).
V
----------------------------------------- -
ocp
Figure
VCC
–
R
sense
SS
I
will be recharged to the V
ss
Rev. 01 — 28 May 2004
CC
9.
will flow as long as the voltage on pin SENSE is
0.5 V
R
will drop again to V
ss
ss
is supplied from pin DRAIN, the R
sense
start-up
CC
V
= I
ocp
I
ss
ss
drops below a level of about 4.5 V (typically,
ss
. At V
6
SENSE
R
UVLO
start
ss
ss
start
(about 0.5 V maximum).
and C
, the I
, etc..
R
C
ss
ss
level, however switching will not
ss
ss
GreenChip II SMPS control IC
.
© Koninklijke Philips Electronics N.V. 2004. All rights reserved.
current source is completely
mgu237
R
sense
ss
sense
value will not affect V
. An internal current
TEA1532
CC
drops to
11 of 27
CC