TEA1532P NXP Semiconductors, TEA1532P Datasheet - Page 9

• Manufacturer Part Number: TEA1532P
• Description: Greenchip Tm Ii Smps Control Ic
• Manufacturer: NXP Semiconductors

Philips Semiconductors
9397 750 14319
Product data sheet
7.13 Valley switching
For the TEA1532P and the TEA1532T the IC always enters the latched mode protection
independent of the voltage on pin CTRL.
A voltage higher than 3 V on pin PROTECT will always latch the IC. This is independent of
the state of the IC.
Refer to
(determined by the sense voltage and the internal control voltage), the switch is opened
and the secondary stroke starts. After the secondary stroke, the drain voltage shows an
oscillation with a frequency of approximately
where L
the drain node.
As soon as the oscillator voltage is high again and the secondary stroke has ended, the
circuit waits for the lowest drain voltage before starting a new primary stroke. This method
is called valley detection.
signal and the oscillator signal.
In an optimum design, the reflected secondary voltage on the primary side will force the
drain voltage to zero. Thus, zero voltage switching is possible, preventing large capacitive
switching losses
results in small and cost effective magnetics.
•
•
When the voltage on pin CTRL is below 0.63 V, the IC is assumed to be out of
regulation (e.g. the control loop is open). In this case activating pin PROTECT
(V
V
repeated until the fault condition is removed (safe restart mode).
When the voltage on pin CTRL is above 0.63 V, the output is assumed to be in
regulation. In this case activating pin PROTECT (V
means, will activate the latch protection of the IC: The voltage on pin V
between V
protection is reset. The latch is reset as soon as V
(this only occurs when the mains has been disconnected). The internal
overtemperature protection will also trigger this latch; see also
UVLO
PROTECT
p
Figure
is the primary self inductance of the transformer and C
, capacitor C
start
> 2.5 V) will cause the converter to stop switching. Once V
8. A new cycle starts when the power switch is activated. After the on-time
P
and V
=
Rev. 02 — 4 February 2005
1
-- -
2
VCC
UVLO
Figure 8
C
will be recharged and the supply will restart. This cycle will be
, but the IC will not start switching again until the latch
V
TEA1532(A)P; TEA1532(A)T
2
shows the drain voltage, valley signal, secondary stroke
f
, and allowing high frequency operation, which
----------------------------------------- -
2
1
CC
L
PROTECT
p
drops below 4.5 V (typical value)
GreenChip II SMPS control IC
© Koninklijke Philips Electronics N.V. 2005. All rights reserved.
C
d
> 2.5 V), by external
d
is the capacitance on
Figure
CC
1.
CC
drops below
will cycle
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