TEA1532CT NXP Semiconductors, TEA1532CT Datasheet - Page 11

• Manufacturer Part Number: TEA1532CT
• Description: (TEA1532BT / TEA1532CT) GreenChip II SMPS control IC
• Manufacturer: NXP Semiconductors

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NXP Semiconductors
TEA1532BT_TEA1532CT_1
Product data sheet
7.15 OverTemperature Protection (OTP)
7.16 Brown-out protection
7.17 Driver
I
For the TEA1532BT 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 or the version of the IC.
The IC provides accurate OTP. The IC will stop switching when the junction temperature
exceeds the thermal shutdown temperature. When V
will be recharged to the V
will drop again to V
Operation only recommences when V
when V
During the so called brown-out test, the input voltage is slowly decreased. Since the
on-time depends on V
This is prevented by stopping the converter when the input voltage drops too low.
When the voltage on pin DEM drops below 50 mV during the on-time (QR mode), the
maximum on-time is set to 25 s. The maximum on-time will be reached while V
Subsequently, the IC stops switching and V
only be recharged and the supply will restart only when voltage V
(V
has to enter a safe restart can be set with a demagnetization resistor. During the primary
stroke, the rectified mains input voltage is measured by sensing the current drawn from
pin DEM. This current depends on the mains voltage, according to the following equation:
Where:
The latter function requires an on-time of at least 2 s. This on-time ensures that a reliable
demagnetization current can be measured.
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 driver circuit to the gate of the power MOSFET has a current sourcing capability of
typically 170 mA and a current sink capability of typically 700 mA. This permits fast
turn-on and turn-off of the power MOSFET for efficient operation.
DEM
mains(oper)(en)
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
mains
-------------- -
R
V
N
DEM
aux
=
is disconnected for a short period).
N
----------- -
, also see
N
aux
--------------------------- -
N
p
R
th(UVLO)
(ratio of the number of auxiliary to the number of primary windings)
V
DEM
mains
Rev. 01 — 18 January 2007
i
, long on-times at low V
Section
startup
, etc.
level, however switching will not restart. Subsequently, V
7.1). In addition to this, a V
TEA1532BT; TEA1532CT
CC
drops below a level of about 4.5 V (typically,
CC
i
drops below V
can damage the (external) power device.
CC
CC
drops to V
drops below 4.5 V (typical value)
GreenChip II SMPS control IC
I
th(UVLO)
level at which the converter
I
th(UVLO)
is high enough
Figure
. Capacitor C
© NXP B.V. 2007. All rights reserved.
, capacitor C
1.
i
is low.
VCC
11 of 23
will
VCC
CC
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