TEA1532CT NXP Semiconductors, TEA1532CT Datasheet - Page 10

• 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
7.13 Control pin protection
7.14 PROTECT and timing input
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
is completely switched off; see
Since the soft start current is supplied from pin DRAIN, the R
current during start-up.
If the pin CTRL becomes open-circuit or is disconnected, a fault condition is assumed and
the converter will stop switching immediately. Operation recommences when the fault
condition is removed.
The PROTECT input (pin 3) is a multi-purpose (high-impedance) input, which can be used
to switch off the IC and create a relatively long timing function. As soon as the voltage on
this pin rises above 2.5 V, switching stops immediately. For the timing function, a current of
typically 50 A flows out of pin PROTECT and charges an external capacitor until the
activation level of 2.5 V is reached. This current source is only activated when the
converter is not in regulation, which is detected by the voltage on pin CTRL
(V
capacitor is not charged, for example, by spikes. A MOSFET switch is added to discharge
the external capacitor and ensure a defined start situation. For the TEA1532CT, the
voltage on pin CTRL determines whether the IC enters latched protection mode, or safe
restart protection mode:
Fig 8. Soft start-up
•
•
CTRL
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
be 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
th(UVLO)
PROTECT
< 0.63 V). A (small) discharge current is also implemented to ensure that the
, capacitor C
startup
> 2.5 V) will cause the converter to stop switching. Once V
and V
Rev. 01 — 18 January 2007
startup(soft)
0.5 V
VCC
th(UVLO)
will be recharged and the supply will restart. This cycle will
Figure
will flow as long as the voltage on pin SENSE is
, but the IC will not start switching again until the latch
TEA1532BT; TEA1532CT
start-up
V
8.
ocp
startup(soft)
I
ss
6
SENSE
. At V
R
C
ss
ss
startup
PROTECT
GreenChip II SMPS control IC
, the I
R
mgu237
sense
ss
value will not affect V
> 2.5 V), by external
startup(soft)
© NXP B.V. 2007. All rights reserved.
CC
current source
CC
drops below
will cycle
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CC
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