tea1553t NXP Semiconductors, tea1553t Datasheet - Page 15

• Manufacturer Part Number: tea1553t
• Description: Tea1553t Greenchip Ii Smps Control Ic
• Manufacturer: NXP Semiconductors

NXP Semiconductors
TEA1553T_1
Product data sheet
7.17 Overtemperature protection
7.18 5 V output
7.19 Open/not connected CTRL pin protection
7.20 Soft start-up (pin ISENSE)
I
An accurate temperature protection is provided in the circuit. When the junction
temperature exceeds the thermal shutdown temperature, the IC will stop switching. When
V
IC will not start switching again. Subsequently, V
and so on.
Operation only recommences when the V
practice this only occurs when the mains input voltage has been disconnected for a short
period of time.
Pin 12 can be used for the supply of external circuitry. The maximum output current must
be limited to 1 mA. If higher peak currents are required, an external RC combination
should limit the current drawn from this pin to 1 mA maximum.
The 5 V output voltage will be available as soon as the start-up voltage is reached. As the
high voltage supply cannot supply the VCC5V pin during start-up or shutdown, during
latched shutdown (via pin 13 or other latched protection such as OVP or OTP), the voltage
is switched to zero.
If the CTRL pin is open/not connected, a fault condition is assumed and the converter will
stop switching. Operation will recommence as soon as the fault condition is removed.
To prevent transformer rattle during hiccup, the transformer peak current through the
sense resistor, I
inserting a resistor and a capacitor between pin ISENSE (pin 3) and the sense resistor,
R
maximum of about 0.5 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
approximately 0.5 V. If the voltage on pin ISENSE exceeds 0.5 V, the soft start current
source will start limiting the current I
source is completely switched off (see
Since the soft start current I
value will affect the V
DM
CC
sense
=
drops to V
R
=
. An internal current source charges the capacitor to V = I
ss
V
--------------------------------------------------------------------------------- -
sense max
C
ss
th(UVLO)
DM
–
, is slowly increased by the soft start function. This can be achieved by
R
I
CC
sense
startup soft
, capacitor C
startup(soft)
Rev. 01 — 3 July 2007
charging current level by a maximum of 60 A (typical value).
startup(soft)
will flow as long as the voltage on pin ISENSE is below
R
VCC
ss
startup(soft)
is subtracted from pin V
Figure
will be recharged to the V
CC
voltage drops below a level of about 4.5 V, in
. At the V
13).
ss
CC
and C
will drop again to the V
startup
ss
.
GreenChip II SMPS control IC
level, the I
CC
startup(soft)
charging current, the R
startup
TEA1553T
level, however the
startup(soft)
© NXP B.V. 2007. All rights reserved.
th(UVLO)
R
ss
, with a
current
level,
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SS