TEA1533T Ver la hoja de datos (PDF) - Philips Electronics
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TEA1533T Datasheet PDF : 24 Pages
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Philips Semiconductors
GreenChipTMII SMPS control IC
Product specification
TEA1533T; TEA1533AT
MGU236
handbook, halfpage
Vsense(max)
0.52 V
(typ)
0.3 V
(typ)
−100 µA
(typ)
IDEM
−24 µA
(typ)
Fig.9 OPP correction curve.
Short winding protection
After the leading edge blanking time, the short winding
protection circuit is activated. If the ‘sense’ voltage
exceeds the short winding protection voltage Vswp, the
converter will stop switching. Once VCC drops below the
UVLO level, capacitor CVCC will be recharged and the
supply will restart again. This cycle will be repeated until
the short-circuit is removed (safe restart mode).
The short winding protection will also protect in case of a
secondary diode short-circuit.
OverTemperature Protection (OTP)
An accurate temperature protection is provided in the
circuit. When the junction temperature exceeds the
thermal shutdown temperature, the IC will stop switching.
When VCC drops to UVLO, capacitor CVCC will be
recharged to the Vstart level.
Regarding the TEA1533T, this IC will not start switching
again. Subsequently, VCC will drop again to the UVLO
level, etc. Operation only recommences when the VCC
voltage drops below a level of approximately 4.5 V
(practically when the Vmains has been disconnected for a
short period).
Regarding the TEA1533AT, when the Vstart level is
reached, switching starts again (safe restart mode). This
process is repeated as long as the OTP condition exists.
Control pin protection
If pin CTRL is open-circuit or not connected, a fault
condition is assumed and the converter will stop switching.
Operation will recommence as soon as the fault condition
is removed.
Burst mode standby
Pin CTRL is also used to implement the burst mode
standby. In burst mode standby, the power supply enters
a special low dissipation state. Figure 11 shows a flyback
converter using the burst mode standby function. The
system enters burst mode standby when the
microcontroller activates NPN transistor T1 on the
secondary side.
When the voltage on Cmicro exceeds a certain voltage,
measured by the microcontroller, the opto-coupler is
activated by T1, sending a large current signal to
pin CTRL. In response to this signal, the IC stops switching
and enters a ‘hiccup’ mode. This burst activation signal
should be present for longer than the ‘burst blank’ period
(typically 30 µs): the blanking time prevents false burst
triggering due to spikes. Figure 12 shows the burst mode
standby signals. The hiccup mode during burst mode
standby operation does not differ from the hiccup mode at
safe restart during a system fault condition (e.g. output
short-circuit). The power is reduced during soft restart
mode.
Burst mode standby operation continues until the
microcontroller stops activating transistor T1. The system
then enters the start-up sequence and begins normal
switching behaviour.
Iburstmode = R-----VC---T-t-h-R---L- + Ith(on)
2002 Aug 23
10
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