TEA1738T_TEA1738LT

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© NXP B.V. 2010. All rights reserved.

Preliminary data sheet

Rev. 1 — 31 December 2010

6 of 21

NXP Semiconductors

TEA1738T; TEA1738LT

GreenChip SMPS control IC

controller stops switching and the TEA1738T enters Restart mode. In Restart mode the

driver output is disabled and the VCC pin voltage is recharged via resistor R3 to the

rectified mains voltage. For the TEA1738LT a VCC undervoltage, which does not occur

during a start-up event, latches the IC in an off-state.

7.3 Supply management

All internal reference voltages are derived from a temperature compensated on-chip band

gap circuit. Internal reference currents are derived from a trimmed and temperature

compensated current reference circuit.

7.4 OverVoltage Protection (VCC pin)

An OVP circuit is connected to the VCC pin. After 8 consecutive OVP cycles the IC

is reached, the counter is reset to zero.

If a lower overvoltage protection level is needed, a Zener diode can be connected

between the VCC pin and the PROTECT pin.

7.5 Input voltage detection (VINSENSE pin)

In a typical application the mains input voltage can be detected by the VINSENSE pin.

Switching does not take place until the voltage on VINSENSE has reached the

(0.72 V typical), the converter stops switching and performs a restart.

An internal clamp of 5.2 V (typical) protects this pin from excessive voltages.

Fig 4.

Start-up sequence, normal operation and restart sequence

001aan170

starting

converter

charging VCC

capacitor

normal

operation

protection

(power-down)

soft start

ISENSE

VINSENSE

PROTECT

OPTIMER

restart

soft start

4.5 V

1.2 V