TEA1733T_TEA1733LT_1

© NXP B.V. 2009. All rights reserved.

Objective data sheet

Rev. 01 — 26 October 2009

4 of 17

NXP Semiconductors

TEA1733T; TEA1733LT

GreenChip SMPS control IC

7.

Functional description

7.1 General control

The TEA1733(L) contains a controller for a flyback circuit. A typical configuration is shown

in Figure 3.

7.2 Start-up and UnderVoltage LockOut (UVLO)

Initially the capacitor on the VCC pin is charged from the high voltage mains via a resistor.

switching. In a typical application the supply voltage is taken over by the auxiliary winding

of the transformer.

If a protection is triggered the controller will stop switching. Depending on which protection

is triggered and on the version of the IC (TEA1733T or TEA1733LT) the protection will

cause a restart or will latch the converter to an off-state.

A restart caused by a protection will charge the OPTIMER pin to 4.5 V (typ.) rapidly. The

TEA1733(L) will then enter the Power-down mode until the OPTIMER pin is discharged to

1.2 V (typ.). In Power-down mode, the IC consumes a very low supply current (10

µA typ.)

and the VCC pin will be clamped to 22 V (typ.) by an internal clamp circuit. A restart will be

made when the voltage on pin OPTIMER drops below 1.2 V (typ.) and the VCC pin

voltage is above the VCC start-up voltage (See Figure 4).

When a latched protection is triggered, the TEA1733(L) will enter Power-down mode

immediately. The VCC pin will be clamped to a voltage just above the latch protection

Fig 3.

Typical configuration

014aaa928

TEA1733T

5

ISENSE

DRIVER

GND

VCC

VINSENSE

PROTECT

CTRL

OPTIMER

6

7

8

4

3

2

1

Θ