TEA2164 View Datasheet(PDF) - STMicroelectronics

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TEA2164

SWITCH MODE POWER SUPPLY PRIMARY CIRCUIT

STMicroelectronics 

TEA2164

In the operation of the master-slave architecture,

four majors cases must be considered :

- normal operating

- stand-by mode

- power supply start-up

- abnormal conditions : off load, short circuit, ...

II.1. Normal Operating (master slave mode)

In this configuration, the master circuit generates a

pulse width modulatedsignal issued from the moni-

toring of the output voltage which needs the best

accuracy (in TV applications : the horizontal deflec-

tion stage supplyvoltage). The master circuit power

supply can be supplied by another output.

The PWM signal are sent towards the primary side

through small differentiating transformer. For the

TEA2164 positive pulses are transistor switching-

on commands ; and negative pulses are transistor

switching-off commands (Figure 4). In this configu-

ration, only by synchronizing the master oscillator,

the switching transistor may be synchronized with

an external signal.

II.2. Stand-by Mode

In this configuration the master circuit no longer

Figure 4 : Master Slave Mode Waveforms

sends PWM signals, the structure is not synchro-

nized ; and the TEA2164 operates in burst mode.

The average power consumption at the secondary

side may be very low 1W ≤ P ≤ 6W (as it is

consumed in TV set during stand by).

By action on the maximum duty cycle control, a

primary loop maintains a semi-regulation of the

output voltages. Voltage on feed-back is applied on

Pin 9.

Burst period is externally programmed by capacitor

C1.

II.3. Power Supply Start-up

After the mains have been switched-on, the VCC

storage capacitor of the TEA2164 is charged

through a high value resistor connected to the

rectified high voltage. When Vcc reaches VCC start

threshold (9V typ), the TEA2164 starts operating in

burst mode. Since available output power is low in

burst mode the output power consumption must

remain low before complete setting-up of output

voltage. In TV application it can be achieved by

maintaining the TV in stand-by mode during start-

up (Figure 6).

SLAVE

CIRCUIT

Synchro.

MASTER

CIRCUIT

Sync.

Pulses

PWM

Signal

Pulse

Input

Base

Current

7/15

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