DocID10955 Rev 2

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AN2063

Charger application

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This 60 mW power at no-load condition can be saved using the transil clamp to replace the

RCD configuration in the snubber circuit.

4.

Optional for the voltage reference devices (TS431 or TL431 or Zener)

The TS431, the TL431 and the Zener can be used as voltage regulators. The TS431 shows

the low minimum operation current with the typical value of 150 A. This feature is quite

useful, because the biasing resistor can be removed without any voltage regulation

performance loss. With this device, the power losses can be saved on the biasing resistor

with typical value of 5-8 mW.

The TL431 is a cost-effective solution for the constant voltage. The weakness of this device,

in this special application, is its operation current higher than 1 mA. In order to get good

voltage regulation performance at full load condition, a biasing resistor is very important, but

this leads to an additional power loss.

If the requirement of the output voltage performance is not so tight, a Zener can be used as

voltage reference. The standby power in no-load condition is lower than 0.1 W with the 3

optional solutions of voltage reference above. The best solution depends on customers'

requests.

5.

The short-circuit of resistors for current limitation on the auxiliary windings.

3.3

Performance results

3.3.1

Input power consumption at no-load condition

As shown in Table 1, the standby power is measured at DC voltage input in order to have

standby power is around 82 mW (with theTL431).

Table 2. Standby power

Input power consumption

505

μA

50.5 mW

252

μA

75.6 mW

215

μA/203 μA

81.7 mW/77.2 mW