TEA1761T データシートの表示（PDF） - NXP Semiconductors.

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TEA1761T

GreenChip synchronous rectifier controller

NXP Semiconductors. 

NXP Semiconductors

TEA1761T

GreenChip synchronous rectifier controller

driver output is pulled to ground. After switch-on of the SR MOSFET, the input signal on

the SRSENSE pin is blanked for 2 µs (typical). This will eliminate false switch-off due to

high frequency ringing at the start of the secondary stroke.

Because the driver output voltage is reduced as soon as the voltage on the SRSENSE pin

is −55 mV, the external power switch can be switched off fast when the current through the

switch reaches zero. With this zero-current switch off, no separate standby mode is

needed to maintain high efficiency during no-load operation. The zero current is detected

by sensing a −12 mV level on the SRSENSE pin. See Figure 3.

VSRSENSE

0V

−12 mV

−55 mV

−310 mV

Primary

current

0A

Secondary

current

0A

VDRIVER

0V

014aaa057

Fig 3. Synchronous rectification signals

If the secondary stroke of the flyback converter is shorter than 2 µs (typical), the driver

output is disabled. This will guarantee stable operation for very low duty cycles. When the

secondary stroke increases above 2.2 µs (typical) then the driver output is again enabled.

7.3 SMPS output voltage and current regulation

The output voltage of the flyback Switched Mode Power Supply (SMPS) can be controlled

by sensing the output voltage via pin VSENSE. The feedback loop via the primary controller

can regulate the output voltage of the switched mode power supply by regulating the

voltage on pin VSENSE, to 2.5 V.

Also the output current of the flyback SMPS can be controlled or limited. The voltage on

pin ISENSE is regulated or limited to 50 mV above the voltage on pin GND.

TEA1761T_2

Product data sheet

Rev. 02 — 25 April 2007

© NXP B.V. 2007. All rights reserved.

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