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AN1645 - APPLICATION NOTE

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revelation mechanism makes circuit operation independent by the forward magnetic reset technique

used, avoiding most of the common problems inherent in self-driven synchronous rectifiers. The IC

operation prevents secondary side shoot-through conditions providing proper timing at the outputs turn-

off transition. This smart function operates through a fast cycle-after-cycle control logic mechanism

based on an internal high frequency oscillator, synchronized by the clock signal. The IC provides a fixed

anticipation in turning-off the OUTGate1 with respect to the clock signal transition, while the anticipation

in turning-off the OUTGate2 can be set through external components. A special Inhibit function allows

the shut-off of one of the two outputs allowing operation during discontinuous conduction mode and

preventing the freewheeling mosfet from sinking current from the output.

The STSR2P automatically turns off the outputs when duty-cycle is lower than 13%, while STSR2PM

works even at very low duty-cycle values.

.

3. PIN CONNECTIONS AND DESCRIPTIONS

The STSR2P is housed in a SO-8 package for SMD assembly. Device pin out is shown in figure 2 and

table 1 briefly summarizes the device pin functionality.

Figure 2: Pin Configuration

Table 1: Pin Configuration

Pin Number

Pin Name

Pin Function

1

OUTGate1

Output for Forward MOSFET Gate Drive

2

Vcc

Supply input from 4V to 5.5V

3

4

CK

Synchronization for IC’s operation

5

INHIBIT

Discontinuous Mode Detector

6

SGLGND

Reference for all the control logic signals

7

OUTGate2

Output for Freewheeling MOSFET Gate Drive

8

PWRGND

Reference for power signals