N.

Name

Function

4

VCC

Supply voltage of the device. A bypass capacitor to GND, located as close to IC pins as possible, helps obtain a

clean supply voltage for the internal control circuitry and acts as an effective energy buffer for the pulsed gate

drive current.

5

DVS

Drain voltage sensing. This pin must be connected to the drain terminal of the synchronous rectifier MOSFET

through a series resistor of at least 300 Ω.

6

VAUX

Auxiliary supply voltage of the device. When VCC voltage is lower than UVLO voltage threshold (VCC_SO_On),

the bypass capacitor on the VCC pin (coupled to application VOUT through a diode) is supplied by the VAUX pin

if this is connected to an auxiliary winding or to an external capacitor sourced by a DVS voltage rectifier.

If the functionality is not used, VAUX pin must be connected to VCC pin.

7

TOFF

Programming pin for blanking time after turn-off. A resistor connected from this pin to GND, supplied by an

internal current source, sets a voltage VTOFF; depending on this voltage level, the user can choose the blanking

time after turn-off suitable for application requirements.

8

TON

Programming pin for blanking time after turn-on. A resistor connected from this pin to GND, supplied by an

internal current source, sets a voltage VTON; depending on this voltage level, the user can choose the blanking

time after turn-on, suitable to mask ZCD comparator output and avoid premature turn-off due to parasitic voltage

oscillation on DVS pin. In tracking with VTON, the thresholds to enter/exit automatic sleep mode are derived.

A capacitor larger than 60 pF (100 pF typ.) between this pin and GND sets the internal timer mode for SR

MOSFET turn-off in mixed CCM/DCM operation. If no capacitor is used, timer mode is set for turn-off in QR or

DCM operation. No capacitor is also required when SYNC signal is used for turn-off.

SRK1001

Block diagram and pin connection

DS13155 - Rev 1

page 3/27