APR34309C datasheet(8/13 Pages) DIODES

8 / 13 page

APR34309C

Document number: DS37492 Rev. 5 - 2

8 of 13

www.diodes.com

June 2015

APR34309C

A Product Line of

Diodes Incorporated

Output Voltage Detect Function Description

VDET

VCC V

VTRIGGER

VOFF

tOSC

VOVP

VTRIGGER

IVCC

IDIS

UVLO

VDIS

IOVP

tDIS

tOSC

tOVP_LAST

Figure 1. Typical Waveforms of APR34309C

When VCC is beyond power-on voltage (VON), the APR34309C starts up. The VDET pin asserts a periodical pulse and the oscillation period is tOSC.

When VCC is beyond the trigger voltage (VTRIGGER), the periodical pulse at VDET pin is discontinued. When VCC is beyond the discharge voltage

(VDIS), the discharge circuit will be enabled, and a 3mA current (IDIS) will flow into VCC pin. When VCC is higher than the overshoot voltage (VOVP),

the APR34309C will enable a discharge circuit, the discharge current (IOVP) will last tOVP_LAST time. After the tOVP_LAST time, APR34309C will stop the

discharge current and detect VCC voltage again. If VCC is still higher than VOVP, the tOVP_LAST time discharge current will be enabled again. Once the

OVP discharge current is asserted, the periodical pulse at VDET pin will be disabled.

When the VCC falls below the power-off voltage (VOFF), the APR34309C will shut down.

Operation Description

MOSFET Driver

The operation of the SR is described with timing diagram shown in Figure 2. APR34309C monitors the MOSFET drain-source voltage. When the

drain voltage is lower than the turn-on threshold voltage VTHON, the IC outputs a positive drive voltage after a turn-on delay time (tDON). The

MOSFET will turn on and the cur

rent will transfer from the body diode into the MOSFET’s channel.

In the process of drain current decreasing linearly toward zero, the drain-source voltage rises synchronically. When it rises over the turn off

threshold voltage VTHOFF, APR34309C pulls the drive signal down after a turn-off delay (tDOFF).

I,V

VDET

VDRISR

VTHON

VTHOFF

0.1VDRISR

0.9VDRISR

0.1VDRISR

0.9VDRISR

tRG

tDON

tFG

tDOFF

Figure 2. Typical Waveforms of APR34309C

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