DAP041 datasheet(18/40 Pages) ONSEMI

18 / 40 page

SCY99194

http://onsemi.com

The information about the fault (permanent Latch or

Autorecovery) is kept during the low consumption off mode

due the safety reason. The reason is not to allow unlatch the

device by the remote control being in off mode.

Start−up of the Controller

At start−up, the current source turns on when the voltage

on the HV pin is higher than VHV(min), and turns off when

VCC reaches VCC(on), then turns on again when VCC reaches

VCC(min), until VCC is supplied by an external source. The

controller actually starts the first time VCC reaches VCC(on)

when the slope on HV pin is positive.

Even though the Dynamic Self−Supply is able to maintain

the VCC voltage between VCC(on) and VCC(min) by turning

the HV start−up current source on and off, it can only be used

in light load condition, otherwise the power dissipation on

the die would be too much. As a result, an auxiliary voltage

source is needed to supply VCC during normal operation.

The Dynamic Self−Supply is useful to keep the controller

alive when no switching pulses are delivered, e.g. in latch or

fault condition, or to prevent the controller from stopping

during load transients when the VCC might drop. The

SCY99194 accepts a supply voltage as high as 28 V, with an

overvoltage threshold VCC(ovp) that latches the controller

off.

Figure 43. VCC Start−up Timing Diagram

time

VHV

time

VCC

time

DRV

V HV(start)

V HV(min)

VCC(on)

V CC(min)

HV current

source = Istart1

HV current

source = Istart2

Waits next

VCC(on)

before starting

VCC(inhibit)

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