bd8621efv ROHM Co. Ltd., bd8621efv Datasheet - Page 10

• Manufacturer Part Number: bd8621efv
• Description: Built-in 1ch Fet Synchronous Rectification Type Dc/dc Converters
• Manufacturer: ROHM Co. Ltd.

Under voltage lock out protection (UVLO)
As for BD8623EFV, the power-supply voltage decrease detection protection circuit is built in.
It the input voltage decrease below the UVLO voltage (2.5V typ), the device state changes to the standby mode
(Moreover, to prevent the chattering of the output) hysteresis width of 100mV(typ) has been installed in the UVLO cancel
voltage.
RT terminal open/short protection function (RTO/RTS)
RT terminal opening/short protection function prevent the clock from abnormal oscillation.
If RT terminal open/short protection function is detected, output voltage changes to low level and is fixed.
Terminal RT opening/short protection function is available if the state continue for 500usec, abnormal
detection operates when the state continues about 500μsec(typ).
Soft start time-out function
If VSS doesn't exceed VSSTH within 64msec (typ) since a soft start began, BD8629FS controls an off latch.
Vo is fixed in a low level.
Thermal shut down function
the DC/DC converter is fixed in a low voltage.
It aims at neither protection nor the guarantee of the set. Therefore, please do not use this function to protect the set.
Over current protection function
The current is controlled in every one cycle of the switching frequency. When an abnormal state continues for about
500μsec(typ), the output is fixed in a low level.
Thermal shut down circuit (TSD circuit) is built into BD8623EFV. When the temperature of the chip exceeds Tjmax=175,
TSD function is aimed to shut down IC from thermal reckless driving under an abnormal state to exceed Tjmax=175.
The over current protection function has been achieved by limiting the current that flows on high side MOSFET.
Fig.5 Soft start time-out
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