bd8621efv ROHM Co. Ltd., bd8621efv Datasheet - Page 8

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

Soft start time set function
As for BD8623EFV, output can do soft start without overshoot by charging soft start capacity (CSS) connected
between SS and SGND terminal.
Also, soft start time (tss) can be set by setting soft start capacity (CSS) arbitrarily.
OSC oscillation frequency setting function
The output oscillation frequency can be set by connecting resistance between terminal RT (20 pins) and SGND
(range = 250kHz - 1MHz)
The relation between RT terminal resistance and the oscillation frequency follows Fig.3.
1000
10
10
100
1000
10000
RT terminal resistance [kΩ]
Fig.3 RT resistance-oscillation frequency
Switching frequency synchronization
An internal transmitter of BD8623EFV can be synchronized with the external clock signal connected with the terminal
SYNCLK (15 pins).
The frequency of external clock can be set within the range of 250kHz-1MHz. In this case, please set the RT resistance
that may become about -20% value of the external clock frequency.
※ Be short-circuited SYNCLK terminal to SGND when a frequency synchronous function is not used.
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