BD95513MUV_10 Datasheet, PDF (11/18 Pages) Rohm – Switching Regulator with MOS FET for DDR-SDRAM Cores

BD95513MUV
●Timing Chart
・Soft Start Function
EN
tSS
SS
VOUT
IIN
・Timer Latch-type Short Circuit Protection
VOUT
VREF×0.70
1ms
SCP
EN/UVLO
・Output Over-Voltage Protection
VOUT
HG
LG
VREF×1.2
Switching
Technical Note
The soft start function is enabled when the EN pin is set high.
Current control circuitry takes effect at startup, yielding a
moderate “ramping start” in output voltage. Soft start timing
and incoming current are given by equation (2) and (3) below:
Soft start period:
t_SS =
VREF×Css _{[sec] ・・・(2)}
2µA(typ)
Rush current:
IIN(ON)= ^Co×VOUT
tss
[A] ・・・(3)
(Css: soft start capacitor; Co: output capacitor)
When output voltage falls to V_REF x 0.70 or less, the output short
circuit protection engages, turning the IC off after a set period of
time to prevent internal damage. When EN is switched back on
or when UVLO is cleared, output continues.
The time period before shutting off is set internally at 1ms.
When output reaches or exceeds V_REF x 1.2, the output
over-voltage protection is engaged, turning the low-side FET
completely on to reduce the output (low gate on, high gate off).
When the output falls, it returns to standard mode.
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11/17
2010.10- Rev.A