BD95500MUV Datasheet, PDF (10/21 Pages) Rohm – Switching Regulator with MOSFET for DDR-SDRAM Cores

BD95500MUV
●Timing Chart
・Soft Start Function
EN
TSS
SS
VOUT
IIN
・Soft Stop Function
EN
1.2V
SS
TSS(OFF)
VOUT
Tdelay
Technical Note
Soft start is exercised with the EN pin set high. Current
control takes effect at startup, enabling a moderate
output voltage “ramping start.” Soft start timing and
incoming current are calculated with formulas (2) and (3)
below.
Soft start time
Tss= ^REF×Css [sec] ・・・(2)
4μA(typ)
Rush current
IIN (ON)=
Co×VOUT
Tss
[A] ・・・(3)
(Css: Soft start capacitor; Co: Output capacitor)
Soft stop is exercised with the EN pin set low. Current
control takes effect at startup, enabling a moderate
output voltage. Soft start timing and incoming current are
calculated with formulas (4) below.
0.1V
Soft stop time
TSS (OFF) = ^{(REF+2VBE)×Css}
1μA (typ)
[sec] ・・・(4)
Spontaneous Discharge
ΔVSS= 1.2[V] (typ)
(It is determined by load and output
capacitor)
Tdelay =
CSS
1μA(typ)
[sec] _{・・・(5)}
・Timer Latch Type Short Circuit Protection
REF×0.70
VOUT
1ms
SCP
When output voltage (Is-) falls to REF×0.7 or less, SCP
comparator inside IC is exercised.
If the status of High is continued 1ms or more
(programmed time inside IC), the IC goes OFF. It can be
restored either by reconnecting the EN pin or disabling
UVLO.
EN/UVLO
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10/20
2010.05 - Rev.C