BD9533EKN_08 Datasheet, PDF (10/21 Pages) Rohm – Switching Regulators for DDR-SDRAM Cores

●Timing Chart
• Soft Start Function
EN
TSS
SS
VOUT
IIN
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)
2μA(typ)
Incoming current
IIN= ^Co×VOUT
Tss
[A] ・・・(3)
(Css: Soft start capacitor; Co: Output capacitor)
・Timer Latch Type Short Circuit Protection
VOUT
REF×0.7
TSCP
SCP
EN/UVLO
・Over Voltage Protection
VOUT
REF×1.2
HG
LG
Switching
Short protection kicks in when output falls to or below
REF X 0.7. When the programmed time period elapses,
output is latched OFF to prevent destruction of the IC.
Output voltage can be restored either by reconnecting
the EN pin or disabling UVLO. Short circuit protection
time is programmed using formula (4) below.
Short protection time setting
Tscp= ^{1.25(V)×CSCP}
2μA(typ)
[sec] ・・・(4)
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