BD9524MUV_10 Datasheet, PDF (10/21 Pages) Rohm – Main Power Supply IC for Note PC (Linear Regulator Integrated)

BD9524MUV
● Timing Chart
• Soft Start Function
EN
TSS
SS
VOUT
IIN
・Timer Latch Type Short Circuit Protection
VOUT
REF×1.4
SCP
EN / UVLO
・Over Voltage Protection
150μs(typ)
or less
150μs(typ)
or more
REF×2.35
VOUT
OVP
150μs(typ)
Latch
EN / UVLO
・Over current protection circuit
tON
tON
2.5usec tON
HG
LG
ILIMIT
IL
Vo
2×REF
increase Io
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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)
2μA(typ)
Incoming current
IIN= ^Co×VOUT
Tss
[A]
・・・(3)
(Css: Soft start capacitor; Co: Output capacitor)
Short protection kicks in when output falls to or below
REF × 1.4 (setting voltage × 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.
When output rise to or above REF×2.35
(output setting voltage ×1.175), output over voltage
protection is exercised, and low side FET goes up
maximum for reducing output（. LG=High, HG=Low）. When
output falls within the programmed time (typ=150μs), it
returns to the standard mode. 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.
During the normal operation, when VOUT becomes less
than reference voltage, HG becomes High during the
time tON . However, when inductor current exceeds
ILIMIT threshold, HG becomes OFF.
After 2.5μsec(typ), HG becomes ON again if the output
voltage is lower than the specific voltage level and IL is
lower than ILIMIT level.
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2010.03 - Rev.C