BD95242MUV ROHM Electronics, BD95242MUV Datasheet - Page 10

• Manufacturer Part Number: BD95242MUV
• Description: 2ch Switching Regurators for Desktop PC
• Manufacturer: ROHM Electronics

●Timing Chart
© 2009 ROHM Co., Ltd. All rights reserved.
www.rohm.com
• Soft Start Function
・Timer Latch Type Short Circuit Protection
・Over Voltage Protection
・Over current protection circuit
EN / UVLO
REF×2.35
EN / UVLO
2×REF
V
VOUT
I
LIMIT
OUT
V
SCP
OVP
EN
SS
HG
I
LG
OUT
IN
Vo
I
L
t
ON
150μs(typ)
or less
increase Io
T
SS
REF×1.4
t
ON
150μs(typ)
150μs(typ)
or more
Latch
2.5μsec
t
ON
10/20
(Css: Soft start capacitor; Co: Output capacitor)
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.
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
Incoming current
Short protection kicks in when output falls to or below
REF × 1.4 (setting voltage ×0.7).
When the programmed time period (typ.=1ms) 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 t
threshold, HG becomes OFF.
After 2.5μsec(typ), HG becomes ON again if the output
voltage is lower than the specific voltage level and I
lower than I
Tss=
I
IN
=
ON
REF×Css
2.5μA(typ)
Co×V
. However, when inductor current exceeds I
LIMIT
Tss
OUT
level.
[sec]
[A]
・・・(2)
・・・(3)
Technical Note
2009.04 - Rev.B
L
LIMIT
is