BD9540EFV ROHM Electronics, BD9540EFV Datasheet - Page 8

• Manufacturer Part Number: BD9540EFV
• Description: 2ch Switching Regulators for Desktop PC
• Manufacturer: ROHM Electronics

●Explanation of Operation
●Timing Chart
© 2009 ROHM Co., Ltd. All rights reserved.
BD9540EFV
www.rohm.com
V
REF
The BD9540EFV is a 2ch switching regulator controller incorporating ROHM’s proprietary H
system. When VOUT drops due to a rapid load change, the system quickly restores VOUT by extending the TON time
interval.
H
(Normal operation)
(VOUT drops due to a rapid load change)
・Soft Start Function
OUT
HG
LG
EN
IIN
FB
3
REF
Reg
FB
HG
LG
Io
TM
control
1msec
8/17
Soft start is utilized when the EN pin is set high. Current
control takes effect at startup, enabling a moderate
“ramping start” on the output voltage. Soft start time is
1msec. And input current is determined via formula
(2) below.
Rush current:
(Co: All capacitors connected with V
When FB falls below the threshold voltage (REF), a drop
is detected, activating the H
HG output is determined by the formula above. (See P13)
LG output operates until FB voltage falls below REF
voltage after HG becomes OFF.
IIN =
When FB (V
voltage remains below REF after the programmed t
interval has elapsed, the system quickly restores V
extending the t
t
ON
=
Co×V
V
V
OUT
1ms
IN
OUT)
OUT
ON
×
drops due to a rapid load change, and the
time, improving transient response.
1
f
[A]
[sec]・・・(1)
・・・(2)
3
3
Reg
Reg
TM
TM
CONTROLLA system.
OUT
CONTROLLA control
Technical Note
2009.04 - Rev.B
)
ON
OUT
time
by