BD95242MUV ROHM Electronics, BD95242MUV Datasheet - Page 9

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

● Explanation of Operation
© 2009 ROHM Co., Ltd. All rights reserved.
www.rohm.com
＊Attention: H
2×REF
The BD95242MUV is a 2ch synchronous buck regulator controller incorporating ROHM’s proprietary H
control system. When VOUT drops due to a rapid load change, the system quickly restores VOUT by extending the TON
time interval. Thus, it serves to improve the regulator’s transient response. Activating the Light Load Mode will also exercise
Simple Light Load Mode (SLLM) control when the load is light, to further increase efficiency.
H
(Normal operation)
(VOUT drops due to a rapid load change)
Light Load Control
(SLLM)
(QLLM)
VOUT
VOUT
3
Reg
HG
HG
LG
LG
Io
TM
2×REF
2×REF
control
LG
HG
0A
HG
LG
0A
from capacitor to load, using the ESR of output
capacitor, and realize the rapid response. Bpass
capacitor used at each load (Ex. Ceramic capacitor)
exercise the effect with connecting to each load side. Do
not put a ceramic capacitor on C
supply.
3
Reg
VOUT
VOUT
TM
CONTROLLA monitors the supplying current
t
ON
+α
OUT
side of power
9/20
In SLLM (MCTL=”High voltage”), when the status of LG is OFF and
the coil current is within 0A (it flows to SW from VOUT.),
SLLM function is operated to prevent output next HG. The status
of HG is ON, when VOUT falls below reference voltage again.
In QLLM (MCTL=”Hiz or Middle voltage”), when the status
of LG is OFF and the coil current is within 0A (it flows to
SW from VOUT.), QLLM function is operated to prevent
output next HG.
Then, VOUT falls below the output programmed voltage
within the programmed time (typ=40μs), the status of HG
is ON. In case VOUT doesn’t fall in the programmed time,
the status of LG is ON forcedly and VOUT falls. As a result,
he status of next HG is ON.
When VOUT falls to a reference voltage (2×REF), the
drop is detected, activating the H
system.
t
When V
voltage remains below reference voltage after the
programmed t
quickly restores V
the transient response.
HG output is determined by the formula above.
ON
=
2×REF
OUT
VIN
drops due to a rapid load change, and the
ON
×
C
time interval has elapsed, the system
OUT
OUT
1
f
by extending the t
[sec]・・・(1)
3
Reg
3
Technical Note
Reg
2009.04 - Rev.B
TM
TM
ON
CONTROLLA
CONTROLLA
time, improving
Load