BD8961NV ROHM Co. Ltd., BD8961NV Datasheet - Page 5

• Manufacturer Part Number: BD8961NV
• Description: Low Noise Step-down Switching Regulator
• Manufacturer: ROHM Co. Ltd.

●Operation
BD8961NV is a synchronous rectifying step-down switching regulator that achieves faster transient response by employing
current mode PWM control system.
○Synchronous rectifier
It does not require the power to be dissipated by a rectifier externally connected to a conventional DC/DC converter IC, and its
P.N junction shoot-through protection circuit limits the shoot-through current during operation, by which the power dissipation
of the set is reduced.
○Current mode PWM control
Synthesizes a PWM control signal with a inductor current feedback loop added to the voltage feedback.
・PWM (Pulse Width Modulation) control
The oscillation frequency for PWM is 1 MHz. SET signal form OSC turns ON a P-channel MOS FET (while a N-channel
MOS FET is turned OFF), and an inductor current I
signals, a current feedback control signal (SENSE: Voltage converted from I
and issues a RESET signal if both input signals are identical to each other, and turns OFF the P-channel MOS FET (while a
N-channel MOS FET is turned ON) for the rest of the fixed period. The PWM control repeat this operation.
V
OUT
Current
RESET
Gm Amp.
Comp
V
SET
SW
OUT
I
L
Level
Shift
Fig.22 PWM switching timing chart
Fig.21 Diagram of current mode PWM control
ITH
FB
SENSE
Current
Comp
RESET
OSC
SET
L
increases. The current comparator (Current Comp) receives two
R Q
S
5/15
Driver
Logic
L
) and a voltage feedback control signal (FB),
SW
PVCC
GND
GND
GND
I
V
L
(AVE)
OUT
I
L
(AVE)
FB
SENSE
Load
V
OUT