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TSZ02201-0J3J0A900260-1-2

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10/22

31.Aug.2012 Rev.001

TSZ22111･15･001

BD91501MUV

Datasheet

●Operation

BD91501MUV is a synchronous Buck Converter that achieves faster transient response by employing current mode PWM

control system.

It utilizes switching operation in PWM (Pulse Width Modulation) mode for heavier load, while it utilizes

SLLM

○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 the inductor current feedback loop added to the voltage feedback. Offers fast

transient response with current mode control system. Improves output voltage drop of

load rapid change.

Figure.25 Transient response

・PWM (Pulse Width Modulation) control

The oscillation frequency for PWM is 1.65 MHz.

SET signal form OSC turns ON a highside MOS FET (while a lowside

The current comparator (Current Comp) receives two

and issues a RESET signal if both input signals are identical to each other, and turns OFF the highside MOS FET (while a

lowside MOS FET is turned ON) for the rest of the fixed period.

The PWM control repeat this operation.

・SLLM

When the control mode is shifted from PWM for heavier load to the one for lighter load or vise versa, the switching pulse is

designed to turn OFF with the device held operated in normal PWM control loop, which allows linear operation without

voltage drop or deterioration in transient response during the mode switching from light load to heavy load or vise versa.

Although the PWM control loop continues to operate with a SET signal from OSC and a RESET signal from Current Comp,

it is so designed that the RESET signal is held issued if shifted to the light load mode, with which the switching is tuned

OFF and the switching pulses are thinned out under control.

Activating the switching intermittently reduces the switching

dissipation and improves the efficiency.

Vo

0.5[V/DIV]

Io

100[mA/DIV]

Vo

0.5[V/DIV]

Io

100[mA/DIV]

Figure.26 Efficiency characteristics

Output current Io[A]

0.001

0.01

0.1

1

0

50

100

①

PWM

SLLM

①Improvements by

SLLM control