BD9102FVM, BD9104FVM, BD9106FVM

Technical Note

8/17

www.rohm.com

2009.05 - Rev.A

© 2009 ROHM Co., Ltd. All rights reserved.

●

Information on advantages

Advantage 1：Offers fast transient response with current mode control system.

Voltage drop due to sudden change in load was reduced by 50%.

Fig.41 Comparison of transient response

Advantage 2： Offers high efficiency for all load range.

・

For lighter load:

Utilizes the current mode control mode called SLLM for lighter load, which reduces various dissipation such as switching

Achieves efficiency improvement for lighter load.

・

For heavier load:

Utilizes the synchronous rectifying mode and the low on-resistance

MOS FETs incorporated as power transistor.

ON resistance of P-channel MOS FET: 0.35 Ω (Typ.)

ON resistance of N-channel MOS FET: 0.25 Ω (Typ.)

Achieves efficiency improvement for heavier load.

Offers high efficiency for all load range with the improvements mentioned above.

Advantage 3：・Supplied in smaller package like MOSP8 due to small-sized power MOS FET incorporated.

・

Allows reduction in size of application products

Reduces a mounting area required.

Fig.43 Example application

・

Output capacitor Co required for current mode control: 10 μF ceramic capacitor

・

Inductance L required for the operating frequency of 1 MHz: 4.7 μH inductor

DC/DC

Convertor

Controller

L

Co

Cin

10mm

15mm

L

228mV

110mV

Conventional product (VOUT of which is 3.3 volts)

0.001

0.01

0.1

1

0

50

100

①

②

PWM

SLLM

TM

①

inprovement by SLLM system

②

improvement by synchronous rectifier

Output current Io[A]

Fig.42 Efficiency