BD9122GUL_09 データシートの表示（PDF） - ROHM Semiconductor

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BD9122GUL_09

Output 0.5A or Less High Efficiency Step-down Switching Regulator with Built-in Power MOSFET

ROHM Semiconductor 

BD9122GUL

●Information on advantages

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

BD9122GUL(transient response IO=50mA⇔125mA)

VOUT

【VOUT=1.8V】

VOUT

Technical Note

【VOUT=1.8V】

IOUT

IOUT

VCC=3.3V

Ta=25℃

VCC=3.3V

Ta=25℃

Io=50→125mA

Fig.19 Comparison of transient response

Io=125→50mA

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

dissipation (PSW), gate charge/discharge dissipation, ESR dissipation of output capacitor (PESR) and on-resistance

dissipation (PRON) that may otherwise cause degradation in efficiency for lighter load.

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 : 0.3Ω(Typ.)

ON resistance of N-channel MOS FET : 0.2Ω(Typ.)

100

SLLMTM

②

50 ① PWM

①inprovement by SLLM system

②improvement by synchronous rectifier

0

0.001 0.01

0.1

1

Output current Io[A]

Achieves efficiency improvement for heavier load.

Fig.20 Efficiency

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

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

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

・Inductance L required for the operating frequency of 1 MHz: 2.2μH inductor

Reduces a mounting area required.

VCC

DC/DC

Convertor

RITH

Controller

CITH

Cin

L

VOUT

Co

8mm

8mm

RITH

CVCC

CITH

CIN CO

L

Fig.21 Example application

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

5/13

2009.05 - Rev.A

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