BD9123MUV_11 Datasheet, PDF (6/18 Pages) Rohm – Output 1.5A or Less High-efficiency Step-down Switching Regulator with Built-in Power MOSFET

BD9123MUV
Technical Note
●Information on advantages
Advantage 1: Offers fast transient response with current mode control system.
Conventional product (Load response IO=0.1A→0.6A)
BD9123MUV (Load response IO=0.6A→0.1A)
VOUT
IOUT
27mV
VOUT
IOUT
37mV
Fig.22 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
dissipation (P_SW), gate charge/discharge dissipation, ESR dissipation of output capacitor (P_ESR) and on-resistance
dissipation (P_RON) 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 Pch side MOS FET : 0.35mΩ(Typ.)
ON resistance of Nch side MOS FET : 0.25mΩ(Typ.)
100
SLLM
②
Achieves efficiency improvement for heavier load.
Offers high efficiency for all load range with the improvements mentioned above.
50 ① _PWM
①inprovement by SLLM system
0
②improvement by synchronous rectifier
0.001 0.01
0.1
1
Output current Io[A]
Advantage 3:
Fig.23 Efficiency
・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: 4.7µH inductor
Reduces a mounting area required.
VCC
VCC
R PGOOD
Cin
RITH
CITH
DC/DC
Convertor
L
VOUT
Co
L
Co
15mm
RITH
CITH
Fig.24 Example application
20mm
Rf
Cf
CIN
R_PGOOD
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6/17
2011.01 - Rev.A