BD9122GUL_09 Datasheet, PDF (5/14 Pages) Rohm – Output 0.5A or Less High Efficiency Step-down Switching Regulator with Built-in Power MOSFET

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 (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 P-channel MOS FET : 0.3Ω(Typ.)
ON resistance of N-channel MOS FET : 0.2Ω(Typ.)
100
SLLM^TM
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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5/13
2009.05 - Rev.A