BD9139MUV Datasheet, PDF (5/17 Pages) Rohm – Output 2A or More High-efficiency Step-down Switching Regulators with Built-in Power MOSFET

BD9139MUV
Technical Note
●Information on advantages
Advantage 1：Offers fast transient response with current mode control system.
Conventional product (Load response IO=1A→3A)
BD9139MUV (Load response IO=1A→3A)
VOUT
145mV
VOUT
70mV
IOUT
IOUT
Voltage drop due to sudden change in load was reduced by about 50%.
Fig.18 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 Highside MOS FET : 100mΩ(Typ.)
ON resistance of Lowside MOS FET : 80mΩ(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}
①improvement by SLLM system
②improvement by synchronous rectifier
0
0.001 0.01
0.1
1
Output current Io[A]
Fig.19 Efficiency
Advantage 3：・Supplied in smaller package due to small-sized power MOS FET incorporated.
・Output capacitor Co required for current mode control: 22μF ceramic capacitor
・Inductance L required for the operating frequency of 1 MHz: 2.2μH inductor
・Incorporates FET + Boot strap diode
Reduces a mounting area required.
VCC
EN
VREF
VCC
BST
Gm Amp
+
Soft
Start
Current
Comp
+ ^RQ
S
SLOPE
CLK
OSC
VCC
UVLO
TSD
SCP
Current
Sense/
Protect
+
Driver
Logic
PVCC
SW
PVCC
PGND
GND
3.3V
Input
Output
15mm
ADJ
R1 ^R2
ITH
RITH CITH
Fig.20 Example application
20mm
Rf
Cf _CBST
R1
R2
RITH
CITH
CIN
L
Co
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5/16
2009.05 - Rev.A