BD91361MUV Datasheet, PDF (6/18 Pages) Rohm – Output 2A More High-efficiency Step-down Switching Regulator with Built-in Power MOS FET

BD91361MUV
Technical Note
●Information on advantages
Advantage 1 : Offers fast transient response with current mode control system.
Conventional product (Load response IO=1A→3A)
BD91361MUV (Load response IO=1A→3A)
VOUT
145mV
VOUT
62mV
IOUT
IOUT
Voltage drop due to sudden change in load was reduced by about 50%.
Fig.20 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 (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 High side MOS FET : 82mΩ(Typ.)
ON resistance of Low side MOS FET : 70mΩ(Typ.)
100
SLLM^TM
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
②improvement by synchronous rectifier
0
0.001 0.01
0.1
1
Output current Io[A]
Fig.21 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.
VID<0>
VID<1>
V CC
EN
VREF
SELECTOR
Gm Amp
+
Soft
Start
Current Comp
+
SLOPE
VCC ^CLK
RQ
S
UVLO
TSD
SCP
Current
Sense/
Protect
+
Driver
Logic
PVCC
VCC
BST
PVCC
Input
SW
Output
PGND
GND
15mm
ADJ
R2
R1
ITH
RITH CITH
Fig.22 Example application
20mm
Rf
R1
Cf _{C BST}
R2 _RITH
CITH
CIN
L
Co
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6/17
2010.06 - Rev.A