BD91361MUV_14 Datasheet, PDF (11/27 Pages) Rohm – Synchronous Buck Converter with Integrated FET

BD91361MUV
Datasheet
3. Information on Advantages
Advantage 1: Offers fast transient response by using current mode control system.
Conventional product (Load response IO=1A to 3A)
BD91361MUV (Load response IO=1A to 3A)
VOUT
145mV
VOUT
62mV
IOUT
IOUT
Voltage drop due to sudden change in load was reduced.
Figure 26. Comparison of Transient Response
Advantage 2: Offers high efficiency for all load ranges.
(a) For lighter load:
This IC utilizes the current mode control called SLLM^TM, which reduces various dissipations such as switching
dissipation (PSW), gate charge/discharge dissipation (PGATE), ESR dissipation of output capacitor (PESR) and
ON-Resistance dissipation (PRON) that may otherwise cause reduction in efficiency.
Achieves efficiency improvement for lighter load.
(b) For heavier load:
This IC utilizes the synchronous rectifying mode and uses low ON-Resistance power MOSFETs.
ON-Resistance of High side MOSFET : 60mΩ(Typ)
ON-Resistance of Low side MOSFET : 55mΩ(Typ)
100
SLLM^TM
②
Achieves efficiency improvement for heavier load.
Offers high efficiency for all load ranges 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 IOUT[A]
Advantage 3: ・Supplied in smaller package due to small-sized power MOS FET.
Figure 27. Efficiency
・Required output capacitance, CO ,for current mode control: 22µF ceramic capacitor
・Required inductance, L, for the operating frequency of 1 MHz: 2.2µH inductor
・Incorporates FET + Boot strap diode
Reduces mounting area requirement.
VID<0>
VID<1>
Vcc
EN
VREF
SELECTOR
Gm Amp
+
Current
Comp
+
SLOPE
VCC ^CLK
Soft
Start
UVLO
TSD
SCP
Current
Sense/
Protect
+
Driver
Logic
VCC
BST
PVCC Input
PVCC
SW
PGND
GND
Output
ADJ
R2
R1
ITH
RITH CITH
20mm
15mm
Rf
Cf _CBST
R1
R2
RITH
CITH
CIN
L
Co
Figure 28. Example Application
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06.Oct.2014 Rev.002