R1234D Datasheet, PDF (10/26 Pages) RICOH electronics devices division – PWM/VFM Step-Down DC/DC CONVERTER with Synchronous Rectifier

R1234D
TYPICAL APPLICATION AND TECHNICAL NOTES
1) Fixed Output Voltage Type
1 ^VIN
CIN
L
Lx 8
2 PGND AGND 7
3 VDD MODE 6
4 CE
5 VOUT
VOUT
LOAD
COUT
CIN
COUT
L
10µF C3216JB0J106M (TDK)
10µF ECSTOJX106R (Panasonic)
10µH LQH3C100K54 (Murata)
2) Adjustable Output Voltage Type
1 ^VIN
Lx 8
CIN
2 PGND AGND 7
3 VDD MODE 6
4 CE
5 VOUT
L
VOUT
LOAD
COUT
Cb
R1
Rb
R2
CIN
COUT
L
10µF C3216JB0J106M (TDK)
10µF ECSTOJX106R (Panasonic)
10µH LQH3C100K54 (Murata)
VFM mode may work with a parasitic diode, but we recommend that VFM mode used with an external diode in
between LX and GND. As for PWM mode, an external diode is not necessary.
As for how to choose Cb, Rb, R1, and R2 values, refer to the technical notes.
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