R1230D Datasheet, PDF (8/20 Pages) RICOH electronics devices division – PWM/VFM Step-down DC/DC Converter with Synchronous Rectifier

s TYPICAL APPLICATION AND TECHNICAL NOTES
1) Fixed Output Voltage Type
VIN
Lx
L
CIN
PGND
AGND
VDD
MODE
CE
VOUT
VOUT
LOAD
COUT
L : 10µH LQH3C100K54(Murata)
COUT : 10µF ECSTOJX106R(Panasonic)
CIN : 10µF C3216JB0J106M(TDK)
2) Adjustable Output Voltage Type
V_IN
L_X
C_IN
PGND
AGND
V_DD
MODE
CE
V_FB
L
V_OUT
R1
Cb
C_OUT
Rb
R2
LOAD
L:
COUT:
CIN:
10µH LQH3C100K54 (Murata)
10µF ECSTOJX106R (Panasonic)
10µF C3216JB0J106M (TDK)
Standard value of the sum of Divider Resistors, R1+R2 is as much as 100kΩ.
Cb value for phase compensation depends on values of L, C, and R1. Refer to the technical notes.
If a ceramic capacitor is used as an output capacitor, add 0.2Ω or more resistance to compensate the ESR of the
capacitor.
When you use these ICs, consider the following issues;
q Input same voltage into Power Supply pins, VIN and VDD. Set the same level as AGND and PGND.
q When you control the CE pin and MODE pin by another power supply, do not make its "H" level more than the
voltage level of VIN / VDD pin.
q Set external components such as an inductor, CIN, COUT as close as possible to the IC, in particular, minimize the
wiring to VIN pin and PGND pin.
q At stand by mode, (CE=”L”), the Lx output is Hi-Z, or both P-channel transistor and N-channel transistor of Lx pin
turn off.
q Use an external capacitor COUT with a capacity of 10µF or more, and with good high frequency characteristics
such as tantalum capacitors.
q At VFM mode, (MODE=”H”), Latch protection circuit does not operate.
Rev. 1.12
-8-