R1211x

9

Use a 1

typical applications above.

• In terms of the capacitor for setting delay time of the latch protection, C2 as shown in typical applications of

the previous page, connect between Delay pin and GND pin of the IC with the minimum wiring distance.

previous page. (Recommended value is from 10

µF to 22µF.) If the operation of the composed DC/DC

converter may be unstable, use a tantalum type capacitor instead of ceramic type.

page. The capacitance value of C4 depends on divider resistors for output voltage setting. Typical value is

between 100pF and 1000pF.

• Output Voltage can be set with divider resistors for voltage setting, R1 and R2 as shown in typical

applications of the previous page. Refer to the next formula.

× (R1+R2)/R2

R1

+R2=100kΩ is recommended range of resistances.

• The operation of Latch protection circuit is as follows: When the IC detects maximum duty cycle, charge to

MOSFET.

To release the latch protection operation, make the IC be standby mode with CE pin and make it active in

terms of B/D version. Otherwise, restart with power on.

the next formula.

t=C2

Once after the maximum duty is detected and released before delay time, charge to the capacitor is halt and

delay pin outputs "L".

• As for R1211x002A/C version, the values and positioning of C4, C5, R3, and R4 shown in the above diagram

R3, shown in typical applications of the previous page. The recommended resistance value of R3 is in the

range from 10k

Ω to 50kΩ. Then, noise level will be decreased.

• As for R1211x002B/D version, EXT pin outputs GND level at standby mode.

• Select the Power MOSFET, the diode, and the inductor within ratings (Voltage, Current, Power) of this IC.

Choose the power MOSFET with low threshold voltage depending on Input Voltage to be able to turn on the

switching speed. When an external transistor is switching, spike voltage may be generated caused by an

voltage or more.

∗ The performance of power circuit with using this IC depends on external components. Choose the most

suitable components for your application.