R1211D002B RICOH [RICOH electronics devices division], R1211D002B Datasheet - Page 9

• Manufacturer Part Number: R1211D002B
• Description: STEP-UP DC/DC CONTROLLER
• Manufacturer: RICOH [RICOH electronics devices division]

• In terms of the capacitor for setting delay time of the latch protection, C2 as shown in typical applications of
• Connect a 1µF or more value of capacitor between V
• Connect a capacitor between V
• Output Voltage can be set with divider resistors for voltage setting, R1 and R2 as shown in typical
• The operation of Latch protection circuit is as follows: When the IC detects maximum duty cycle, charge to
• As for R1211x002A/C version, the values and positioning of C4, C5, R3, and R4 shown in the above diagram
• 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.
∗ The performance of power circuit with using this IC depends on external components. Choose the most
Use a 1µF or more capacitance value of bypass capacitor between V
typical applications above.
the previous page, connect between Delay pin and GND pin of the IC with the minimum wiring distance.
previous page. (Recommended value is from 10µF 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.
applications of the previous page. Refer to the next formula.
an external capacitor, C2 of DELAY pin starts. And maximum duty cycle continues and the voltage of D
pin reaches delay voltage detector threshold, V
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 delay time of latch protection can be calculated with C2, V
the next formula.
Once after the maximum duty is detected and released before delay time, charge to the capacitor is halt and
delay pin outputs "L".
are just an example combination. These are for making phase compensation. If the spike noise of V
be large, the spike noise may be picked into V
R3, shown in typical applications of the previous page. The recommended resistance value of R3 is in the
range from 10kΩ to 50kΩ. Then, noise level will be decreased.
Choose the power MOSFET with low threshold voltage depending on Input Voltage to be able to turn on the
FET completely. Choose the diode with low V
switching speed. When an external transistor is switching, spike voltage may be generated caused by an
inductor, therefore recommended voltage tolerance of capacitor connected to V
voltage or more.
suitable components for your application.
Output Voltage = V
R1+R2=100kΩ is recommended range of resistances.
t=C2×V
DLY
/I
DLY1
FB
× (R1+R2)/R2
OUT
and the dividing point, C4 as shown in typical applications of the previous
F
FB
such as Shottky type with low reverse current I
DLY
pin and make the operation unstable. In this case, a resistor
, outputs "L" to EXT pin and turns off the external power
OUT
and GND, C3 as shown in typical applications of the
DLY
, and Delay Pin Charge Current, I
IN
pin and GND, C1 as shown in the
OUT
is three times of setting
R
, and with fast
DLY1
R1211x
OUT
, as in
may
ELAY
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