R1211D002A RICOH electronics devices division, R1211D002A Datasheet - Page 10

• Manufacturer Part Number: R1211D002A
• Description: Step-up DC/DC Controller
• Manufacturer: RICOH electronics devices division

applications above.
previous page, connect between Delay pin and GND pin of the IC with the minimum wiring distance.
previous page. (Recommended value is from 10 F to 22 F.) If the operation of the composed DC/DC converter may
be unstable, use a tantalum type capacitor instead of ceramic type.
The capacitance value of C4 depends on divider resistors for output voltage setting. Typical value is between 100pF
and 1000pF.
the previous page. Refer to the next formula.
R1+R2=100k
external capacitor, C2 of DELAY pin starts. And maximum duty cycle continues and the voltage of DELAY pin
reaches delay voltage detector threshold, V
B/D version. Otherwise, restart with power on.
The delay time of latch protection can be calculated with C2, V
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”.
just an example combination. These are for making phase compensation. If the spike noise of V
the spike noise may be picked into V
typical applications of the previous page. The recommended resistance value of R3 is in the range from 10k
50k . Then, noise level will be decreased.
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
When an external transistor is switching, spike voltage may be generated caused by an inductor, therefore
recommended voltage tolerance of capacitor connected to V
components for your application.
Rev. 1.10
To release the latch protection operation, make the IC be standby mode with CE pin and make it active in terms of
t=C2 V
The performance of power circuit with using this IC depends on external components. Choose the most suitable
Output Voltage = V
Connect a capacitor between V
Use a 1 F or more capacitance value of bypass capacitor between V
Output Voltage can be set with divider resistors for voltage setting, R1 and R2 as shown in typical applications of
As for R1211X002A/C version, the values and positioning of C4, C5, R3, and R4 shown in the above diagram are
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
In terms of the capacitor for setting delay time of the latch protection, C2 as shown in typical applications of the
Connect a 1 F or more value of capacitor between V
The operation of Latch protection circuit is as follows: When the IC detects maximum duty cycle, charge to an
DLY
/I
DLY1
is recommended range of resistances.
FB
(R1+R2)/R2
F
such as Shottky type, and with low reverse current I
OUT
FB
and the dividing point, C4 as shown in typical applications of the previous page.
pin and make the operation unstable. In this case, a resistor R3, shown in
DLY
, outputs “L” to EXT pin and turns off the external power MOSFET.
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OUT
OUT
and GND, C3 as shown in typical applications of the
DLY
is three times of setting voltage or more.
, and Delay Pin Charge Current, I
IN
pin and GND, C1 as shown in the typical
R,
and with fast switching speed.
OUT
DLY1
may be large,
, as in the
to