2001.6.16
2CH PWM DC/DC Controller
R1280D002X Series
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OUTLINE
The R1280D002X Series are 2-channel PWM Step-up (as Channel 1)/Inverting (as Channel 2) DC/DC converter
controllers with CMOS process.
Each of the R1280D002X Series consists of an oscillator, a PWM control circuit, a reference voltage unit, an error
amplifier, a reference current unit, a protection circuit, and an under voltage lockout (UVLO) circuit. A high efficiency
Step-up/Inverting DC/DC converter can be composed of this IC with inductors, diodes, power MOSFETs, resisters,
and capacitors. Each Output Voltage can be adjustable with external resistors, while soft-start time can be adjustable
with external capacitors..
Maximum Duty Cycle of R1280D002A and C series can be also adjustable with external resistors.
Maximum Duty Cycle of R1280D002B is built-in as 90%(TYP.).
When CE pin of R1280D002B is set at GND level, this IC turns off external power MOSFETs of Step-up/Inverting as
Standby-mode.
Standby current is typically 0µA.
As for a protection circuit, if Maximum duty cycle of either Step-up DC/DC converter side or Inverting DC/DC
converter side is continued for a certain time, the R1280D Series latch both external drivers with their off state by its
Latch-type protection circuit. Delay time for protection is internally fixed typically at 100ms. To release the protection
circuit, restart with power-on (Voltage supplier is equal or less than UVLO detector threshold level), or as for
R1280D002B, once after making the circuit be stand-by with chip enable pin and enable the circuit again.
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FEATURES
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Input Voltage Range
• • • • • • • • • • • • •
2.5V to 5.5V
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Built-in Latch-type Protection Function by monitoring duty cycle (Fixed Delay Time TYP. 100ms)
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Oscillator Frequency
• • • • • • • • • • • • •
700kHz(R1280D002A,B)/200kHz(r1280D002C)
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Maximum Duty Cycle
• • • • • • • • • • • • •
TYP. 90%(Only applied to R1280D002B Series)
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High Reference Voltage Accuracy
• • • • • • ±1.5%
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U.V.L.O. Threshold
• • • • • • • • • • •
TYP. 2.2V (Hysteresis: TYP. 0.1V)
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Small Package
• • • • • • • • • • • • • • • •
thin SON-10 (package thickness MAX. 0.9mm)
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APPLICATIONS
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Constant Voltage Power Source for portable equipment.
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Constant Voltage Power Source for LCD and CCD.
Rev. 1.10
-1-
RICOH [ RICOH ELECTRONICS DEVICES DIVISION ]
