VFM STEP-UP DC/DC CONVERTER
RH5RI××1B/××2B/××3B SERIES
OUTLINE
The RH5RI××1B/××2B/××3B Series are VFM (Chopper) Step-up DC/DC converter ICs with ultra low supply
current by CMOS process.
The RH5RI××1B IC consists of an oscillator, a VFM control circuit, a driver transistor (Lx switch), a reference
voltage unit, an error amplifier, resistors for voltage detection, and an Lx switch protection circuit. A low ripple,
high efficiency step-up DC/DC converter can be constructed of this RH5RI××1B IC with only three external com-
ponents, that is, an inductor, a diode and a capacitor.
The RH5RI××2B IC uses the same chip as that employed in the RH5RI××1B IC and is provided with a drive
pin (EXT) for an external transistor instead of an Lx pin, so that a power transistor with a low saturation voltage
can be externally provided, whereby a large current can be caused to flow through the inductor and accordingly a
large current can be obtained. Therefore, the RH5RI××2B IC is recommendable to the user who need a current
as large as several tens mA toseveral hundreds mA.
The RH5RI××3B IC also includes an internal chip enable circuit so that it is possible to set the standby sup-
ply current at MAX. 0.5µA.
These RH5RI××1B/××2B/××3B ICs are suitable for use with battery-powered instruments with low noise
and ultra low supply current.
FEATURES
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Small Number of External Components
Only an inductor, a diode and a capacitor (RH5RI 1B)
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Ultra Low Input Current
TYP. 4µA (RH5RI301B/303B at no load,with 1.5V input)
±2.5%
High Output Voltage Accuracy
Low Ripple and Low Noise
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Low Start-up Voltage (When the output current is 1mA)
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MAX. 0.9V
High Efficiency
TYP.80%
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Low Temperature-Drift Coefficient of Output Voltage
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TYP. ±50 ppm/˚C
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Small Packages
SOT-89 (RH5RI 1B, RH5RI 2B)
SOT-89-5 (RH5RI××3B)
APPLICATIONS
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Power source for battery-powered equipment.
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Power source for cameras, camcorders, VCRs, PDAs, electronic data banks,and hand-held communication
equipment.
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Power source for appliances which require higher cell voltage than that of batteries used in the appliances.
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RICOH [ RICOH ELECTRONICS DEVICES DIVISION ]
