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RICOH electronics devices division |
RN5RK SERIES
VFM STEP-UP DC/DC CONVERTER
NO.EA-045-111124
OUTLINE
The RN5RKxx1A/xx1B/xx2A Series are CMOS-based VFM (Chopper) Step-up DC/DC converter ICs with ultra
low supply current and high output voltage accuracy.
Each of the RN5RKxx1A/xx1B consists of an oscillator, a VFM control circuit, a driver transistor to have low
ON resistance (Lx switch), a reference voltage unit, a high speed comparator, resistors for voltage detection, an
Lx switch protection circuit and an internal chip enable circuit. A low ripple, high efficiency step-up DC/DC
converter can be composed of this RN5RKxx1A/xx1B with only three external components: an inductor, a diode
and a capacitor.
The RN5RKxx2A uses the same chip as what is employed in the RN5RKxx1A/1B IC and has a drive pin (EXT)
for an external transistor instead of an Lx pin. As it is possible to load a large output current with a power
transistor which has a low saturation voltage, RN5RKxx2A IC is recommendable to users who need an output
current as large as between several tens mA and several hundreds mA.
Using the chip enable function, it is possible to make the supply current on standby minimized.
Since the package for these ICs is SOT-23-5, high density mounting of the ICs on board is possible.
FEATURES
• Small Number of External Components .............................. Only an inductor, a diode and a capacitor
(RN5RKxx1A/xx1B)
• Standby Current ................................................................... Typ. 0μA
• Low Temperature-Drift Coefficient of Output Voltage........... Typ. ±100ppm/°C
• Output Voltage Range.......................................................... 2.0V to 5.5V
• Two Kinds of Duty Ratio....................................................... 77% (xx1A, xx2A)/ 55% (xx1B)
• High Output Voltage Accuracy ............................................. ±2.5%
• Small Packages ................................................................. SOT-23-5
• High Efficiency ..................................................................... Typ. 85% (RN5RK301B, VIN=2V, IOUT=10mA)
• Low Ripple and Low Noise
• Including a Driver Transistor with Low ON Resistance........ Only RN5RKxx1A/xx1B
• Low Start-up Voltage............................................................ Max.0.9V
APPLICATIONS
• Power source for battery-powered equipment.
• Power source for cameras, camcorders, VCRs, and hand-held communication equipment.
• Power source for those appliances which require higher cell voltage than that of batteries.
1
RN5RK
OUTLINE DIAGRAM
RN5RKxx1x
Lx 5
VLX limiter
Vref
Buffer
LxSW
VFM Control
-
+
OSC 100kHz Error Amp.
Chip Enable
1
CE
2 VOUT
4 GND
EXT 5
RN5RKxx2A
Vref
Buffer
VFM Control
-
+
OSC 100kHz Error Amp.
Chip Enable
1
CE
2 VOUT
4 GND
SELECTION GUIDE
The output voltage, the driver type and the duty cycle for the ICs can be selected at the user's request.
Product Name
RN5RKxx∗$-TR-FE
Package
SOT-23-5
Quantity per Reel
3,000 pcs
Pb Free
○
Halogen Free
○
xx:The output voltage can be designed in the range from 2.0V(20) to 5.5V(55) in 0.1V steps.
∗ :Designation of Driver
(1)Internal Lx Tr. Driver
(2)External Tr. Driver
$ :Designation of Duty Cycle
(A)77%
(B)55%
2
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