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
•
Small Number of External Components ..........Only an inductor, a diode and a capacitor (RH5RI
××
1B)
•
Ultra Low Input Current ...................................TYP. 4µA (RH5RI301B/303B at no load,with 1.5V input)
•
High Output Voltage Accuracy .........................±2.5%
•
Low Ripple and Low Noise
•
Low Start-up Voltage (When the output current is 1mA) ......................MAX. 0.9V
•
High Efficiency ...................................................TYP.80%
•
Low Temperature-Drift Coefficient of Output Voltage ..........................TYP. ±50 ppm/˚C
•
Small Packages ...................................................SOT-89 (RH5RI
××
1B, RH5RI
××
2B)
SOT-89-5 (RH5RI
××
3B)
APPLICATIONS
•
Power source for battery-powered equipment.
•
Power source for cameras, camcorders, VCRs, PDAs, electronic data banks,and hand-held communication
equipment.
•
Power source for appliances which require higher cell voltage than that of batteries used in the appliances.
1
RH5RI
BLOCK DIAGRAM
V
LX
limiter
LxSW
Buffer
–
Lx
Vref
OUT
Vss
VFM Control
+
OSC 100kHz
EXT
Chip Enable
Error Amp.
CE
(Note) Lx Pin............only for RH5RI
××
1B and RH5RI
××
3B
EXT Pin.........only for RH5RI
××
2B and RH5RI
××
3B
CE Pin...........only for RH5RI
××
3B
SELECTION GUIDE
In RH5RI Series, the output voltage, the driver, and the taping type for the ICs can be selected at the user's
request. The selection can be made by designating the part number as shown below :
RH5RI
××××
–
××
←
Part Number
}
}
↑ ↑
a b
}
↑
c
Code
Contents
a
Setting Output Voltage (V
OUT
):
Stepwise setting with a step of 0.1V in the range of 2.5V to 7.5V is possible.
Designation of Driver:
1B: Internal Lx Tr. Driver (Oscillator Frequency 100kHz)
2B: External Tr. Driver (Oscillator Frequency 100kHz)
3B: Internal Tr./External Tr. (selectively available) (Oscillator Frequency 100kHz, with chip
enable function)
Designation of Taping type :
Ex. SOT-89 : T1, T2
SOT-89-5 : T1, T2
(refer to Taping Specification)
“T1” is prescribed as a standard.
b
c
For example, the product with Output Voltage 5.0V, the External Driver (the Oscillator Frequency 100kHz)
and Taping Type T1, is designated by Part Number RH5RI502B-T1.
2
RH5RI
ABSOLUTE MAXIMUM RATINGS
Symbol
Item
Rating
Unit
Vss=0V
Note
V
OUT
V
LX
V
EXT
V
CE
I
LX
I
EXT
P
D
Topt
Tstg
Tsolder
Output Pin Voltage
Lx Pin Voltage
EXT Pin Voltage
CE Pin Voltage
Lx Pin Output Current
EXT Pin Current
Power Dissipation
Operating Temperature Range
Storage Temperature Range
Lead Temperature (Soldering)
+12
+12
–0.3 to V
OUT
+0.3
–0.3 to V
OUT
+0.3
250
±50
500
–30 to +80
–55 to +125
260˚C,10s
V
V
V
V
mA
mA
mW
˚C
˚C
Note1
Note2
Note3
Note1
Note2
(Note
1) Applicable to RH5RI
××
1A and RH5RI
××
3B.
(Note 2) Applicable to RH5RI
××
2B and RH5RI
××
3B.
(Note 3) Applicable to RH5RI
××
3B.
ABSOLUTE MAXIMUM RATINGS
Absolute Maximum ratings are threshold limit values that must not be exceeded even for an instant under any
conditions. Moreover, such values for any two items must not be reached simultaneously. Operation above
these absolute maximum ratings may cause degradation or permanent damage to the device. These are stress
ratings only and do not necessarily imply functional operation below these limits.
4
Embedded System
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