PWM Step-up DC/DC Converter
R1210N××1× Series
OUTLINE
The R1210N××1× Series are PWM step-up DC/DC Converter, with high accuracy, low supply current by CMOS
process.
Each of the R1210N××1× Series consists of an oscillator, a PWM circuit, a reference voltage unit, an error amplifier,
phase compensation circuit, resistors for voltage detection, a chip enable circuit. Further, includes a controller against
drastic load transient, a control transistor with low ON-Resistance, ‘L
X
switch’, and a protection circuit for L
X
switch
and an output voltage detector. R1210N××1A Series contain further a circuit for changeover oscillator frequency each.
A low ripple, high efficiency step-up DC/DC converter can be composed of this IC with only three external compo-
nents, or an inductor, a diode and a capacitor.
The R1210N Series can detect drastic change of output voltage with a circuit controller. The load transient re-
sponse is improved compared with current model, furthermore the R1210N××1A Series have another function, that is,
when the load current is small, oscillator frequency is decreased by a circuit for switching oscillator frequency from
TYP 100kHz to 35kHz, therefore, supply current is reduced.
.
The built-in chip enable circuit can make the standby mode with ultra low quiescent current.
Since the package for these ICs is small SOT-23-5, high density mounting of the ICs on board is possible.
FEATURES
•
External Components ................................................................. Only an inductor, a diode, and a capacitor
•
Standby Current ......................................................................... TYP 0µA
.
•
Low Temperature-Drift Coefficient of Output Voltage.............. TYP ±100ppm/°C
.
•
Output Voltage............................................................................. Stepwise Setting with a step of 0.1V in the range of
2.2V to 6.0V (××1C/D)
2.2V to 3.5V (××1A)
•
Two choices of Basic Oscillator Frequency................................ 100kHz (××1A/C), 180kHz (××1D)
•
Small Package .............................................................................. SOT-23-5 (Mini-mold)
•
High Efficiency ............................................................................ TYP 88%
.
(V
IN
=Set Output Voltage×0.6 [V], I
OUT
=10mA)
•
Low Ripple, Low Noise
•
Built-in a driver transistor with low on-resistance
•
Start-up Voltage........................................................................... MAX. 0.9V
•
Basic Frequency change-over circuit (only for
××1A
type)....... from TYP. 100kHz to 35kHz
1
R1210N××1×
APPLICATIONS
•
Power source for battery-powered equipment.
•
Power source for portable communication appliances, cameras, VCRs
•
Power source for appliances of which require higher voltage than battery voltage.
BLOCK DIAGRAM
Vref Circuit
L
X
5
V
LX
limiter
Buffer
PWM Controller
OSC
fosc Control
Phase Comp.
2 V
OUT
4 GND
Chip Enable
1
CE
SELECTION GUIDE
In the R1210N Series, the output voltage, the oscillator frequency, the optional function, 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 ;
R1210N××1×-××
↑ ↑ ↑
a b c
Code
Setting Output Voltage (V
OUT
) :
a
Stepwise setting with a step of 0.1V in the range of 2.2V to 6.0V (for
××1C/D
version) or
2.2V to 3.5V (for
××1A
version) is possible.
Designation of Oscillator Frequency
b
A : 100kHz with a Frequency Change-over circuit
C : 100kHz without a Frequency Change-over circuit
D : 180kHz without a Frequency Change-over circuit
c
Designation of Taping Type; Ex. :TR, TL (refer to Taping Specification)
“TR” is prescribed as a standard.
Contents
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