RN5RK Series
8V Input VFM Step-up DC/DC Converter
No.EK-045-111001 Step-up DC/DC Converter
The RN5RK Series are low suppl y current, CMOS-b ased VFM step-up DC/DC con verters. B y simply using an inductor, a diode, and a
capacitor as external components, a high-efficiency step-up DC/DC converter can be easily configured. RN5RK comes in two
versions: xx1 version with an internal output transistor and xx2 version with an external transistor.
FEATURES
• Supply Current (IDD1)·······················Typ. 35μA (RN5RK301x, at continuous oscillation)
• Supply Current (IDD2)·······················Typ. 2μA (VOUT=SET VOUT+0.5V)
• Standby Current (Istandby) ·················Max. 0.5μA (In standby)
• Input Voltage Range (VIN)··············· Max. 8.0V
• Start-up Voltage (Vstart)····················Max. 0.9V (xx1 Version)
Max. 0.8V (xx2 Version)
• Output Voltage Range (VOUT)··········2.0V to 5.5V
(
internally fixed
)
• Output Voltage Accuracy········± 2.5%
• Oscillator Frequency (fosc)·······100kHz
• Oscillator Duty Cycle (Duty) ···77% (A Version)
55% (B Version)
• Efficiency ································Typ. 85% (RN5RK301B,
VIN=2.0V, IOUT=10mA)
• Package·································· SOT-23-5
BLOCK DIAGRAMS
RN5RKxx1x RN5RKxx2A
(Internal output transistor type) (External transistor type)
2
5
1
Vref
VOUT
GND
CE
4
VLX Limiter
Buffer
Lx
LxSW
Error Amp.
VFM Control
OSC 100kHz
Chip Enable
+
-
+
2
5
1
Vref
V
OUT
GND
CE
-
4
Buffer
EXT
VFM Control
OSC 100kHz
Chip Enable
Error Amp.
SELECTION GUIDE TYPICAL APPLICATIONS
Halogen Free
Package
Q'ty per Reel
Part No.
SOT-23-5 3,000 pcs RN5RK
.
xx∗$
-TR-FE RN5RKxx1x
Lx
C
L
GND
V
OUT
L
V
IN
CE
SD
LOAD
5
4
2
1
RN5RKxx2A
C
L
Rb
Cb
L
V
IN
Tr EXT
GND
V
OUT
CE
SD
LOAD
5
4
2
1
.
xx
.
:
Specify the output voltage within the range of
2.0V (
.
20
.
) to 5.5V (
.
55
.
) in 0.1V steps.
.
∗
.
: Select from (
.
1
.
) internal output transistor type or
(
.
2
.
) external transistor type.
.
$
.
:
Select from (
.
A
.
) duty cycle of 77% or
(
.
B
.
)
duty cycle of 55%
.
(The RN5RKxx2B-TR-F does not exist.)
L=100μH, SD=MA721, CL=47μF L=27μH, SD=RB111C, CL=47μF×2,
Tr=2SD1628G, Rb=300Ω, Cb=0.01μF
PACKAGE (Top View) TYPICAL CHARACTERISTICS
SOT-23-5
1 3
5 4
2
1 CE
2 VOUT
3 NC
4 GND
5 LX or EXT
RN5RK301x
Efficiency vs. Output Current
L=100μH
Output Current I
OUT
(mA)
100
90
80
70
60
30
20
10
40
50
0
1606040200 14080 100 120
V
IN
=2.0V
V
IN
=1.5V
V
IN
=1.3V
V
IN
=1.0V
V
IN
=0.9V
Efficiency
η (%)
RN5RK302A
Efficiency vs. Output Current
L=27μH
Efficiency
η (%)
Output Current I
OUT
(mA)
100
90
80
70
60
50
30
40
20
10
0
V
IN
=2.0V
V
IN
=1.5V
V
IN
=1.3V
V
IN
=1.0V
V
IN
=0.9V
0 200 400 600 800
APPLICATIONS
• Power source for battery-powered equipment
• Power source for hand-held communication equipment, cameras, and VCRs
• Power source for equipment that requires a voltage higher than battery voltage
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