RN5RK Series
VFM Step-up DC/DC Converter
The RN5RK Series are low supply current, CMOS-based VFM step-up DC/DC converters. By 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 (I
DD1
)·······················Typ. 35μA (RN5RK301x, at continuous oscillation)
•
Supply Current (I
DD2
)·······················Typ. 2μA (V
OUT
=SET V
OUT
+0.5V)
•
Standby Current (I
standby
) ·················Max. 0.5μA (In standby)
•
Input Voltage Range (V
IN
) ···············Max. 8V
•
Start-up Voltage (V
start
) ····················Max. 0.9V (xx1 Version)
•
Max. 0.8V (xx2 Version)
Output Voltage Range (V
OUT
)··········2.0V to 5.5V (internally fixed)
•
Output Voltage Accuracy ········
±
2.5%
•
Oscillator Frequency (f
osc
)······· 100kHz
•
Oscillator Duty Cycle (Duty) ··· 77% (A Version)
•
•
55% (B Version)
Efficiency ································ Typ. 85% (RN5RK301B,
V
IN
=2V, I
OUT
=10mA)
Package·································· SOT-23-5
BLOCK DIAGRAMS
RN5RKxx1x
(Internal output transistor type)
Lx
Vref
RN5RKxx2A
(External transistor type)
V
OUT
EXT
Vref
Buffer
VFM Control
5
LxSW
V
LX
Limiter
Buffer
VFM Control
OSC 100kHz
Chip Enable
2
-
+
Error Amp.
5
2
-
+
V
OUT
OSC 100kHz Error Amp.
Chip Enable
4
1
CE
GND
4
1
CE
GND
SELECTION GUIDE
Package
SOT-23-5
Quantity per Reel
Part No.
3,000 pcs
RN5RK.xx∗$ -TR-F
TYPICAL APPLICATIONS
RN5RKxx1x
SD
RN5RKxx2A
SD
Rb
.xx.
: Specify the output voltage within the range
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
V
IN
C
L
4
LOAD
GND
CE
1
V
IN
Cb
4
C
L
GND
CE
1
L=100μH, SD=MA721, C
L
=47μF
L=27μH, SD=RB111C, C
L
=47μF×2,
Tr=2SD1628G, Rb=300Ω, Cb=0.01μF
PACKAGE (Top View)
SOT-23-5
5
4
TYPICAL CHARACTERISTICS
RN5RK301x
Efficiency vs. Output Current
100
90
80
L=100μH
RN5RK302A
Efficiency vs. Output Current
100
90
80
Efficiency
η
(%)
L=27μH
1
2
3
Efficiency
η
(%)
70
60
50
40
30
20
10
0
0
20
V
IN
=2.0V
V
IN
=1.5V
V
IN
=1.3V
V
IN
=1.0V
V
IN
=0.9V
40 60 80 100 120 140 160
Output Current I
OUT
(mA)
70
60
50
40
30
20
10
0
0
V
IN
=2.0V
V
IN
=1.5V
V
IN
=1.3V
V
IN
=1.0V
V
IN
=0.9V
200
400
600
Output Current I
OUT
(mA)
800
1
2
3
4
5
CE
V
OUT
NC
GND
L
X
or EXT
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
No.EK-077-091101
Step-up DC/DC Converter
LOAD
5
Lx
V
OUT
2
L
Tr
5
EXT V
OUT
2
1. The products and the product specifications described in this document are subject to change or
discontinuation of production without notice for reasons such as improvement. Therefore, before
deciding to use the products, please refer to Ricoh sales representatives for the latest
information thereon.
2. The materials in this document may not be copied or otherwise reproduced in whole or in part
without prior written consent of Ricoh.
3. Please be sure to take any necessary formalities under relevant laws or regulations before
exporting or otherwise taking out of your country the products or the technical information
described herein.
4. The technical information described in this document shows typical characteristics of and
example application circuits for the products. The release of such information is not to be
construed as a warranty of or a grant of license under Ricoh's or any third party's intellectual
property rights or any other rights.
5. The products listed in this document are intended and designed for use as general electronic
components in standard applications (office equipment, telecommunication equipment,
measuring instruments, consumer electronic products, amusement equipment etc.). Those
customers intending to use a product in an application requiring extreme quality and reliability,
for example, in a highly specific application where the failure or misoperation of the product
could result in human injury or death (aircraft, spacevehicle, nuclear reactor control system,
traffic control system, automotive and transportation equipment, combustion equipment, safety
devices, life support system etc.) should first contact us.
6. We are making our continuous effort to improve the quality and reliability of our products, but
semiconductor products are likely to fail with certain probability. In order to prevent any injury to
persons or damages to property resulting from such failure, customers should be careful enough
to incorporate safety measures in their design, such as redundancy feature, firecontainment
feature and fail-safe feature. We do not assume any liability or responsibility for any loss or
damage arising from misuse or inappropriate use of the products.
7. Anti-radiation design is not implemented in the products described in this document.
8. Please contact Ricoh sales representatives should you have any questions or comments
concerning the products or the technical information.
RICOH COMPANY., LTD.
Electronic Devices Company
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