RN5RK SERIES

VFM STEP-UP DC/DC CONVERTER

NO.EA-045-0602

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 (Mini-mold), 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

•

High Output Voltage Accuracy .............................................

±2.5%

•

Low Ripple and Low Noise

•

Low Start-up Voltage............................................................ Max.0.9V

•

High Efficiency ..................................................................... Typ. 80%

•

Including a Driver Transistor with Low ON Resistance........ Only RN5RKxx1A/xx1B

•

Two Kinds of Duty Ratio....................................................... 77% (xx1A, xx2A)/ 55% (xx1B)

•

Output Voltage Range.......................................................... 2.0V to 5.5V

•

Low Temperature-Drift Coefficient of Output Voltage........... Typ.

±100ppm/°C

•

Small Packages ................................................................. SOT-23-5 (Mini-Mold)

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

Vref

V

LX

limiter

Buffer

LxSW

VFM Control

OSC 100kHz

Chip Enable

－

＋

Error Amp.

RN5RKxx2A

Vref

Buffer

VFM Control

－

＋

Lx 5

2 V

OUT

EXT 5

2 V

OUT

OSC 100kHz Error Amp.

Chip Enable

4 GND

1

CE

1

CE

4 GND

SELECTION GUIDE

The output voltage, the driver type, the duty cycle 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:

RN5RKxxxx-xx

↑ ↑↑ ↑

a bc d

Code

a

b

←Part

Number

Contents

Setting Output Voltage (V

OUT

) :

Stepwise setting with a step of 0.1V in the range of 2.0V to 5.5V is possible.

Designation of Driver

1: Internal Lx Tr. Driver

2: External Tr. Driver

Designation of Duty Cycle

A: 77%

B: 55%

Designation of Taping type

Ex. TR, TL (refer to Taping Specifications, TR type is prescribed as a standard.)

c

d

2

RN5RK

PIN CONFIGURATIONS

•

5

SOT-23-5

4

(mark side)

1

2

3

PIN DISCRIPTION

•

RN5RKxx1x

Pin No.

1

2

3

4

5

Symbol

CE

V

OUT

NC

GND

L

X

Description

Chip Enable Pin

Step-up Output Monitoring Pin,

Power Supply (for device itself)

No Connection

Ground Pin

Switching Pin

(Nch Open Drain)

•

RN5RKxx2x

Pin No.

1

2

3

4

5

Symbol

CE

V

OUT

NC

GND

EXT

Description

Chip Enable Pin

Step-up Output Monitoring Pin,

Power Supply (for device itself)

No Connection

Ground Pin

External Tr. Drive Pin

(CMOS Output)

ABSOLUTE MAXIMUM RATINGS

Symbol

V

OUT

V

LX

V

EXT

V

CE

I

LX

I

EXT

P

D

Topt

Tstg

LX Pin Voltage

EXT Pin Voltage

CE Pin Voltage

Lx Pin Output Current

EXT Pin Output Current

Power Dissipation (SOT-23-5)*

1

Operating Temperature Range

Storage Temperature Range

Item

Step-up Output Pin Voltage

Rating

9.0

–0.3

to V

OUT

+0.3

–0.3

to V

OUT

+0.3

500

±30

420

–40

to +85

–55

to +125

Unit

V

mA

mW

°C

*1)For Power Dissipation, please refer to PACKAGE INFORMATION to be described.

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.

3

RN5RK

ELECTRICAL CHARACTERISTICS

•

RN5RKxx1A/xx1B

Topt=25°C

Symbol

V

OUT

V

IN

∆V

OUT

/

∆Topt

Vstart

∆Vstart/

∆Topt

Vhold

I

DD2

Istandby

I

LXleak

fosc

∆fosc/

∆Topt

Duty

Vlxlim

V

CEH

V

CEL

I

CEH

I

CEL

Item

Output Voltage

Input Voltage

Output Voltage

Temperature Coefficient

Start-Up Voltage

Temperature Coefficient

Hold-on Voltage (xx1A)

Hold-on Voltage (xx1B)

Supply Current2

Supply Current (Standby)

Lx Leakage Current

Maximum Oscillator

Frequency

Frequency Temperature

Coefficient

−40°C

<

=

Conditions

V

IN

=Set

V

OUT

×0.6,

I

OUT

=1mA

Min.

×0.975

Typ.

Max.

×1.025

8.0

Unit

V

ppm

/°C

Topt

<

=

85°C

±100

0.75

-1.6

0.7

0.9

2

5

0.5

1

80

100

0.41

70

47

0.4

0.9

0.3

-0.5

0.0

25

30

35

40

45

50

60

0.5

50

55

60

65

75

80

90

77

55

0.6

85

63

0.8

120

0.90

V

IN

=0V→2V*

1

-40°C

<

Topt

<

85°C

=

1

V

IN

=0V→2V*

V

IN

=2V→0V*

1

V

IN

=2V→0V*

1

V

OUT

=V

CE

=Set V

OUT

+0.5V

V

OUT

=6V,

V

CE

=0V

V

OUT

=V

LX

=8V

V

OUT

=V

CE

=Set V

OUT

×0.96

-40°C

<

=

V

mV/

°C

V

µA

kHz

kHz/

°C

%

V

µA

Topt

<

=

85°C

Oscillator Duty Cycle (xx1A) V

OUT

=V

CE

=Set

V

OUT

×0.96,

Oscillator Duty Cycle (xx1B) ON (V

LX

“L” side)

V

LX

Voltage Limit

CE “H” Input Voltage

CE “L” Input Voltage

CE “H” Input Current

CE “L” Input Current

V

OUT

=V

CE

=1.95, Lx Switch ON

V

OUT

=V

CE

=Set V

OUT

×0.96,

Judgment is made by the Lx

waveform

V

OUT

=6.0V,

V

CE

=6.0V

V

OUT

=6.0V,

V

CE

=0.0V

2.0V

2.5V

3.0V

<

=

<

=

<

=

<

=

<

=

<

=

<

=

V

OUT

V

OUT

V

OUT

V

OUT

V

OUT

V

OUT

V

OUT

<

=

<

=

<

=

<

=

<

=

<

=

<

=

2.4V

2.9V

3.4V

3.9V

4.4V

4.9V

5.5V

I

DD1

Supply Current1 *

2

3.5V

4.0V

4.5V

5.0V

µA

4

RN5RK

Symbol

Item

2.0V

2.5V

3.0V

I

LX

Lx Switching Current

3.5V

4.0V

4.5V

5.0V

<

=

<

=

<

=

<

=

<

=

<

=

<

=

Conditions

V

OUT

V

OUT

V

OUT

V

OUT

V

OUT

V

OUT

V

OUT

<

=

<

=

<

=

<

=

<

=

<

=

<

=

Min.

80

100

120

140

160

180

200

Typ.

Max.

Unit

2.4V, V

LX

=0.4V

2.9V, V

LX

=0.4V

3.4V, V

LX

=0.4V

3.9V, V

LX

=0.4V

4.4V, V

LX

=0.4V

4.9V, V

LX

=0.4V

5.5V, V

LX

=0.4V

mA

*1)Condition: An Output load resistor R

L

is connected between V

OUT

and GND.

Note that the resistor R

L

has a resistance which makes an output current 1mA after step-up operation.

*2)The Supply Current 1 (I

DD1

) for IC itself is measured when the internal oscillator works continuously.

If the oscillator works intermittently, the supply current becomes smaller than the value which is written on

the above table.

Measurement condition: V

OUT

=V

CE

=Setting

Output Voltage×0.96

5

参数名称	属性值
是否Rohs认证	符合
厂商名称	RICOH Electronic Devices Co., Ltd.
包装说明	,
Reach Compliance Code	unknown
湿度敏感等级	1

RN5RK291A-TL-F

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RN5RK291A-TL-F规格参数

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