Datasheet RE5RE20AA-RF, RE5RE20AA-RR, RE5RE20AA-TZ, RE5RE20AC, RE5RE21AA-RF Datasheet (RICOH)

VOLTAGE REGULATOR

FOR MIDDLE OUTPUT CURRENT

R×5RE SERIES

APPLICATION MANUAL

NO.EA-016-0006

VOLTAGE REGULATOR

FOR MIDDLE OUTPUT CURRENT

1

R×5RE SERIES

OUTLINE

The R×5RE Series are voltage regulator ICs with high output voltage accuracy and ultra-low quiescent

current by CMOS process. Each of these ICs consists of a voltage reference unit, an error amplifier, a driver

transistor, and resistors for setting output voltage, and a current limit circuit. By use of these ICs, a con-

stant voltage power supply circuit with high efficiency can be constructed because the dropout voltage and

quiescent current of these ICs are very small. Furthermore, theses ICs have a built-in current limit circuit.

The output voltage of these ICs is fixed with high accuracy.

Two types of packages, TO-92 and SOT-89 (Mini-power Mold) are available.

• Ultra-low Quiescent Current

...........................

TYP. 1.1µA (R

×5RE30A,VIN=5.0V)

• Ultra-low Dropout Voltage

...............................

TYP. 0.5V (R

×5RE50A,IOUT=60mA)

• Large Output Current

......................................

TYP. 120mA (R

×5RE50A)

• Low Temperature-Drift Coefficient of Output Voltage

...........................

TYP. ±100ppm/˚C

• Broad Operating Voltage Range

......................

MAX. 10.0V

• Excellent Line Regulation

................................

TYP. 0.1%/V

• High Accuracy Output Voltage

........................

±2.5%

• Output Voltage

...................................................

Stepwise setting with a step of 0.1V in the range of 2.0V to 6.0V is

possible (refer to Selection Guide)

• Two Types of Packages

..................................

TO-92, SOT-89 (Mini-power Mold)

FEATURES

APPLICATIONS

• Power source for battery-powered equipment.

• Power source for cameras, video instruments such as camcorders, VCRs, and hand- held communication equipment.

• Precision voltage references.

BLOCK DIAGRAM

2

1

3

Vref

V

OUT

GND

V

IN

–

+

2

R

×5RE××××–×× ← Part Number

↑↑↑↑↑

abcde

SELECTION GUIDE

The package type, the output voltage, the packing type, and the taping type of R×5RE Series can be

designated at the user's request by specifying the part number as follows.

}

}

For example, the product with Package Type SOT-89,Output Voltage 5.0V,Version A and Taping Type T1 are

designated by Part Number RH5RE50AA-T1.

Code Contents

Designation of Package Type:

a E: TO-92

H: SOT-89 (Mini-power Mold)

b

Setting Output Voltage (V

OUT):

Stepwise setting with a step of 0.1V in the range of 2.0V to 6.0V is possible.

cA

Designation of Packing Type:

d A: Taping

C: Antistatic bag for TO-92 and samples

Designation of Taping Type:

Ex. TO-92 : RF, RR, TZ

e

SOT-89: T1, T2

(refer to Taping Specifications)

“TZ” and “T1” are prescribed as a standard.

R×5RE

3

• TO-92

PIN CONFIGURATION

• SOT-89

PIN DESCRIPTION

• TO-92 • SOT-89

Pin No. Symbol

1 GND

2VIN

3VOUT

Pin No. Symbol

1 GND

2VIN

3VOUT

R×5RE

(mark side)

12

3

(mark side)

12

3

4

ABSOLUTE MAXIMUM RATINGS

Symbol Item

VIN Input Voltage

VOUT Output Voltage

IOUT Output Current

PD Power Dissipation

Topt Operating Temperature

Tstg Storage Temperature

Tsolder Lead Temperature (Soldering)

Rating Unit

+12 V

–0.3 to VIN+0.3 V

300 mA

300 mW

–40 to +85 ˚C

–55 to +25 ˚C

260˚C, 10s

R×5RE

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.

ABSOLUTE MAXIMUM RATINGS

5

ELECTRICAL CHARACTERISTICS

Symbol Item

VOUT Output Voltage

IOUT Output Current

∆

V

OUT

Load Regulation

∆IOUT

VDIF Dropout Voltage

ISS Quiescent Current

∆V

OUT

∆

V

IN

Line Regulation

VIN Input Voltage

Ilim Current Limit

∆V

OUT Output Voltage

∆

Topt Temperature Coefficient

Conditions MIN. TYP. MAX. Unit

VIN=4.0V,IOUT=10mA 1.950 2.000 2.050 V

VIN=4.0V 40 60 mA

V

IN=4.0V

1mA≤IOUT

≤

50mA

40 80 mV

IOUT=30mA 0.5 0.7 V

VIN=4.0V 1.0 3.0 µA

I

OUT=10mA

VOUT+

1.0V≤V

IN

≤

10V

0.1 %/V

10 V

240 mA

I

OUT=10mA

±100 ppm/˚C

–40˚C≤Topt≤85˚C

Topt=25˚C

• R×5RE30A

Topt=25˚C

R×5RE

Symbol Item

VOUT Output Voltage

IOUT Output Current

∆V

OUT

Load Regulation

∆IOUT

VDIF Dropout Voltage

ISS Quiescent Current

∆

V

OUT

∆VIN

Line Regulation

VIN Input Voltage

Ilim Current Limit

∆V

OUT Output Voltage

∆Topt Temperature Coefficient

Conditions MIN. TYP. MAX. Unit

VIN=5.0V,IOUT=10mA 2.925 3.000 3.075 V

VIN=5.0V 50 80 mA

V

IN=5.0V

1mA≤IOUT≤60mA

40 80 mV

IOUT=40mA 0.5 0.7 V

VIN=5.0V 1.1 3.3 µA

I

OUT=10mA

VOUT+1.0V≤VIN≤10V

0.1 %/V

10 V

240 mA

I

OUT=10mA

±100 ppm/˚C

–

40

˚C≤

Topt≤85

˚C

6

• R×5RE50A

Topt=25˚C

R×5RE

• R×5RE40A

Topt=25˚C

Symbol Item

VOUT Output Voltage

IOUT Output Current

∆V

OUT

Load Regulation

∆IOUT

VDIF Dropout Voltage

ISS Quiescent Current

∆

V

OUT

∆VIN

Line Regulation

VIN Input Voltage

Ilim Current Limit

∆V

OUT Output Voltage

∆Topt Temperature Coefficient

Conditions MIN. TYP. MAX. Unit

VIN=6.0V,IOUT=10mA 3.900 4.000 4.100 V

VIN=6.0V 65 100 mA

V

IN=6.0V

1mA≤IOUT≤70mA

40 80 mV

IOUT=50mA 0.5 0.7 V

VIN=6.0V 1.2 3.6 µA

I

OUT=10mA

VOUT+1.0V≤VIN≤10V

0.1 %/V

10 V

240 mA

I

OUT=10mA

±100 ppm/˚C

–

40

˚C≤

Topt≤85

˚C

Symbol Item

VOUT Output Voltage

IOUT Output Current

∆V

OUT

Load Regulation

∆

I

OUT

VDIF Dropout Voltage

ISS Quiescent Current

∆V

OUT

∆VIN

Line Regulation

VIN Input Voltage

Ilim Current Limit

∆V

OUT Output Voltage

∆

Topt Temperature Coefficient

Conditions MIN. TYP. MAX. Unit

VIN=7.0V,IOUT=10mA 4.875 5.000 5.125 V

VIN=7.0V 80 120 mA

V

IN=7.0V

1mA≤IOUT

≤

80mA

40 80 mV

IOUT=60mA 0.5 0.7 V

VIN=7.0V 1.3 3.9 µA

I

OUT=10mA

VOUT+1.0V≤VIN≤10V

0.1 %/V

10 V

240 mA

I

OUT=10mA

±100 ppm/˚C

–40˚C≤Topt≤85˚C

7

• R×5RE60A

Topt=25˚C

R×5RE

Symbol Item

VOUT Output Voltage

IOUT Output Current

∆V

OUT

Load Regulation

∆

I

OUT

VDIF Dropout Voltage

ISS Quiescent Current

∆V

OUT

∆VIN

Line Regulation

VIN Input Voltage

Ilim Current Limit

∆V

OUT Output Voltage

∆

Topt Temperature Coefficient

Conditions MIN. TYP. MAX. Unit

VIN=8.0V,IOUT=10mA 5.850 6.000 6.150 V

VIN=8.0V 80 120 mA

V

IN=8.0V

1mA≤IOUT

≤

80mA

40 80 mV

IOUT=60mA 0.5 0.7 V

VIN=8.0V 1.4 4.2 µA

I

OUT=10mA

VOUT+1.0V≤VIN≤10V

0.1 %/V

10 V

240 mA

I

OUT=10mA

±100 ppm/˚C

–40˚C≤Topt≤85˚C

8

ELECTRICAL CHARACTERISTICS BY OUTPUT VOLTAGE

R×5RE

VIN–

V

OUT

=2.0V

1mA≤

40 60

I

OUT

≤50mA

VIN–

V

OUT

=2.0V

1mA≤

I

OUT

≤60mA

50 80

V

IN–

VOUT

=2.0V

40 80

1mA≤

I

OUT

≤70mA

65 100

V

IN–

V

OUT

=2.0V

1mA≤

80 120 I

OUT

≤80mA

R×5RE20A 1.950 2.000 2.050
R×5RE21A 2.048 2.100 2.152
R×5RE22A 2.145 2.200 2.255
R×5RE23A 2.243 2.300 2.357
R×5RE24A 2.340 2.400 2.460
R×5RE25A 2.438 2.500 2.562
R×5RE26A 2.535 2.600 2.665
R×5RE27A 2.633 2.700 2.767
R×5RE28A 2.730 2.800 2.870
R×5RE29A 2.828 2.900 2.972
R×5RE30A 2.925 3.000 3.075
R×5RE31A 3.023 3.100 3.177
R×5RE32A 3.120 3.200 3.280
R×5RE33A 3.218 3.300 3.382
R×5RE34A 3.315 3.400 3.485
R×5RE35A 3.413 3.500 3.587
R×5RE36A 3.510 3.600 3.690
R×5RE37A 3.608 3.700 3.792
R×5RE38A 3.705 3.800 3.895
R×5RE39A 3.803 3.900 3.997
R×5RE40A 3.900 4.000 4.100
R×5RE41A 3.998 4.100 4.202
R×5RE42A 4.095 4.200 4.305
R×5RE43A 4.193 4.300 4.407
R×5RE44A 4.290 4.400 4.510
R×5RE45A 4.388 4.500 4.612
R×5RE46A 4.485 4.600 4.715
R×5RE47A 4.583 4.700 4.817
R×5RE48A 4.680 4.800 4.920
R×5RE49A 4.778 4.900 5.022
R×5RE50A 4.875 5.000 5.125
R×5RE51A 4.973 5.100 5.227
R×5RE52A 5.070 5.200 5.330
R×5RE53A 5.168 5.300 5.432
R×5RE54A 5.265 5.400 5.535
R×5RE55A 5.363 5.500 5.637
R×5RE56A 5.460 5.600 5.740
R×5RE57A 5.558 5.700 5.842
R×5RE58A 5.655 5.800 5.945
R×5RE59A 5.753 5.900 6.047
R

×

5RE60A 5.850 6.000 6.150

Output Voltage OutputCurrent Load Regulation

Part Number

V

OUT(V) IOUT(mA) ∆VOUT/∆IOUT(mV)

Conditions

MIN. TYP. MAX.

Conditions

MIN. TYP.

Conditions

TYP. MAX.

VIN

–

V

OUT

=2.0V

I

OUT

=10mA

VIN–

VOUT

=2.0V

IOUT

=30mA

IOUT

=40mA

0.5 0.7

I

OUT

=

50mA

IOUT

=60mA

Dropout Voltage

V

DIF(V)

Conditions

TYP. MAX.

9

R×5RE

Topt=25˚C

1.0 3.0

1.1 3.3

I

OUT

=10mA

IOUT

VIN–

=10mA

VOUT

1.2 3.6 0.1 10 240 ±100

=2.0V

V

OUT+

–40˚C

≤

1.0V≤ Topt

V

IN ≤85˚C

≤10V

1.3 3.9

1.4 4.2

Quiescent Current Line Regulation

Input Voltage Current Limit

Output Voltage Tempco.

Iss(µA) ∆VOUT/∆VIN(%/V) VIN(V) Ilim(mA)

∆VOUT/∆T(ppm/˚C)

Conditions

TYP. MAX.

Conditions

TYP. MAX. TYP.

Conditions

TYP.

10

OPERATION

Output Voltage VOUT divided at the node between

Registers R1 and R2 is compared with Reference Voltage

by Error Amplifier, so that a constant voltage is output.

TEST CIRCUITS

FIG. 2 Test Circuit

FIG. 3 Quiescent Current Test Circuit

FIG. 4 Line Transient Response Test Circuit

FIG. 1 Brock Diagram

R×5RE

GNDGND

V

IN

–
+

Error Amplifire

V

OUT

R2

R1

Vref

CI

1µF

Co
1µF

V

IN

GND

R×5RE
SERIES

VOUT

IOUT

VOUT

VIN

+

+

ISS

CI

1µF

V

IN

GND

R×5RE

SERIES

VOUT

VIN

+

Ro

Co

0.1µF

P.G

GND

R×5RE

SERIES

VOUT

VOUT

VIN

+

11

TYPICAL CHARACTERISTICS

1) Output Voltage vs. Output Current

R

×5RE40A

R

×5RE50A

R

×5RE50A

R×5RE

Output Current IOUT(mA)

Output Voltage VOUT(V)

0

3.7

3.8

3.9

4.1

4.0

V

IN=6.0V

50 100

150 200

Topt=–40˚C

85˚C

25˚C

4.7

4.8

4.9

5.1

5.0

V

IN=7.0V

0

50 100 150 200 250

Output Voltage VOUT(V)

Output Current IOUT(mA)

with heatsink

without heatsink

4.7

4.8

4.9

5.1

5.0

V

IN=7.0V

0

50 100 150 200 250

heatsink
30

×30×1mm

Output Voltage VOUT(V)

Output Current IOUT(mA)

4.7

4.8

4.9

5.1

5.0

V

IN=7.0V

0 50 100 150 200 250 300 350

25˚C

Topt=–40˚C

85˚C

R×5RE30A

Output Voltage VOUT(V)

Output Current IOUT(mA)

2.7

2.8

2.9

3.1

3.0

V

IN=5.0V

0

50 100

150 200

250

Topt=–40˚C

25˚C

85˚C

R×5RE20A

2) Output Voltage vs. Input Voltage

IOUT=1µA

Topt=25˚C

1.0 3.0 4.02.0 5.0
Input Voltage V

IN(V)

1mA

10mA

Output Voltage VOUT(V)

1.0

1.2

0.8

1.4

1.6

1.8

2.0

2.2

2.4

Topt=25˚C

245367

Input Voltage V

IN(V)

Output Voltage VOUT(V)

1.98

1.96

2.00

2.02

2.04

IOUT=1µA

1mA

10mA

12

R

×5RE30A

R

×5RE40A

R

×5RE30A

R

×5RE40A

R×5RE

R×5RE50A R×5RE50A

Topt=25˚C

2.0 3.0 3.52.5 4.0 4.5

Input Voltage V

IN(V)

Output Voltage VOUT(V)

2.0

2.2

1.8

2.4

2.6

2.8

3.0

3.2

3.4

IOUT=1mA

50mA

10mA

2.5 4.53.5 5.5
Input Voltage V

IN(V)

Topt=25˚C

Output Voltage VOUT(V)

3.4

3.2

3.6

3.8

4.0

4.2

IOUT=1mA

50mA

10mA

Topt=25˚C

3.0 5.0 6.04.0 7.0 8.0
Input Voltage V

IN(V)

Output Voltage VOUT(V)

2.96

2.95

2.97

2.98

2.99

3.00

IOUT=1µA

1mA

10mA

Topt=25˚C

467589

Input Voltage V

IN(V)

Output Voltage VOUT(V)

3.98

3.96

4.00

4.02

4.04

4.06

1mA

IOUT=1µA

10mA

Topt=25˚C

4.54.0 5.5 6.05.0 6.5
Input Voltage V

IN(V)

Output Voltage VOUT(V)

4.4

4.2

4.6

4.8

5.0

5.1

IOUT=1mA

50mA

10mA

Topt=25˚C

6589710

Input Voltage V

IN(V)

Output Voltage VOUT(V)

4.97

4.98

4.95

4.96

4.99

5.00

5.01

5.02

5.03

5.04

5.05

10mA

IOUT=1µA

1mA

13

R

×5RE30A

R

×5RE40A

R

×5RE50A

3) Dropout Voltage vs. Output Curret

R×5RE

Output Current IOUT(mA)

Dropout Voltage VDIF(V)

0

20 40 60 80 100

Topt=–40˚C

25˚C

85˚C

0.0

0.4

0.6

0.2

0.8

1.0

1.2

1.4

Output Current IOUT(mA)

Dropout Voltage VDIF(V)

0

20 40 60 80 100

85˚C

25˚C

Topt= –40˚C

0.0

0.4

0.5

0.7

0.6

0.2

0.3

0.1

0.8

Output Current IOUT(mA)

Dropout Voltage VDIF(V)

0

20 40 60 80 100

0.0

0.2

0.4

0.6

0.8

1.0

25˚C

Topt=–40˚C

85˚C

R×5RE30A

4) Output Voltage vs.Temperature

Temperature Topt(˚C)

Output Voltage VOUT(V)

-50-30-101030507090

2.9

3.0

3.1

IOUT=10mA

R×5RE40A

Temperature Topt(˚C)

Output Voltage VOUT(V)

3.9

4.0

4.1

-50-30-101030507090

IOUT=10mA

14

R

×5RE50A

R

×5RE20A

5) Quiescent Current vs. Input Voltage

R×5RE

R×5RE40A

R

×5RE50A

Temperature Topt(˚C)

Output Voltage VOUT(V)

4.9

4.8

5.0

5.2

5.1

-50-30-101030507090

IOUT=10mA

Input Voltage VIN(V)

0.6
345678910

0.7

0.8

0.9

1.0

1.1

Quiescent Current Iss(µA)

Topt=25˚C

R×5RE30A

Input Voltage VIN(V)

1.0
243 5678910

1.1

1.2

1.3

1.4

Quiescent Current Iss(µA)

Topt=25˚C

Input Voltage VIN(V)

1.0
465 7 8 9 10 11

1.1

1.2

1.3

1.4

1.5

Quiescent Current Iss(µA)

Topt=25˚C

Input Voltage VIN(V)

0.5

0.6

76589101112

0.7

0.8

0.9

1.0

1.1

1.2

1.3

1.5

1.4

Quiescent Current Iss(µA)

Topt=25˚C

15

R

×5RE20A

R

×5RE50A

R

×5RE40A

6) Quiescent Current vs. Temperature

R×5RE

0.5

0.7

0.9

1.1

1.3

1.7

1.5

Quiescent Current Iss(µA)

VIN=4.0V

–40 –20 0 20 40 60 80 100

Temperature Topt(˚C)

0.5

0.7

0.9

1.1

1.3

1.7

1.5

Quiescent Current Iss(µA)

VIN=6.0V

–40 –20 0 20 40 60 80 100

Temperature Topt(˚C)

R×5RE30A

0.8

1.0

1.2

1.6

1.4

Quiescent Current Iss(µA)

VIN=5.0V

–40 –20 0 20 40 60 80 100

Temperature Topt(˚C)

VIN=7.0V

0.5

0.7

0.6

0.8

0.9

1.0

1.2

1.1

1.5

1.3

1.4

Quiescent Current Iss(µA)

–20–40 0 20 40 60 80 100

Temperature Topt(˚C)

7) Dropout Voltage vs. Set Output Voltage
R

×5RE SERIES

01234 56

0.0

0.2

0.1

0.3

0.4

0.5

0.6

0.7

Set Output Voltage Vreg(V)

Dropout Voltage VDIF(V)

1mA

Topt=25˚C

10mA

IOUT=50mA

16

8) Line Transient Response (1)

R×5RE

R×5RE30A

R

×5RE40A

R×5RE20A

R

×5RE50A

9) Line Transient Response (2)

R×5RE20A

R

×5RE30A

1.5 2.0 2.5 3.0 3.5 4.0 4.5

1.0

2.0

1.5

2.5

3.0

4.5

4.5

3.5

5.0

Input Voltage/Output Voltage V(V)

IOUT=1mA

Time t(ms)

Input Voltage

Output Voltage

1.5 2.0 2.5 3.0 3.5 4.0 4.5

2.0

4.0

3.0

5.0

7.0

6.0

8.0

Input Voltage/Output Voltage V(V)

IOUT=1mA

Time t(ms)

Input Voltage

Output Voltage

1.5 2.0 2.5 3.0 3.5 4.0 4.5

1.0

3.0

2.0

4.0

6.0

5.0

7.0

Input Voltage/Output Voltage V(V)

IOUT=1mA

Time t(ms)

Input Voltage

Output Voltage

0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0

Output Voltage

3.0

5.0

4.0

6.0

8.0

7.0

9.0

Input Voltage/Output Voltage V(V)

IOUT=1mA

Time t(ms)

Input Voltage

1.5 2.0 2.5 3.0 3.5 4.0 4.5

0.0

1.0

1.5

0.5

2.0

2.5

4.0

4.5

3.5

3.0

5.0

Input Voltage/Output Voltage V(V)

IOUT=30mA

Time t(ms)

Input Voltage

Output Voltage

1.5 2.0 2.5 3.0 3.5 4.0 4.5

1.0

3.0

2.0

4.0

6.0

5.0

7.0

Input Voltage/Output Voltage V(V)

IOUT=30mA

Time t(ms)

Input Voltage

Output Voltage

17

R

×5RE40A

R

×5RE50A

R×5RE

1.5 2.0 2.5 3.0 3.5 4.0 4.5

2.0

4.0

3.0

5.0

7.0

6.0

8.0

Input Voltage/Output Voltage V(V)

IOUT=30mA

Time t(ms)

Input Voltage

Output Voltage

IOUT=30mA

0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0

Output Voltage

3.0

5.0

4.0

6.0

8.0

7.0

9.0

Input Voltage/Output Voltage V(V)

Time t(ms)

Input Voltage

18

TYPICAL APPLICATION

In R×5RE Series, a constant voltage can be obtained

without using Capacitors C1 and C2. However, when the

wire connected to V

IN is long, use Capacitor C1. Output

noise can be reduced by using Capacitor C2.

Insert Capacitors C1 and C2 with the capacitance of

0.1µF to 2.0µF between Input/Output Pins and GND Pin

with minimum wiring.

The output voltage can be obtained by the follow-

ing formula :

V

OUT=Vreg · (1+R2/R1) + ISS · R2

Since the quiescent current of R

×5RE Series is so

small that the resistances of R1 and R2 can be set as

large as several hundreds kΩ and therefore the sup-

ply current of “Voltage Boost Circuit” itself can be

reduced.

Furthermore, since R

×5RE Series are operated by

a constant voltage, the supply current of “Voltage

Boost Circuit” is not substantially affected by the

input voltage.

As shown in the circuit diagram, a dual power sup-

ply circuit can be constructed by using two R

×5RE

Series.

This circuit diagram shows a dual power supply

circuit with an output of 3V and an output of 5V.

When the minimum output current of IC2 is larger

than I

SS of IC1, Resistor R is unnecessary. Diode D is

a protection diode for the case where V

OUT2

becomes larger than V

OUT1.

• VOLTAGE BOOST CIRCUIT

• DUAL POWER SUPPLY CIRCUIT

R×5RE

C2

C1

V

IN

GND

GND

GND

R

×5RE

SERIES

VOUT

VOUT

VIN

+

+

C2

C1

V

IN

GND

GND

R

×5RE

SERIES

VOUT

VOUT

VIN

R1

R2

ISS

+

+

C1

C2

V

IN

GND

GNDGND

R

×5RE20A

R×5RE30A

VOUT

VOUT1

5V

V

OUT2

3V

V

IN

C3

GND

VOUT

VIN

R

I

SS

IC1

IC2

D

+

+

+

*

1) Vreg : Set Output Voltage of R×5RE Series.

*

1

APPLICATION CIRCUITS

19

• CURRENT BOOST CIRCUIT

Output current of 120mA or more can be obtained

by the current boost circuit constructed as shown in

this circuit diagram.

• CURRENT BOOST CIRCUIT WITH OVERCURRENT LIMIT CIRCUIT

• CURRENT SOURCE

A current source with the structure as shown in

this circuit diagram can be used. Output Current

I

OUT is obtained as follows :

I

OUT=Vreg /R + ISS

Take care that Output Current IOUT does not exceed

its allowable current.

R×5RE

C2

GND

GND

GND

R

×5RE

SERIES

VOUT

VOUT

C1

VIN

VIN

Tr.1

+

+

C2

GND

GND

GND

R

×5RE

SERIES

VOUT

VOUT

VIN

VIN

Tr.1

Tr.2

R1

R2

I

OUT

Vbe2

+

+

GND

R

×5RE

SERIES

C1

VIN

VIN

R

I

OUT

ISS

VOUT

+

A circuit for protecting Tr.1 from the destruction

caused by output short-circuit or overcurrent is shown in

this circuit diagram.

When the voltage reduction caused by the current ( aa

I

OUT) which flows through R2 reaches Vbe2 of Tr.2 by

additionally providing the current boost circuit with Tr.2

and R2, Tr.2 is turned ON and the base current of Tr.1 is

increased, so that the output current is limited.

Current limit of Overcurrent Limit Circuit is obtained

as follows :

I

OUT Vbe2/R2

*

1) Vreg : Set Output Voltage of R×5RE Series.

*

1