REF01 View Datasheet(PDF) - Analog Devices

Part Name

Description

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REF01

Precision 2.5 V, 5.0 V, and 10.0 V Voltage References

Analog Devices 

REF01/REF02/REF03

APPLICATIONS INFORMATION

BASIC REFERENCE APPLICATION

Figure 38 shows the basic configuration for any REF0x device.

Input and output capacitance values can be tailored for

performance, provided they follow the guidelines described

in the Input and Output Capacitors section.

U1

VIN

C1

0.1µF

REF01/

REF02/

REF03

VIN VOUT

TEMP TRIM

GND

VO

C2

0.1µF

Figure 38. Basic Reference Application

LOW COST CURRENT SOURCE

Unlike most references, the quiescent current of the REF0x

series remains constant with respect to the load current (refer to

Figure 22). As a result, a simple, low cost current source can be

constructed by configuring the reference as shown in Figure 39.

VIN

IIN

REF01/

REF02/ VOUT

REF03

GND

RSET

ISET = (VOUT – VL)/RSET

IQ ≈ 0.6mA

RL

VL

IL = ISET + IQ

Figure 39. Simple Current Source

In this configuration, the current through the resistor RSET (ISET)

is equal to (VOUT − VL)/RSET. IL is simply the sum of ISET and IQ.

However, since IQ typically varies from 0.55 mA to 0.65 mA,

this circuit should be limited to low precision, general-purpose

applications.

PRECISION CURRENT SOURCE WITH ADJUSTABLE

OUTPUT

A higher-precision current source can be implemented with the

circuit shown in Figure 40.

U1

+12V

REF02

VIN VOUT

TEMP TRIM

GND

0V TO (5V + VL)

B

AD5201 W

100kΩ

A

+12V

U2

V+

OP1177

–5V TO VL V–

RSET

1kΩ

VL

–12V

RL 1kΩ IL

Figure 40. Programmable 0 mA to 5 mA Current Source

By adding a mechanical or digital potentiometer, this circuit

becomes an adjustable current source. If a digital potentiometer

is used, the load current is simply the voltage across terminal B

to terminal W of the digital potentiometer divided by the value

of the resistor RSET.

IL

=

VREF × D

RSET

[A]

where D is the decimal equivalent of the digital potentiometer

input code.

A dual-supply op amp should be used since the ground

potential of REF02 can swing from −5.0 V to VL while the

potentiometer is swung from zero-scale to full-scale.

PRECISION BOOSTED OUTPUT REGULATOR

The output current sourcing capability of the REF0x series can

be boosted by using an external op amp and MOSFET, as shown

in Figure 41.

N1

VIN

U1

2N7002

RL

200Ω

CL VO

1µF

REF01/

REF02/

15V

REF03

R1

R2

100Ω

100Ω

VIN

VOUT

V+

OP1177

TEMP TRIM

V–

GND

U2

C1

1000pF

Figure 41. Precision Boosted Output Regulator

In this circuit, U2 forces VO to VREF by regulating the current

through N1, thereby sourcing the load current directly from the

input voltage source connected at VIN. Using the components

shown, this circuit can source up to 50 mA with an input volt-

age of 15.0 V. The circuit’s current sourcing capability can be

further increased by replacing N1 with a higher-power MOSFET.

Rev. K | Page 16 of 20

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