Data Sheet

ADR01/ADR02/ADR03/ADR06

Rev. R | Page 15 of 20

APPLICATIONS INFORMATION

OVERVIEW

The ADR01/ADR02/ADR03/ADR06 are high precision, low

drift 10.0 V, 5.0 V, 2.5 V, and 3.0 V voltage references available

in an ultracompact footprint. The 8-lead SOIC versions of the

devices are drop-in replacements of the REF01/REF02/REF03

sockets with improved cost and performance.

These devices are standard band gap references (see Figure 34).

The band gap cell contains two NPN transistors (Q18 and Q19)

produces a proportional-to-absolute temperature current (PTAT)

With an internal op amp and the feedback network of R5 and

ADR01, ADR02, ADR06, and ADR03, respectively. Precision

laser trimming of the resistors and other proprietary circuit

techniques are used to further enhance the initial accuracy,

temperature curvature, and drift performance of the ADR01/

ADR02/ADR03/ADR06.

The PTAT voltage is made available at the TEMP pin of the

ADR01/ADR02/ADR03/ADR06. It has a stable 1.96 mV/°C

temperature coefficient, such that users can estimate the

temperature change of the device by knowing the voltage

change at the TEMP pin.

APPLYING THE ADR01/ADR02/ADR03/ADR06

Input and Output Capacitors

Although the ADR01/ADR02/ADR03/ADR06 are designed to

function stably without any external components, connecting a

0.1 μF ceramic capacitor to the output is highly recommended

to improve stability and filter out low level voltage noise. An

additional 1 μF to 10 μF electrolytic, tantalum, or ceramic

capacitor can be added in parallel to improve transient per-

formance in response to sudden changes in load current;

however, the designer should keep in mind that doing so

increases the turn-on time of the device.

A 1 μF to 10 μF electrolytic, tantalum or ceramic capacitor can

also be connected to the input to improve transient response in

applications where the supply voltage may fluctuate. An addi-

tional 0.1 μF ceramic capacitor should be connected in parallel

to reduce supply noise. Mount both input and output capacitors

as close to the device pins as possible.

Output Adjustment

The ADR01/ADR02/ADR03/ADR06 trim terminal can be used

to adjust the output voltage over a nominal voltage. This feature

allows a system designer to trim system errors by setting the

reference to a voltage other than 10.0 V/5.0 V/2.5 V/3.0 V. For

finer adjustment, add a series resistor of 470 kΩ. With the con-

figuration shown in Figure 35, the ADR01 can be adjusted from

9.70 V to 10.05 V, the ADR02 can be adjusted from 4.95 V to

5.02 V, the ADR06 can be adjusted from 2.8 V to 3.3 V, and the

ADR03 can be adjusted from 2.3 V to 2.8 V. Adjustment of the

output does not significantly affect the temperature performance

of the device, provided the temperature coefficients of the resis-

tors are relatively low.

U1

ADR01/

ADR02/

ADR03/

ADR06

C2

0.1µF

C1

0.1µF

TEMP TRIM

GND

Figure 33. Basic Configuration

R1

R2

R3

R4

Q23

Q1

Q2

Q7

Q8

Q9

Q3

Q10

D1

D2

Q4

D3

C1

R13

Q12

Q13

R5

I1

R12

Q14 Q15

2×

1×

R20

TRIM

Q18

TEMP

R27

Q19

Q16

Q17

Q20

R6

R42

R41

R24

R32

R11

R17

R14

GND

Figure 34. Simplified Schematic Diagram

U1

ADR01/

ADR02/

ADR03/

ADR06

TEMP TRIM

GND

POT

10kΩ

R2

1kΩ

R1

470kΩ

Figure 35. Optional Trim Adjustment

Temperature Monitoring

As described at the end of the Overview section, the ADR01/

ADR02/ADR03/ADR06 provide a TEMP output (Pin 1 in Figure 1

and Pin 3 in Figure 2) that varies linearly with temperature.

This output can be used to monitor the temperature change in the

and the temperature coefficient is approximately 1.96 mV/°C

(see Figure 36). A voltage change of 39.2 mV at the TEMP pin

corresponds to a 20°C change in temperature.