ADR01/ADR02/ADR03/ADR06

Rev. F | Page 15 of 20

APPLICATIONS

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

drift 10 V, 5 V, 2.5 V, and 3.0 V voltage references available in an

ultracompact footprint. The SOIC-8 version of the devices is a

drop-in replacement of the REF01/REF02/ REF03 sockets with

improved cost and performance.

These devices are standard band gap references. The band gap

cell contains two NPN transistors (Q18 and Q19) that differ in

proportional-to-absolute temperature current (PTAT) in R14,

precisely at 10 V, 5 V, 2.5 V, and 3.0 V for the 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.

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

2X

1X

R20

TRIM

Q18

TEMP

R27

Q19

Q16

Q17

Q20

R6

R42

R41

R24

R32

R11

R17

R14

GND

Figure 34. Simplified Schematic Diagram

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

The devices can be used without any external components to

achieve the specified performance. Because of the internal op

amp amplifying the band gap cell to 10 V/5 V/2.5 V/3.0 V,

power supply decoupling helps the transient response of the

ADR01/ADR02/ADR03/ADR06. As a result, a 0.1 µF ceramic

type decoupling capacitor should be applied as close as possible

to the input and output pins of the device. An optional 1 µF to

maintain the input under transient disturbance.

U1

ADR01/

ADR02/

ADR03/

ADR06

C2

0.1

µF

C1

0.1

µF

TEMP TRIM

GND

Figure 35. Basic Configuration

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 V/5 V/2.5 V/3.0 V. For finer

adjustment, a series resistor of 470 kΩ can be added. With the

configuration shown in Figure 36, 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 per-

formance of the device, provided the temperature coefficients of

the resistors are relatively low.

U1

ADR01/

ADR02/

ADR03/

ADR06

TEMP TRIM

GND

pot

10k

Ω

R2

1k

Ω

R1

470k

Ω

Figure 36. Optional Trim Adjustment

Temperature Monitoring

As described previously, the ADR01/ADR02/ADR03/ADR06

provide a TEMP output (Pin 3) that varies linearly with tem-

perature. This output can be used to monitor the temperature

change in the system. The voltage at VTEMP is approximately

550 mV at 25°C, and the temperature coefficient is approximately

1.96 mV/°C (see Figure 37). A voltage change of 39.2 mV at the

TEMP pin corresponds to a 20°C change in temperature.