Analog Devices AD680JR, AD680JN, AD680AR, AD680AN Datasheet

Low Power, Low Cost

a

FEATURES
Low Quiescent Current: 250 ␮A Max
Laser Trimmed to High Accuracy:

2.5 V ⴞ5 mV Max (AN, AR Grade)

Trimmed Temperature Coefficient:

20 ppm/ⴗC Max (AN, AR Grade)

Low Noise: 8 ␮V p-p from 0.1 Hz to 10 Hz

250 nV/√Hz Wideband

Temperature Output Pin (N, R Packages)
Available in Three Package Styles:

8-Lead Plastic DIP, 8-Lead SOIC and 3-Pin TO-92

PRODUCT DESCRIPTION

The AD680 is a bandgap voltage reference that provides a fixed

2.5 V output from inputs between 4.5 V and 36 V. The archi­tecture of the AD680 enables the reference to be operated at a
very low quiescent current while still realizing excellent dc
characteristics and noise performance. Trimming of the high
stability thin-film resistors is performed for initial accuracy and
temperature coefficient, resulting in low errors over temperature.

The precision dc characteristics of the AD680 make it ideal for
use as a reference for D/A converters which require an external
precision reference. The device is also ideal for A/D converters
and, in general, can offer better performance than the standard
on-chip references.

Based upon the low quiescent current of the AD680, which
rivals that of many incomplete two-terminal references, the
AD680 is recommended for low power applications such as
hand-held battery equipment.

A temperature output pin is provided on the 8-lead package
versions of the AD680. The temperature output pin provides an
output voltage that varies linearly with temperature and allows
the AD680 to be configured as a temperature transducer while
providing a stable 2.5 V output.

The AD680 is available in five grades. The AD680AN is specified
for operation from –40°C to +85°C, while the AD680JN is
specified for 0°C to 70°C operation. Both the AD680AN and
AD680JN are available in 8-lead plastic DIP packages. The
AD680AR is specified for operation from –40°C to +85°C,
while the AD680JR is specified for 0°C to 70°C operation. Both
are available in an 8-lead Small Outline IC (SOIC) package.
The AD680JT is specified for 0°C to 70°C operation and is
available in a 3-pin TO-92 package.

2. 5 V Reference

AD680*

CONNECTION DIAGRAMS

1

TP*

2

IN

3

4

AD680

TOP VIEW

(Not to Scale)

+V

TEMP

* TP DENOTES FACTORY TEST POINT.

NO CONNECTIONS SHOULD BE MADE
TO THESE PINS.

8

TP*

7

TP*

6

V

OUT

5

NCGND

PRODUCT HIGHLIGHTS

1. The AD680 bandgap reference operates on a very low quiescent
current which rivals that of many two-terminal references.
This makes the complete, higher accuracy AD680 ideal for
use in power sensitive applications.

2. Laser trimming of both initial accuracy and temperature
coefficients results in low errors over temperature without the
use of external components. The AD680AN and AD680AR
have a maximum variation of 6.25 mV between –40°C
and +85°C.

3. The AD680 noise is low, typically 8 µV p-p from 0.1 Hz to
10 Hz. Spectral density is also low, typically 250 nV/√Hz.

4. The temperature output pin on the 8-lead package versions
enables the AD680 to be configured as a temperature
transducer.

5. Plastic DIP packaging provides machine insertability, while
SOIC packaging provides surface mount capability. TO-92
packaging offers a cost effective alternative to two-terminal
references, offering a complete solution in the same package
in which two-terminal references are usually found.

AD680

BOTTOM VIEW

(Not to Scale)

32

+V

V

IN

OUT

1

GND

*Protected by U.S. Patent Nos. 4,902,959; 4,250,445; and 4,857,862.

REV. D

Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties that
may result from its use. No license is granted by implication or otherwise
under any patent or patent rights of Analog Devices.

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: [phone] www.analog.com
Fax: [phone] © Analog Devices, Inc., 2001

AD680–SPECIFICATIONS

(TA = 25ⴗC, VIN = 5 V, unless otherwise noted.)

AD680AN/AR AD680JN/JR AD680JT

Model Min Typ Max Min Typ Max Min Typ Max Unit

OUTPUT VOLTAGE

Output Voltage, V
Initial Accuracy, V

O

OERR

2.495 2.500 2.505 2.490 2.500 2.510 2.490 2.500 2.510 V
–5 +5 –10 +10 –10 +10 ±mV
–0.20 +0.20 –0.40 +0.40 –0.40 +0.40 %

OUTPUT VOLTAGE DRIFT

1

0°C to 70°C 10 10 25 10 30 ppm/°C
–40°C to +85°C202525

LINE REGULATION

4.5 V ≤ +VIN ≤ 15 V 40 40 40 µV/V
(@ T

MIN

15 V ≤ +V
(@ T

MIN

to T

≤ 36 V 40 40 40

IN

to T

)404040

MAX

)404040

MAX

LOAD REGULATION

0 < I
(@ T

< 10 mA 80 100 80 100 80 100 µV/mA

OUT

MIN

to T

) 80 100 80 100 80 100

MAX

QUIESCENT CURRENT 195 250 195 250 195 250 µA

(@ T

MIN

to T

) 280 280 280

MAX

POWER DISSIPATION 1 1.25 1 1.25 1 1.25 mW

OUTPUT NOISE

0.1 Hz to 10 Hz 8 10 8 10 8 10 µV p-p
Spectral Density, 100 Hz 250 250 250 nV/√Hz

CAPACITIVE LOAD 50 50 50 nF

LONG TERM STABILITY 25 25 25 ppm/1000 hr

SHORT CIRCUIT CURRENT

TO GROUND 25 50 25 50 25 50 mA

TEMPERATURE PIN

Voltage Output @ 25°C 540 596 660 540 596 660 mV
Temperature Sensitivity 2 2 mV/°C
Output Current –5 +5 –5 +5 µA
Output Resistance 12 12 kΩ

TEMPERATURE RANGE

Specified Performance –40 [phone] ° C
Operating Performance

NOTES

1

Maximum output voltage drift is guaranteed for all packages.

2

The operating temperature range is defined as the temperature extremes at which the device will still function. Parts may deviate from their specified performance
outside their specified temperature range.

Specifications subject to change without notice.
Specifications in boldface are tested on all production units at final electrical test. Results from those tests are used to calculate outgoing quality levels. All min and
max specifications are guaranteed.

2

–40 +85 –40 +85 –40 +85 °C

–2–

REV. D

AD680

ABSOLUTE MAXIMUM RATINGS*

VIN to Ground . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 V

Power Dissipation (25°C) . . . . . . . . . . . . . . . . . . . . . 500 mW

Storage Temperature . . . . . . . . . . . . . . . . . . –65°C to +125°C

Lead Temperature (Soldering, 10 sec) . . . . . . . . . . . . . 300°C

Package Thermal Resistance

(All Packages) . . . . . . . . . . . . . . . . . . . . . . . . 120°C/W

θ

JA

Output Protection: Output safe for indefinite short to ground
and momentary short to V

*Stresses above those listed under Absolute Maximum Ratings may cause perma-

nent damage to the device. This is a stress rating only; functional operation of the
device at these or any other conditions above those indicated in the operational
sections of this specification is not implied. Exposure to absolute maximum rating
conditions for extended periods may affect device reliability.

.

IN

8-Lead Plastic DIP

and

8-Lead SOIC Packages

1

TP*

2

+V

TEMP

* TP DENOTES FACTORY TEST POINT.

NO CONNECTIONS SHOULD BE MADE
TO THESE PINS.

AD680

IN

TOP VIEW

3

(Not to Scale)

4

NC = NO CONNECT

8

TP*

7

TP*

6

V

OUT

5

NCGND

TO-92 Package

AD680

BOTTOM VIEW

(Not to Scale)

32

+V

IN

1

V

GND

OUT

Figure 1. Connection Diagrams

THEORY OF OPERATION

Bandgap references are the high-performance solution for low
supply voltage operation. A typical precision bandgap will con­sist of a reference core and buffer amplifier. Based on a new,
patented bandgap reference design (Figure 2), the AD680

merges the amplifier and the core bandgap function to produce
a compact, complete precision reference. Central to the device
is a high gain amplifier with an intentionally large Proportional
To Absolute Temperature (PTAT) input offset. This offset is
controlled by the area ratio of the amplifier input pair, Q1 and
Q2, and is developed across resistor R1. Transistor Q12’s base
emitter voltage has a Complementary To Absolute Temperature
(CTAT) characteristic. Resistor R2 and the parallel combina­tion of R3 and R4 “multiply” the PTAT voltage across R1.
Trimming resistors R3 and R4 to the proper ratio produces a
temperature invariant 2.5 V at the output. The result is an
accurate, stable output voltage accomplished with a minimum
number of components.

+V

IN

R5

TEMP

GND

Q9

Q10

R6

R7

Q2

Q3

Q8

8ⴛ

Q1
1ⴛ

Q6

Q4

Q11

V

Q5

R1

C1

R2

Q12

Q7

OUT

R3

R4

Figure 2. Schematic Diagram

An additional feature with this approach is the ability to minimize
the noise while maintaining very low overall power dissipation
for the entire circuit. Frequently it is difficult to independently
control the dominant noise sources for bandgap references:
bandgap transistor noise and resistor thermal noise. By properly
choosing the operating currents of Q1 and Q2 and separately
sizing R1, low wideband noise is realized while maintaining
1 mW typical power dissipation.

ORDERING GUIDE

Output Initial Temperature No. of Temperature
Voltage Accuracy Coefficient Package Package Parts Range

Model V

O

mV % ppm/ⴗC Description Option per Reel ⴗC

AD680AN 2.5 5 0.20 20 Plastic N-8 48 –40 to +85
AD680AR 2.5 5 0.20 20 SOIC R-8A 98 –40 to +85
AD680JN 2.5 10 0.40 25 Plastic N-8 48 0 to 70
AD680JR 2.5 10 0.40 25 SOIC R-8A 98 0 to 70
AD680JT 2.5 10 0.40 30 TO-92 TO-92 100 0 to 70

REV. D

–3–