Analog Devices AD680JR, AD680JN, AD680AR, AD680AN Datasheet

a		Low Power, Low Cost
		2. 5 V Reference
		AD680*

FEATURES

Low Quiescent Current: 250 A Max

Laser Trimmed to High Accuracy: 2.5 V 5 mV Max (AN, AR Grade)

Trimmed Temperature Coefficient: 20 ppm/ C 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.

CONNECTION DIAGRAMS

						TP*		AD680
TP*	1				8
							BOTTOM VIEW
+VIN		AD680				TP*
	2				7		(Not to Scale)
TEMP		TOP VIEW				V
	3	(Not to Scale)			6		3	2	1
						OUT
GND						NC	+VIN	VOUT	GND
	4				5

*TP DENOTES FACTORY TEST POINT. NO CONNECTIONS SHOULD BE MADE TO THESE PINS.

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 V 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.

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

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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 = 25 C, 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, VO	2.495	2.500	2.505	2.490	2.500	2.510	2.490	2.500	2.510	V
Initial Accuracy, VOERR	–5		+5	–10		+10	–10		+10	±mV
	–0.20		+0.20	–0.40		+0.40	–0.40		+0.40	%
OUTPUT VOLTAGE DRIFT1
0°C to 70°C		10			10	25		10	30	ppm/°C
–40°C to +85°C			20		25			25
LINE REGULATION
4.5 V ≤ +VIN ≤ 15 V			40			40			40	µV/V
(@ TMIN to TMAX)			40			40			40
15 V ≤ +VIN ≤ 36 V			40			40			40
(@ TMIN to TMAX)			40			40			40
LOAD REGULATION										µV/mA
0 < IOUT < 10 mA		80	100		80	100		80	100
(@ TMIN to TMAX)		80	100		80	100		80	100
QUIESCENT CURRENT		195	250		195	250		195	250	µA
(@ TMIN to TMAX)			280			280			280
POWER DISSIPATION		1	1.25		1	1.25		1	1.25	mW
OUTPUT NOISE										µV p-p
0.1 Hz to 10 Hz		8	10		8	10		8	10
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										°C
Specified Performance	–40		+85	0		70	0		70
Operating Performance2	–40		+85	–40		+85	–40		+85	°C

NOTES

1Maximum output voltage drift is guaranteed for all packages.

2The 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.

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

Output Protection: Output safe for indefinite short to ground and momentary short to VIN.

*Stresses above those listed under Absolute Maximum Ratings may cause permanent 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.

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.

+VIN

8-Lead Plastic DIP

and

8-Lead SOIC Packages

TP*

1

8

TP*

+VIN	2	AD680	7	TP*
TEMP		TOP VIEW		VOUT
	3	(Not to Scale)	6
GND				NC
	4		5

NC = NO CONNECT

*TP DENOTES FACTORY TEST POINT. NO CONNECTIONS SHOULD BE MADE TO THESE PINS.

TO-92 Package

AD680

BOTTOM VIEW (Not to Scale)

3

2

1

+VIN VOUT GND

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

	Q9		Q8
					Q11
			Q3	Q4	VOUT
					Q5
			Q1
			1		R1
			Q2		R3
	Q10		8	C1	R2
R5					Q12
		R6	Q6		Q7
TEMP
					R4
		R7
GND

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	VO	mV		%	ppm/ C	Description	Option	per Reel	C
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

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