a
FEATURES
Laser Trimmed to High Accuracy: 2.500 V 0.4%
3-Terminal Device: Voltage In/Voltage Out
Excellent Temperature Stability: 10 ppm/ C (AD580M, U)
Excellent Long-Term Stability: 250 V (25 V/Month)
Low Quiescent Current: 1.5 mA max
Small, Hermetic IC Package: TO-52 Can
MIL-STD-883 Compliant Versions Available
High Precision
2.5 V IC Reference
AD580*
FUNCTIONAL BLOCK DIAGRAM
PRODUCT DESCRIPTION
PRODUCT HIGHLIGHTS
The AD580 is a three-terminal, low cost, temperature compen-
sated, bandgap voltage reference which provides a fixed 2.5 V
output for inputs between 4.5 V and 30 V. A unique combina-
tion of advanced circuit design and laser-wafer trimmed thin-
film resistors provide the AD580 with an initial tolerance of
±
0.4%, a temperature stability of better than 10 ppm/°C and
long-term stability of better than 250
µV.
In addition, the low
quiescent current drain of 1.5 mA max offers a clear advantage
over classical Zener techniques.
The AD580 is recommended as a stable reference for all 8-, 10-
and 12-bit D-to-A converters that require an external reference.
In addition, the wide input range of the AD580 allows operation
with 5 volt logic supplies making the AD580 ideal for digital
panel meter applications or whenever only a single logic power
supply is available.
The AD580J, K, L and M are specified for operation over the
0°C to +70°C temperature range; the AD580S, T and U are
specified for operation over the extended temperature range of
–55°C to +125°C.
1. Laser-trimming of the thin-film resistors minimizes the
AD580 output error. For example, the AD580L output
tolerance is
±
10 mV.
2. The three-terminal voltage in/voltage out operation of
the AD580 provides regulated output voltage without
any external components.
3. The AD580 provides a stable 2.5 V output voltage for
input voltages between 4.5 V and 30 V. The capability
to provide a stable output voltage using a 5-volt input
makes the AD580 an ideal choice for systems that con-
tain a single logic power supply.
4. Thin-film resistor technology and tightly controlled
bipolar processing provide the AD580 with temperature
stabilities to 10 ppm/°C and long-term stability better
than 250
µV.
5. The low quiescent current drain of the AD580 makes it
ideal for CMOS and other low power applications.
6. The AD580 is available in versions compliant with
MIL-STD-883. Refer to the Analog Devices Military
Products Databook or current AD580/883B data sheet
for detailed specifications.
*Protected by Patent Nos. 3,887,863; RE30,586.
REV. A
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
which 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: 617/329-4700
Fax: 617/326-8703
AD580–SPECIFICATIONS
(@ E
Model
Min
OUTPUT VOLTAGE TOLERANCE
(Error from Nominal 2.500 Volt Output)
OUTPUT VOLTAGE CHANGE
T
MIN
to T
MAX
LINE REGULATION
7 V
≤
V
IN
≤
30 V
4.5 V
≤
V
IN
≤
7 V
LOAD REGULATION
∆I
= 10 mA
QUIESCENT CURRENT
NOISE (0.1 Hz to 10 Hz)
STABILITY
Long Term
Per Month
TEMPERATURE PERFORMANCE
Specified
Operating
Storage
PACKAGE OPTION*
TO-52 (H-03A)
0
–55
–65
AD580JH
1.0
8
250
25
AD580J
Typ
IN
= +15 V and +25 C )
Min
AD580K
Typ
Max
25
7
40
1.5
0.3
4
2
10
1.0
8
250
25
1.5
1.0
8
250
25
+70
+125
+175
AD580KH
0
–55
–65
AD580LH
+70
+125
+175
0
–55
–65
AD580MH
Min
AD580L
Typ
Max
10
4.3
25
2
1
10
1.5
1.0
8
250
25
+70
+125
+175
Min
AD580M
Typ
Max
10
1.75
10
2
1
10
1.5
Units
mV
mV
ppm/°C
mV
mV
mV
mA
µV
(p-p)
µV
µV
°C
°C
°C
Max
75
15
85
1.5
0.3
6
3
10
1.5
+70
+125
+175
0
–55
–65
Model
Min
OUTPUT VOLTAGE TOLERANCE
(Error from Nominal 2.500 Volt Output)
OUTPUT VOLTAGE CHANGE
T
MIN
to T
MAX
LINE REGULATION
7 V
≤
V
IN
≤
30 V
4.5 V
≤
V
IN
≤
7 V
LOAD REGULATION
∆I
= 10 mA
QUIESCENT CURRENT
NOISE (0.1 Hz to 10 Hz)
STABILITY
Long Term
Per Month
TEMPERATURE PERFORMANCE
Specified
Operating
Storage
PACKAGE OPTION*
TO-52 (H-03A)
–55
–55
–65
AD580S
Typ
Max
25
25
55
1.5
0.3
6
3
10
1.0
8
250
25
+125
+150
+175
AD580SH
1.5
Min
AD580T
Typ
Max
10
11
25
2
1
10
1.0
8
250
25
1.5
Min
AD580U
Typ
Max
10
4.5
10
2
1
10
1.0
8
250
25
1.5
Units
mV
mV
ppm/°C
mV
mV
mV
mA
µV
(p-p)
µV
µV
–55
–55
–65
+125
+150
+175
AD580TH
–55
–55
–65
AD580UH
+125
+150
+175
°C
°C
°C
NOTES
*H = Metal Can.
Specifications subject to change without notice.
Specifications shown 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, although only those shown in
boldface
are tested on all production units.
–2–
REV. A
AD580
ABSOLUTE MAXIMUM RATINGS
THEORY OF OPERATION
Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 V
Power Dissipation @ +25°C
Ambient Temperature . . . . . . . . . . . . . . . . . . . . . . . 350 mW
Derate above +25°C . . . . . . . . . . . . . . . . . . . . . . . 2.8 mW/°C
Lead Temperature (Soldering 10 sec) . . . . . . . . . . . . . +300°C
Thermal Resistance
Junction-to-Case . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100°C
Junction-to-Ambient . . . . . . . . . . . . . . . . . . . . . . . 360°C/W
AD580 CHIP DIMENSIONS
AND PAD LAYOUT
Dimensions shown in inches and (mm).
The AD580 family (AD580, AD581, AD584, AD589) uses
the “bandgap” concept to produce a stable, low temperature
coefficient voltage reference suitable for high accuracy data ac-
quisition components and systems. The device makes use of the
underlying physical nature of a silicon transistor base-emitter
voltage in the forward-biased operating region. All such transis-
tors have approximately a –2 mV/°C temperature coefficient,
unsuitable for use directly as a low TC reference; however,
extrapolation of the temperature characteristic of any one of
these devices to absolute zero (with emitter current proportional
to absolute temperature) reveals that it will go to a V
BE
of 1.205
volts at 0K, as shown in Figure 1. Thus, if a voltage could be
developed with an opposing temperature coefficient to sum with
V
BE
to total 1.205 volts, a zero-TC reference would result and
operation from a single, low voltage supply would be possible.
The AD580 circuit provides such a compensating voltage, V
1
in
Figure 2, by driving two transistors at different current densities
and amplifying the resulting V
BE
difference (∆V
BE
—which now
has a positive TC); the sum (V
Z
) is then buffered and amplified
up to 2.5 volts to provide a usable reference-voltage output. Fig-
ure 3 is the schematic diagram of the AD580.
The AD580 operates as a three-terminal reference, which means
that no additional components are required for biasing or cur-
rent setting. The connection diagram, Figure 4 is quite simple.
The AD580 is also available in chip form. Consult the factory
for specifications and applications information.
Figure 1. Extrapolated Variation of Base-Emitter Voltage
with Temperature (I
E
α
T), and Required Compensation,
Shown for Two Different Devices
Figure 2. Basic Bandgap-Reference Regulator Circuit
REV. A
–3–
AD580
Figure 5. Typical AD580K Output Voltage vs. Temperature
The AD580M guarantees a maximum deviation of 1.75 mV
over the 0°C to +70°C temperature range. This can be shown to
be equivalent to 10 ppm/°C average maximum; i.e.,
Figure 3. AD580 Schematic Diagram
1.75
mV
max
1
×
=10
ppm/°C
max
average
70°C
2.5V
The AD580 typically exhibits a variation of 1.5 mV over the
power supply range of 7 volts to 30 volts. Figure 6 is a plot of
AD580 line rejection versus frequency.
NOISE PERFORMANCE
Figure 4. AD580 Connection Diagram
VOLTAGE VARIATION VS. TEMPERATURE
Figure 7 represents the peak-to-peak noise of the AD580 from
1 Hz (3 dB point) to a 3 dB high end shown on the horizontal
axis. Peak-to-peak noise from 1 Hz to 1 MHz is approximately
600
µV.
Some confusion exists in the area of defining and specifying
reference voltage error over temperature. Historically, references
are characterized using a maximum deviation per degree Centi-
grade; i.e., 10 ppm/°C. However, because of the inconsistent
nonlinearities in Zener references (butterfly or “S” type charac-
teristics), most manufacturers use a maximum limit error band
approach to characterize their references. This technique mea-
sures the output voltage at 3 to 5 different temperatures and
guarantees that the output voltage deviation will fall within the
guaranteed error band at these discrete temperatures. This ap-
proach, of course, makes no mention or guarantee of perfor-
mance at any other temperature within the operating tempera-
ture range of the device.
The consistent Voltage vs. Temperature performance of a typi-
cal AD580 is shown in Figure 5. Note that the characteristic is
quasi-parabolic, not the possible “S” type characteristics of clas-
sical Zener references. This parabolic characteristic permits a
maximum output deviation specification over the device’s full
operating temperature range, rather than just at 3 to 5 discrete
temperatures.
Figure 6. AD580 Line Rejection Plot
Figure 7. Peak-to-Peak Output Noise vs. Frequency
–4–
REV. A
AD580
THE AD580 AS A LOW POWER, LOW VOLTAGE
PRECISION REFERENCE FOR DATA CONVERTERS
The AD580 has a number of features that make it ideally suited
for use with A/D and D/A data converters used in complex
microprocessor-based systems. The calibrated 2.500 volt output
minimizes user trim requirements and allows operation from a
single low voltage supply. Low power consumption (1 mA
quiescent current) is commensurate with that of CMOS-type de-
vices, while the low cost and small package complements the de-
creasing cost and size of the latest converters.
Figure 10 shows the AD580 used as a reference for the AD7542
12-bit CMOS DAC with complete microprocessor interface.
The AD580 and the AD7542 are specified to operate from a
single 5 volt supply; this eliminates the need to provide a +15
volt power supply for the sole purpose of operating a reference.
The AD7542 includes three 4-bit data registers, a 12-bit DAC
register, and address decoding logic; it may thus be interfaced
directly to a 4-, 8- or 16-bit data bus. Only 8 mA of quiescent
current from the single +5 volt supply is required to operate the
AD7542 which is packaged in a small 16-pin DIP. The AD544
output amplifier is also low power, requiring only 2.5 mA quies-
cent current. Its laser-trimmed offset voltage preserves the
±
1/2 LSB linearity of the AD7542KN without user trims and it
typically settles to
±
1/2 LSB in less than 3
µs.
It will provide the
0 volt to –2.5 volt output swing from
±
5 volt supplies.
Figure 8. Input Current vs. Input Voltage (Integral Loads)
THE AD580 AS A CURRENT LIMITER
The AD580 represents an excellent alternative to current lim-
iter diodes which require factory-selection to achieve a desired
current. This approach often results in temperature coefficients
of 1%/°C. The AD580 approach is not limited to a specially
selected factory set current limit; it can be programmed from
1 mA to 10 mA with the insertion of a single external resistor.
The approximate temperature coefficient of current limit for
the AD580 used in this mode is 0.13%/°C for I
LIM
= 1 mA and
0.01%/°C for I
LIM
= 13 mA (see Figure 9). Figure 8 displays
the high output impedance of the AD580 used as a current lim-
iter for I
LIM
= 1, 2, 3, 4, 5 mA.
Figure 9. A Two-Component Precision Current Limiter
Figure 10. Low Power, Low Voltage Reference for the
AD7542 Microprocessor-Compatible 12-Bit DAC
REV. A
–5–
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