AD1580ART-REEL7 [ADI]
1.2 V Micropower, Precision Shunt Voltage Reference; 1.2 V微功耗，精密并联型电压基准
| 型号： | AD1580ART-REEL7 |
| 厂家： | 
ADI |
| 描述： | 1.2 V Micropower, Precision Shunt Voltage Reference |
| 文件： | 总8页 (文件大小：164K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
1.2 V Micropower, Precision
Shunt Voltage Reference
a
AD1580
P IN CO NFIGURATIO N
SO T-23 P ackage
FEATURES
Wide Operating Range: 50 A–10 m A
Initial Accuracy: ؎0.1% m ax
Tem perature Drift: ؎50 ppm / ؇C m ax
Output Im pedance: 0.5 ⍀ m ax
Wideband Noise (10 Hz–10 kHz): 20 V rm s
Operating Tem perature Range: –40؇C to +85؇C
High ESD Rating
1
2
V+
V–
3
NC (OR V–)
TOP
VIEW
NC = NO CONNECT
4 kV Hum an Body Model
400 V Machine Model
Com pact, Surface-Mount, SOT-23 Package
50
45
40
35
30
25
20
15
10
GENERAL D ESCRIP TIO N
T he AD1580 is a low cost, two-terminal (shunt), precision
bandgap reference. It provides an accurate 1.225 V output for
input currents between 50 µA and 10 mA.
T he AD1580’s superior accuracy and stability is made possible
by the precise matching and thermal tracking of on-chip
components. Proprietary curvature correction design techniques
have been used to minimize the nonlinearities in the voltage
output temperature characteristics. T he AD1580 is stable with
any value of capacitive load.
5
0
–40
–30
–20
–10
10
20
30
40
0
T he low minimum operating current makes the AD1580 ideal
for use in battery powered 3 V or 5 V systems. However, the
wide operating current range means that the AD1580 is
extremely versatile and suitable for use in a wide variety of high
current applications.
TEMPERATURE DRIFT – ppm/°C
Reverse Voltage Tem perature Drift Distribution
T he AD1580 is available in two grades, A and B, both of which
are provided in an SOT -23 package, the smallest surface mount
package available on the market. Both grades are specified over
the industrial temperature range of –40°C to +85°C.
300
250
200
150
100
50
TARGET AP P LICATIO NS
1. Portable, Battery-Powered Equipment:
Cellular Phones, Notebook Computers, PDAs, GPS and
DMM.
2. Computer Workstations
Suitable for use with a wide range of video RAMDACs.
3. Smart Industrial T ransmitters
4. PCMCIA Cards.
0
–10
–8
–6
–4
–2
0
2
4
6
8
10
OUTPUT ERROR – mV
5. Automotive.
6. 3 V/5 V 8–12-Bit Data Converters.
Reverse Voltage Error Distribution
REV. 0
Inform ation furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assum ed by Analog Devices for its
use, nor for any infringem ents of patents or other rights of third parties
which m ay result from its use. No license is granted by im plication or
otherwise under any patent or patent rights of Analog Devices.
© Analog Devices, Inc., 1995
One Technology Way, P.O. Box 9106, Norw ood, MA 02062-9106, U.S.A.
Tel: 617/ 329-4700
Fax: 617/ 326-8703
(@ T = +25؇C, I = 100 A, unless otherwise noted)
AD1580–SPECIFICATIONS
A
IN
Model
AD 1580A
Typ
AD 1580B
Typ
Min
Max
Min
Max
Units
Reverse Voltage Output
1.215 1.225
1.235
1.224
1.225
1.226
V
Reverse Voltage T emperature Drift
–40°C to +85°C
100
50
50
50
ppm/°C
µA
Minimum Operating Current, T MIN to T MAX
Reverse Voltage Change with Reverse Current
50 µA < IIN < 10 mA, T MIN to T MAX
50 µA < IIN < 1 mA, T MIN to T MAX
2.5
0.5
5
1
2.5
0.5
5
mV
mV
Dynamic Output Impedance (∆VR/∆IR)
IIN = 1 mA ±100 µA (f = 120 Hz)
0.4
0.4
0.5
Ω
OUT PUT NOISE
RMS Noise Voltage: 10 Hz to 10 kHz
Low Frequency Noise Voltage: 0.1 Hz to 10 Hz
20
5
20
5
µV rms
µV p-p
T urn-On Settling T ime to 0.1%1
Output Voltage Hysteresis2
5
5
µs
80
80
µV
T emperature Range
Specified Performance, TMIN to T MAX
–40
–55
+85
+125
–40
–55
+85
+125
°C
°C
Operating Range3
NOT ES
1Measured with no load capacitor.
2Output hysteresis is defined as the change in the +25°C output voltage after a temperature excursion to +85°C and then to –40°C.
3T he operating temperature range is defined as the temperature extremes at which the device will continue to function. Parts may deviate from their specified
performance.
Specifications subject to change without notice.
ABSO LUTE MAXIMUM RATINGS1
O RD ERING GUID E
Reverse Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 mA
Initial O utput Tem perature
P ackage
O ption
Forward Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 mA
Model
Error
Coefficient
Internal Power Dissipation2
SOT -23 (RT ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.3 Watts
Storage T emperature Range . . . . . . . . . . . . –65°C to +150°C
Operating T emperature Range
AD1580/RT . . . . . . . . . . . . . . . . . . . . . . . –55°C to +125°C
Lead T emperature, Soldering
Vapor Phase (60 sec) . . . . . . . . . . . . . . . . . . . . . . . . +215°C
Infrared (15 sec) . . . . . . . . . . . . . . . . . . . . . . . . . . . . +220°C
ESD Susceptibility3
AD1580ART
10 mV
10 mV
10 mV
1 mV
1 mV
1 mV
100 ppm/°C
100 ppm/°C
100 ppm/°C
50 ppm/°C
50 ppm/°C
50 ppm/°C
RT
RT
RT
RT
RT
RT
AD1580ART -REEL1
AD1580ART -REEL72
AD1580BRT
AD1580BRT -REEL1
AD1580BRT -REEL72
NOT ES
1Provided on a 13-inch reel containing 7,000 pieces.
2Provided on a 7-inch reel containing 2,000 pieces.
Human Body Model . . . . . . . . . . . . . . . . . . . . . . . . . . 4 kV
Machine Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 400 V
NOT ES
P ACKAGE BRAND ING INFO RMATIO N
1Stresses above those listed under “Absolute Maximum Ratings” may cause
permanent damage to the device. T his is a stress rating only and functional
operation of the device at these or any other conditions above those indicated in
the operational section of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect device reliability.
2Specification is for device in free air at +25°C: SOT -23 Package: θJA = 300°C/Watt.
3T he human body model is a 100 pF capacitor discharged through 1.5 kΩ. For the
machine model, a 200 pF capacitor is discharged directly into the device.
Four marking fields identify the device generic, grade, and date
of processing. T he first field is the product identifier. A “0”
identifies the generic as the AD1580. T he second field indicates
the device grade; “A” or “B.” In the third field a numeral or
letter indicates a calendar year; “5” for 1995, “A” for 2001. In
the fourth field, letters A-Z represent a two week window within
the calendar year; starting with “A” for the first two weeks of
January.
CAUTIO N
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily
accumulate on the human body and test equipment and can discharge without detection. Although
the AD1580 features proprietary ESD protection circuitry, permanent damage may occur on
devices subjected to high energy electrostatic discharges. T herefore, proper ESD precautions are
recommended to avoid performance degradation or loss of functionality.
WARNING!
ESD SENSITIVE DEVICE
–2–
REV. 0
Typical Performance Characteristics–AD1580
1000
500
600
400
200
0
–500
~20ppm/°C
–1000
–1500
–2000
1.0
10
100
1k
10k
100k
1M
–55
–35
–15
5
25
45
65
85
105
125
TEMPERATURE – °C
FREQUENCY – Hz
Figure 1. Output Drift for Different Tem perature
Characteristics
Figure 3. Noise Spectral Density
4
3
100
80
60
40
20
0
T
= 125°C
A
2
1
+85°C
T
=
A
–40°C – +85°C
0
+25°C
–40°C
–1
0.01
0.1
1
10
0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
REVERSE CURRENT – mA
REVERSE VOLTAGE – V
Figure 2. Output Voltage Error vs. Reverse Current
Figure 4. Reverse Current vs. Reverse Voltage
1.0
0.8
0.6
0.4
0.2
0
+25°C
–40°C
+85°C
0.01
0.1
1
10
100
FORWARD CURRENT – mA
Figure 5. Forward Voltage vs. Forward Current
REV. 0
–3–
AD1580
V
+5V(+3V) ±10%
S
TH EO RY O F O P ERATIO N
T he AD1580 uses the “bandgap” concept to produce a stable,
low temperature coefficient voltage reference suitable for high
accuracy data acquisition components and systems. T he device
makes use of the underlying physical nature of a silicon
transistor base-emitter voltage in the forward-biased operating
region. All such transistors have approximately a –2 mV/°C
temperature coefficient, unsuitable for use directly as a low T C
reference; however, extrapolation of the temperature characteristic
of any one of these devices to absolute zero (with collector
current proportional to absolute temperature) reveals that its
VBE will go to approximately the silicon bandgap voltage. T hus,
if a voltage could be developed with an opposing temperature
coefficient to sum with VBE, a zero T C reference would result.
T he AD1580 circuit in Figure 6, provides such a compensating
voltage, V1 by driving two transistors at different current
I
+ I
L
R
2.94kΩ
(1.30kΩ)
R
S
R
S
I
L
V
V
R
R
I
R
V
V
OUT
OUT
(a)
(b)
Figure 7. Typical Connection Diagram
TEMP ERATURE P ERFO RMANCE
T he AD1580 is designed for reference applications where
stable temperature performance is important. Extensive
temperature testing and characterization ensures that the device’s
performance is maintained over the specified temperature range.
densities and amplifying the resultant VBE difference (∆VBE
—
which has a positive T C). T he sum of VBE and V1 provide a
stable voltage reference.
Some confusion exists in the area of defining and specifying
reference voltage error over temperature. Historically, references
have been characterized using a maximum deviation per degree
centigrade, i.e., 50 ppm/°C. However, because of nonlinearities
in temperature characteristics which originated in standard
Zener references (such as “S” type characteristics), most
manufacturers now use a maximum limit error band approach
to specify devices. T his technique involves the measurement of
the output at three or more different temperatures to guarantee
that the voltage will fall within the given error band. T he
proprietary curvature correction design techniques used to
minimize the AD1580 nonlinearities allow the temperature
performance to be guaranteed using the maximum deviation
method. T his method is of more use to a designer than the one
which simply guarantees the maximum error band over the
entire temperature change.
V+
V1
∆V
BE
V
BE
V–
Figure 8 shows a typical output voltage drift for the AD1580
and illustrates the methodology. T he maximum slope of the
two diagonals drawn from the initial output value at 25°C to the
output values at 85°C and –40°C determines the performance
grade of the device. For a given grade of the AD1580 the
designer can easily determine the maximum total error from the
initial tolerance plus temperature variation. For example, the
AD1580BRT initial tolerance is ±1 mV, a ±50 ppm/°C
Figure 6. Schem atic Diagram
AP P LYING TH E AD 1580
T he AD1580 is simple to use in virtually all applications. T o
operate the AD1580 as a conventional shunt regulator (Figure
7a), an external series resistor is connected between the supply
voltage and the AD1580. For a given supply voltage the series
resistor, RS, determines the reverse current flowing through the
AD1580. T he value of RS must be chosen to accommodate the
expected variations of the supply voltage, VS, load current, IL,
and the AD1580 reverse voltage, VR, while maintaining an
acceptable reverse current, IR, through the AD1580.
temperature coefficient corresponds to an error band of ±4 mV
1.2258
(V
– V )
O
MAX
1.2256
1.2254
SLOPE = TC = ———————————––––
–6
(85°C – 25°C) x 1.225 x 10
V
MAX
T he minimum value for RS should be chosen when VS is at
its minimum, and IL and VR are at their maximum while
maintaining the minimum acceptable reverse current.
1.2252
1.2250
V
O
1.2248
1.2246
1.2244
T he value of RS should be large enough to limit IR to 10 mA
when VS is at its maximum, and IL and VR are at their minimum.
T he equation for selecting RS is as follows:
(V
– V )
O
MIN
1.2242
1.2240
1.2238
SLOPE = TC = ———————————–––––
–6
(–40°C – 25°C) x 1.225 x 10
RS = (VS – VR)/(IR + IL)
Figure 7b shows a typical connection with the AD1580BRT
operating at a minimum of 100 µA that can provide ±1 mA to
its load, while accommodating ±10% power supply variations.
V
MIN
–55
–35
–15
5
25
45
65
85
105
125
TEMPERATURE – °C
Figure 8. Output Voltage vs. Tem perature
–4–
REV. 0
AD1580
(50 × 10–6 × 1.225 V × 65°C) thus, the unit is guaranteed to be
1.225 V ± 5 mV over the operating temperature range.
O UTP UT IMP ED ANCE VERSUS FREQ UENCY
Understanding the effect of the reverse dynamic output
impedance in a practical application may be important to
successfully apply the AD1580. A voltage divider is formed by
the AD1580’s output impedance and the external source
impedance. When using an external source resistor of about
30 kΩ (IR = 100 µA), 1% of the noise from a 100 kHz switching
power supply is developed at the output of the AD1580. Figure
11 shows how a 1 µF load capacitor connected directly across
the AD1580 reduces the affect of power supply noise to less
than 0.01%.
Duplication of these results requires a combination of high
accuracy and stable temperature control in a test system.
Evaluation of the AD1580 will produce a curve similar to that in
Figures 1 and 8.
VO LTAGE O UTP UT NO NLINEARITY VERSUS
TEMP ERATURE
When using a reference with data converters it is important to
understand how temperature drift affects the overall converter
performance. T he nonlinearity of the reference output drift
represents additional error that is not easily calibrated out of the
system. T his characteristic (Figure 9) is generated by normal-
izing the measured drift characteristic to the end point average
drift. T he residual drift error of approximately 500 ppm shows
that the AD1580 is compatible with systems that require 10-bit
accurate temperature performance.
1k
100
C
= 0
L
10
1
600
∆I = 0.1I
R
R
500
I
= 100µA
R
C
= 1µF
L
I
= 1mA
R
400
0.1
300
200
10
100
1k
10k
100k
1M
FREQUENCY – Hz
Figure 11. Output Im pedance vs. Frequency
100
0
NO ISE P ERFO RMANCE AND RED UCTIO N
The noise generated by the AD1580 is typically less than 5 µV p-p
over the 0.1 Hz to 10 Hz band. Figure 12 shows the 0.1 Hz to
10 Hz noise of a typical AD1580. Noise in a 10 H z–10 kH z
bandwidth is approximately 20 µ V rms (Figure 13a). If further
noise reduction is desired, a 1-pole low-pass filter may be added
between the output pin and ground. A time constant of 0.2 ms
will have a –3 dB point at about 800 Hz, and will reduce the high
frequency noise to about 6.5 µV rms, (Figure 13b). A time
constant of 960 ms will have a –3 dB point at 165 Hz, and will
reduce the high frequency noise to about 2.9 µV rms (Figure
13c).
–55
–35
–15
5
65
85
25
45
105
125
TEMPERATURE – °C
Figure 9. Residual Drift Error
REVERSE VO LTAGE H YSTERESIS
A major requirement for high performance industrial equipment
manufacturers is a consistent output voltage at nominal tempera-
ture following operation over the operating temperature range.
T his characteristic is generated by measuring the difference
between the output voltage at +25°C after operation at +85°C,
and the output, also at +25°C after operation at –40°C. Figure 10
displays the hysteresis associated with AD1580. This characteristic
exists in all references and has been minimized in the AD1580.
4.5µV p-p
40
35
30
25
20
15
10
1s/DIV
1µV/DIV
5
0
Figure 12. 0.1 Hz–10 Hz Voltage Noise
–400 –300
–200
–100
0
100
200
300
400
HYSTERESIS VOLTAGE – µV
Figure 10. Reverse Voltage Hysteresis Distribution
REV. 0
–5–
AD1580
Output turn-on time is modified when an external noise reduction
filter is used. When present, the time constant of the filter will
dominate overall settling.
21µV rms
40µV/DIV
(a)
(b)
2.4V
6.5µV rms
τ = 0.2ms
20µV/DIV
V
IN
0V
OUTPUT ERROR
1mV/DIV 2 µs/DIV
2.9µV rms
τ = 960ms
10µV/DIV
10ms/DIV
(c)
Figure 13. Total RMS Noise
TURN-O N TIME
OUTPUT
0.5mV/DIV 2 ms/DIV
Many low power instrument manufacturers are becoming
increasingly concerned with the turn-on characteristics of
components being used in their systems. Fast turn-on components
often enable the end user to keep power off when not needed,
and yet respond quickly when the power is turned on for
operation. Figure 14a displays the turn-on characteristic of the
AD1580. Upon application of power (cold start), the time
required for the output voltage to reach its final value within a
specified error is the turn-on settling time. T wo components
normally associated with this are: time for active circuits to
settle and time for thermal gradients on the chip to stabilize.
T his characteristic is generated from cold-start operation and
represents the true turn-on waveform after power up. Figure 15
shows both the coarse and fine turn-on settling characteristics of
the device; the total settling time to within 1.0 mV is about 6 us,
and there is no long thermal tail when the horizontal scale is
expanded to 2 ms/div.
Figure 15. Turn-On Settling
TRANSIENT RESP O NSE
Many A/D and D/A converters present transient current loads
to the reference, and poor reference response can degrade the
converter’s performance.
Figure 16 displays both the coarse and fine settling characteristics
of the device to load transients of ±50 µA.
1mV/DIV
20mV/DIV
I
= 100µA + 50µA STEP
R
(a)
(b)
2.4V
I
= 100µA – 50µA STEP
R
V
IN
0V
C
= 200pF
1µs/DIV
1mV/DIV
L
20mV/DIV
Figure 16. Transient Settling
Figure 16a shows the settling characteristics of the device for an
increased reverse current of 50 µA. Figure 16b shows the
response when the reverse current is decreased by 50 µA. T he
transients settle to 1 mV in about 3 µs.
250mV/DIV
5µs/DIV
Attempts to drive a large capacitive load (in excess of 1,000 pF)
may result in ringing, as shown in the step response photo
(Figure 17). T his is due to the additional poles formed by the
load capacitance and the output impedance of the reference. A
recommended method of driving capacitive loads of this magnitude
is shown in Figure 14b. A resistor isolates the capacitive load from
the output stage, while the capacitor provides a single pole low-
pass filter and lowers the output noise.
Figure 14a. Response Tim e
R
R
= 11.5kΩ
L
S
V
V
C
IN
OUT
V
L
R
Figure 14b. Turn-On, Settling, and Transient Test Circuit
–6–
REV. 0
AD1580
One family of ADCs that the AD1580 is well suited for is the
AD7714-3 and AD7715-3. T he AD7714/AD7715 are charge-
balancing (sigma-delta) A/D converters with on-chip digital
filtering intended for the measurement of wide dynamic range,
low frequency signals such as those representing chemical,
physical or biological processes. Figure 19 shows the AD1580
connected to the AD7714/AD7715 for 3 V operation.
2.0V
V
IN
1.8V
3V
C
= 0.01µF
L
34.8kΩ
AD7714/15–3
REFIN(+)
R
SW
5kΩ (TYP)
HIGH
IMPEDANCE
>1GΩ
AD1580
REFIN(–)
50µs/DIV
10mV/DIV
C
REF
(3–8pF)
SWITCHING
FREQUENCY DEPENDS
ON F
Figure 17. Transient Response with Capacitive Load
CLKIN
P RECISIO N MICRO P O WER LO W D RO P O UT
REFERENCE
Figure 19. Reference Circuit for the AD7714/AD7715–3
T he circuit in Figure 18 provides an ideal solution for making a
stable voltage reference with low standby power consumption,
low input/output dropout capability, and minimum noise
output. T he amplifier both buffers and optionally scales up the
AD1580 output voltage, VR. Output voltages as high as 2.1 V
can supply 1 mA of load current. A one-pole filter connected
between the AD1580 and the OP193 input may be used to
achieve low output noise. The nominal quiescent power consump-
tion is a mere 200 µW.
T he AD1580 is ideal for creating the reference level to use with
12-bit multiplying DACs such as the AD7943, AD7945, and
AD7948. In the single supply bias mode (Figure 20), the
impedance seen looking into the IOUT 2 terminal changes with
DAC code. If the AD1580 drives IOUT 2 and AGND directly,
less than 0.2 LSBs of additional linearity error will result. T he
buffer amp eliminates any linearity degradation that could result
from variations in the reference level .
+3.3V
3V
34.8kΩ
205Ω
V
OP193
RBF
DD
V
= +1.225V
OUT
C1
OR
V
I
I
OUT1
4.7µF
= +1.225 (1+R2/R3)
V
OUT
REF
V
DAC
A1
V
IN
OUT
OUT2
AD1580
AGND
A1: OP295
AD822
AD7943/45/48
OP2283
R3
R2
DGND
+3.3V
41.2kΩ
A1
Figure 18. Micropower Buffered Reference
AD1580
USING TH E AD 1580 WITH 3 V D ATA CO NVERTERS
T he AD1580’s low output drift (50 ppm/°C) and compact sub-
miniature SOT -23 package makes it ideally suited for today’s
high performance converters in space critical applications.
SIGNAL GROUND
Figure 20. Single Supply System
REV. 0
–7–
AD1580
O UTLINE D IMENSIO NS
D imensions shown in inches and (mm).
SO T-23
0.1200 (3.048)
0.1102 (2.799)
0.550 (1.397)
0.0470 (1.194)
0.1040 (2.642)
0.0827 (2.101)
PIN 1
0.0413 (1.049)
0.0236 (0.599)
0.0177 (0.450)
0.0374 (0.950)
0.0807 (2.050)
0.0701 (1.781)
0.0059 (0.150)
0.0034 (0.086)
0.0440 (1.118)
0.0320 (0.813)
0.0040 (0.102)
0.0005 (0.013)
0.0100 (0.254)
0.0050 (0.127)
0.0210 (0.533)
0.0146 (0.371)
0.027 (0.686)
REF
SEATING
PLANE
TAP E AND REEL D IMENSIO NS
D imensions shown in millimeters.
14.4 MAX
1.8 ± 0.1
0.30 ± 0.05
4.0 ± 0.10
+0.05
–0.00
1.5
1.75 ± 0.10
1.5 MIN
2.0 ± 0.05
13.0 ± 0.2
180 (7")
OR
50 (7") MIN
OR
20.2 MIN
2.7 ± 0.1
330 (13")
100 (13") MIN
3.1 ± 0.1
DIRECTION OF UNREELING
1.0 MIN
0.75 MIN
+1.5
–0.0
8.4
–8–
REV. 0
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