CONNECTION DIAGRAMS
TP*+V IN TEMP GND
TP*TP*
V OUT NC
NC = NO CONNECT井柏然个人资料
TP DENOTES FACTORY TEST POINT.NO CONNECTIONS SHOULD BE MADE TO THESE PINS.
*REV.C
Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its u, nor for any infringements of patents or other rights of third parties which may result from its u. No licen is granted by implication or otherwi under any patent or patent rights of Analog Devices.
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Low Power, Low Cost饮料英语怎么读
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2.5 V Reference
AD680*
FEATURES
Low Quiescent Current: 250 A max Lar Trimmed to High Accuracy:2.5 V ؎5 mV max (AN, AR Grade)Trimmed Temperature Coefficient:20 ppm/؇C max (AN, AR Grade)
Low Noi: 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-Pin Plastic DIP, 8-Pin SOIC and 3-Pin TO-92
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.Tel: 617/329-4700Fax: 617/326-8703
PRODUCT DESCRIPTION
The AD680 is a bandgap voltage reference which 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 noi 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 u 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.
Bad upon the low quiescent current of the AD680, which rivals that of many incomplete two-termin
al references, the AD680 is recommended for low power applications such as hand-held battery equipment.
A temperature output pin is provided on the 8-pin package ver-sions 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 speci-fied 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-pin 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-pin Small Outline IC (SOIC) pack-age. The AD680JT is specified for 0°C to +70°C operation and is available in a 3-pin TO-92 package.
*Protected by U.S. Patent Nos. 4,902,959; 4,250,445 and 4,857,862.
PRODUCT HIGHLIGHTS
1. The AD680 bandgap reference operates on a very low quies-cent current which rivals that of man
y two-terminal refer-ences. This makes the complete, higher accuracy AD680ideal for u in power nsitive applications.
2. Lar trimming of both initial accuracy and temperature
coefficients results in low errors over temperature without the u of external components. The AD680AN and AD680AR have a maximum variation of 6.25 mV between –40°C and +85°C.3. The AD680 noi 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-pin package versions enables the AD680 to be configured as a temperature trans-ducer.5. Plastic DIP packaging provides machine inrtability, while SOIC packaging provides surface mount capability. TO-92packaging 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–SPECIFICATIONS
(T A = +25؇C, V IN = +5 V, unless otherwi noted)
AD680AN/AR AD680JN/JR AD680JT
Model Min Typ Max Min Typ Max Min Typ Max Units OUTPUT VOLTAGE 2.495 2.505 2.490 2.510 2.490 2.510V
OUTPUT VOLTAGE DRIFT1
0°C to +70°C1010251030ppm/°C –40°C to +85°C202525
LINE REGULATION
4.5 V ≤ +V IN≤ 15 V40**µV/V
(@ T MIN to T MAX)40**
15 V ≤ +V IN≤ 36 V40**
(@ T MIN to T MAX)40**
LOAD REGULATION
0 < I OUT < 10 mA80100****µV/mA
(@ T MIN to T MAX)80100****
QUIESCENT CURRENT195250****µA (@ T MIN to T MAX)280**
POWER DISSIPATION1 1.25****mW OUTPUT NOISE
0.1 Hz to 10 Hz810****mV p-p
Spectral Density, 100 Hz250**nV/√Hz CAPACITIVE LOAD50**nF
LONG TERM STABILITY25**ppm/1000 hr SHORT CIRCUIT CURRENT
TO GROUND2550****mA TEMPERATURE PIN
Voltage Output @ +25°C540596660***mV
Temperature Sensitivity2*mV/°C Output Current–5+5**µA
Output Resistance12*kΩTEMPERATURE RANGE
Specified Performance–40+850+700+70°C
Operating Performance2–40+85–40+85–40+85
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.
*Same as AD680AN/AR specification.
Specifications subject to change without notice.
Specifications in boldface are tested on all production units at final eleetrical test. Results from tho tests are ud to calculate out going quality levels. All min and max specifications are guaranteed.
–2–
REV. C
AD680
REV. C –3–
THEORY OF OPERATION
Bandgap references are the high performance solution for low supply voltage operation. A typical precision bandgap will con-sist of a reference core and buffer amplifier. Bad 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 offt. This offt is controlled by the area ratio of the amplifier input pair, Q1 and Q2, and is developed across resistor R1. Transistor Q12’s ba emitter voltage has a Complementary To Absolute Temperature (CTAT) characteristic. Resistor R2 and the parallel combina-tion 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.
R5
OUT
+V IN
Figure 2.AD680 Schematic Diagram
An additional feature with this approach is the ability to mini-mize the noi while maintaining very low overall power dissipation for the entire circuit. Frequently it is difficult to independently control the dominant noi sources for bandgap references: bandgap transistor noi and resistor thermal noi.By properly choosing the operating currents of Q1 and Q2 and parately sizing R1, low wideband noi is realized while main-taining 1 mW typical power dissipation.
ABSOLUTE MAXIMUM RATINGS*我的老师作文开头
V IN to Ground . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36 V Power Dissipation (25°C) . . . . . . . . . . . . . . . . . . . . . .500 mW Storage Temperature . . . . . . . . . . . . . . . . . . .–65°
C to +125°C Lead Temperature (Soldering, 10 c) . . . . . . . . . . . . . .300°C Package Thermal Resistance
θJA (All Packages) . . . . . . . . . . . . . . . . . . . . . . . .120°C/W Output Protection: Output safe for indefinite short to ground and momentary short to V IN .
*Stress above tho listed under “Absolute Maximum Ratings” may cau permanent damage to the device. This is a stress rating only and functional operation of the device at the or any other conditions above tho indicated in the operational ctions of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect device reliability.
8-Pin Plastic DIP
and
8-Pin SOIC Packages
TP*+V IN TEMP GND
TP*TP*V OUT NC
NC = NO CONNECT
TP DENOTES FACTORY TEST POINT.NO CONNECTIONS SHOULD BE MADE TO THESE PINS.
*TO-92 Package
怎么把表格缩小Figure 1. Connection Diagrams
ORDERING GUIDE
Initial Temperature Error Coeff.Temperature Package Package Model mV ppm/°C Range Description Option*AD680JN 10250°C to +70°C Plastic N-8AD680JR 10250°C to +70°C SOIC SO-8AD680JT 10300°C to +70°C TO-92TO-92AD680AN 520–40°C to +85°C Plastic N-8AD680AR
5
20
–40°C to +85°C
SOIC
SO-8
*N = Plastic DIP Package; SO = SOIC Package; T = TO-92 Package.
AD680
REV. C
–4–APPLYING THE AD680
The AD680 is simple to u in virtually all precision reference applications. When power is applied to +V IN and the GND pin is tied to ground, V OUT provides a +2.5 V output. The AD680typically requires less than 250 µA of current when operating from a supply of +4.5 V to +36 V.
To operate the AD680, the +V IN pin must be bypasd to the GND pin with a 0.1 µF capacitor tied as clo to the AD680 as possible. Although the ground current for the AD680 is small (typically 195 µA), a direct connection should be made between the AD680 GND pin and the system ground plane.
Reference outputs are frequently required to handle fast tran-sients caud by input switching networks, as are commonly found in ADCs and measurement instrumentation equipment.Many of the dynamic problems associated with this situation can be minimized with a few simple techniques. Using a ries resistor between the reference output and the load will tend to “decouple” the reference output from the transient source. Or a relatively large capacitor connected from the reference output to ground can rve as a charge storage element to absorb and de-liver charge as is required by the dynamic load. A 50 nF capaci-tor is recommended for the AD680 in this ca; this is large enough to store the required charge, but small enough so as not to disrupt the stability of the reference.
The 8-pin plastic DIP and SOIC packaged versions of the AD680 also provide a temperature output pin. The voltage on this pin is nominally 596 mV at 25°C. This pin will provide an output linearly proportional to temperature with a characteristic of 2 mV/°C.
NOISE PERFORMANCE
The noi generated by the AD680 is typically less than 8 µV p-p over the 0.1 Hz to 10 Hz band. Figure 3 shows the 0.1 Hz to 10 Hz noi of a typical AD680. The noi measurement is made with a bandpass filter made of a 1-pole high-pass filter with a corner frequency at 0.1 Hz and a 2-pole low-pass filter with a corner frequency at 12.6 Hz to create a filter with a
9.922 Hz bandwidth.
Figure 3.0.1 Hz to 10 Hz Noi
Noi in a 300 kHz bandwidth is approximately 800 µV p-p.
Figure 4 shows the broadband noi of a typical AD680.
Figure 4.Broadband Noi at 300 kHz
TURN-ON TIME
Upon application of power (cold start), the time required for the output voltage to reach its final value within a specified error band is defined as the turn-on ttling time. Two components normally associated with this are: the time for the active circuits to ttle, and the time for the thermal gradients on the chip to stabilize. Figure 5 shows the turn-on ttling time of the AD680to be about 20 µ
s to 0.025% of its final value.
Figure 5.Turn-On Settling Time
白菜花怎么炒好吃The AD680 thermal ttling characteristic benefits from its
compact design. Once initial turn-on is achieved, the output lin-early approaches its final value; the output is typically within 0.01% of its final value after 25 ms.
DYNAMIC PERFORMANCE
The output stage of the ampliflier is designed to provide the AD680 with static and dynamic load regulation superior to less complete references.
AD680
REV. C –5–康熙和乾隆
Figure 6 displays the characteristics of the AD680 output ampli-fier driving a 0 mA to 10 mA load. Longer ttling times will re-sult if the reference is forced to sink any transient current.In some applications, a varying load may be both resistive and capacitive in nature, or the load may be connected to the AD680 by a long capacitive cable.
+V
OUT
0.1 µF
Figure 6a.Transient Load Test Circuit
Figure 6b.Large-Scale Transient Respon
Figure 6c.Fine Scale Settling for Transient Load
Figure 7 displays the output amplifier characteristics driving a 1000 pF, 0 mA to 10 mA load.
OUT
+V 0.1 µF
Figure 7a.Capacitive Load Transient Respon Test Circuit
Figure 7b.Output Respon with Capacitive Load
LOAD REGULATION
Figure 8 shows the load regulation characteristics of the AD680.
Figure 8.Typical Load Regulation Characteristics
AD680
REV. C
–6–TEMPERATURE PERFORMANCE
The AD680 is designed for reference applications where tem-perature performancc is important. Extensivc temperature test-ing and characterization ensures that the device’s performance is maintained over the specified temperature range.
Some confusion exists in thc area of defining and specifying ref-erence voltage error over temperature. Historically, references have been characterized using a maximum deviation per degre
e centigrade, i.e., ppm/°C. However, becau of nonlinearities in temperature characteristics which originated in standard Zener references (such as “S” type characteristics), most manufactur-ers now u a maximum limit error band approach to specify devices. This technique involves the measurement of the output at three or more different temperatures to specify an output voltage error band.
TEMPERATURE – C
Figure 9.Typical AD680AN/AP Temperature Drift
Figure 9 shows a typical output voltage drift for the AD680AN/AR and illustrates the test methodology. The box in Figure 9 is bounded on the sides by the operating temperature extremes,and on the top and bottom by the maximum and minimum out-put voltages measured over the operating temperature range.The maximum height of thc box for the appropriate tempera-ture range and device grade is shown in Table I. Duplication of the results requires a combination of high accuracy and stable temperature control in a test system. Evaluation of the AD680will produce a curve similar to that in Figure 9, but output read-ings may vary depending upon the test equipment utilized.
TEMPERATURE OUTPUT PIN
The 8-pin packaged versions of the AD680 provide a tempera-ture output pin on Pin 3 of each device. The output of Pin 3(TEMP) is a voltage that varies linearly with temperature.V TEMP at 25°C is 596 mV, and the temperature coefficient is 2 mV/°C. Figure 10 shows the output of this pin over temperature.
The temperature pin has an output resistance of 12 k Ω and is capable of sinking or sourcing currents of up to 5 µA without disturbing the reference output, enabling the temp pin to be buffered by any of a number of inexpensive operational amplifi-ers that have bias currents below this value.
760440
90
520480
–40–506005606406807208060504020100–10–20–303070TEMPERATURE – C
T E M P P I N V O L T A G E – m V
Figure 10.Temp Pin Transfer Characteristic
DIFFERENTIAL TEMPERATURE TRANSDUCER
Figure 11 shows a differential temperature transducer that can be ud to measure temperature changes in the AD680’s envi-ronment. This circuit operates from a +5 V supply. The tem-perature dependent voltage from the TEMP pin of the AD680is amplified by a factor of 5 to provide wider full-scale range and more current sourcing capability. An exact gain of 5 can be achieved by adjusting the trim potentiometer until the output varies by 10 mV/°C. To minimize resistance changes with tem-perature, resistors with low temperature coefficients, such as metal film resistors, should be ud.
洋葱发芽了还能吃吗0.1µF
= 10mV/ C OUT
∆V ∆T
Figure 11.Differential Temperature Transducer LOW POWER, LOW VOLTAGE REFERENCE FOR DATA CONVERTERS
The AD680 has a number of features that make it ideally suited for u with A/D and D/A converters. The low supply voltage required makes it possible to u the AD680 with today’s convertcrs that run on 5 V supplies without having to add a higher supply voltage for the reference. The low quiescent cur-rent (195 µA), combined with the completeness and accuracy of the AD680 make it ideal for low power applications such as handheld, battery operated meters.
