AD680ANZ Analog Devices Inc, AD680ANZ Datasheet - Page 9

• Manufacturer Part Number: AD680ANZ
• Description: IC VREF PREC 2.5V LP 8-DIP
• Manufacturer: Analog Devices Inc
• Type: Voltage Referencer

Specifications of AD680ANZ

• Temperature Coefficient: 20ppm/°C
• Reference Type: Series
• Voltage - Output: 2.5V
• Tolerance: ±0.2%
• Voltage - Input: 4.5 ~ 36 V
• Number Of Channels: 1
• Current - Quiescent: 250µA
• Current - Output: 50mA
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Through Hole
• Package / Case: 8-DIP (0.300", 7.62mm)
• Topology: Series
• Input Voltage: 4.5V To 36V
• Reference Voltage: 2.5V
• Reference Voltage Tolerance: 5mV
• Voltage Reference Case Style: DIP
• No. Of Pins: 8
• Current, Output: 0 to 10 mA
• Current, Supply: 195 μA
• Package Type: PDIP-8
• Power Dissipation: 1 mW
• Regulation, Line: 40 μV/V
• Regulation, Load: 80 μV/mA
• Regulator Type: Switching
• Temperature, Operating, Range: -40 to +85 °C
• Voltage, Input: 5 V
• Voltage, Noise: 8 μVp-p
• Voltage, Output: 2.5 V
• Voltage, Supply: 4.5 to 5 V
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Cathode: -
• Lead Free Status / Rohs Status: RoHS Compliant part Electrostatic Device

TEMPERATURE OUTPUT PIN
The 8-lead package 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
at 25°C is 596 mV, and the temperature coefficient is 2 mV/°C.
Figure 16 shows the output of this pin over temperature.
The temperature pin has an output resistance of 12 kΩ and is
capable of sinking or sourcing currents of up to 5 μA without
disturbing the reference output. This enables the TEMP pin to
be buffered by many inexpensive operational amplifiers that
have bias currents below this value.
DIFFERENTIAL TEMPERATURE TRANSDUCER
Figure 17 shows a differential temperature transducer that can
be used to measure temperature changes in the environment of
the AD680. This circuit operates from a 5 V supply. The
temperature-dependent voltage from the TEMP pin of the
AD680 is 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 temperature, use resistors with low temperature
coefficients, such as metal film resistors.
0.1μF
760
720
680
640
600
560
520
480
440
–50 –40 –30 –20 –10 0
Figure 17. Differential Temperature Transducer
Figure 16. TEMP Pin Transfer Characteristics
AD680
GND
V
5V
TEMP
2
4
IN
100Ω
R
BP
3
TEMPERATURE (°C)
R
1.69kΩ
1%
B
3
2
10 20 30 40 50 60 70 80 90
+
–
OP90
5V
7
4
6.98kΩ
1%
R
F
6
Δ
V
Δ
OUT
T
= 10mV/°C
TEMP
Rev. H | Page 9 of 12
LOW POWER, LOW VOLTAGE REFERENCE FOR
DATA CONVERTERS
The AD680 has a number of features that make it ideally suited
for use with ADCs and DACs. The low supply voltage required
makes it possible to use the AD680 with today’s converters that
run on 5 V supplies without having to add a higher supply
voltage for the reference. The low quiescent current (195 μA),
combined with the completeness and accuracy of the AD680,
make it ideal for low power applications, such as hand-held,
battery-operated meters.
The
Figure 18 shows the AD680 used as the reference for this
converter. The
filtering intended for the measurement of wide dynamic range
and low frequency signals, such as those representing chemical,
physical, or biological processes. It contains a charge balancing
(Σ–Δ) ADC, a calibration microcontroller with on-chip static
RAM, a clock oscillator, and a serial communications port.
This entire circuit runs on ±5 V supplies. The power dissipation
of the
the power dissipation of the AD680 (1 mW), the entire circuit
consumes just 26 mW of power.
ANALOG
SUPPLY
CALIBRATE
+5V
AD7701
ANALOG
ANALOG
ANALOG
SUPPLY
SELECT
RANGE
AD7701
INPUT
0.1μF
GND
–5V
Figure 18. Low Power, Low Voltage Supply Reference
0.1μF
is an ADC that is well-suited for the AD680.
0.1μF
AD7701
is typically 25 mW and, when combined with
AD680
10μF
GND
for the
0.1μF
is a 16-bit ADC with on-chip digital
V
V
IN
OUT
10μF
AD7701
AV
V
BP/UP
CAL
A
AGND
AV
REF
IN
DD
SS
16-Bit ADC
AD7701
CLKOUT
SDATA
SLEEP
MODE
CLKIN
DGND
DRDY
SCLK
DV
DV
SC1
SC2
CS
DD
SS
DATA READY
READ (TRANSMIT)
SERIAL CLOCK
SERIAL DATA
0.1μF
0.1μF
AD680