AD822ACHIPS Ver la hoja de datos (PDF) - Analog Devices
Número de pieza
componentes Descripción
Fabricante
AD822ACHIPS Datasheet PDF : 16 Pages
| |||
AD822
APPLICATIONS
Single Supply Voltage-to-Frequency Converter
The circuit shown in Figure 44 uses the AD822 to drive a low
power timer, which produces a stable pulse of width t1. The
positive going output pulse is integrated by R1-C1 and used as
one input to the AD822, which is connected as a differential
integrator. The other input (nonloading) is the unknown
voltage, VIN. The AD822 output drives the timer trigger input,
closing the overall feedback loop.
+10V
C5
0.1µF
U4
2
REF-02
6 VREF =
5V
3
5
RSCALE **
10k
4
CMOS
74HCO4
U3B
U3A
4
32
1
C3
0.1µF
R2
499k, 1%
R1
VIN
499k, 1%
0V TO 2.5V
FULL SCALE C2
0.01µF, 2%
0.01µF, 2%
U1
C1
R3*
116k
1/2
AD822B
C6
390pF
5%
(NPO)
U2
CMOS 555
48
6R
THR
2
TR
7
DIS
V+
3
OUT
5
CV
GND
1
C4
0.01µF
OUT2
OUT1
NOTES:
fOUT = VIN/(VREF*t1), t1 = 1.1*R3*C6
= 25kHz fS AS SHOWN.
* = 1% METAL FILM, <50ppm/°C TC
** = 10%, 20T FILM, <100ppm/°C TC
t1 = 33µs FOR fOUT = 20kHz @ VIN = 2.0V
Figure 44. Single Supply Voltage-to-Frequency Converter
Typical AD822 bias currents of 2 pA allow megaohm-range
source impedances with negligible dc errors. Linearity errors on
the order of 0.01% full scale can be achieved with this circuit.
This performance is obtained with a 5 volt single supply which
delivers less than 1 mA to the entire circuit.
Single Supply Programmable Gain Instrumentation Amplifier
The AD822 can be configured as a single supply instrumenta-
tion amplifier that is able to operate from single supplies down
to 3 V, or dual supplies up to ± 15 V. Using only one AD822
rather than three separate op amps, this circuit is cost and power
efficient. AD822 FET inputs’ 2 pA bias currents minimize offset
errors caused by high unbalanced source impedances.
An array of precision thin-film resistors sets the in amp gain to
be either 10 or 100. These resistors are laser-trimmed to ratio
match to 0.01%, and have a maximum differential TC of
5 ppm/°C.
Table I. AD822 In Amp Performance
Parameters
CMRR
Common-Mode
Voltage Range
3 dB BW, G = 10
G = 100
tSETTLING
2 V Step (VS = 0 V, 3 V)
5 V (VS = ± 5 V)
Noise @ f = 1 kHz, G = 10
G = 100
ISUPPLY (Total)
VS = 3 V, 0 V VS = ؎5 V
74 dB
80 dB
–0.2 V to +2 V –5.2 V to +4 V
180 kHz
180 kHz
18 kHz
18 kHz
2 µs
270 nV/√Hz
2.2 µV/√Hz
1.10 mA
5 µs
270 nV/√Hz
2.2 µV/√Hz
1.15 mA
5µ s
100
90
10
0%
1V
Figure 45a. Pulse Response of In Amp to a 500 mV p-p
Input Signal; VS = +5 V, 0 V; Gain = 10
VREF
R1
R2
R3
R4
R5
R6
90k
9k
1k
1k
9k
90k
OHMTEK
PART # 1043
G =10
G =100 G =100
+VS
0.1µF
G =10
2
6
RP
VIN1
1/2 8 1
3 AD822
1kΩ RP
1/2
7
5 AD822
4
VOUT
VIN2
1kΩ
(G =10)
VOUT
=
(VIN1
–VIN2 )
(1+ R6
R4 + R5
)
+VREF
(G =100)
VOUT
=
(VIN1
–VIN2 )
(1+ R5 + R6
R4
)
+VREF
FOR R1 = R6, R2 = R5, AND R3 = R4
Figure 45b. A Single Supply Programmable
Instrumentation Amplifier
REV. A
–15–
Share Link: 