Datasheet

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OPA 627
GND
GND
GND
GND
GND
GND
Pin1
Pin5
Pin 7
−
Pin 2
+
Pin3
Pin4
Pin 6
−15V
+15 V
Vin
2.2 F
100 nF
1 k
22 pF
10 pF
1 k
22 pF
200 
100 
33.2 k
2.2 F
2.2 F
100 nF
2.2 F
R1
IN
AGND
R2
IN
R3
IN
CAP
AGND2
ADS8508
ADS8508
SLAS433 – SEPTEMBER 2005
The external reference voltage can vary from 2.3 V to 2.7 V. The reference voltage determines the size of the
least significant bit (LSB). The larger reference voltages produce a larger LSB, which can improve SNR. Smaller
reference voltages can degrade SNR.
Figure 27. Typical Driving Circuitry (±10 V, No Trim)
Table 3. Input Range Connections (see Figure 28 and Figure 29 for complete
information)
ANALOG CONNECT R1
IN
VIA CONNECT R2
IN
VIA CONNECT
IMPEDANCE
INPUT RANGE 200 Ω TO 100 Ω TO R3 TO
±10 V V
IN
AGND CAP 11.5 k Ω
±5 V AGND V
IN
CAP 6.7 k Ω
±3.33 V V
IN
V
IN
CAP 5.4 k Ω
0 V to 10 V AGND V
IN
AGND 6.7 k Ω
0 V to 5 V AGND AGND V
IN
5.0 k Ω
0 V to 4 V V
IN
AGND V
IN
5.4 k Ω
Table 4. Control Truth Table
SPECIFIC FUNCTION CS R/ C BUSY EXT/ INT DATACLK PWRD SB/ BTC OPERATION
Initiate conversion and out- 1 > 0 0 1 0 Output 0 x Initiates conversion n. Data from conversion n - 1
put data using internal clock clocked out on DATA synchronized to 16 clock
0 1 > 0 1 0 Output 0 x
pulses output on DATACLK.
Initiate conversion and out- 1 > 0 0 1 1 Input 0 x Initiates conversion n.
put data using external clock
0 1 > 0 1 1 Input 0 x Initiates conversion n.
1 > 0 1 1 1 Input x x Outputs a pulse on SYNC followed by data from
conversion n clocked out synchronized to external
DATACLK.
1 > 0 1 0 1 Input 0 x Outputs a pulse on SYNC followed by data from
conversion n - 1 clocked out synchronized to
0 0 > 1 0 1 Input 0 x
external DATACLK.
(1)
Conversion n in process.
Incorrect conversions 0 0 0 > 1 x x 0 x CS or R/ C must be HIGH or a new conversion will
be initiated without time for acquisition.
Power down x x x x x 0 x Analog circuitry powered. Conversion can pro-
ceed..
x x x x x 1 x Analog circuitry disabled. Data from previous
conversion maintained in output registers.
(1) See Figure XXX for the constraints on previous data valid during a conversion.
19