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OPA 627

GND

GND

GND

GND

Pin 1

Pin 7

−

Pin 2

+

Pin3

Pin4

Pin 6

−15 V

+15V

Vin

2.2 mF

100 nF

2 kW

22 pF

2 kW

22 pF

2.2 mF

2.2 mF

100 nF

2.2 mF

GND

CAP

REF

ADS8513

OPA 132

or

GND

ADS8513

SLAS486 – JUNE 2007

ANALOG INPUT (continued)

Table 4. Complete list of Ideal Input Ranges (continued)

ANALOG

CONNECT

CONNECT

CONNECT

INPUT

INPUT

R1IN

R2IN

R3IN

IMPEDANCE

COMMENT

RANGE (V)

TO

TO

TO

(k

Ω)

±10

VIN

BUF

GND

45.7

Specified offset and gain

0.833 to 7.5

VIN

GND

VIN

21.3

Offset and gain not specified

–2.5 to 17.5

VIN

GND

BUF

45.7

Exceeds absolute maximum VIN

2.5 to 22.5

VIN

GND

GND

45.7

Exceeds absolute maximum VIN

0 to 2.857

BUF

VIN

VIN

45.7

Offset and gain not specified

–1 to 3

BUF

VIN

BUF

21.3

VIN cannot go below GND – 0.3V

0 to 4

BUF

VIN

GND

21.3

Specified offset and gain

–6.25 to 3.75

BUF

BUF

VIN

26.7

Offset and gain not specified

0 to 10

BUF

GND

VIN

26.7

Specified offset and gain

0.357 to 3.214

GND

VIN

VIN

45.7

Offset and gain not specified

–0.5 to 3.5

GND

VIN

BUF

21.3

VIN cannot go below GND – 0.3V

0.5 to 4.5

GND

VIN

GND

21.3

Specified offset and gain

±5

GND

BUF

VIN

26.7

Specified offset and gain

1.25 to 11.25

GND

GND

VIN

26.7

Offset and gain not specified

Figure 11. Typical Driving Circuit (±10 V, No Trim)

The input impedance results from the various connections and the internal resistor values (refer to the block

diagram on the front page of this data sheet). The internal resistor values are typical and can change by ±30%,

due to process variations. However, the ratio matching of the resistors is considerably better than this. Thus, the

input range will vary only a few tenths of a percent from part to part, while the input impedance can vary up to

±30%.

The Specifications table contains the maximum limits for the variation of the analog input range, but only for

those ranges where the comment field shows that the offset and gain are specified (this includes all the ranges

listed in Table 1). For the other ranges, the offset and gain are not tested and are not specified.

Five of the input ranges in Table 4 are not recommended for general use. The upper-end of the –2.5V to +17.5V

range and +2.5V to +22.5V range exceed the absolute maximum analog input voltage. These ranges can still be

used as long as the input voltage remains under the absolute maximum, but this will moderately to significantly

reduce the full-scale range of the converter.

Copyright © 2007, Texas Instruments Incorporated

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