5

LTC1279

Note 7: Integral nonlinearity is defined as the deviation of a code from a

straight line passing through the actual endpoints of the transfer curve. The

deviation is measured from the center of the quantization band.

Note 8: Bipolar offset is the offset voltage measured from – 1/2LSB when

the output code flickers between 0000 0000 0000 and 1111 1111 1111.

Note 9: Guaranteed by design, not subject to test.

Note 10: The AC test is for bipolar mode. The signal-to-noise plus

distortion ratio is about 1dB lower for unipolar mode, so the typical

S/(N + D) at 100kHz in unipolar mode is 71dB.

Note 11: Recommended operating conditions.

specified accuracy. Therefore the minimum supply voltage for the unipolar

mode is 4.95V. The minimum for the bipolar mode is 4.75V, – 2.45V.

Note 13: The falling CONVST edge starts a conversion. If CONVST returns

high at a bit decision point during the conversion it can create small errors.

For best performance ensure that CONVST returns high either within 120ns

after conversion start (i.e., before the first bit decision) or after BUSY rises

(i.e., after the last bit test). See mode 1a and 1b (Figures 12 and 13) timing

diagrams.

TI I G CHARACTERISTICS

Note 1: Absolute maximum ratings are those values beyond which the life

of a device may be impaired.

Note 2: All voltage values are with respect to ground with DGND and

AGND wired together (unless otherwise noted).

mode), they will be clamped by internal diodes. This product can handle

Note 6: Linearity, offset and full scale specifications apply for unipolar and

bipolar modes.

(Note 5)

OUTPUT CODE

0

4096

1279 G02

1024

2048

3072

1.0

0.5

0

–0.5

–1.0

512

1536

2560

3584

OUTPUT CODE

0

4096

1279 G01

1024

2048

3072

1.0

0.5

0

–0.5

–1.0

512

1536

2560

3584

Integral Nonlinearity vs

Output Code

FREQUENCY (Hz)

10k

100k

1M

5M

1279 G03

12

11

10

9

8

7

6

5

4

3

2

1

0

74

68

62

56

50

NYQUIST

FREQUENCY

ENOBs and S/(N + D) vs

Input Frequency

Differential Nonlinearity vs

Output Code