Electrical characteristics – Rainbow Electronics ADC1251 User Manual

Page 6

Electrical Characteristics

(Continued)

Note 7

A diode exists between AV

and DV

as shown below

TL H 11025 – 5

To guarantee accuracy it is required that the AV

and DV

be connected together to a power supply with separate bypass filters at each V

Note 8

Accuracy is guaranteed at f

CLK

3 5 MHz At higher or lower clock frequencies accuracy may degrade see the typical performance characteristic curves

Note 9

Typicals are at T

25 C and represent most likely parametric norm

Note 10

Limits are guaranteed to National’s AOQL (Average Outgoing Quality Level)

Note 11

Positive linearity error is defined as the deviation of the analog value expressed in LSBs from the straight line that passes through positive full scale and

zero For negative linearity error the straight line passes through negative full scale and zero (See

Figures 1b and 1c )

Note 12

The ADC12451’s self-calibration technique ensures linearity full scale and offset errors as specified but noise inherent in the self-calibration process will

result in a repeatability uncertainty of

0 20 LSB

Note 13

If T

changes then an Auto-Zero or Auto-Cal cycle will have to be re-started see the typical performance characteristic curves

Note 14

After an Auto-Zero or Auto-Cal cycle at the specified power supply extremes

Note 15

When using the WR control to start a conversion if the clock is asynchronous to the rising edge of WR an uncertainty of one clock period will exist in the

end of the interval of t

therefore making t

end a minimum 6 clock periods or a maximum 7 clock periods after the rising edge of WR If the falling edge of the

clock is synchronous to the rising edge of WR then t

will end exactly 6 5 clock periods after the rising edge of WR This does not occur when S H control is used

Note 16

The CAL line must be high before a conversion is started

Note 17

The specifications for these parameters are valid after an Auto-Cal cycle has been completed

Note 18

The ADC12451 reference ladder is composed solely of capacitors

Note 19

A military RETS electrical test specification is available on request At time of printing the ADC12451CMJ 883 RETS specification complies fully with the

boldface

limits in this column

TL H 11025 – 6

FIGURE 1a Transfer Characteristic