AD9040A

REV. B

–9–

Figure 9. PCB Bottom View

Table II. Digital Coding

Analog

Voltage

Out-of-

Input

Level

Range

Digital Output

MSB . . . LSB

+1.002 V

Positive Full Scale + 1 LSB 1

1111111111

+1 V

Positive Full Scale

0

1111111111

Full Scale – 1 LSB

0

1111111110

+1/2 V

Positive 1/2 Scale

0

1100000000

1/2 Scale – 1 LSB

0

1011111111

0 V

Bipolar Zero

0

10000000000

0

01111111111

–1/2 V

1/2 Scale + 1 LSB

0

0100000000

Negative 1/2 Scale

0

0011111111

–1 V

Full Scale + 1 LSB

0

0000000001

Negative Full Scale

0

0000000000

–1.002 V

Negative Full Scale – 1 LSB 1

0000000000

Figure 8. PCB Top View

DAC Reconstruction

The AD9040A evaluation board provides an onboard AD9721

reconstruction DAC for observing the digitized analog input

signal. The AD9721 is terminated into 51 ohms to provide a

1 V p-p signal at the output (RC OUTPUT).

Output Data

The output data bits are latched with a CMOS 74AC574 which

drives a 40-pin connector (AMP p/n 102153-9). The data and

clock signals are available on the connector per the pin assign-

ments shown on the schematic of the evaluation board. Output

data are available on the falling edge of the clock.