Data can be written to the DAC while it is in shutdown.

A control word with A1 = 1 and E0 = 0 disables the

DAC while allowing data to be written to the DAC. The

eight bits following this control word are shifted into the

DAC register. Conversion takes place once the DAC is

enabled.

Two control words are necessary to enable the ADC.

The first control word brings the ADC out of shutdown,

and sets the T/H in acquisition mode. The second con-

trol word initiates the conversion.

Bit 2 (E2) controls the reference. A logic “1” enables

the reference, a logic “0” disables the reference, further

reducing power consumption.

Power Supply Bypassing and Layout

For best performance, use printed circuit boards. Wire-

wrap boards are not recommended. Board layout

should ensure that digital and analog signal lines are

separated from each other. Do not run analog and digi-

tal (especially clock) lines parallel to one another or run

digital lines underneath the device.

Figure 10 shows the recommended system-ground

connections. A single-point analog ground (star-ground

point) should be established at the device ground.

Connect all analog grounds to the star ground. No digi-

tal-system ground should be connected to this point.

The ground return to the power supply for the star

ground should be connected to this point. The ground

return to the power supply for the star ground should

be low impedance and as short as possible for noise-

free operation. High-frequency noise in the VDD power

supply may affect device performance. Bypass the

supply to the star ground with 0.1µF and 1µF capaci-

tors close to the device. Minimize capacitor lead

lengths for best supply-noise rejection. If the power

supply is very noisy, connect a 10

Ω resistor in series

with VDD to form a lowpass filter.

Chip Information

TRANSISTOR COUNT: 3226

PROCESS: BiCMOS

8-Bit CODECs

______________________________________________________________________________________

15

GND

+3V/+5V

SYSTEM POWER SUPPLIES

DGND

1

µF

10

Ω

0.1

µF

GND

DIGITAL

CIRCUITRY

MAX1102

MAX1103

MAX1104

Figure 10. Power-Supply Connections