TLC5618, TLC5618A

PROGRAMMABLE DUAL 12-BIT DIGITAL-TO-ANALOG CONVERTERS

SLAS156E – JULY 1997 – REVISED SEPTEMBER 1999

21

POST OFFICE BOX 655303

APPLICATION INFORMATION

power-supply bypassing and ground management

Printed-circuit boards that use separate analog and digital ground planes offer the best system performance.

Wire-wrap boards do not perform well and should not be used. The two ground planes should be connected

together at the low-impedance power-supply source. The best ground connection may be achieved by

connecting the DAC AGND terminal to the system analog ground plane making sure that analog ground

currents are well-managed.

A 0.1-

as close as possible to the device. Use of ferrite beads may further isolate the system analog and digital power

supplies.

Figure 27 shows the ground plane layout and bypassing technique.

0.1

µF

Analog Ground Plane

1

2

3

4

8

7

6

5

Figure 27. Power-Supply Bypassing

saving power

Setting the DAC register to all 0s minimizes power consumption by the reference resistor array and the output

load when the system is not using the DAC.

ac considerations/analog feedthrough

Higher frequency analog input signals may couple to the output through internal stray capacitance. Analog

feedthrough is tested by holding CS high, setting the DAC code to all 0s, sweeping the frequency applied to

REFIN, and monitoring the DAC output.