TLV5627C, TLV5627I

2.7V TO 5.5V 8BIT 4CHANNEL DIGITALTOANALOG CONVERTERS

WITH POWER DOWN

SLAS232A − JUNE1999 − REVISED JULY 2002

16

POST OFFICE BOX 655303

• DALLAS, TEXAS 75265

APPLICATION INFORMATION

linearity, offset, and gain error using single ended supplies (continued)

The offset error, not the linearity error, produces this breakpoint. The transfer function would have followed the

dotted line if the output buffer could drive below the ground rail.

For a DAC, linearity is measured between zero-input code (all inputs 0) and full-scale code (all inputs 1) after

offset and full scale are adjusted out or accounted for in some way. However, single supply operation does not

allow for adjustment when the offset is negative due to the breakpoint in the transfer function. So the linearity

is measured between full-scale code and the lowest code that produces a positive output voltage.

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 and there are negligible voltage drops across the ground plane.

A 0.1-

µF ceramic-capacitor bypass should be connected between VDDand AGND and mounted with short leads

as close as possible to the device. Use of ferrite beads may further isolate the system analog supply from the

digital power supply.

Figure 20 shows the ground plane layout and bypassing technique.

0.1

µF

Analog Ground Plane

1

2

3

4

8

7

6

5

Figure 20. Power-Supply Bypassing