TLC7225C, TLC7225I

QUADRUPLE 8-BIT DIGITAL-TO-ANALOG CONVERTERS

SLAS109B – OCTOBER 1996 – REVISED FEBRUARY 2001

11

POST OFFICE BOX 655303

APPLICATION INFORMATION

ground management and layout

The TLC7225 contains four reference inputs that can be driven from ac sources (see multiplying DAC using ac

input to the REF terminals section) so careful layout and grounding is important to minimize analog crosstalk

between the four channels. The dynamic performance of the four DACs depends upon the optimum choice of

board layout. Figure 6 shows the relationship between input frequency and channel-to-channel isolation.

Figure 7 shows a printed circuit board layout that minimizes crosstalk and feedthrough. The four input signals

output amplifier during measurements.

– 80

– 70

– 60

– 50

– 40

– 30

20 k

50 k

100 k

200 k

500 k

1 M

fI – Input Frequency – Hz

TA = 25°C

VDD = 15 V

VSS = – 5 V

Vref = 1.24 VPP

– 20

10 k

Figure 6. Channel-to-Channel Isolation

MSB

LSB

Terminal 1

System GND

OUTB

OUTA

VSS

REFB

REFA

AGND

DGND

OUTC

OUTD

VDD

REFC

REFD

Figure 7. Suggested PCB Layout (Top View)