AC Considerations

Digital Feedthrough

High-speed serial data at any of the digital input or output

pins may couple through the DAC package and cause

internal stray capacitance to appear at the DAC output as

noise, even though

CS is held high (see Typical Operating

Characteristics). This digital feedthrough is tested by hold-

ing CS high, transmitting 555 hex from DIN to DOUT.

Analog Feedthrough

Because of internal stray capacitance, higher frequency

analog input signals may couple to the output as shown in

the Analog Feedthrough vs. Frequency graph in the

Typical Operating Characteristics. It is tested by holding

CS high, setting the DAC code to all 0s, and sweeping

REFIN.

+5V, Low-Power, Voltage-Output,

Serial 12-Bit DACs

______________________________________________________________________________________

13

MAX531

INVERTED

R-2R DAC

DIN DOUT

SIGNAL

IN

2.048V

REFIN

2R

2R

CS CLR

BIPOFF

RFB

VOUT

REFOUT

Figure 9. MAX531 Connected as Four-Quadrant Multiplier. The

1

2

3

4

12 3

45678

0

POSITIVE OFFSET

NEGATIVE OFFSET

DAC CODE (LSB)

Figure 10. Single-Supply Offset

8

10

9

14

13

12

11

5

6

2

3

4

7

1

8

7

6

5

1

2

3

4

0.1

µF

(b) MAX538/MAX539 BYPASSING

(a) MAX531 BYPASSING

ANALOG GROUND PLANE

0.1

µF

0.1

µF

Figure 11. Power-Supply Bypassing