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All data sheets are subject to change without notice

©2003 Maxwell Technologies.

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12-Bit Serial Daisy-Chain D/A Converter

8143

07.23.03 REV 3

Application Tips

In most applications, linearity depends on the potential of I

to each other. In most applications, the DAC is connected to an external Op Amp with its noninverting input tied to

ground (see Figures 16 and 17). The amplifier selected should have a low input bias current and low drift over temper-

ature. The amplifier’s input offset voltage should be nulled to less than ±200 µ V (less than 10% of 1 LSB).

The operational amplifier’s noninverting input should have a minimum resistance connection to ground; the usual bias

current compensation resistor should not be used. This resistor can cause a variable offset voltage appearing as a

varying output error. All grounded pins should tie to a single common ground point, avoiding ground loops. The V

DD

power supply should have a low noise level with no transients greater than 17V.

It is recommended that the digital input be taken to ground or V

accumulation of static charge if the PC card is disconnected from the system.

Peak supply current flows as the digital input pass through the transition region (see Figure 4). The supply current

decreases as the input voltage approaches the supply rails (V

very near the supply rails will minimize supply current.

Interfacing to the MC6800

As shown in Figure, the 8143 may be interfaced to the 6800 by successively executing memory WRITE instruction

while manipulating the data between WRITEs, so that each WRITE presents the next bit.

In this example, the most significant bits are found in memory locations 0000 and 0001. The four MSBs are found in

the lower half of 0000, the eight LSBs in 0001. The data is taken from the DB

The serial data loading is triggered by STB

W, and f2. A WRITE to another address location transfers data from input register to DAC register.