ICM7362/7342/7322

Rev. A8

ICmic reserves the right to change the specifications without prior notice

.

7

IC MICROSYSTEMS

APPLICATIONS INFORMATION

Power

Supply

Bypassing

and

Layout

Considerations

As in any precision circuit, careful consideration has to be

given to layout of the supply and ground. The return path

from the GND to the supply ground should be short with

low impedance. Using a ground plane would be ideal. The

supply should have some bypassing on it. A 10 µF

tantalum capacitor in parallel with a 0.1 µF ceramic with a

low ESR can be used. Ideally these would be placed as

close as possible to the device. Avoid crossing digital and

analog signals, specially the reference, or running them

close to each other.

Output Swing Limitations

however, offset and gain error limit this ability. Figure 5

illustrates how a negative offset error will affect the output.

The output will limit close to ground since this is single

supply part, resulting in a dead-band area. As a larger

input is loaded into the DAC the output will eventually rise

above ground. This is why the linearity is specified for a

starting code greater than zero.

Figure 6 illustrates how a gain error or positive offset error

error or positive offset will cause the output to be limited to

the positive supply voltage resulting in a dead-band of

codes close to full-scale. This can be avoided by using a

DEADBAND

NEGATIVE

OFFSET

Figure 5: Effect of Negative Offset

DEADBAND

POSITIVE

OFFSET

OFFSET AND

GAIN ERROR

Figure 6: Effect of Gain Error and Positive Offset