10

LTC1664

Voltage Outputs

Each of the four rail-to-rail output amplifiers contained in

these parts can source or sink up to 5mA. The outputs

swing to within a few millivolts of either supply rail when

unloaded and have an equivalent output resistance of 85

Ω

when driving a load to the rails. The output amplifiers are

stable driving capacitive loads up to 1000pF.

A small resistor placed in series with the output can be

used to achieve stability for any load capacitance. A 1

µF

load can be successfully driven by inserting a 20

Ω resis-

tor; a 2.2

µF load needs only a 10Ω resistor. In either case,

larger values of resistance, capacitance or both may be

safely substituted for the values given.

Rail-to-Rail Output Considerations

In any rail-to-rail voltage output DAC, the output is limited

to voltages within the supply range.

If the DAC offset is negative, the output for the lowest

codes limits at 0V as shown in Figure 3b.

Similarly, limiting can occur near full scale when the REF

(FSE) is positive, the output for the highest codes limits at

Offset and linearity are defined and tested over the region

of the DAC transfer function where no output limiting can

occur.

OPERATIO