DAC

AS5181

AS5181

Rev. 0.4 01/10

Micross Components reserves the right to change products or specifications without notice.

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DETAILED DESCRIPTION

The AS5181 is a 10-bit digital-to-analog converters

(DACs) capable of operating with clock speeds up to 40MHz.

Each converter consists of separate input and DAC registers,

followed by a current source array capable of generating up

to 1.5mA full-scale output current (Figure 1). An integrated

1.2V voltage reference and control amplifier determine the

data

converters’ full-scale output currents/voltages. Careful

reference design ensures close gain matching and excellent

drift characteristics.

Internal Reference and Control Amplifier

The AS5181 provide an integrated 50ppm/°C, 1.2V,

low-noise bandgap reference that can be disabled and

overridden by an external reference voltage. REFO serves

either as an external reference input or an integrated reference

output. If REN\ is connected to DGND, the internal reference

is selected and provides a +1.2V output. Due to its limited

10μA output drive capability, REFO must be buffered with an

external amplifier, if heavier loading is required.

The AS5181 also employ a control amplifier designed to

regulate simultaneously the full-scale output current (I

both outputs of the devices. The output current is calculated as

follows:

I

.

I

REF

where I

and I

resistor that determines the amplifier’s output current on the

AS5181 (Figure 2). This current is mirrored into the current

source array, where it is equally distributed between matched

current segments and summed to valid output current readings

for the DACs.

FIGURE 1: Functional Diagram