DAC0890 datasheet(8/12 Pages) NSC

8 / 12 page

Functional Description

The DAC0890 is a monolithic dual 8-bit bipolar Digital-to-An-

alog converter comprising six major functional blocks de-

signed to operate on a single supply as low as 5V (g5%)

These include two latchDAC combinations two high-speed

output amplifiers band-gap reference and controlinterface

logic

The two internal 8-bit DACs use equal valued current sourc-

es Controlled by a corresponding bit in the input data each

current source’s output is switched into either an R2R lad-

der or AGND Each internal DAC has an 8-bit latch to store

a digital input See

Figure 1

The high-speed output amplifiers operate in the non-invert-

ing mode The R-2R’s output current is applied to the output

amplifier and converted to a voltage The amplifier’s gain is

externally set through the range select pin The two ranges

are 0V to 255V and 0V to 102V The internal resistors that

set the gain are matched to the unit resistor of the R2R

ladder This ensures that these resistors match over pro-

cess variations and temperature This greatly reduces gain

variations that would exist if external gain setting resistors

were used

An internal band-gap reference and its control amplifier gen-

erate a full scale reference voltage for the DACs It produc-

es a 12V output from a single supply

The DAC0890 provides a TTL and CMOS-compatible con-

trol interface and allows writing and latching digital values to

each of the internal DACs

TLH10592 – 7

FIGURE 1 Simplified Internal Schematic (One DAC Shown)

DAC0890 Scheda tecnica(PDF) 8 Page - National Semiconductor (TI)