DAC0890CIJ National Semiconductor, DAC0890CIJ Datasheet - Page 8

• Manufacturer Part Number: DAC0890CIJ
• Description: Dual 8-bit mP-Compatible Digital-to-Analog Converter
• Manufacturer: National Semiconductor

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 (
These include two latch DAC combinations two high-speed
output amplifiers band-gap reference and control interface
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 R 2R 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
FIGURE 1 Simplified Internal Schematic (One DAC Shown)
g
5%)
8
externally set through the range select pin The two ranges
are 0V to 2 55V and 0V to 10 2V The internal resistors that
set the gain are matched to the unit resistor of the R 2R
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 1 2V 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
TL H 10592 – 7