EVAL-ADUC832QSZ Analog Devices Inc, EVAL-ADUC832QSZ Datasheet - Page 34

• Manufacturer Part Number: EVAL-ADUC832QSZ
• Description: KIT DEV FOR ADUC832 QUICK START
• Manufacturer: Analog Devices Inc
• Series: QuickStart™ Kitr
• Type: MCUr

Specifications of EVAL-ADUC832QSZ

• Contents: Evaluation Board, Cable, Power Supply, Software and Documentation
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With/related Products: ADuC832
• Lead Free Status / RoHS Status: Compliant, Lead free / RoHS Compliant
• Other names: EVAL-ADUC832QS; EVAL-ADUC832QS

ADuC832
To reduce the effects of the saturation of the output amplifier at
values close to ground and to give reduced offset and gain errors,
the internal buffer can be bypassed. This is done by setting the
DBUF bit in the CFG832 register. This allows a full rail-to-rail
output from the DAC, which should then be buffered externally
using a dual supply op amp in order to get a rail-to-rail output.
This external buffer should be located as near as physically possible
to the DAC output pin on the PCB. Note that the unbuffered
mode only works in the 0 to V
Figure 24. Source and Sink Current Capability
with V
4
3
1
0
0
REF
DAC LOADED WITH 0FFFH
DAC LOADED WITH 0000H
= V
DD
SOURCE/SINK CURRENT – mA
= 3 V
5
REF
range.
10
15
–34–
To drive significant loads with the DAC outputs, external buff-
ering may be required (even with the internal buffer enabled), as
illustrated in Figure 25. A list of recommended op amps is in
Table VI.
The DAC output buffer also features a high impedance disable
function. In the chip’s default power-on state, both DACs are
disabled, and their outputs are in a high impedance state (or
“three-state”) where they remain inactive until enabled in software.
This means that if a zero output is desired during power-up or
power-down transient conditions, then a pull-down resistor must
be added to each DAC output. Assuming this resistor is in place,
the DAC outputs will remain at ground potential whenever the
DAC is disabled.
Figure 25. Buffering the DAC Outputs
DAC0
DAC1
ADuC832
REV. 0