ADUC832 Analog Devices, ADUC832 Datasheet - Page 53

• Manufacturer Part Number: ADUC832
• Description: Precision Analog Microcontroller: 1.3MIPS 8052 MCU + 62kB Flash + 8-Ch 12-Bit ADC + Dual 12-Bit DAC
• Manufacturer: Analog Devices

Specifications of ADUC832

• Mcu Core: 8052
• Mcu Speed (mips): 1.3
• Sram (bytes): 2304Bytes
• Gpio Pins: 34
• Adc # Channels: 8
• Other: PWM

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 to obtain 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 V to V
Figure 54. Source and Sink Current Capability with V
4
3
1
0
0
DAC LOADED WITH 0FFFH
DAC LOADED WITH 0000H
SOURCE/SINK CURRENT (mA)
5
REF
range.
10
REF
= AV
DD
15
= 3 V
Rev. A | Page 53 of 92
To drive significant loads with the DAC outputs, external
buffering may be required (even with the internal buffer
enabled), as illustrated in Figure 55. A list of recommended op
amps is shown in Table 20.
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 remain at ground
potential whenever the DAC is disabled.
Figure 55. Buffering the DAC Outputs
DAC0
DAC1
ADuC832
ADuC832