XE88LC05 Datasheet, PDF (33/39 Pages) List of Unclassifed Manufacturers – 16 + 10 bit Data Acquisition Ultra Low-Power Microcontroller

Data Acquisition Microcontroller
XE88LC05
9 Digital to analog converters (DACs)
The XE88LC05 includes 2 DACs: a signal DAC and a bias DAC.
9.1 Bias DAC
The bias DAC is a low resolution (8 bits) DAC with a buffer perfectly adapted to sensor bridge
bias. It can be used to bias a bridge in current (figure) or in voltage by choosing the pins con-
nection.
Figure 9.1:
General block diagram of the bias DAC
The bias DAC itself is built of a series of resistors which two extremes are available outside
the chip, so that one can connect it to an external source when the output of the DAC should
not be ratiometric to the power supply.
9.2 The DAC of bias DAC
Table 9.1:
Note:
The DAC convertor is a resistive divider connected between pads DAB_R_m and DAB_R_p.
sym
description
min
typ
max
unit
wda
number of input bits
8
bits
tstep
step response
100
ms
range
DAC output range DAB_R_m
DAB_R_p
INL
integral non-linearity
1
LSB
DNL differential non-linearity
1
LSB
Comments
1
2
3
3
DAC performances
1) Time to reach the final value within 5%. Node not charged.
2) In most cases DAB_R_m will be connected to VSS and DAB_R_p to VDD.
3) For DAB_R_m connected to VSS and DAB_R_p to VDD, VDD > 2.4 V.
9.3 The amplifier of bias DAC
The amplifier can be used in several configurations as for biasing a bridge in voltage or current.
Application examples are given in application note AN8000.03.
Table 9.2:
33
sym
gain
GBW
description
gain at DC
gain bandwidth product
Amplifier performances
min typ max
60
100
unit Comments
dB
1
Hz
1
D0109-40