XE8805 SEMTECH [Semtech Corporation], XE8805 Datasheet - Page 128

• Manufacturer Part Number: XE8805
• Description: Data Acquisition MCU
• Manufacturer: SEMTECH [Semtech Corporation]

The output range of the D/A is for code 0h0000 is VSS and for code 0hFFFF is (VBAT-VSS)(2
18.5 Amplifier
The amplifier can be used to implement the low pass filter and/or a 4-20mA loop. The amplifier is enabled using the
bit Enable(1)=1. The amplifier has two different modes selected by the bit BW: a low frequency mode (BW=0) that
allows driving a high capacitive load and a high frequency mode (BW=1).
The first mode is particularly adapted when a voltage output is used. The second mode is more adapted for a 4-
20mA loop since loads are small and higher bandwidth is required to reject current consumption changes in the
loop.
Table 18-8 shows the specification of the amplifier.
Note that the amplifier can not be used to generate signals that are larger than the supply voltages VBAT and VSS
since the amplifier inputs and outputs are clamped to these voltages. The amplifier inputs and outputs should stay
within the input and output ranges specified below.
© Semtech 2006
Table 18-7. Low pass cut-off frequency as a function of the selected MPW modulation and required resolution for a
NsOrder=2, f
Resolution
(bit)
RC
10
11
12
13
14
15
16
8
9
=2MHz, Fin=0, LpOrder=2
PWM modulation m
5638.4
3986.9
2819.2
1993.5
1409.6
996.7
704.8
498.4
352.4
4
3906.3
2762.1
1953.1
1381.1
976.6
690.5
488.3
345.3
244.1
5
second order noise shaper.
1953.1
1381.1
976.6
690.5
488.3
345.3
244.1
172.6
122.1
6
18-7
976.6
690.5
488.3
345.3
244.1
172.6
122.1
86.3
61.0
7
488.3
345.3
244.1
172.6
122.1
86.3
61.0
43.2
30.5
8
244.1
172.6
122.1
86.3
61.0
43.2
30.5
21.6
15.3
9
122.1
86.3
61.0
43.2
30.5
21.6
15.3
10.8
7.6
10
m
XE8805/05A
-1)/2
m
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.
61.0
43.2
30.5
21.6
15.3
10.8
7.6
5.4
3.8
11