xe88lc05 ETC-unknow, xe88lc05 Datasheet - Page 19

• Manufacturer Part Number: xe88lc05
• Description: 16 10 Bit Data Acquisition Ultra Low-power Microcontroller
• Manufacturer: ETC-unknow

8 ZoomingADC
8.1 PGA 1
Table 8.1:
Note:
19
Figure 8.1:
GD_preci
symbol
GD_TC
Zin1p
GD1
Zin1
VN1
fs
Temperature dependency of gain settings
The fully differential acquisition chain is formed of a programmable gain (0.5 - 1000) and offset
amplifier and a programmable speed and resolution ADC (example: 12 bits at 4 kHz, 16 bits
at 1 kHz). It can handle inputs with very low full scale signal and large offsets.
Input selection is made from 1 of 4 differential pair or 1 of seven single signal versus AC_A(0).
Reference is chosen from the 2 differential references.
The gain of each amplifier is programmed individually. Each amplifier is powered on and off on
command to minimize the total current requirement. All blocks can be set to low frequency op-
eration and lower their current requirement by a factor 2 or 4.
The ADC can run continuously (end of conversion signalled by an interrupt, event or by pooling
the ready bit), or it can be started on request.
PGA1 Performances
1) Measured with block connected to inputs through AMUX block. Normalized input sampling
frequency for input impedance is 512 kHz. This figure has to be multiplied by 2 for fs = 256 kHz
and 4 for fs = 128 kHz.
2) Input referred rms noise is 205 uV per input sample with gain = 1, 20.5 uV with gain = 10.
This corresponds to 28.6 nV/sqrt(Hz) for fs = 512 kHz and gain = 10.
Acquisition channel block diagram
Input impedance for gain 1
Precision on gain settings
input sampling frequency
Input referred noise
PGA1 Signal Gain
Input impedance
description
Data Acquisition Microcontroller
1500
min
150
-5
-5
1
28.6
typ
max
512
10
+5
+5
sqrt(Hz)
ppm/°C
unit
kHz
nV/
kΩ
kΩ
%
-
XE88LC05
GD1 = 1 or 10
Comments
1
1
2
D0109-40