Microchip Technology SAM R30 Xplained Pro User Manual page 10

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The current measurement front-end is a high side shunt measurement with a pre-amplifier and a second
active filter stage with gain as shown in
measurement ranges, which are defined by two shunt resistors and the two parallel second stage active
filters with gain.
3.2.2 EDBG Interface
The XAM is connected to the EDBG with the following interfaces:
2
• I C: This is used to control and configure the XAM.
• SPI: Current measurement data is streamed to the EDBG via this interface. This is a unidirectional
channel from the XAM to the EDBG.
• SWD: The MCU in the XAM is programmed via SWD from the EDBG.
• Clock sync: Signal used to synchronize ADC measurements with the EDBG.
• Reference clock: Reference clock for the XAM.
3.2.3 Sample Rate
The raw sampling rate of the XAM is up to 250 kHz and with the default averaging configuration (average
of 16 samples), the actual output of the XAM is 16.67 ksps.
3.2.4 Measurement Ranges and Accuracy
The XAM has four measurement ranges. These are defined by two shunt resistors and two gain stages.
Table 3-2. XAM Measurement Ranges and Accuracy
Measurement
Range
Range 1
Range 2
Range 3
Range 4
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Analog-to-Digital Converter
Signal processing
Control/communication interface to the EDBG
Info: The XAM output sample rate is not an integer fraction of the raw sampling.
Hardware
Low current shunt and
high gain stage
Low current shunt and
low gain stage
High current shunt and
high gain stage
High current shunt and
low gain stage
Figure 3-1. The wide dynamic range is achieved by four
Resolution Accuracy
20 nA 1 LSB ±1% Accuracy will decrease below
150 nA 1 LSB ±1%
10 μA 1 LSB ±1%
100 μA 1 LSB ±1% Accuracy will decrease
User Guide
ATSAMR30-XPRO
Comments
1μA. Typical accuracy for
300nA is 1 LSB ± 10%.
above 100 mA. Typical
accuracy is 1 LSB ±5% at
400 mA. Maximum current is
400 mA.
DS50002612A-page 10