TOBY-L4 series - System Integration Manual
UBX-16024839 - R04
Design-in
Page 113 of 143
2.9
ADC interfaces
The ADC pins are not supported by the "50" product version.
2.9.1.1
Guidelines for ADC circuit design
TOBY-L4 series modules include Analog to Digital Converter inputs (
ADC1
,
ADC2
), which can be handled by
means of the dedicated uCPU API.
The ADC pins can be connected to external circuits for general purpose voltage measurements.
The voltage value at the ADC input must be within the range reported in the
TOBY-L4 series
Data Sheet
If an external voltage divider is implemented to increase the measurement voltage range, check the input
resistance of the ADC inputs reported in the
TOBY-L4 series
Data Sheet
[1]: if the Thévenin's equivalent of the
external circuit has a significant value as compared to the input resistance of the ADC inputs, this should be
taken into account and corrected to properly associate the ADC response to the voltage source value,
implementing an appropriate ADC calibration procedure.
The ESD sensitivity rating of ADC interface pins is 1 kV (Human Body Model according to JESD22-A114).
A higher protection level could be required if the lines are externally accessible and it can be achieved by
mounting an ESD protection (e.g. EPCOS CA05P4S14THSG varistor array) close to the accessible points.
If the ADC pins are not used, they can be left unconnected on the application board.
2.9.1.2
Guidelines for ADC layout design
The Analog to Digital Converters (
ADC1
,
ADC2
) are high impedance analog inputs. The conversion accuracy will
be degraded if noise is injected. Low-pass filter may be used to improve noise rejection; typically L-C tuned for RF
rejection gives better results.
