Analog Interfaces; Adc; Comparator; Low Power Comparator - Ublox NORA-B1 Series System Integration Manual

1.9 Analog interfaces

Eight of the 48 digital GPIOs can be multiplexed with the following analog functions:
•
1x 8-channel ADC
•
1x analog comparator*
•
1x low-power analog comparator*
*Only one of the comparators can be used simultaneously.
1.9.1

ADC

The Analog-to-Digital Converter (ADC) can sample up to 200 kHz using different inputs as sample
triggers. Both one-shot conversion and continuous sampling are supported. Table 2 shows the
sample speed in correlation to the maximum source impedance. It supports 8/10/12-bit resolution.
The ADC includes 14-bit resolution if oversampling is used. Any of the eight analog inputs or VDD can
be used either as single-ended inputs or differential pairs for measuring the voltage between them.
The ADC supports the full 0 V to VDD input range. If the sampled signal level is much lower than VDD,
it is possible to lower the input range of the ADC to encompass the desired signal and obtain a higher
effective resolution. Continuous sampling can be chosen for a configurable time interval, or actively
triggered for different internal or external events – with any CPU involvement.
ACQ [us]
3
5
10
15
20
40
Table 2: Acquisition versus source impedance
1.9.2

Comparator

The comparator compares voltages from any analog pin with different references, as shown in Table
3. It supports the full 0 V to VDD input range and can generate different software events to the rest
of the system. The comparator can operate in one of the following two modes:
•
Single-ended Mode: A single reference level or an upper and lower hysteresis selectable from a
64-level reference ladder with a range from 0 V to VREF, as described in Table 3.
•
Differential Mode: Two analog pin voltage levels are compared, optionally with a ~35 mV
hysteresis.
1.9.3

Low power comparator

The low-power comparator operates in the same way as the normal comparator, with reduced
functionality. It can be used during system OFF modes as a wake-up source.
UBX-20027617 - R02
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NORA-B1 series - System integration manual
Maximum source resistance [kΩ]
10
40
100
200
400
800
System description Page 12 of 58