Installation Instructions

SIM5216A _HD_V1.02 Hardware Design
SIM5216A _HD_V1.02 26.08.2010
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3.14 ADC interface
SIM5216A has an analog-to-digital converter (ADC) that is available for digitizing analog signals
such as battery voltage, temperature and so on, it is on PIN 30, namely HKADC0, This HKADC0
is 8 bit successive-approximation circuit, and performance specification is shown in the following
table:
Table 23：ADC Characteristics
Specification
Min Typ Max Unit Comments/Conditions
Resolution 8 Bits
differential
nonlinearity
-4 +4 LSB
Integral nonlinearity -8 +8 LSB
Gain Error -2.5 +2.5 %
Offset Error -4 +40 LSB
. Analog Vdd = ADC reference
300 kHz - 1.2 MHz sample rate
Input Range GND 2.2 V
3dB input
bandwidth
2500 Source resistance = 50 Ω
Input serial
resistance
2 kΩ Sample and hold switch resistance
Input capacitance 53 pF
Power-down to
wakeup
9.6 19.2
μs
One can introduce a signal into this ADC pin directly and use AT+CADC to get the raw data value
between 0 and 255 which can then be transformed to any other type such as voltage, temperature
etc.
Note: if the signal is voltage then the voltage value must no more than 2.2V.
Show an application sample:
You can use it as a temperature ADC channel, too. The reference design of a temperature ADC
circuit is as the figure below. R1 is 0Ω, R2 is 47 kΩ and R3 is 68 kΩ for reference. ,,the return
value is supposed to 158 by AT+CADC, and you can use some arithmetic to translate “158” to a
specifically temperature.