Auxadc & Lpc - Realtek RTL8762C Hardware Instructions

8 AUXADC & LPC
RTL8762C integrates a 12bits SAR ADC module, which is time-divisionally switched to different
channels by Analog Mux for general analog-to-digital conversion. The ADC pin can be
multiplexed as normal IO.
VABT
ADC of RTL8762C can work in single-ended input mode and differential input mode. The VBAT
channel can directly detect the voltage of VBAT pin.
RTK ADC lib could use internal K value to correctly obtain the actual voltage value. ADC
measured voltage must not exceed VBAT or VDDIO level. ADC pin does not have an
anti-backflow function. If the ADC pin is powered on during shutdown, it may be reversed to
VBAT and the IC may start unexpectedly.
The RTL8762C has a built-in low-power comparator that can wakeup the chip when the voltage is
greater or less than the setting value. It can be switched to either ADC Channel or VBAT Channel.
There are two modes for RTL8762C AUXADC:
Bypass mode (range: 0~0.9V):
ADC maximum input voltage cannot exceed 0.9V in this mode, and AUXADC full-scale voltage
is about 0.9V. If the input voltage exceeds the ADC range, IC will be damaged.
For example, when measuring lithium batteries, it is recommended to use the following circuit,
where R1=220K, R2=1000K, C1=0.1uF. Because the ADC impedance is large, the first sample
P2_0
P2_1
Analog
mux
P2_6
P2_7
RTL8762C Evaluation Board User Manual
12bits
SARADC
ADC must be used with RTK ADC lib. Only
14