GD32W51x User Manual
910
Table 26-1. Pin and analog switch state in a charge-transfer sequence
Step
Nam e
ASW_0
ASW_1
Pin0
Pin1
1
Discharge
Close
Close
Input Floating
Pull Dow n
2
Buffer Time1
Open
Open
Input Floating
Input Floating
3
Charge
Open
Open
Output High
Input Floating
4
Extend Charge
Open
Open
Output High
Input Floating
5
Buffer Time2
Open
Open
Input Floating
Input Floating
6
Charge Transfer
Close
Close
Input Floating
Input Floating
7
Buffer Time3
Open
Open
Input Floating
Input Floating
8
Compare
Open
Open
Input Floating
Input Floating
1.
Discharge
Both C
x
and C
s
are discharged by closing ASW_0 and ASW_1 and configuring PIN1 to pull
down. This step is the initial operation for a correct charge transfer sequence and is performed
by software before starting a charge transfer sequence. Discharging time in this step s hould
be guaranteed to ensure that the voltage of C
x
and C
s
are discharged to zero.
2.
Buffer Time1
Buffer time with ASW_0 and ASW_1 open, PIN0 is configured to input floating.
3.
Charge
Channel pin PIN0 is configured to output high, in order to charge C
x
. ASW_0 and ASW_1
remain open during this step. The charging time should be configured (see Register Section
for detail) to ensure that the voltage of C
x
is charged to V
DD
.
4.
Extend Charge
This is an optional step in a charge-transfer sequence and the behavior of all pins and analog
switches in this step is the same as Step 3. The only difference between this and step 3 is the
duration time, which is configurable in TSI registers. The duration of this step changes in each
loop of a charge-transfer sequence, spreading the spectrum.
5.
Buffer Time2
Buffer time with ASW_0 and ASW_1 open, PIN0 is configured to input floating.