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Basic Information
Functional Description
Question 1
What OPA functions can be implemented by OPA0 and OPA1?
Answer
- 1. The OPA1 and OPA1 can implement functions such as Inverting Amplifier, Non-inverting Amplifier, Voltage Follower, Non-cascade Amplifier, Cascade Amplifier, Comparator, Schmitt Trigger, Integrators and Differentiators etc.
- OPA1 can also implement a PGA (Programmable Gain Amplifier) function.
Question 2
How do I set the PA0, PA1 and PC6 pins to be V+ and V- OPA1 inputs and OPA1 output pins?
Answer
Setting the A1NC, A1PC and A1XC bits to 1 in the COPA3C register will route the OPA1 output to an MCU pin and at the same time disable its original I/O function and pull-high resistor.
COPA3C ( comparator, OPA control register 3)
Bit # |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0 |
OPA3C |
A1XC |
A1PC |
A1NC |
A0XC |
A0PC |
A0NC |
CPC |
CNC |
POR |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
Question 3
How do I implement a calibration for OPA0 and OPA1?
Answer
Before using the OPA, a V+ and V- offset voltage calibration should be first implemented.
The calibration steps are as follows:
- Set AnOFM=1 to setup the offset cancellation mode (S3 is closed.)
- et AnRS to select which input pin is to be used as the reference voltage (S1 or S2 is closed.)
- Adjust AnOF[3:0] until the output status changes.
- Set AnOFM=0 to enter the normal OPA mode.
Question 4
What are the functions of A0PS[2:0] and A1PS[2:0] in the COPA0C and COPA1C registers?
Answer
To select the V+ input source of OPA0 and OPA1 - refer to the following table:
|
A0PS[2:0]
MA0P selection |
A1PS[2:0]
MA1P selection |
000 |
A0P pin |
A1P pin |
001 |
0.7VDD |
0.7VDD |
010 |
0.5VDD |
0.5VDD |
011 |
0.1VDD |
0.1VDD |
100 |
VSS |
VSS |
101 |
- |
A0X |
110 |
- |
- |
111 |
- |
- |
Question 5
What is the function of A1G[2:0] in the COPA1C register?
Answer
A1G is used to select the PGA amplifying ratio of OPA1 as the reference as shown in the following table. For the circuit diagram, refer to the 39th page of the datasheet.
A1G[2:0] |
R2/R1 |
000 |
6.25 |
001 |
12.5 |
010 |
18.75 |
011 |
25 |
100 |
31.25 |
101 |
37.5 |
110 |
43.75 |
111 |
50 |
Question 6
What is the function of A1NS[2;0] in the COPA1C?
Answer
It is used to select the V- input source for OPA1. Refer to the table below.
|
A1NS[1:0]
MA1N selection |
00 |
A1N pin |
01 |
A0X |
10 |
VSS |
11 |
- |
Question 7
How do I setup the register if using OPA0 as an inverting amplifier as shown in figure 1?
 Figure 1 Inverting Amplifier Circuit Diagram Answer
The equivalent circuit of the HT48R066G is as shown in figure 2.
 Figure 2 Inverting Amplifier Equivalent Circuit
The relevant register configurations are as follows:
Question 8
How do I setup the relevant register configurations when using OPA0 and OPA1 as a non-inverting cascade amplifier as shown in figure 1?
 Figure 1 Nov-inverting Cascade Amplifier Circuit Answer
The equivalent circuit of the HT48R066G is shown in figure 2 below.
 Figure Non-inverting Cascade Amplifier Equivalent Circuit The relevant register configurations are as follows:
Question 9
How do I setup the relevant register configurations when using OPA0 as an integrator as shown in figure 1?
Figure 1 Integrator Circuit
Answer
Figure 2 Integrator Equivalent Circuit
The relevant register configurations are as follows:
Question 10
How do I set the PC0, PC1 and PC7 pins to have V+ and V- and output comparator functions.?
Answer
Set the CPC, CNC and CXC in the COPA2C and COPA3C registers as 1 to route the comparator output pin to the external MCU and to disable its original I/O function and pull-high resistor.
COPA2C ( comparator, OPA control register 2)
Bit # |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0 |
OPA2C |
S24 |
S23 |
S22 |
S21 |
S13 |
S12 |
S11 |
CXC |
POR |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
COPA3C ( comparator, OPA control register 3)
Bit # |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0 |
OPA2C |
A1XC |
A1PC |
A1NC |
A0XC |
A0PC |
A0NC |
CPC |
CNC |
POR |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
Question 11
What is the function of CPS[2:0] in the COPA0C register?
Answer
It is used to select the V+ input source of the comparator. See the table below for details.
|
CPS[2:0]
MCP selection |
000 |
CP pin |
001 |
0.7VDD |
010 |
0.5VDD |
011 |
0.1VDD |
100 |
VSS |
101 |
- |
110 |
- |
111 |
- |
Question 12
What is the function of CNS[1:0] in the COPA0C register?
Answer
It is used to select the V- input source of the comparator. See the table below for details.
|
CNS[1:0]
MCN selection |
00 |
CN pin |
01 |
A0X |
10 |
VSS |
11 |
- |
Question 13
What is the function of CPCS[1:0] in the CMP0C register?
Answer
These two bits in the CPCS register are used to select the operating current of the comparator. The larger the current is, the faster the comparator speed will be. When the operating current of the comparator is selected as 1uA, the comparator will still function in the Halt Mode.
Question 14
What is the function of the A0VRC, A1VRC and CPVRC bits in the CMP1C register?
Answer
When these three bits are set to 1, it means that the V+ reference voltage is to be routed to corresponding I/O pins (A0P, A1P, and CX pins.) By adding an RC filter to the I/O pin, circuit, generated noise can be reduced.
Application Description
Points to Note
Question 1
When using the HIRC, if the I/O pin which is shared with OSC1 is to be used as an AC zero crossing detector, will there be any influence on the HIRC oscillation frequency? If yes, which MCUs will be affected and how can this problem be resolved?? Answer
If the HIRC is used and if the I/O pin which is shared with OSC1 is used as an AC zero crossing detector pin, the HIRC oscillation frequency will be influenced.
The affected MCUs are:
All MCUs whose I/O pin is pin-shared with OSC1 (including the enhanced OTP type MCU and Flash type MCU etc.)
How to resolve this issue:
1. Avoid using the I/O pin that is shared with OSC1 as AC zero crossing detector pin.
2. If the problem can still not be resolved, add external circuitry to ensure that the voltage applied on the OSC1 pin remains withing the range of VDD and VSS.
Others
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