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CHAPTER 13 OPERATIONAL AMPLIFIER
User’s Manual U19780EJ2V0UD
361
13.4 Operation of Operational Amplifier
The operational amplifiers amplify the potential difference of the analog voltages input from two pins (the AMPn-
pin and the AMPn+ pin) and output the amplified voltage from the AMPnOUT pin.The amplification factor can be
changed by inserting external components such as resistors.
The amplified voltage can be used as an analog input of the A/D converter, because the AMPnOUT pin is
alternatively used with analog input pin of the A/D converter.
The procedure for starting operation in single amplifier mode is described below.
<1> Use the port mode register x (PMx) register to set the pins (AMPn-, AMPn+, AMPnOUT) to be used in single
amplifier mode as input mode.
<2> Use the A/D port configuration register (ADPC) to set the pins (AMPn-, AMPn+, AMPnOUT) to be used in
single amplifier mode to analog input.
<3> Specify the operating mode by using the OAIM1 and OAIM0 bits of the operational amplifier control register
(OAC).
<4> Enable operation by setting the OAENn bit of the OAC register to 1.
<5> Program the software to wait for the turn-on time required for the operational amplifier to stabilize.
Caution To use as an input of the A/D converter a output of operational amplifier, enable operation in
operational
amplifier before selecting an analog input channel by using the ADS register.
Remark
n = 0 to 2, x = 2, 8