Operations Of Operational Amplifier - Fujitsu MB95F430 Series Application Note

Operational Amplifier Version 1.0
Chapter 3 Operations of Operational Amplifier

3 Operations of Operational Amplifier

Operations of Operational Amplifier
The operational amplifier can be activated by setting the PD bit in the OPCR register using the The operational amplifier can be activated by setting the PD bit in the OPCR register using the
software. It can operate in closed loop mode or open loop mode, depending on the settings of software. It can operate in closed loop mode or open loop mode, depending on the settings of
the RES2, RES1 and RES0 bits in the OPCR register. the RES2, RES1 and RES0 bits in the OPCR register.
■ Activating Operational Amplifier by Software ■ Activating Operational Amplifier by Software
The settings shown in Figure 24.5-1 are required for activating the operational amplifier using The settings shown in Figure 24.5-1 are required for activating the operational amplifier using
the software. the software.
Figure 3 Settings for Activating Operational Amplifier
After the bits in the OPCR register are set as shown above, the operational amplifier will not After the bits in the OPCR register are set as shown above, the operational amplifier will not
start operating until it stabilizes. start operating until it stabilizes.
■ Operations of OPAMP in Closed Loop Mode ■ Operations of OPAMP in Closed Loop Mode
Before being activated, the operational amplifier can be set to operate in closed loop mode in Before being activated, the operational amplifier can be set to operate in closed loop mode in
advance by setting RES[2:0] in the OPCR register to "000B", "001B", "010B", "011B", "100B" or advance by setting RES[2:0] in the OPCR register to "000B", "001B", "010B", "011B", "100B" or
"101B". "101B".
Six different closed loop gains are available to be used in closed loop mode. Select a desired Six different closed loop gains are available to be used in closed loop mode. Select a desired
closed loop gain by setting RES[2:0] in OPCR to the value corresponding to that gain. closed loop gain by setting RES[2:0] in OPCR to the value corresponding to that gain.
■ Operations of OPAMP in Open Loop Mode
Before being activated, the operational amplifier can be set to operate in open loop mode in
advance by setting RES [2:0] in the OPCR register to "110B".
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