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Comparator_A+ Operation

21.2 Comparator_A+ Operation

The Comparator_A+ module is configured with user software. The setup and operation of Comparator_A+

is discussed in the following sections.

21.2.1 Comparator

The comparator compares the analog voltages at the + and - input terminals. If the + terminal is more

positive than the - terminal, the comparator output CAOUT is high. The comparator can be switched on or

off using control bit CAON. The comparator should be switched off when not in use to reduce current

consumption. When the comparator is switched off, the CAOUT is always low.

21.2.2 Input Analog Switches

The analog input switches connect or disconnect the two comparator input terminals to associated port

pins using the P2CAx bits. Both comparator terminal inputs can be controlled individually. The P2CAx bits

allow:

• Application of an external signal to the + and - terminals of the comparator

• Routing of an internal reference voltage to an associated output port pin

Internally, the input switch is constructed as a T-switch to suppress distortion in the signal path.

NOTE: Comparator Input Connection

When the comparator is on, the input terminals should be connected to a signal, power, or

ground. Otherwise, floating levels may cause unexpected interrupts and increased current

consumption.

NOTE: MSP430G2210: Comparator channels 0, 1, 3, and 4 are implemented but not available at

the device pins. To avoid floating inputs, these comparator inputs should not be enabled.

The CAEX bit controls the input multiplexer, exchanging which input signals are connected to the

comparator’s + and - terminals. Additionally, when the comparator terminals are exchanged, the output

signal from the comparator is inverted. This allows the user to determine or compensate for the

comparator input offset voltage.

525

SLAU144J–December 2004–Revised July 2013 Comparator_A+

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