ST7LITE49K2 datasheet(177/245 Pages) STMICROELECTRONICS

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ST7LITE49K2

On-chip peripherals

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11.8

Analog comparator (CMP)

11.8.1

Introduction

The CMP block consists of two analog comparators (CMPA and CMPB) and an internal

voltage reference. The voltage reference can be external or internal, selectable under

program control. The comparator input pins COMPIN+ and COMPIN- are also connected to

the A/D converter (ADC).

11.8.2

Main features

On-chip analog comparators

The analog comparator compares the voltage at two input pins COMPIN+ and COMPIN-

which are connected to VP and VN at the comparator input. When the analog input at

COMPIN+ is less than the analog input at COMPIN-, the output of the comparator is 0.

When the analog input at COMPIN+ is greater than the analog input at COMPIN-, the output

of the comparator is 1.

The result of the comparison as 0 or 1 at COMPOUT is shown in Figure 82 on page 179.

Note:

To obtain a stable result, the comparator requires a stabilization time of 500 ns. Please refer

to Section 13: Electrical characteristics on page 192.

Table 58.

Comparison result

Programmable external/internal voltage reference

The voltage reference module can be configured to connect the comparator pin COMPIN- to

one of the following:

●

Fixed internal voltage bandgap

●

Programmable internal reference voltage

●

External voltage reference

Fixed Internal Voltage Bandgap

The voltage reference module can generate a fixed voltage reference of 1.2V on the VN

input. This is done by setting the VCBGR bit in the VREFCR register.

Programmable Internal Voltage Reference

The internal voltage reference module can provide 16 distinct internally generated

voltage levels from 3.2V to 0.2V each at a step of 0.2V on comparator pin VN. The

voltage is selected through the VR[3:0] bits in the VREFCR register.

External Reference Voltage

If a reference voltage other than that generated by the internal voltage reference

module is required, COMPIN- can be connected to an external voltage source. This

configuration can be selected by setting the VCEXT bit in the VREFCR register.

CINV

Input conditions

COMPOUT

VP > VN

VN > VP

VP > VN

VN > VP

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