HCS08 datasheet(111/316 Pages) NXP

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MC9S08SG8 MCU Series Data Sheet, Rev. 8

Freescale Semiconductor

111

Chapter 8



5-V Analog Comparator (S08ACMPV2)

8.1

Introduction

The analog comparator module (ACMP) provides a circuit for comparing two analog input voltages or for

comparing one analog input voltage to an internal reference voltage. The comparator circuit is designed to

operate across the full range of the supply voltage (rail-to-rail operation).

Figure 8-1 shows the MC9S08SG8 block diagram with the ACMP module highlighted.

8.1.1

ACMP Configuration Information

When using the bandgap reference voltage for input to ACMP+, the user must enable the bandgap buffer

by setting BGBE =1 in SPMSC1 see Section 5.7.6, “System Power Management Status and Control 1

8.1.2

ACMP in Stop3 Mode

S08ACMPV2 continues to operate in stop3 mode if enabled. If ACOPE is enabled, comparator output will

operate as in the normal operating mode and will control ACMPO pin. The MCU is brought out of stop

when a compare event occurs and ACIE is enabled; ACF flag sets accordingly.

8.1.3

ACMP/TPM Configuration Information

The ACMP module can be configured to connect the output of the analog comparator to TPM1 input

capture channel 0 by setting ACIC in SOPT2. With ACIC set, the TPM1CH0 pin is not available externally

regardless of the configuration of the TPM1 module for channel 0.

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