MC9S08QG8 Datasheet, PDF (105/300 Pages) Freescale Semiconductor, Inc – 8-BIT HCS08 Central Processor Unit

Chapter 8
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 MC9S08QG8/4 block diagram with the ACMP 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 5.8.8, “System Power Management Status and Control 1
Register (SPMSC1)”. For value of bandgap voltage reference see Section A.5, “DC Characteristics”.
8.1.2 ACMP/TPM Configuration Information
The ACMP module can be configured to connect the output of the analog comparator to TPM input capture
channel 0 by setting ACIC in SOPT2. With ACIC set, the TPMCH0 pin is not available externally
regardless of the configuration of the TPM module.
MC9S08QG8 and MC9S08QG4 Data Sheet, Rev. 1.01
Freescale Semiconductor
105