mc68hc11k4vfu4 Freescale Semiconductor, Inc, mc68hc11k4vfu4 Datasheet - Page 60

• Manufacturer Part Number: mc68hc11k4vfu4
• Description: 8-bit Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

9 Analog-to-Digital Converter
60
MOTOROLA
The analog-to-digital (A/D) converter system uses an all-capacitive charge-redistribution technique to
convert analog signals to digital values. The A/D converter system contained in M68HC11 K-series
MCUs is an 8-channel,8-bit, multiplexed-input, successive-approximation converter. It does not require
external sample and hold circuits.
The clock source for the A/D converter’s charge pump, like the clock source for the EEPROM charge
pump, is selected with the CSEL bit in the OPTION register. When the E clock is slower than 1 MHz,
the CSEL bit must be set to ensure that the successive approximation sequence for the A/D converter
will be completed before any charge loss occurs. In the case of the EEPROM, it is the efficiency of the
charge pump that is affected.
The A/D converter can operate in single or multiple conversion modes. Multiple conversions are per-
formed in sequences of four. Sequences can be performed on a single channel or an a group of chan-
nels.
Dedicated lines V
PE0/
PE1/
PE2/
PE3/
PE4/
PE5/
PE6/
PE7/
AN0
AN1
AN2
AN3
AN4
AN5
AN6
AN7
ANALOG
ADDR 1 A/D RESULT 1
MUX
RH
and V
RESULT
RL
Figure 14 A/D Converter Block Diagram
provide the reference supply voltage inputs.
ADDR 2 A/D RESULT 2
SUCCESSIVE APPROXIMATION
REGISTER AND CONTROL
WITH SAMPLE AND HOLD
8-BIT CAPACITIVE DAC
RESULT REGISTER INTERFACE
ADDR 3 A/D RESULT 3
ADCTL A/D CONTROL
ADDR 4 A/D RESULT 4
M68HC11 K Series
MC68HC11KTS/D
V RH
V RL
DATA BUS
INTERNAL