XC68HC705JJ7 Motorola, XC68HC705JJ7 Datasheet - Page 108

• Manufacturer Part Number: XC68HC705JJ7
• Description: MICROCONTROLLER
• Manufacturer: Motorola

Analog Subsystem
8.2 Introduction
Advance Information
108
The analog subsystem of the MC68HC705JJ7/MC68HC705JP7 is
based on two on-chip voltage comparators and a selectable current
charge/discharge function as shown in
This configuration provides several features:
Voltages are resolved by measuring the time it takes an external
capacitor to charge up to the level of the unknown input voltage being
measured. The beginning of the A/D conversion time can be started by
several means:
•
•
•
•
•
Two independent voltage comparators with external access to
both inverting and non-inverting inputs
One voltage comparator can be connected as a single-slope
analog-to-digital (A/D) and the other connected as a
single-voltage comparator. The possible single-slope A/D
connection provides these features:
– A/D conversions can use V
– Channel access of up to four inputs via multiplexer control with
– Access to V
– Divide by 2 to extend input voltage range
– Each comparator can be inverted to calculate input offsets.
– Internal sample and hold capacitor
– Direct digital output of comparator 1 to the PB4 pin
Output compare from the 16-bit programmable timer
Timer overflow from the 16-bit programmable timer
Direct software control via a register bit
reference with software used to calculate ratiometric or
absolute results
independent multiplexer control allowing mixed input
connections
Analog Subsystem
DD
and V
SS
MC68HC705JJ7 • MC68HC705JP7 — REV 4
for calibration
DD
Figure
or an external voltage as a
8-1.
MOTOROLA