XC68HC705JJ7 Motorola, XC68HC705JJ7 Datasheet - Page 122

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

Analog Subsystem
8.6 A/D Conversion Methods
Advance Information
122
The control bits in the ACR provide various options to charge or
discharge current through the PB0/AN0 pin to perform single-slope A/D
conversions using an external capacitor from the PB0/AN0 pin to V
shown in
given in
The top three bits of the ACR control the charging and discharging
current into or out of the PB0/AN0 pin. These three bits will have no
effect on the PB0/AN0 pin if the ISEN enable bit is cleared. Any clearing
of the ISEN bit will immediately disable both the charge current source
and the discharge device. Since all these bits and the ISEN bit are
VOLTAGE ON
CONNECTED
TO (+) INPUT
CAPACITOR
Table
Figure
Figure 8-7. Single-Slope A/D Conversion Method
OR REFERENCE
UNKNOWN
SIGNALS
8-3.
Analog Subsystem
8-7. The various A/D conversion triggering options are
TO MATCH UNKNOWN
CHARGE TIME
Charge Time =
MAXIMUM CHARGE TIME
RAMP
CAP
TO V
DD
–1.5 Vdc
MC68HC705JJ7 • MC68HC705JP7 — REV 4
PB0/AN0
PB4/AN4
PB3/AN3
PB2/AN2
PB1/AN1
C x V
I
X
MC68HC705JJ7
MC68HC705JP7
+ 5 V
UNKNOWN VOLTAGE ON (–) INPUT
V
V
DD
SS
V
DISCHARGE TIME
TO RESET CAPACITOR
DD
–1.5 Vdc
MOTOROLA
SS
as