MC68HC11E0CFNE3 Datasheet, PDF (58/242 Pages) Freescale Semiconductor, Inc – M68HC11E Family

Analog-to-Digital (A/D) Converter
PE0
AN0
PE1
AN1
PE2
AN2
PE3
AN3
ANALOG
MUX
PE4
AN4
PE5
AN5
PE6
AN6
PE7
AN7
8-BIT CAPACITIVE DAC
WITH SAMPLE AND HOLD
SUCCESSIVE APPROXIMATION
REGISTER AND CONTROL
RESULT
ADCTL A/D CONTROL
RESULT REGISTER INTERFACE
V_RH
V_Rl
INTERNAL
DATA BUS
ADR1 A/D RESULT 1
ADR2 A/D RESULT 2
ADR3 A/D RESULT 3
ADR4 A/D RESULT 4
Figure 3-1. A/D Converter Block Diagram
ANALOG
INPUT
PIN
< 2 pF
+ ~20 V
– ~0.7 V
INPUT
PROTECTION
DEVICE
+ ~12V
– ~0.7V
DUMMY N-CHANNEL
OUTPUT DEVICE
DIFFUSION/POLY
COUPLER
ð 4 kΩ
400 nA
JUNCTION
LEAKAGE
*
~ 20 pF
DAC
CAPACITANCE
V_RL
* THIS ANALOG SWITCH IS CLOSED ONLY DURING THE 12-CYCLE SAMPLE TIME.
Figure 3-2. Electrical Model of an A/D Input Pin (Sample Mode)
M68HC11E Family Data Sheet, Rev. 5.1
58
Freescale Semiconductor