MC68HCP11 Datasheet, PDF (42/45 Pages) Motorola, Inc – 8-Bit Microcontroller

E CLOCK
12 E CYCLES
SAMPLE ANALOG INPUT
MSB
4
CYCLES
BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 LSB 2
2
2
2
2
2
2
2 CYC
CYC CYC CYC CYC CYC CYC CYC END
SUCCESSIVE APPROXIMATION SEQUENCE
CONVERT FIRST
CONVERT SECOND
CONVERT THIRD
CONVERT FOURTH
CHANNEL, UPDATE
CHANNEL, UPDATE
CHANNEL, UPDATE
CHANNEL, UPDATE
0
ADR1
32
ADR2
64
ADR3
96
ADR4
128 — E CYCLES
Figure 14 A/D Conversion Sequence
A/D CONVERSION TIM
ANALOG
INPUT
PIN
< 2 pF
+ ~20V
– ~0.7V
INPUT
PROTECTION
DEVICE
+ ~12V
– ~0.7V
DUMMY N-CHANNEL
OUTPUT DEVICE
DIFFUSION/POLY
COUPLER
≤ 4 KΩ
400 nA
JUNCTION
LEAKAGE
*
~ 20 pF
DAC
CAPACITANCE
V_RL
* THIS ANALOG SWITCH IS CLOSED ONLY DURING THE 12-CYCLE SAMPLE TIME.
ANALOG INPUT PIN
Figure 15 Electrical Model of an Analog Input Pin (Sample Mode)
ADCTL — A/D Control/Status
Bit 7
6
5
4
3
2
1
CCF
0
SCAN MULT
CD
CC
CB
RESET: U
0
U
U
U
U
U
CCF — Conversions Complete Flag
Set after an A/D conversion cycle. Cleared when ADCTL is written.
SCAN — Continuous Scan Control
0 = Do four conversions and stop
1 = Convert four channels in selected group continuously
MULT — Multiple Channel/Single Channel Control
0 = Convert single channel selected
1 = Convert four channels in selected group
$1030
Bit 0
CA
U
MOTOROLA
42
MC68HC11A8
MC68HC11A8TS/D