Datasheet

Electrical Specifications
Analog-to-Digital Converter Characteristics
MC68HC908QY4•MC68HC908QT4•MC68HC908QY2•MC68HC908QT2•MC68HC908QY1•MC68HC908QT1
MOTOROLA Electrical Specifications 221
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18.13 Analog-to-Digital Converter Characteristics
Characteristic Symbol Min Max Unit Comments
Supply voltage
V
DDAD
2.7
(V
DD
min)
5.5
(V
DD
max)
V —
Input voltages
V
ADIN
V
SS
V
DD
V —
Resolution
B
AD
88Bits —
Absolute accuracy
A
AD
± 0.5 ± 1.5 LSB Includes quantization
ADC internal clock
f
ADIC
0.5 1.048 MHz
t
ADIC
= 1/f
ADIC
,
tested only at 1 MHz
Conversion range
R
AD
V
SS
V
DD
V —
Power-up time
t
ADPU
16
t
ADIC
cycles t
ADIC
= 1/f
ADIC
Conversion time
t
ADC
16 17
t
ADIC
cycles t
ADIC
= 1/f
ADIC
Sample time
(1)
t
ADS
5 —
t
ADIC
cycles t
ADIC
= 1/f
ADIC
Zero input reading
(2)
Z
ADI
00 01 Hex
V
IN
= V
SS
Full-scale reading
(3)
F
ADI
FE FF Hex
V
IN
= V
DD
Input capacitance
C
ADI
— 8pF Not tested
Input leakage
(3)
—— ± 1 µA —
1. Source impedances greater than 10 kΩ adversely affect internal RC charging time during input sampling.
2. Zero-input/full-scale reading requires sufficient decoupling measures for accurate conversions.
3. The external system error caused by input leakage current is approximately equal to the product of R source and input
current.