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23.10 ADC Characteristics
Characteristic
Supply voltage
Input voltages
Resolution
Absolute accuracy
(V
= 0 V,
REFL
= 5 V ± 10%)
V
= V
REFH
DDAD
ADC internal clock
Conversion range
Power-up time
Conversion time
(2)
Sample time
(3)
Zero input reading
(3)
Full-scale reading
Input capacitance
(4)
Input leakage
Port B
Notes:
= 5.0 Vdc ± 10%, V
1. V
DD
2. Source impedances greater than 10 kΩ adversely affect internal RC charging time during input sampling.
3. Zero-input/full-scale reading requires sufficient decoupling measures for accurate conversions.
4. The external system error caused by input leakage current is approximately equal to the product of R source and input
current.
MC68HC908AB32
Rev. 1.0
—
MOTOROLA
(1)
Symbol
V
DDAD
V
ADIN
V
REFH
B
AD
A
AD
f
ADIC
R
AD
t
ADPU
t
ADC
t
ADS
Z
ADI
F
ADI
C
ADI
—
= 5.0 Vdc ± 10%, V
= V
DDA
DDAREF
Electrical Specifications
Min
Max
4.5
5.5
(V
min)
(V
max)
DD
DD
V
0
DDAREF
1.5
V
DDAREF
8
8
± 1/2
± 1
0.5
1.048
V
V
REFL
REFH
16
16
17
5
—
00
01
FE
FF
—
(20) 8
± 1
—
= 5.0 Vdc ± 10%, V
REFH
Electrical Specifications
ADC Characteristics
Unit
Comments
V
should be tied
DDAREF
to the same potential as
V
V
via separate
DD
traces.
V
V
ADIN
Bits
LSB
Includes quantization
t
= 1/f
AIC
ADIC
MHz
only at 1 MHz
V
V
REFL
t
cycles
AIC
t
cycles
AIC
t
cycles
AIC
V
Hex
IN
V
Hex
IN
pF
Not tested
µA
= 0 Vdc, V
= V
SS
REFL
≤ V
REFH
, tested
= V
SSA
= V
REFL
= V
REFH
= 0 Vdc
SSA
Technical Data
379
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