Datasheet

Electrical Specifications
MC68HC908GP32 Data Sheet, Rev. 10
246 Freescale Semiconductor
19.12 ADC Characteristics
Characteristic
(1)
1. V
DD
= 5.0 Vdc ± 10%, V
SS
= 0 Vdc, V
DDAD
= 5.0 Vdc ± 10%, V
SSAD
= 0 Vdc, V
REFH
= 5.0 Vdc ± 10%, V
REFL
= 0
Symbol Min Max Unit Comments
Supply voltage
V
DDAD
2.7
(V
DD
min)
5.5
(V
DD
max)
V
V
DDAD
should be tied to
the same potential as V
DD
via separate traces.
Input voltages
V
ADIN
0
V
DDAD
V
V
ADIN
≤ V
REFH
Resolution
B
AD
8 8 Bits
Absolute accuracy
(V
REFL
= 0 V,
V
REFH
= V
DDAD
= 5 V ± 10%)
A
AD
— ± 1 LSB Includes quantization
ADC internal clock
f
ADIC
0.5 1.048 MHz
t
AIC
= 1/f
ADIC
, tested only
at 1 MHz
Conversion range
R
AD
V
REFL
V
REFH
V
V
REFH
= V
DDAD
V
REFL
= V
SSAD
Power-up time
t
ADPU
16
t
AIC
cycles
Conversion time
t
ADC
16 17
t
AIC
cycles
Sample time
(2)
2. Source impedances greater than 10 kΩ adversely affect internal RC charging time during input sampling.
t
ADS
5—
t
AIC
cycles
Zero input reading
(3)
3. Zero-input/full-scale reading requires sufficient decoupling measures for accurate conversions.
Z
ADI
00 01 Hex
V
IN
= V
REFL
Full-scale reading
(3)
F
ADI
FE FF Hex
V
IN
= V
REFH
Input capacitance
C
ADI
— (20) 8 pF Not tested
Input leakage
(4)
Port B
4. The external system error caused by input leakage current is approximately equal to the product of R source and input
current.
—— ± 1 µA
Notes: