Datasheet

Electrical Specifications
Technical Data MC68HC908GR8 — Rev 4.0
378 Electrical Specifications MOTOROLA
23.12 ADC Characteristics
Characteristic
(1)
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
88Bits
Absolute accuracy
(V
REFL
= 0 V, V
DDAD
= V
REFH
=
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)
t
ADS
5 —
t
AIC
cycles
Zero input reading
(3)
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
——
± 1 µA
Notes:
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
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.
Frees
cale Semiconductor,
I
Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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