M68HC16 Z SERIES
ELECTRICAL CHARACTERISTICS
USER’S MANUAL
A-67
Table A-38 ADC Conversion Characteristics (Operating)
(V
DD
and V
DDA
= 5.0 Vdc
±
5% for 20/25 MHz,
±
10% for 16 MHz, V
SS
= 0 Vdc, T
A
= T
L
to T
H
,
0.5 MHz
≤
f
ADCLK
≤
1.0 MHz, 2 clock input sample time)
Num
Parameter
Symbol
Min
Typical
Max
Unit
1
8-Bit Resolution
1
NOTES:
1. At V
RH
– V
RL
= 5.12 V, one 10-bit count = 5 mV and one 8-bit count = 20 mV.
1 Count
—
20
—
mV
2
8-Bit Differential Nonlinearity
DNL
–0.5
—
0.5
Counts
3
8-Bit Integral Nonlinearity
INL
–1
—
1
Counts
4
8-Bit Absolute Error
2
2. 8-bit absolute error of 1 count (20 mV) includes 1/2 count (10 mV) inherent quantization error and 1/2 count
(10 mV) circuit (differential, integral, and offset) error.
AE
–1
—
1
Counts
5
10-Bit Resolution
1
1 Count
—
5
—
mV
6
10-Bit Differential Nonlinearity
3
3. Conversion accuracy varies with f
ADCLK
rate. Reduced conversion accuracy occurs at maximum f
ADCLK
. As-
sumes that minimum sample time (2 ADC clocks) is selected.
DNL
–1
—
1
Counts
7
10-Bit Integral Nonlinearity
3
INL
–2.0
—
2.0
Counts
8
10-Bit Absolute Error
3,4
4. 10-bit absolute error of 2.5 counts (12.5 mV) includes 1/2 count (2.5 mV) inherent quantization error and 2
counts (10 mV) circuit (differential, integral, and offset) error.
AE
–2.5
—
2.5
Counts
9
Source Impedance at Input
5
5. Maximum source impedance is application-dependent. Error resulting from pin leakage depends on junction
leakage into the pin and on leakage due to charge-sharing with internal capacitance.
Error from junction leakage is a function of external source impedance and input leakage current. Expected
error in result value due to junction leakage is expressed in voltage (V
ERRJ
):
where I
OFF
is a function of operating temperature, as shown in
Charge-sharing leakage is a function of input source impedance, conversion rate, change in voltage between
successive conversions, and the size of the decoupling capacitor used. Error levels are best determined
empirically. In general, continuous conversion of the same channel may not be compatible with high source
impedance.
R
S
—
20
—
k
Ω
V
ERRJ
R
S
I
OFF
×
=
F
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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