
MC68F375
ELECTRICAL CHARACTERISTICS
MOTOROLA
REFERENCE MANUAL
Rev. 25 June 03
E-27
Table E-13 QADC64 Conversion Characteristics (Operating)
(VDDL= 3.3 Vdc ± ± 10%, VDDH, VDDA = 5.0 Vdc ± 10%, VSS and VSSA = 0 Vdc, TA within operating
temperature range0.5 MHz
≤ FQCLK ≤ 2.1 MHz, 2 clock input sample time)
Num
Parameter
Symbol
Min
Typ
Max
Unit
1
Resolution
1
NOTES:
1. At VRH - VRL = 5.12 V, one count = 5 mV.
1 Count
—
5
—
mV
3
Integral nonlinearity
INL
—
±2.0
Counts
4
Absolute error2
,3,4
FQCLK = 0.987MHz
5
PQA
PQB
FQCLK = 2.098 MHz
6
PQA
PQB
2. This parameter is periodically sampled rather that 100% tested.
3. Absolute error includes 1/2 count (2.5mV) of inherent quantization error and circuit (differential, integral, and offset) error.
Specification assumes that adequate low-pass filtering is present on analog input pins — capacitive filter with 0.01
F to 0.1
F capacitor between analog input and analog ground, typical source isolation impedance of 20 K.
4. Assumes fsys = 16.78 MHz.
5. Assumes clock prescaler values of:
QACR0: PSH =%01100, PSA =%0, PSL = %011
CCW: BYP =%0
6. Assumes clock prescaler values of:
QACR0: PSH =%00101, PSA =%0, PSL = %001
CCW: BYP =%0
AE
—
±2.5
±4.0
Counts
5
Source impedance at input
7
7. 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. In the following expression, expected error in result value due to junction leak-
age is expressed in voltage (Verrj):
Verrj = RS X IOF
where IOFF is a function of operating temperature. (See
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, contin-
uous conversion of the same channel may not be compatible with high source impedance.
RS
—
100
—
K
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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