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QADC64E Electrical Characteristics
10
Absolute error includes 1/2 count (~2.5 mV) 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 µF to 0.1 µF capacitor between analog input and analog ground, typical source isolation
impedance of 10 KΩ.
11
Input signals with large slew rates or high frequency noise components cannot be converted accurately. These signals
may affect the conversion accuracy of other channels.
12
Below disruptive current conditions, the channel being stressed has conversion values of 0x3FF for analog inputs
greater than V
and 0x000 for values less than V
RH
presence of the sample amplifier. Other channels are not affected by non-disruptive conditions.
13
Exceeding limit may cause conversion error on stressed channels and on unstressed channels. Transitions within the
limit do not affect device reliability or cause permanent damage.
14
Input must be current limited to the value specified. To determine the value of the required current-limiting
resistor, calculate resistance values using V
V, then use the larger of the calculated values. The diode drop voltage is a function of current and varies approximately
0.4 to 0.8 V over temperature
15
This parameter is periodically sampled rather 100% tested.
16
Derate linearly to 0.3 mA if VDDH - VDDA = 1 V. This specification is preliminary and may change after further
characterization.
17
Condition applies to two adjacent pins.
18
Condition applies to all analog channels.
19
Current Coupling Ratio, K, is defined as the ratio of the output current, I
injection current, I
, when both adjacent pins are overstressed with the specified injection current. K = I
INJ
input voltage error on the channel under test is calculated as Verr = I
20
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 leakage is expressed in voltage (V
temperature. Charge-sharing leakage is a function of input source impedance, conversion rate, change in voltage
between successive conversions, and the size of the filtering capacitor used. Error levels are best determined
empirically. In general, continuous conversion of the same channel may not be compatible with high source
impedance
For a maximum sampling error of the input voltage <= 1LSB, then the external filter capacitor, C
21
The value of C
in the new design may be reduced.
SAMP
K-56
PRELIMINARY—SUBJECT TO CHANGE WITHOUT NOTICE
. This assumes that V
RL
= (the lower of V
POSCLAMP
): V
ERRJ
ERRJ
MPC533 Reference Manual
<= V
and V
RH
DDA
RL
or V
) + 0.3 V and V
DDA
DDH
, measured on the pin under test to the
OUT
* K * R
.
INJ
S
= R
* I
where I
is a function of operating
S
OFF
OFF
>= V
due to the
SSA
= – 0.3
NEGCLAMP
/ I
The
OUT
INJ
>= 1024 * C
.
f
SAMP
MOTOROLA
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