
Preliminary Electrical Specifications
QADC Electrical Characteristics
MMC2114 MMC2113 MMC2112 — Rev. 1.0
Advance Information
MOTOROLA
Preliminary Electrical Specifications
623
Pre
limin
ary
7. Below disruptive current conditions, the channel being stressed has conversion values of $3FF for analog inputs greater
than VRH and $000 for values less than VRL. This assumes that VRH < VDDA and VRL > VSSA due to the presence of the
sample amplifier. Other channels are not affected by non-disruptive conditions.
8. 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.
9. Input must be current limited to the value specified. To determine the value of the required current-limiting resister, calculate
resistance values using VPOSCLAMP = VDDA + 0.5V and VNEGCLAMP = – 0.3 V, then use the larger of the calculated values.
10. Condition applies to two adjacent pins.
11. Current coupling ratio, K, is defined as the ratio of the output current, IOut, measured on the pin under test to the injection
current, Iinj, when both adjacent pins are overstressed with the specified injection current. K = IOut/ Iinj The input voltage
error on the channel under test is calculated as Verr = Iinj * K * RS.
12. Performance expected with production silicon.
13. 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 this expression,
expected error in result value due to junction leakage is expressed in voltage (Verrj):
Verrj = RS * IOFF
where IOFF is a function of operating 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.
14. For a maximum sampling error of the input voltage <= 1 LSB, then the external filter capacitor, Cf >= 1024 * Csamp. The
value of Csamp in the new design may be reduced.