Typical Applications (Continued)
Sampling an AC Input Signal
Note 11: Oversample whenever possible [keep fs > 2f(−60)] to eliminate input frequency folding (aliasing) and to allow for the skirt response of the filter.
Note 12: Consider the amplitude errors which are introduced within the passband of the filter.
70% Power Savings by Clock Gating
(Complete shutdown takes ≈ 30 seconds.)
Power Savings by A/D and VREF Shutdown
*Use ADC0801, 02, 03 or 05 for lowest power consumption.
Note: Logic inputs can be driven to VCC with A/D supply at zero volts.
Buffer prevents data bus from overdriving output of A/D when in shutdown mode.
1.0 UNDERSTANDING A/D ERROR SPECS
A perfect A/D transfer characteristic (staircase waveform) is
shown in Figure 1. The horizontal scale is analog input volt-
age and the particular points labeled are in steps of 1 LSB
(19.53 mV with 2.5V tied to the VREF/2 pin). The digital out-
put codes that correspond to these inputs are shown as D−1,
D, and D+1. For the perfect A/D, not only will center-value
(A−1, A, A+1, . . . . ) analog inputs produce the correct out-
put digital codes, but also each riser (the transitions between
adjacent output codes) will be located ±1⁄2 LSB away from
each center-value. As shown, the risers are ideal and have
no width. Correct digital output codes will be provided for a
range of analog input voltages that extend ±1⁄2 LSB from the
ideal center-values. Each tread (the range of analog input
voltage that provides the same digital output code) is there-
fore 1 LSB wide.