DESCRIPTION
Both inputs are digital inputs. In many applications, amplification and level shifting will be required to obtain proper digital signals for these inputs. The ICM7226 can function as a frequency counter, period counter, frequency ratio (fA/fB) counter, time interval counter or as a totalizing counter. The devices require either a 10MHz or 1MHz quartz crystal timebase, or if desired an external timebase can also be used. For period and time interval, the 10MHz timebase gives a 0.1µs resolution. In period average and time interval average, the resolution can be in the nanosecond range. In the frequency mode, the user can select accumulation times of 0.01s, 0.1s, 1s and 10s. With a 10s accumulation time, the frequency can be displayed to a resolution of 0.1Hz. There is 0.2s between measurements in all ranges. Control signals are provided to enable gating and storing of prescaler data. Leading zero blanking has been incorporated with frequency display in kHz and time in µs. The display is multiplexed at a 500Hz rate with a 12.2% duty cycle for each digit.
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