Features: • CMOS Design for Very Low Power
• Output Drivers Directly Drive Both Digits and Segments of Large 8-Digit LED Displays
• Measures Frequencies from DC to 10MHz; Periods from 0.5s to 10s
• Stable High Frequency Oscillator uses either 1MHz or 10MHz Crystal
• Both Common Anode and Common Cathode Available
• Control Signals Available for External Systems Interfacing
• Multiplexed BCD OutputsApplication• Frequency Counter
• Period Counter
• Unit Counter
• Frequency Ratio Counter
• Time Interval CounterPinout
SpecificationsMaximum Supply Voltage (VDD - VSS). . . . . . . . . . . . . . . . . . . .6.5V
Maximum Digit Output Current . . . . . . . . . . . . . . . . .. . . . . . .400mA
Maximum Segment Output Current . . . . . . . . . . . . . . . . . . . . .60mA
Voltage On Any Input or
Output Terminal (Note 1) . . . . . . . . . . . . . . VDD +0.3V to VSS -0.3V
CAUTION: Stresses above those listed in "Absolute Maximum Ratings" may cause permanent damage to the device. This is a stress only rating and operation of the device at these or any other conditions above those indicated in the operational sections of this specification is not implied.
DescriptionThe ICM7226A is a fully integrated Universal Counter and LED display driver. It combines a high frequency oscillator, a decade timebase counter, an 8-decade data counter and latches, a 7-segment decoder, digit multiplexer and segment and digit drivers which can directly drive large LED displays. The counter inputs accept a maximum frequency of 10MHz in frequency and unit counter modes and 2MHz in the other modes. Both inputs are digital inputs. In many applications, amplification and level shifting will be required to obtain proper digital signals for these inputs.
The ICM7226A 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 0.1s 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 of the ICM7226A has been incorporated with frequency display in kHz and time in s. The display is multiplexed at a 500Hz rate with a 12.2% duty cycle for each digit. The ICM7226A is designed for common anode displays with typical peak segment currents of 25mA, and the ICM7226B is designed for common cathode displays with typical segment currents of 12mA. In the display off mode, both digit drivers and segment drivers are turned off, allowing the display to be used for other functions.
ICM7226A Data Sheet
