MM74C925 * MM74C926 4-Digit Counters with …

1 2004 Fairchild Semiconductor 1987 Revised January 2004MM74C925 MM74C926 4-Digit Counters with multiplexed 7-Segment Output DriversMM74C925 MM74C926 4-Digit Counters with multiplexed 7-Segment Output DriversGeneral DescriptionThe MM74C925 and MM74C926 CMOS Counters consistof a 4-Digit counter , an internal output latch, NPN outputsourcing drivers for a 7-segment display, and an internalmultiplexing circuitry with four multiplexing outputs. Themultiplexing circuit has its own free-running oscillator, andrequires no external clock. The Counters advance on nega-tive edge of clock.

2 A HIGH signal on the Reset input willreset the counter to zero, and reset the carry-out LOW. ALOW signal on the Latch Enable input will latch the numberin the Counters into the internal output latches. A HIGH sig-nal on Display Select input will select the number in thecounter to be displayed; a LOW level signal on the DisplaySelect will select the number in the output latch to be MM74C925 is a 4-decade counter and has LatchEnable, Clock and Reset MM74C926 is like the MM74C925 except that it has adisplay select and a carry-out used for cascading carry-out signal goes HIGH at 6000, goes back LOWat Wide supply voltage range: 3V to 6V Guaranteed noise margin: 1V High noise immunity: VCC (typ.)

3 High segment sourcing current: 40 mA @ VCC , VCC = 5V Internal multiplexing circuitryDesign ConsiderationsSegment resistors are desirable to minimize power dissipa-tion and chip heating. The DS75492 serves as a good digitdriver when it is desired to drive bright displays. Whenusing this driver with a 5V supply at room temperature, thedisplay can be driven without segment resistors to full illu-mination. The user must use caution in this mode however,to prevent overheating of the device by using too high asupply voltage or by operating at high ambient input protection circuitry consists of a series resistor,and a diode to ground.

4 Thus input signals exceeding VCCwill not be clamped. This input signal should not be allowedto exceed 15V. Ordering Code: Connection DiagramsPin Assignments for DIPTo p Vie wMM74C925 Top ViewMM74C926 Order NumberPackage NumberPackage DescriptionMM74C925NN16E16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, " WideMM74C926NN18B18-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, " MM74C926 Functional DescriptionReset Asynchronous, active highDisplay Select High, displays output of counter Low, displays output of latchLatch Enable High, flow through conditionLow, latch conditionClock Negative edge sensitiveSegment Output Current sourcing with 40 mA @VOUT=VCC (typ.)

5 Also, sink capability = 2 LTTL loa dsDigit Output Current sourcing with 1 mA @VOUT = Also, sink capability = 2 LTTL loadsCarry-Out 2 LTTL loads. See carry-out MM74C926 Absolute Maximum Ratings(Note 1)Note 1: Absolute Maximum Ratings are those values beyond which thesafety of the device cannot be guaranteed. Except for Operating Tempera-ture Range they are not meant to imply that the devices should be oper-ated at these limits. The Electrical Characteristics table provides conditionsfor actual device Electrical CharacteristicsMin/Max limits apply at 40 C tj + 85 C, unless otherwise notedNote 2.

6 JA measured in free-air with device soldered into printed circuit at Any Output PinGND to VCC + at Any Input PinGND to +15 VOperating TemperatureRange (TA) 40 C to +85 CStorage Temperature Range 65 C to +150 CPower Dissipation (PD)Refer to PD(MAX) vs TA GraphOperating VCC Range3V to Temperature(Soldering, 10 seconds)260 CSymbolParameterConditionsMinTypMaxUnits CMOS TO CMOSVIN(1)Logical 1 Input VoltageVCC = (0)Logical 0 Input VoltageVCC = (1)Logical 1 Output VoltageVCC = 5V, IO = 10 A(Carry-Out and digit Output Only) (0)Logical 0 Output VoltageVCC = 5V, IO = 10 (1)Logical 1 Input CurrentVCC = 5V, VIN = AIIN(0)Logical 0 Input CurrentVCC = 5V, VIN = 0V 1 AICCS upply CurrentVCC = 5V, Outputs Open Circuit,201000 AVIN = 0V or 5 VCMOS/LPTTL INTERFACEVIN(1)Logical 1 Input VoltageVCC = 2 VVIN(0)Logical 0 Input VoltageVCC = (1)Logical 1 Output VoltageVCC = ,(Carry-Out and digit Output Only)IO = 360 (0)Logical 0 Output VoltageVCC = , IO = 360 DRIVEVOUTO utput Voltage IOUT = 65 mA, VCC = 5V, Tj = 25 CVCC 2 VCC (Segment Sourcing Output)

7 IOUT = 40 mA, VCC = 5 VTj = 100 CVCC = 150 CVCC 2 VCC Resistance IOUT = 65 mA, VCC = 5V, Tj = 25 C2032 (Segment Sourcing Output)IOUT = 40 mA, VCC = 5 VTj = 100 C3040 Tj = 150 C3550 Output Resistance (Segment Output) CTemperature CoefficientISOURCEO utput Source CurrentVCC = , VOUT = , Tj = 150 C 1 2mA( digit Output)ISOURCEO utput Source CurrentVCC = 5V, VOUT = 0V, Tj = 25 C (Carry-Out)ISINKO utput Sink CurrentVCC = 5V, VOUT = VCC, Tj = 25 (All Outputs) jAThermal ResistanceMM74C925: (Note 2)75100 C/WMM74C9267090 MM74C926AC Electrical Characteristics (Note 3)TA = 25 C, CL = 50 pF, unless otherwise notedNote 3: AC Parameters are guaranteed by DC correlated 4: Capacitance is guaranteed by periodic Performance CharacteristicsTypical Segment Currentvs Output VoltageNote.

8 VD = Voltage across digit driverMaximum Power Dissipationvs Ambient TemperatureTypical Average SegmentCurrent vs SegmentResistor Value SymbolParameterConditionsMinTypMaxUnitsf MAXM aximum Clock FrequencyVCC = 5V,Tj = 25 C24 MHzSquare Wave Clock Tj = 100 , tfMaximum Clock Rise or Fall TimeVCC = 5V15 stWRReset Pulse WidthVCC = 5 VTj = 25 C250100nsTj = 100 C320125nstWLEL atch Enable Pulse WidthVCC = 5 VTj = 25 C250100nsTj = 100 C320125nstSET(CK, LE)Clock to Latch Enable Set-Up TimeVCC = 5 VTj = 25 C25001250nsTj = 100 C32001600nstLRLatch Enable to Reset Wait TimeVCC = 5 VTj = 25 C0 100nsTj = 100 C0 100nstSET(R, LE)Reset to Latch Enable Set-Up TimeVCC = 5 VTj = 25 C320160nsTj = 100 C400200nsfMUXM ultiplexing Output FrequencyVCC = 5V1000 HzCINI nput CapacitanceAny Input (Note 4) MM74C926 Typical Performance Characteristics (Continued)

9 Segment Output DriverInput Protection Common Cathode LED DisplaySegment MM74C926 Switching Time Waveforms Input WaveformsMultiplexing Output WaveformsT = 1/fMUXC arry-Out MM74C926 Physical Dimensions inches (millimeters) unless otherwise noted16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, " WidePackage Number MM74C926 4-Digit Counters with multiplexed 7-Segment Output DriversPhysical Dimensions inches (millimeters) unless otherwise noted (Continued)18-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, " WidePackage Number N18 BFairchild does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied andFairchild reserves the right at any time without notice to change said circuitry and SUPPORT POLICYFAIRCHILD S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORTDEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF FAIRCHILDSEMICONDUCTOR CORPORATION.

10 As used herein:1. Life support devices or systems are devices or systemswhich, (a) are intended for surgical implant into thebody, or (b) support or sustain life, and (c) whose failureto perform when properly used in accordance withinstructions for use provided in the labeling, can be rea-sonably expected to result in a significant injury to A critical component in any component of a life supportdevice or system whose failure to perform can be rea-sonably expected to cause the failure of the life supportdevice or system, or to affect its safety or