MM74C925, MM74C926, MM74C927, MM74C928 4-Digit Counters with Multiplexed 7-Segment Output Drivers General Description These CMOS counters consist of a 4-digit counter, an internal output latch, NPN output sourcing drivers for a 7-segment display, and an internal multiplexing circuitry with four multiplexing outputs. The multiplexing circuit has its own free-running oscillator, and requires no external clock. The counters advance on negative edge of clock. A high signal on the Reset input will reset the counter to zero, and reset the carry-out low. A low signal on the Latch Enable input will latch the number in the counters into the internal output latches. A high signal on Display Select input will select the number in the counter to be displayed; a low level signal on the Display Select will select the number in the output latch to be displayed. The MM74C925 is a 4-decade counter and has Latch Enable, Clock and Reset inputs. The MM74C926 is like the MM74C925 except that it has a display select and a carry-out used for cascading counters. The carry-out signal goes high at 6000, goes back low at 0000. The MM74C927 is like the MM74C926 except the second most significant digit divides by 6 rather than 10. Thus, if the clock input frequency is 10 Hz, the display would read tenths of seconds and minutes (i.e., 9:59.9). The MM74C928 is like the MM74C926 except the most significant digit divides by 2 rather than 10 and the carry-out is an overflow indicator which is high at 2000, and it goes back low only when the counter is reset. Thus, this is a 3(/2-digit counter. Features Y Y Y Y Wide supply voltage range Guaranteed noise margin High noise immunity High segment sourcing current @ Y 3V to 6V 1V 0.45 VCC (typ.) 40 mA VCC b 1.6V, VCC e 5V Internal multiplexing circuitry Design Considerations Segment resistors are desirable to minimize power dissipation and chip heating. The DS75492 serves as a good digit driver when it is desired to drive bright displays. When using this driver with a 5V supply at room temperature, the display can be driven without segment resistors to full illumination. The user must use caution in this mode however, to prevent overheating of the device by using too high a supply voltage or by operating at high ambient temperatures. The input protection circuitry consists of a series resistor, and a diode to ground. Thus input signals exceeding VCC will not be clamped. This input signal should not be allowed to exceed 15V. Connection Diagrams Dual-In-Line Package Dual-In-Line Package TL/F/5919 – 1 TL/F/5919 – 2 Top View Top View Order Number MM74C925 Order Number MM74C926, MM74C927 or MM74C928 C1995 National Semiconductor Corporation TL/F/5919 RRD-B30M105/Printed in U. S. A. MM74C925, MM74C926, MM74C927, MM74C928 4-Digit Counters with Multiplexed 7-Segment Output Drivers March 1988 Absolute Maximum Ratings (Note 1) Storage Temperature Range If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/Distributors for availability and specifications. Voltage at Any Output Pin Voltage at Any Input Pin Operating Temperature Range (TA) Power Dissipation (PD) b 65§ C to a 150§ C Refer to PD(MAX) vs TA Graph Operating VCC Range GND b 0.3V to VCC a 0.3V GND b 0.3V to a 15V 3V to 6V 6.5V VCC Lead Temperature (Soldering, 10 seconds) b 40§ C to a 85§ C 260§ C DC Electrical Characteristics Min/Max limits apply at b40§ C s Tj s a 85§ C, unless otherwise noted Symbol Parameter Conditions Min Typ Max Units CMOS TO CMOS VIN(1) Logical ‘‘1’’ Input Voltage VIN(0) Logical ‘‘0’’ Input Voltage VCC e 5V VOUT(1) Logical ‘‘1’’ Output Voltage (Carry-Out and Digit Output Only) VCC e 5V, IO e b10 mA Logical ‘‘0’’ Output Voltage VCC e 5V, IO e 10 mA IIN(1) Logical ‘‘1’’ Input Current VCC e 5V, VIN e 15V IIN(0) Logical ‘‘0’’ Input Current VCC e 5V, VIN e 0V ICC Supply Current VCC e 5V, Outputs Open Circuit, VIN e 0V or 5V VOUT(0) VCC e 5V 3.5 V 1.5 4.5 V 0.5 0.005 b1 V 1 b 0.005 20 V mA mA 1000 mA CMOS/LPTTL INTERFACE VIN(1) Logical ‘‘1’’ Input Voltage VCC e 4.75V VIN(0) Logical ‘‘0’’ Input Voltage VCC e 4.75V VOUT(1) Logical ‘‘1’’ Output Voltage (Carry-Out and Digit Output Only) VCC e 4.75V, IO e b360 mA Logical ‘‘0’’ Output Voltage VCC e 4.75V, IO e 360 mA VOUT(0) VCC b 2 V 0.8 2.4 V V 0.4 V OUTPUT DRIVE VOUT Output Voltage (Segment Sourcing Output) IOUT e b65 mA, VCC e 5V, Tj e 25§ C Tj e 100§ C IOUT e b40 mA, VCC e 5V Tj e 150§ C RON Output Resistance (Segment Sourcing Output) IOUT e b65 mA, VCC e 5V, Tj e 25§ C Tj e 100§ C IOUT e b40 mA, VCC e 5V Tj e 150§ C Ð VCC b 2 VCC b 1.6 VCC b 2 20 30 35 0.6 Ð Output Resistance (Segment Output) Temperature Coefficient ISOURCE Output Source Current (Digit Output) VCC e 4.75V, VOUT e 1.75V, Tj e 150§ C ISOURCE Output Source Current (Carry-Out) VCC e 5V, VOUT e 0V, Tj e 25§ C ISINK Output Sink Current (All Outputs) VCC e 5V, VOUT e VCC, Tj e 25§ C ijA Thermal Resistance MM74C925 (Note 4) MM74C926, MM74C927, MM74C928 VCC b 1.3 VCC b 1.2 VCC b 1.4 V V V 32 40 50 0.8 X X X %/§ C b1 b2 mA b 1.75 b 3.3 mA 1.75 3.6 mA 75 70 100 90 § C/W § C/W Note 1: ‘‘Absolute Maximum Ratings’’ are those values beyond which the safety of the device cannot be guaranteed. Except for ‘‘Operating Temperature Range’’ they are not meant to imply that the devices should be operated at these limits. The table of ‘‘Electrical Characteristics’’ provides conditions for actual device operation. Note 2: Capacitance is guaranteed by periodic testing. Note 3: CPD determines the no load AC power consumption of any CMOS device. For complete explanation see 54C/74C Family Characteristics application note, AN-90. Note 4: ijA measured in free-air with device soldered into printed circuit board. 2 AC Electrical Characteristics* TA e 25§ C, CL e 50 pF, unless otherwise noted Symbol Parameter Conditions Tj e 25§ C Tj e 100§ C Min Typ 2 1.5 4 3 Max Units fMAX Maximum Clock Frequency VCC e 5V, Square Wave Clock MHz MHz tr, tf Maximum Clock Rise or Fall Time VCC e 5V tWR Reset Pulse Width VCC e 5V Tj e 25§ C Tj e 100§ C 250 320 100 125 ns ns tWLE Latch Enable Pulse Width VCC e 5V Tj e 25§ C Tj e 100§ C 250 320 100 125 ns ns tSET(CK, LE) Clock to Latch Enable Set-Up Time VCC e 5V Tj e 25§ C Tj e 100§ C 2500 3200 1250 1600 ns ns tLR Latch Enable to Reset Wait Time VCC e 5V Tj e 25§ C Tj e 100§ C 0 0 b 100 b 100 ns ns tSET(R, LE) Reset to Latch Enable Set-Up Time VCC e 5V Tj e 25§ C Tj e 100§ C 320 400 160 200 ns ns fMUX Multiplexing Output Frequency VCC e 5V 1000 Hz CIN Input Capacitance Any Input (Note 2) 5 pF 15 ms *AC Parameters are guaranteed by DC correlated testing. Functional Description Reset Display Select Latch Enable Clock Segment Output Ð Current sourcing with 40 mA @ VOUT e VCC b 1.6V (typ.) Also, sink capability e 2 LTTL loads Digit Output Ð Current sourcing with 1 mA @ VOUT e 1.75V. Also, sink capability e 2 LTTL loads Carry-Out Ð 2 LTTL loads. See carry-out waveforms. Ð Asynchronous, active high Ð High, displays output of counter Low, displays output of latch Ð High, flow through condition Low, latch condition Ð Negative edge sensitive Typical Performance Characteristics Typical Segment Current vs Output Voltage Maximum Power Dissipation vs Ambient Temperature Typical Average Segment Current vs Segment Resistor Value TL/F/5919 – 3 Note: VD e Voltage across digit driver 3 Logic and Block Diagrams MM74C925 TL/F/5919 – 4 MM74C926 TL/F/5919 – 5 MM74C927 TL/F/5919 – 6 MM74C928 TL/F/5919 – 7 4 Logic and Block Diagrams (Continued) Segment Output Driver Input Protection TL/F/5919 – 9 TL/F/5919 – 8 Common Cathode LED Display Segment Identification TL/F/5919 – 10 TL/F/5919 – 11 Switching Time Waveforms Input Waveforms Multiplexing Output Waveforms TL/F/5919 – 12 TL/F/5919 – 13 T e 1/fMUX 5 Switching Time Waveforms (Continued) Carry-Out Waveforms TL/F/5919 – 14 Physical Dimensions inches (millimeters) Ceramic Dual-In-Line Package (J) Order Number MM74C925J NS Package Number J16A 6 Physical Dimensions inches (millimeters) (Continued) Ceramic Dual-In-Line Package (J) Order Number MM74C926J, MM74C927J or MM74C928J NS Package Number J18A Molded Dual-In-Line Package (N) Order Number MM74C925N NS Package Number N16E 7 MM74C925, MM74C926, MM74C927, MM74C928 4-Digit Counters with Multiplexed 7-Segment Output Drivers Physical Dimensions inches (millimeters) (Continued) Molded Dual-In-Line Package (N) Order Number MM74C926N, MM74C927N or MM74C928N NS Package Number N18A LIFE SUPPORT POLICY NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein: 1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, and whose failure to perform, when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury to the user. National Semiconductor Corporation 1111 West Bardin Road Arlington, TX 76017 Tel: 1(800) 272-9959 Fax: 1(800) 737-7018 2. A critical component is any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness. National Semiconductor Europe Fax: (a49) 0-180-530 85 86 Email: cnjwge @ tevm2.nsc.com Deutsch Tel: (a49) 0-180-530 85 85 English Tel: (a49) 0-180-532 78 32 Fran3ais Tel: (a49) 0-180-532 93 58 Italiano Tel: (a49) 0-180-534 16 80 National Semiconductor Hong Kong Ltd. 13th Floor, Straight Block, Ocean Centre, 5 Canton Rd. Tsimshatsui, Kowloon Hong Kong Tel: (852) 2737-1600 Fax: (852) 2736-9960 National Semiconductor Japan Ltd. Tel: 81-043-299-2309 Fax: 81-043-299-2408 National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications.