Revised January 1999 MM74C925 • MM74C926 • MM74C927 • MM74C928 4-Digit Counters with Multiplexed 7-Segment Output Drivers General Description The MM74C925, MM74C926, MM74C927 and MM74C928 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 3½-digit counter. Features ■ Wide supply voltage range: ■ Guaranteed noise margin: ■ High noise immunity: 3V to 6V 1V 0.45 VCC (typ.) ■ High segment sourcing current: 40 mA @ VCC − 1.6V, VCC = 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. Ordering Code: Order Number Package Number Package Description MM74C925N N16E 16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300” Wide MM74C926N N18A 18-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300” Wide MM74C927N N18A 18-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300” Wide MM74C928N N18A 18-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300” Wide © 1999 Fairchild Semiconductor Corporation DS005919.prf www.fairchildsemi.com MM74C925 • MM74C926 • MM74C927 • MM74C928 4-Digit Counters with Multiplexed 7-Segment Output Drivers October 1987 MM74C925 • MM74C926 • MM74C927 • MM74C928 Connection Diagrams Pin Assignments for DIP Top View MM74C925 Top View MM74C926, MM74C927, MM74C928 Functional Description Reset Segment Output — Current sourcing with 40 mA @VOUT = VCC − 1.6V (typ.) Also, sink capability = 2 LTTL loads — Asynchronous, active high Display Select — High, displays output of counter Low, displays output of latch Digit Output — Current sourcing with 1 mA @VOUT = 1.75V. Also, sink capability = 2 LTTL loads Latch Enable — High, flow through condition Low, latch condition Clock Carry-Out —Negative edge sensitive Logic Diagrams MM74C925 www.fairchildsemi.com 2 — 2 LTTL loads. See carry-out waveforms. MM74C925 • MM74C926 • MM74C927 • MM74C928 Logic Diagrams (Continued) MM74C926 MM74C927 MM74C928 3 www.fairchildsemi.com MM74C925 • MM74C926 • MM74C927 • MM74C928 Absolute Maximum Ratings(Note 1) Operating VCC Range GND − 0.3V to VCC + 0.3V Voltage at Any Output Pin (Soldering, 10 seconds) Operating Temperature −40°C to +85°C Range (TA) Storage Temperature Range 260°C 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 Electrical Characteristics table provides conditions for actual device operation. −65°C to +150°C Power Dissipation (PD) 6.5V Lead Temperature GND − 0.3V to +15V Voltage at Any Input Pin 3V to 6V VCC Refer to PD(MAX) vs TA Graph DC Electrical Characteristics Min/Max limits apply at −40°C ≤ tj≤ + 85°C, unless otherwise noted Symbol Parameter Conditions Min Typ Max Units 1.5 V CMOS TO CMOS VIN(1) Logical “1” Input Voltage VCC = 5V VIN(0) Logical “0” Input Voltage VCC = 5V VOUT(1) Logical “1” Output Voltage VCC = 5V, IO = −10 µA 3.5 (Carry-Out and Digit Output V 4.5 V Only) VOUT(0) Logical “0” Output Voltage VCC = 5V, IO = 10 µA IIN(1) Logical “1” Input Current VCC = 5V, VIN = 15V IIN(0) Logical “0” Input Current VCC = 5V, VIN = 0V ICC Supply Current VCC = 5V, Outputs Open Circuit, 0.005 −1 0.5 V 1 µA −0.005 20 µA 1000 µA 0.8 V VIN = 0V or 5V CMOS/LPTTL INTERFACE VIN(1) Logical “1” Input Voltage VCC = 4.75V VIN(0) Logical “0” Input Voltage VCC = 4.75V VOUT(1) Logical “1” Output Voltage VCC = 4.75V, (Carry-Out and Digit IO = −360 µA VCC − 2 V 2.4 V Output Only) VOUT(0) Logical “0” Output Voltage VCC = 4.75V, IO = 360 µA 0.4 V OUTPUT DRIVE VOUT Output Voltage (Segment IOUT = −65 mA, VCC = 5V, Tj = 25°C Sourcing Output) IOUT = −40 mA, VCC = 5V Tj = 100°C Tj = 150°C RON VCC − 2 VCC − 1.3 V VCC − 1.6 VCC − 1.2 V VCC − 2 VCC − 1.4 V Output Resistance (Segment IOUT = −65 mA, VCC = 5V, Tj = 25°C 20 32 Ω Sourcing Output) IOUT = −40 mA, VCC = 5V Tj = 100°C 30 40 Ω 35 50 Ω 0.6 0.8 %/°C Tj = 150°C Output Resistance (Segment Output) Temperature Coefficient ISOURCE Output Source Current VCC = 4.75V, VOUT = 1.75V, Tj = 150°C −1 −2 mA VCC = 5V, VOUT = 0V, Tj = 25°C −1.75 −3.3 mA VCC = 5V, VOUT = VCC, Tj = 25°C 1.75 3.6 mA (Digit Output) ISOURCE Output Source Current (Carry-Out) ISINK Output Sink Current (All Outputs) θjA Thermal Resistance (Note 2) 75 100 °C/W MM74C926, MM74C927, MM74C928 70 90 °C/W MM74C925: Note 2: θjA measured in free-air with device soldered into printed circuit board. www.fairchildsemi.com 4 (Note 3) Symbol fMAX Parameter Maximum Clock Frequency Conditions VCC = 5V, Tj = 25°C Square Wave Clock Tj = 100°C tr, tf Maximum Clock Rise or Fall Time VCC = 5V tWR Reset Pulse Width VCC = 5V tWLE Latch Enable Pulse Width tSET(CK, LE) Clock to Latch Enable Set-Up Time VCC = 5V Latch Enable to Reset Wait Time VCC = 5V tSET(R, LE) Reset to Latch Enable Set-Up Time VCC = 5V Typ 2 4 1.5 3 Max fMUX Multiplexing Output Frequency VCC = 5V CIN Input Capacitance Any Input (Note 4) Units MHz MHz 15 VCC = 5V tLR Min µs Tj = 25°C 250 100 ns Tj = 100°C 320 125 ns Tj = 25°C 250 100 ns Tj = 100°C 320 125 ns Tj = 25°C 2500 1250 ns Tj = 100°C 3200 1600 ns Tj = 25°C 0 −100 ns Tj = 100°C 0 −100 ns Tj = 25°C 320 160 ns Tj = 100°C 400 200 ns 1000 Hz 5 pF Note 3: AC Parameters are guaranteed by DC correlated testing. Note 4: Capacitance is guaranteed by periodic testing. Typical Performance Characteristics Typical Segment Current vs Output Voltage Maximum Power Dissipation vs Ambient Temperature Note: VD = Voltage across digit driver Typical Average Segment Current vs Segment Resistor Value 5 www.fairchildsemi.com MM74C925 • MM74C926 • MM74C927 • MM74C928 AC Electrical Characteristics TA = 25°C, CL = 50 pF, unless otherwise noted MM74C925 • MM74C926 • MM74C927 • MM74C928 Typical Performance Characteristics (Continued) Segment Output Driver Input Protection Common Cathode LED Display Segment Identification www.fairchildsemi.com 6 Input Waveforms Multiplexing Output Waveforms T = 1/fMUX Carry-Out Waveforms 7 www.fairchildsemi.com MM74C925 • MM74C926 • MM74C927 • MM74C928 Switching Time Waveforms MM74C925 • MM74C926 • MM74C927 • MM74C928 Physical Dimensions inches (millimeters) unless otherwise noted 16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300” Wide Package Number N16E www.fairchildsemi.com 8 18-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300” Wide Package Number N18A LIFE SUPPORT POLICY FAIRCHILD’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 FAIRCHILD SEMICONDUCTOR CORPORATION. As used herein: 2. A critical component in any component of a life support 1. Life support devices or systems are devices or systems device or system whose failure to perform can be reawhich, (a) are intended for surgical implant into the sonably expected to cause the failure of the life support body, or (b) support or sustain life, and (c) whose failure device or system, or to affect its safety or effectiveness. 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 www.fairchildsemi.com user. Fairchild does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and Fairchild reserves the right at any time without notice to change said circuitry and specifications. MM74C925 • MM74C926 • MM74C927 • MM74C928 4-Digit Counters with Multiplexed 7-Segment Output Drivers Physical Dimensions inches (millimeters) unless otherwise noted (Continued)