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MM74C911 4-Digit Expandable Segment Display Controller
October 1987 Revised January 1999
MM74C911 4-Digit Expandable Segment Display Controller
General Description
The MM74C911 display controller is an interface element with memory that drives a 4-digit, 8-segment LED display. The MM74C911 allows individual control of any segment in the 4-digit display. The number of segments per digit can be expanded without any external components. For example, two MM74C911's can be cascaded to drive a 16-segment alpha-numeric display. The display controllers receive data information through 8 data lines a, b...DP, and digit information through 2 address inputs K1 and K2. The input data is written into the register selected by the address information when CHIP ENABLE, CE, and WRITE ENABLE, WE, are LOW and is latched when either CE or WE return HIGH. Data hold time is not required. A self-contained internal oscillator sequentially presents the stored data to high drive (100 mA typ.) 3-STATE output drivers which directly drive the LED display. The drivers are active when the control pin labeled SEGMENT OUTPUT ENABLE, SOE, is LOW and go into 3-STATE when SOE is HIGH. This feature allows for duty cycle brightness control, or for disabling the output drive for power conservation. The digit outputs directly drive the base of the digit transistor when the control pin labeled DIGIT INPUT OUTPUT, DIO, is LOW. When DIO is HIGH, the digit lines turn into inputs and the internal scanning multiplexer is disabled. When any digit line is forced HIGH by an external device, usually another MM74C911, the data information for that digit is presented to the output. In this manner, 16-segment alpha-numeric displays, 24- or 32-segment displays, or an array of discrete LED's can be controlled by the simple cascading of expandable segment display controllers. All inputs except digit inputs are TTL compatible and do not clamp input voltages above VCC.
Features
s Direct segment drive (100 mA typ.) 3-STATE s 4 registers addressed like RAM s Internal oscillator and scanning circuit s Direct base drive to digit transistor s Segment expandability without external components s TTL compatible inputs s Power saver mode--5 W (typ.)
Ordering Code:
Order Number MM74C991N Package Number N28B Package Description 28-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-010, 0.600" Wide
Connection Diagram
Pin Assignments for DIP
Top View
(c) 1999 Fairchild Semiconductor Corporation
DS005915.prf
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MM74C911
Truth Tables
Input Control Digit CE Address K2 0 0 0 0 0 0 0 0 1 0 0 0 0 1 1 1 1 X K1 0 0 1 1 0 0 1 1 X 0 1 0 1 0 1 0 1 X Write Digit 1 Latch Digit 1 Write Digit 2 Latch Digit 2 Write Digit 3 Latch Digit 3 Write Digit 4 Latch Digit 4 Disable Writing WE Operation 0 0 1 1 1 1 1 1 0 1 0 0 0 0 0 1 DIO SOE Output Control Digit Lines D4 D3 D2 D1 R R 0 0 0 0 1 0 R R 0 0 0 1 0 0 R R 0 0 1 0 0 0 R R 0 1 0 0 0 0 Refresh Display Disable Segment Outputs Digits Are Now Inputs Display Digit 1 Display Digit 2 Display Digit 3 Display Digit 4 Power Saver Mode Operation
R = Refresh (digit lines sequentially pulsed) X = Don't Care
Functional Description
The MM74C911 display controller is manufactured on standard metal gate CMOS technology. A single 5V 74 series TTL supply can be used for power and should be bypassed at the VCC pin to suppress current transients. The digit outputs directly drive the base of a grounded emitter digit transistor without the need of a Darlington configuration. If an MM74C911 is driving a digit transistor and also supplying digit information to a cascaded MM74C911, base resistors are needed in the digit transistors to provide an adequate high level to the digit inputs of the cascaded MM74C911. As seen in the Block Diagram, these display controllers contain four 8-bit registers; any one may be randomly written into. In normal operation, the internal multiplexer scans the registers and refreshes the display. In cascaded operation, 1 MM74C911 serves as a master refresh device and cascaded MM74C911's are slaved to it through digit lines operating as inputs. The MM74C911 appears to a microprocessor as memory and to the user as a self-scan display. Since every segment is under microprocessor control, great versatility is obtained. Low power standby operation occurs with both SOE and DIO inputs HIGH. This condition forces the MM74C911 to a quiescent state typically drawing less than 1 A of supply current with a standby supply voltage as low as 3V.
Logic Diagram
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MM74C911
Absolute Maximum Ratings(Note 1)
(Note 2) Voltage at Any Pin except Inputs Voltage at Any Input except Digits Operating Temperature Range, (TA) Storage Temperature Range Power Dissipation (PD) -40C to +85C -65C to +150C Refer to PD(MAX) vs TA Graph -0.3V to +15V -0.3V to VCC + 0.3V
Operating VCC Range Absolute Maximum VCC Lead Temperature (Soldering, 10 seconds)
3V to 6V 6.5V 260C
Note 1: "Absolute Maximum Ratings" are those values beyond which the safety of the device cannot be guaranteed. Except for "Operating Range", they are not meant to imply that the device should be operated at these limits. The table of "Electrical Characteristics" provides conditions for actual device operation. Note 2: All voltage reference to ground.
DC Electrical Characteristics
Min/Max limits apply at -40C TJ +85C, unless otherwise noted Symbol VIN(1) VIN(0) IIN(1) IIN(0) ICC ICC Parameter Logical "1" Input Voltage Logical "0" Input Voltage Logical "1" Input Current Logical "0" Input Current Supply Current (Normal) Supply Current (Power Saver) VCC = 5V, VIN = 15V VCC = 5V, VIN = 0V VCC = 5V, Outputs Open VCC = 5V, SOE, DIO = "1", D1, D2, D3, D4 = "0" IOUT 3-STATE Output Current VO = 5V VO = 0V CMOS/LPTTL INTERFACE VIN(1) VIN(0) ISH Logical "1" Input Voltage Logical "0" Input Voltage HIGH Level Segment Current VCC = 4.75V VCC = 4.75V VCC = 5V, VO = 3.4V TJ = 25C TJ = 100C IDH HIGH Level Digit Current VCC = 5V, VO = 3V TJ = 25C TJ = 100C VCC = 5V, VO = 1V TJ = 25C TJ = 100C VOUT(1) VOUT(0) JA Logical "1" Output Voltage, Any Digit Logical "0" Output Voltage, Any Output Thermal Resistance (Note 3) 100 C/W
Note 3: JA measured in free-air with device soldered into printed circuit board.
Conditions VCC = 5V
Min 3.0
Typ
Max
Units V
1.5 0.005 -1.0 -0.005 0.50 1 2.5 600 1.0
V A A mA A A
0.03 -10 VCC - 2 -0.03
10
V 0.8 V
OUTPUT DRIVE -60 -40 -10 -7 -15 -10 4.6 0.4 -100 -60 -20 -10 -40 -15 mA mA mA mA mA mA V V
VCC = 5V, IO = -360 A VCC = 5V, IO = 360 A
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MM74C911
AC Electrical Characteristics
VCC = 5V, tr = tf = 20 ns, CL = 50 pF Symbol tCW tAW tWW tDW tWD tWA tWC t1H, t0H Parameter Chip Enable to Write Enable Set-Up Time Address to Write Enable Set-Up Time Write Enable Width Data to Write Enable Set-Up Time Write Enable to Data Hold Time Write Enable to Address Hold Time Write Enable to Chip Enable Hold Time
(Note 4)
Conditions TJ = 25C TJ = 125C TJ = 25C TJ = 125C TJ = 25C TJ = 125C TJ = 25C TJ = 125C TJ = 25C TJ = 125C TJ = 25C TJ = 125C TJ = 25C TJ = 125C Min 35 50 35 50 400 450 390 430 0 0 0 0 55 75 Typ 15 20 15 20 225 250 225 250 -10 -15 -10 -15 30 40 275 325 325 375 500 700 5 10 10 20 525 375 5 30 7.5 50 500 600 600 700 1000 1400 Max Units ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns s s Hz Hz pF pF
Logical "1", Logical "0" Levels into 3-STATE RL=10k, CL=10 pF TJ = 25C TJ = 125C
tH1, tH0
3-STATE to Logical "1" or Logical "0" Levels
RL=10k, CL=10 pF TJ = 25C TJ = 125C TJ = 25C TJ = 125C TJ = 25C TJ = 125C TJ = 25C TJ = 125C (Note 5) (Note 5)
tD1, tD0 tIB fMUX CIN COUT
Propagation Delay from Digit Input to Segment Output Interdigit Blanking Time Multiplex Scan Frequency Input Capacitance 3-STATE Output Capacitance
Note 4: AC Parameters are guaranteed by DC correlated testing. Note 5: Capacitance guaranteed by periodic testing.
Switching Time Waveforms
Write Data Waveforms 3-STATE Waveforms
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MM74C911
Switching Time Waveforms
Multiplexing Output Waveforms
(Continued) Read Data Waveforms
Note A: All other digit lines are at a low level. DIO at a HIGH level.
Typical Performance Characteristics
Segment outputs if shorted to ground will exceed maximum power dissipation of the device.
VCE is the saturation voltage of the digit drive transistor.
Power Dissipation vs Temperature for Plastic Packages
Applications
Segment Output Structure Digit Output Structure
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MM74C911
Input Protection
Segment Expansion
Typical Application
*Base resistors may be necessary to limit base current.
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MM74C911
4-Digit, 16-Segment Alpha-Numeric Display
Segment Identification
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MM74C911 4-Digit Expandable Segment Display Controller
Physical Dimensions inches (millimeters) unless otherwise noted
28-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-010, 0.600" Wide Package Number N28B
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.

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