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MM5451N Datasheet

LED Display Drivers

MM5451N Datasheet Preview

February 1995
MM5450 MM5451 LED Display Drivers
General Description
The MM5450 and MM5451 are monolithic MOS integrated
circuits utilizing N-channel metal-gate low threshold en-
hancement mode and ion-implanted depletion mode devic-
es They are available in 40-pin molded or cavity dual-in-line
packages The MM5450 MM5451 is designed to drive com-
mon anode-separate cathode LED displays A single pin
controls the LED display brightness by setting a reference
current through a variable resistor connected to VDD
Y COPSTM or microprocessor displays
Y Industrial control indicator
Y Relay driver
Y Digital clock thermometer counter voltmeter
Y Instrumentation readouts
Y Continuous brightness control
Y Serial data input
Y No load signal required
Y Enable (on MM5450)
Y Wide power supply operation
Y TTL compatibility
Y 34 or 35 outputs 15 mA sink capability
Y Alphanumeric capability
Board e 49 C W
Socket e 54 C W
Block Diagram
TL F 6136–1
COPSTM is a trademark of National Semiconductor Corporation
C1995 National Semiconductor Corporation TL F 6136
RRD-B30M105 Printed in U S A
Page 1

Absolute Maximum Ratings
If Military Aerospace specified devices are required
please contact the National Semiconductor Sales
Office Distributors for availability and specifications
Voltage at Any Pin
Operating Temperature
VSS b 0 3V to VSS a 12V
b25 C to a85 C
Storage Temperature
b65 C to a150 C
Junction Temperature
a150 C
Lead Temperature (Soldering 10 sec )
300 C
Power Dissipation at a25 C
Molded DIP Package Board Mount
2 5W
Molded DIP Package Socket Mount
2 3W
Molded DIP Package board mount iJA e 49 C W
Derate 20 4 mW C above 25 C
Molded DIP Package socket mount iJA e 54 C W
Derate 18 5 mW C above 25 C
Electrical Characteristics TA within operating range VDD e 4 75V to 11 0V VSS e 0V unless otherwise specified
Min Typ Max Units
Power Supply
4 75
11 V
Power Supply Current
Excluding Output Loads
7 mA
Input Voltages
Logical ‘‘0’’ Level (VL)
Logical ‘‘1’’ Level (VH)
Brightness Input (Note 2)
g10 mA Input Bias
4 75V s VDD s 5 25V
VDD l 5 25V
b0 3
VDD b 2V
0 75
Output Sink Current
Segment OFF
Segment ON
VOUT e 3 0V
VOUT e 1V (Note 3)
Brightness Input e 0 mA
Brightness Input e 100 mA
Brightness Input e 750 mA
27 4
Brightness Input Voltage (Pin 19)
Input Current 750 mA
43 V
Output Matching (Note 1)
g 20
Clock Input
Frequency fC
High Time th
Low Time tl
(Notes 5 and 6)
500 kHz
Data Input
Set-Up Time tDS
Hold Time tDH
300 ns
300 ns
Data Enable Input
Set-Up Time tDES
100 ns
Note 1 Output matching is calculated as the percent variation (IMAX a IMIN) 2
Note 2 With a fixed resistor on the brightness input pin some variation in brightness will occur from one device to another Maximum brightness input current can
be 2 mA as long as Note 3 and junction temperature equation are complied with
Note 3 See Figures 5 6 and 7 for Recommended Operating Conditions and limits Absolute maximum for each output should be limited to 40 mA
Note 4 The VOUT voltage should be regulated by the user See Figures 6 and 7 for allowable VOUT vs IOUT operation
Note 5 AC input waveform specification for test purpose tr s 20 ns tf s 20 ns f e 500 kHz 50% g10% duty cycle
Note 6 Clock input rise and fall times must not exceed 300 ns
Connection Diagrams
Dual-In-Line Package
Dual-In-Line Package
Top View
TL F 6136–2
Top View
Order Number MM5450N MM5451N MM5450V or MM5451V
See NS Package Number N40A or V44A
TL F 6136–3
Page 2

Connection Diagrams (Continued)
Plastic Chip Carrier
Top View
Plastic Chip Carrier
TL F 6136–13
Top View
TL F 6136–14
Page 3

Functional Description
Both the MM5450 and the MM5451 are specifically de-
signed to operate 4- or 5-digit alphanumeric displays with
minimal interface with the display and the data source Seri-
al data transfer from the data source to the display driver is
accomplished with 2 signals serial data and clock Using a
format of a leading ‘‘1’’ followed by the 35 data bits allows
data transfer without an additional load signal The 35 data
bits are latched after the 36th bit is complete thus providing
non-multiplexed direct drive to the display Outputs change
only if the serial data bits differ from the previous time Dis-
play brightness is determined by control of the output cur-
rent for LED displays A 0 001 capacitor should be connect-
ed to brightness control pin 19 to prevent possible oscilla-
A block diagram is shown in Figure 1 For the MM5450 a
DATA ENABLE is used instead of the 35th output The
DATA ENABLE input is a metal option for the MM5450 The
output current is typically 20 times greater than the current
into pin 19 which is set by an external variable resistor
There is an internal limiting resistor of 400X nominal value
Figure 4 shows the input data format A start bit of logical
‘‘1’’ precedes the 35 bits of data At the 36th clock a LOAD
signal is generated synchronously with the high state of the
clock which loads the 35 bits of the shift registers into the
latches At the low state of the clock a RESET signal is
generated which clears all the shift registers for the next set
of data The shift registers are static master-slave configura-
tion There is no clear for the master portion of the first shift
register thus allowing continuous operation
There must be a complete set of 36 clocks or the shift regis-
ters will not clear
When the chip first powers ON an internal power ON reset
signal is generated which resets all registers and all latches
The START bit and the first clock return the chip to its nor-
mal operation
Figure 2 shows the pin-out of the MM5450 and MM5451 Bit
1 is the first bit following the start bit and it will appear on pin
18 A logical ‘‘1’’ at the input will turn on the appropriate
Figure 3 shows the timing relationships between data clock
and DATA ENABLE A max clock frequency of 0 5 MHz is
For applications where a lesser number of outputs are used
it is possible to either increase the current per output or
operate the part at higher than 1V VOUT The following
equation can be used for calculations
Tj e (VOUT) (ILED) (No of segments)(iJA) a TA
Tj e junction temperature 150 C max
VOUT e the voltage at the LED driver outputs
ILED e the LED current
iJA e thermal coefficient of the package
TA e ambient temperature
iJA (Socket Mount) e 54 C W
iJA (Board Mount) e 49 C W
The above equation was used to plot Figure 5 Figure 6 and
Figure 7
TL F 6136–4
Page 4
Part Number MM5451N
Manufactur National
Description LED Display Drivers
Total Page 8 Pages
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