MM5450/5451
Micrel
May 2000
1
MM5450/5451
MM5450/5451
LED Display Driver
General Description
The MM5450 and MM5451 LED display drivers are monolithic
MOS IC's fabricated in an N-Channel, metal-gate process.
The technology produces low-threshold, enhancement-mode,
and ion-implanted depletion-mode devices.
A single pin controls the LED display brightness by setting a
reference current through a variable resistor connected to
the supply.
Applications
Industrial control indicator
Relay driver
Digital clock, thermometer, counter, voltmeter
Instrumentation readouts
Features
Continuous brightness control
Serial data input
No load signal requirement
Enable (on MM5450)
Wide power supply operation
TTL compatibility
34 or 35 outputs, 15mA capability
Alphanumeric capability
870 01
Figure 1.
35 OUTPUT BUFFERS
35 LATCHES
35-BIT SHIFT
REGISTERS
LOAD
RESET
RESET
(only available
in die form)
SERIAL DATA
22
CLOCK
21
DATA ENABLE/OUT 35
(See Note 1)
23
19
20
24
OUT 34
18
OUT 1
1
BRIGHTNESS
CONTROL
VDD
Note 1: Pin 23 is Data Enable in MM5450
Pin 23 is Output 35 in MM5451
Block Diagram
Micrel, Inc. 1849 Fortune Drive San Jose, CA 95131 USA tel + 1 (408) 944-0800 fax + 1 (408) 944-0970 http://www.micrel.com
Ordering Information
Part Number
Junction Temp. Range
Package
MM5450BN
40
C to +85
C
40-pin Plastic DIP
MM5451BN
40
C to +85
C
40-pin Plastic DIP
MM5450BV
40
C to +85
C
44-pin PLCC
MM5451BV
40
C to +85
C
44-pin PLCC
MM5450/5451
Micrel
MM5450/5451
2
May 2000
Connection Diagram: Die
Figure 3a, 3b.
Note: Die size is 0.106" x 0.099"
Connection Diagram: Dual-in-line Package
Figure 2.
V
OUTPUT BIT 24
ENABLE
DATA
CLK
BRIGHTNESS CONTROL
RESET
MM5450/5451
DIE PINOUT
OUTPUT BIT 25
OUTPUT BIT 26
OUTPUT BIT 27
OUTPUT BIT 28
OUTPUT BIT 29
OUTPUT BIT 30
OUTPUT BIT 31
OUTPUT BIT 32
OUTPUT BIT 33
OUTPUT BIT 1
OUTPUT BIT 2
OUTPUT BIT 35
OUTPUT BIT 34
V
DD
SS
V SS
OUTPUT BIT 12
OUTPUT BIT 11
OUTPUT BIT 10
OUTPUT BIT 9
OUTPUT BIT 8
OUTPUT BIT 7
OUTPUT BIT 6
OUTPUT BIT 5
OUTPUT BIT 4
OUTPUT BIT 3
V
SS
OUTPUT BIT 13
OUTPUT BIT 14
OUTPUT BIT 15
OUTPUT BIT 16
OUTPUT BIT 17
OUTPUT BIT 1
8
OUTPUT BIT 1
9
OUTPUT BIT 2
0
OUTPUT BIT 21
OUTPUT BIT 2
2
OUTPUT BIT 2
3
1
40
2
39
3
38
4
37
5
36
6
35
7
34
8
33
9
32
10
31
11
30
12
29
13
28
14
27
15
26
16
25
17
24
18
23
19
22
20
21
OUTPUT BIT 18
CLOCK IN
MM5450BN
V SS
V DD
OUTPUT BIT 17
OUTPUT BIT 16
OUTPUT BIT 15
OUTPUT BIT 14
OUTPUT BIT 13
OUTPUT BIT 12
OUTPUT BIT 11
OUTPUT BIT 10
OUTPUT BIT 9
OUTPUT BIT 8
OUTPUT BIT 7
OUTPUT BIT 6
OUTPUT BIT 5
OUTPUT BIT 4
OUTPUT BIT 3
OUTPUT BIT 2
OUTPUT BIT 1
BRIGHTNESS
CONTROL
DATA IN
DATA ENABLE
OUTPUT BIT 19
OUTPUT BIT 20
OUTPUT BIT 21
OUTPUT BIT 22
OUTPUT BIT 23
OUTPUT BIT 24
OUTPUT BIT 25
OUTPUT BIT 26
OUTPUT BIT 27
OUTPUT BIT 28
OUTPUT BIT 29
OUTPUT BIT 30
OUTPUT BIT 31
OUTPUT BIT 32
OUTPUT BIT 33
OUTPUT BIT 34
1
40
2
39
3
38
4
37
5
36
6
35
7
34
8
33
9
32
10
31
11
30
12
29
13
28
14
27
15
26
16
25
17
24
18
23
19
22
20
21
OUTPUT BIT 18
V SS
V DD
OUTPUT BIT 17
OUTPUT BIT 16
OUTPUT BIT 15
OUTPUT BIT 14
OUTPUT BIT 13
OUTPUT BIT 12
OUTPUT BIT 11
OUTPUT BIT 10
OUTPUT BIT 9
OUTPUT BIT 8
OUTPUT BIT 7
OUTPUT BIT 6
OUTPUT BIT 5
OUTPUT BIT 4
OUTPUT BIT 3
OUTPUT BIT 2
OUTPUT BIT 1
BRIGHTNESS
CONTROL
MM5450/5451
Micrel
May 2000
3
MM5450/5451
Connection Diagram: Plastic Leaded Chip Carrier
Figure 4a, 4b.
1
2
39
3
38
4
37
5
36
7
35
8
34
9
33
10
32
11
31
12
30
13
29
14
15
16
17
V
SS
OUTPUT BIT 14
OUTPUT BIT 15
OUTPUT BIT 16
OUTPUT BIT 17
OUTPUT BIT 13
OUTPUT BIT 23
NC
6
44
43
42
41
40
NC
OUTPUT BIT 18
OUTPUT BIT 19
OUTPUT BIT 20
OUTPUT BIT 21
22
21
20
19
18
24
25
26
27
28
OUTPUT BIT 22
1
2
39
3
38
4
37
5
36
7
35
8
34
9
33
10
32
11
31
12
30
13
29
14
15
16
17
MM5450BV
V
SS
OUTPUT BIT 14
OUTPUT BIT 15
OUTPUT BIT 16
OUTPUT BIT 17
OUTPUT BIT 13
OUTPUT BIT 12
OUTPUT BIT 11
OUTPUT BIT 10
OUTPUT BIT 9
OUTPUT BIT 8
OUTPUT BIT 7
OUTPUT BIT 6
OUTPUT BIT 5
OUTPUT BIT 4
OUTPUT BIT 23
OUTPUT BIT 24
OUTPUT BIT 25
OUTPUT BIT 26
OUTPUT BIT 27
NC
OUTPUT BIT 28
OUTPUT BIT 29
OUTPUT BIT 30
OUTPUT BIT 31
OUTPUT BIT 32
NC
6
44
43
42
41
40
NC
OUTPUT BIT 18
OUTPUT BIT 19
OUTPUT BIT 20
OUTPUT BIT 21
OUTPUT BIT 3
OUTPUT BIT 2
OUTPUT BIT 1
BRIGHTNESS CONTROL
NC
CLOCK IN
DATA IN
DATA ENABLE
OUTPUT BIT 34
OUTPUT BIT 33
23
22
21
20
19
18
24
25
26
27
28
OUTPUT BIT 22
V
DD
MM5450/5451
Micrel
MM5450/5451
4
May 2000
Absolute Maximum Ratings
Voltage (any pin) ...................................... V
SS
to V
SS
+12V
Power Dissipation (P
D
)
+25
C ......................................................................... 1W
+85
C .................................................................. 560mW
Junction Temperature (T
J
) ...................................... +150
C
Storage Temperature (T
S
) ....................... 65
C to +150
C
Lead Temperature (soldering, 10 sec.) ................... +300
C
Operating Ratings
Supply Voltage (V
DD
V
SS
) ....................... +4.75V to +11V
Ambient Temperature Range (T
A
) ............. 40
C to +85
C
Electrical Characteristics
4.5V
V
DD
11V, V
SS
= 0V; T
A
= 25
C, bold values indicate 40
C
T
A
+85
C; unless noted
Symbol
Parameter
Condition
Min
Typ
Max
Units
Power Supply Current
25
C to +85
C, excluding output loads
8.5
mA
40
C to +85
C, excluding output loads
10
mA
Data Input Voltage
V
L
logic-0 level,
10
A input bias
0.3
0.8
V
V
H
logic-1 level, 4.75V
V
DD
5.25V
2.2
V
DD
V
V
DD
> 5.25V
V
DD
2
V
DD
V
Brightness Control Input Current
Note 2
0
0.75
mA
Output Sink Current
segment off, V
OUT
=
3.0V
10
A
segment on, V
OUT
=
1.0V, Note 3
brightness input = 0
A
0
10
A
brightness input = 100
A
2.0
2.7
4
mA
brightness input = 750
A
15
25
mA
Brightness Control Input Voltage
input current = 750
A
3.0
4.3
V
Output Matching
Note 1
20
%
f
C
Clock Input Frequency
Notes 5, 6
500
kHz
t
H
Clock Input High Time
Notes 5, 6
950
ns
t
L
Clock Input Low Time
Notes 5, 6
950
ns
t
DS
Data Input Setup Time
300
ns
t
DH
Data Input Hold Time
300
ns
t
DES
Data Enable Input Setup Time
100
ns
Reset Pad Current
die
8
A
Note 1:
Output matching is calculated as the percent variation (I
MAX
+ I
MIN
)
2.
Note 2:
With a fixed resistor on the brightness input pin, some variation in brightness will occur among devices.
Maximum brightness control input current can be 2mA providing it complies with Note 3 and the junction temperature equation.
Note 3:
See Figures 7, 8 and 9 for recommended operating conditions and limits. Absolute maximum for each output should be limited to 40mA.
Note 4:
V
OUT
should be regulated by the user. See Figures 8 and 9 for allowable V
OUT
vs. I
OUT
operation.
Note 5:
AC input waveform specification for test purpose: t
R
20ns, t
F
20ns, f = 500kHz, 50%
10% duty cycle.
Note 6:
Clock input rise and fall times must not exceed 300ns.
MM5450/5451
Micrel
May 2000
5
MM5450/5451
Functional Description
The MM5450 and MM5451 were designed to drive either 4- or
5-digit alphanumeric LED displays with the added benefit of
requiring minimal interface with the display or data source.
Data is transferred serially via 2 signals; clock and serial data.
Data transfer without the added inconvenience of an external
load signal is accomplished by using a format of a leading "1"
followed by the allowed 35 data bits. These 35 data bits are
latched after the 36th has been transferred. This scheme
provides non multiplexed, direct drive to the LED display.
Characters currently displayed (thus, data output) changes
only if the serial data bits differ from those previously transferred.
Control of the output current for LED displays provides for the
display brightness. To prevent oscillations, a 1nF capacitor
should be connected to pin 19, brightness control.
The block diagram is shown in Figure 1. For the MIC5450, the
DATA ENABLE is a metal option and is used instead of the
35th output. The output current is typically 20-times greater
that the current into pin 19, which is set by an external variable
resistor.
There is an external reset connection shown which is available
on unpackaged (die) only. Figure 2 illustrates the die pad
locations for bonding in "chip on board" applications.
Figure 5 shows the input data format. A leading "1" is followed
by 35 bits of data. After the 36th had been transferred, a LOAD
signal is generated synchronously with the clock high state.
This loads the 35 bits of data into the latches. The low side of
the clock is used to generate a RESET signal which clears all
shift registers for the next set of data. All shift registers are
static master-slave, with no clear for the master portion of the
first register, allowing continuous operation.
There must be a complete set of 36 clocks or the shift registers
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 normal
operation.
Figure 3 and 4 show the pin-out of the MIC5450 and MIC5451.
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
LED.
Figure 5 shows the timing relationships between data, clock
and DATA ENABLE. A maximum clock frequency of 0.5MHz
is assumed.
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 V
OUT
. The following
equation can be used for calculations.
T
J
= (V
OUT
) (I
LED
) (No. of segments) (124
C/W) + T
A
where:
T
J
= junction temperature + 150
C max
V
OUT
= the voltage at the LED driver outputs
I
LED
= the LED current
124
C/W = thermal resistance of the package
T
A
= ambient temperature
The above equation was used to plot Figures 79.
Figure 5.
CLOCK
DATA
DATA ENABLE
300 nS MIN
100 nS MIN
CLOCK
1
DATA
LOAD
(INTERNAL)
RESET
(INTERNAL)
START BIT 1
BIT 36
36
37
BIT 35
Figure 6. Input Data Format
MM5450/5451
Micrel
MM5450/5451
6
May 2000
Typical Performance Characteristics
Typical Applications
Figure 10. Typical Application of Constant Current
Brightness Control
CD4046
(VCO)
5V
MM74HC123
10 S
MM5450
Q 19
20
1
Figure 11. Brightness Control Varying the Duty Cycle
Figure 7.
Figure 8.
2.5
2.0
1.5
1.0
0.5
0
0
4
8
12
16
20
24
28
I (mA)
LED
V (V )
OUT
O
T = 85C
T = 150C (MAX)
A
J
20 SEG
M
30 SEGM
34 SEGM
1.0
0.8
0.6
0.4
0.2
0
0
20
40
60
80
TEMPERATURE (C)
POWER DISSIPATION (W)
34 SEGMENTS
V = 1V
15 mA/SEGMENT
OUT
SAFE OPERATING
AREA
100
Figure 9.
110
100
90
80
70
60
50
40
30
20
10
0
0
5
10
15
20
25
30
34
NUMBER OF SEGMENTS
OUTPUT CURRENT (mA)
V = 1V
OUT
V = 1.5V
OUT
V = 2V
OUT
T = 85C
A
LM324
MM5450
LM317
+
V
240
RAW DC
> 9 V
V
1K
I19 =
2N2907
I19
PIN 19
5V
20
1
5k
7V
1k
MM5450/5451
Micrel
May 2000
7
MM5450/5451
Typical Applications
Figure 12. Basic Electronically Tuned Radio System
Figure 13. Duplexing 8 Digits with One MM5450.
LED DISPLAY
34
MM5450
DISPLAY DRIVER
ELECTRONIC
TUNING
CONTROLLER
PLL
SYNTHESIZER
KEYBOARD
STATION DETECT, ETC.
AM
FM
916
28, 40 3239
2431
18 21 22 19
20
1 23 17
100k
TYP.
MM5450
V
LED
V
LED
V
LED
= 3.0V
V
LED
= 3.0V
CLOCK IN
DATA IN
V
DD
BRIGHTNESS
CONTROL
MM5450/5451
Micrel
MM5450/5451
8
May 2000
MICREL INC.
1849 FORTUNE DRIVE
SAN JOSE, CA 95131
USA
TEL
+ 1 (408) 944-0800
FAX
+ 1 (408) 944-0970
WEB
http://www.micrel.com
This information is believed to be accurate and reliable, however no responsibility is assumed by Micrel for its use nor for any infringement of patents or
other rights of third parties resulting from its use. No license is granted by implication or otherwise under any patent or patent right of Micrel Inc.
2000 Micrel Incorporated
Package Information
2.040
.100
.150
.075
.125 MIN
.018 TYP
.060
.002
.100 TYP
.020 MIN
.010
.625
.025
105
/90
.030 NOM
.546
.010
.080 NOM
1
40
20
21
40-Pin Plastic DIP (N)
TOP VIEW
0.690
0.005
0.652
.610
.015
0.050 TYP
NON-ACCUM
0.045
0.045
0.094
0.015
0.137 TYP
0.125 DIA x 0.005 DEEP
4 PLCS (EJECTOR PIN)
BOTTOM VIEW
0.045
0.045
0.035 R
0.010
0.062 DIA
x 0.020 DEEP
DETAIL A
0.020 MIN
0.104
0.172
DETAIL A
0.062
TYP
0.030
TYP
0.018
0.104
0.028
SIDE VIEW
44-Pin PLCC (V)
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