MM5450/5451
LED Display Driver
SuperSwitcher and Super ßeta PNP are trademarks of Micrel, Inc.
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (
408
) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
February 2006
M9999-021606
(408) 955-1690
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
Ordering Information
Part Number
Standard Pb-Free Junction
Temp. Range Package
MM5450BN MM5450YN –40°C to+85°C 40-pin PDIP
MM5451BN MM5451YN –40°C to+85°C 40-pin PDIP
MM5450BV MM5450YV –40°C to+85°C 44-pin PLCC
MM5451BV MM5451YV –40°C to+85°C 44-pin PLCC
____________________________________________________________________________________________________________
Block Diagram
35 OUTPUT BUFFERS
35 LATCHES
35-BIT SHIFT
REGISTER
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
Figure 1.
Micrel, Inc. MM5450/5451
February 2006
2 M9999-021606
(408) 955-1690
Connection Diagram: Die
Figure 2.
Connection Diagram: Dual-in-line Package
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/YN
VSS
VDD
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
CLOCK IN
MM5451BN/YN
VSS
VDD
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
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
OUTPUT BIT 35
Figure 3a, 3b.
Micrel, Inc. MM5450/5451
February 2006
3 M9999-021606
(408) 955-1690
Connection Diagram: Plastic Leaded Chip Carrier
12
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
MM5451BV/YV
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
232221201918 24 25 26 27 28
12
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/YV
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
232221201918 24 25 26 27 28
Figure 4a, 4b.
Micrel, Inc. MM5450/5451
February 2006
4 M9999-021606
(408) 955-1690
Absolute Maximum Ratings
Voltage (any pin) ........................................V
SS
to V
SS
+ 12V
Power Dissipation
+25°C........................................................................1W
+85°C.................................................................560mW
Junction Temperature (T
J
) ....................................... +150°C
Storage Temperature (T
S
).........................–65°C to +150°C
Lead Temperature (soldering, 10sec.)..................... +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 otherwise noted.
Symbol Parameter Condition Min Typ Max Units
Power Supply Current
–25°C to +85°C, excluding output loads
–40°C to +85°C, excluding output loads
8.5
10 mA
mA
V
L
V
H
Data Input Voltage
logic-0 level, ±10 µA input bias
logic-1 level, 4.75V ≤ V
DD
≤ 5.25V
V
DD
> 5.25V
–0.3
2.2
V
DD
–2
0.8
V
DD
V
DD
V
V
V
Brightness Control Input Current Note 2 0 0.75 mA
segment off, V
OUT
= 3.0V 10 µA Output Sink Current
segment on, V
OUT
= 1.8V, Note 3
brightness input = 0µA
brightness input = 100µA
brightness input = 750µA
0
2.0
15
2.7
10
4
25
µA
mA
mA
Brightness Control Input Voltage input current = 750 µA 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 Setup Time 300
ns
t
DES
Data Enable Input Setup Time 100 ns
Reset Pad Current die 8 8 µA
Notes:
1. Output matching is calculated as the percent variation (I
MAX
+ I
MIN
) / 2.
2. With a fixed resistor on the brightness input pin, some variation in brightness will occur among devices.
3. See Figures 7, 8 and 9 for recommended operating conditions and limits. Absolute maximum for each output should be limited to 40mA.
4. V
OUT
should be regulated by user. See Figures 8 and 9 for allowable V
OUT
vs. I
OUT
operation.
5. AC input waveform specification for test purpose: t
R
≤ 200ns, t
F
≤ 20ns, f = 500kHz, 50% ±10% duty cycle.
6. Clock input rise and fall times must not exceed 300ns.
Micrel, Inc. MM5450/5451
February 2006
5 M9999-021606
(408) 955-1690
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.
The MIC37252 regulator is fully protected from damage
due to fault conditions. Current limiting is provided. This
limiting is linear; output current during overload
conditions is constant. Thermal shutdown disables the
device when the die temperature exceeds the maximum
safe operating temperature. Transient protection allows
device (and load) survival even when the input voltage
spikes above and below nominal. The output structure of
these regulators allows voltages in excess of the desired
output voltage to be applied without reverse current flow.
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 pinout 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 7–9.
Micrel, Inc. MM5450/5451
February 2006
6 M9999-021606
(408) 955-1690
Figure 5.
Figure 6. Input Data Format
Micrel, Inc. MM5450/5451
February 2006
7 M9999-021606
(408) 955-1690
Typical Performance Characteristics
Figure 7. Figure 8.
LED
OTUO
A
J
G
E
S
0
2M
Figure 9.
Typical Applications
LM324
MM5450
LM317
–
+
240
RAW DC
> 9 V
1K
I19 =
2N2907
I19
PIN 19
5V
20
1
5k
7V
1k
CD4046
(VCO)
5V
MM74HC123
10 µS
MM5450
Q19
20
1
Figure 10. Typical Application of Constant Current Figure 11. Brightness Control Varying the Du ty Cycle
Brightness Control
Micrel, Inc. MM5450/5451
February 2006
8 M9999-021606
(408) 955-1690
Typical Applications
LED DISPLAY
34
MM5450
DISPLAY DRIVER
ELECTRONIC
TUNING
CONTROLLER
PLL
SYNTHESIZER
KEYBOARD
STATION DETECT, ETC.
AM
FM
Figure 12. Basic Electronically Tuned Radio System
9–16 2–8, 40 32–39 24–31
18 21 22 19 20 123 17
100k
TYP.
MM5450
VLED VLED
VLED=3.0V VLED =3.0V
CLOCK IN
DATA IN VDD
BRIGHTNESS
CONTROL
Figure 13. Duplexing 8 Digits with One MM5450
Micrel, Inc. MM5450/5451
February 2006
9 M9999-021606
(408) 955-1690
Package Information
40-Pin Plastic DIP (N)
44-Pin PLCC (V)
MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA
TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB http:/www.micrel.com
The information furnished by Micrel in this data sheet is believed to be accurate and reliable. However, no responsibility is assumed by Micrel for its
use. Micrel reserves the right to change circuitry and specifications at any time without notification to the customer.
Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product
can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical implant
into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. A
Purchaser’s use or sale of Micrel Products for use in life support appliances, devices or systems is a Purchaser’s own risk and Purchaser agrees to fully
indemnify Micrel for any damages resulting from such use or sale.
© 2002 Micrel, Incorporated.
