MM5450YN - MICREL SEMICONDUCTOR

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

LOAD

RESET RESET

(only available

in die form)

SERIAL DATA 22

CLOCK 21

DATA ENABLE/OUT 35

(See Note 1)

20 24

OUT 34

OUT 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

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

OUTPUT BIT 28

OUTPUT BIT 29

OUTPUT BIT 30

OUTPUT BIT 31

OUTPUT BIT 32

6 44 43 42 41 40

232221201918 24 25 26 27 28

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

OUTPUT BIT 28

OUTPUT BIT 29

OUTPUT BIT 30

OUTPUT BIT 31

OUTPUT BIT 32

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

to V

+ 12V

Power Dissipation

+25°C........................................................................1W

+85°C.................................................................560mW

Junction Temperature (T

) ....................................... +150°C

Storage Temperature (T

).........................–65°C to +150°C

Lead Temperature (soldering, 10sec.)..................... +300°C

Operating Ratings

Supply voltage (V

– V

).......................... +4.75V to +11V

Ambient Temperature Range (T

) .............–40°C to +85°C

Electrical Characteristics

4.5V ≤ V

≤ 11V, V

= 0V; T

= 25°C, bold values indicate –40°C ≤ T

≤ +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

Data Input Voltage

logic-0 level, ±10 µA input bias

logic-1 level, 4.75V ≤ V

≤ 5.25V

> 5.25V

–0.3

2.2

–2

0.8

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

2.0

2.7

µA

Brightness Control Input Voltage input current = 750 µA 3.0 4.3 V

Output Matching Note 1

±20 %

Clock Input Frequency Notes 5, 6

500 kHz

Clock Input High Time Notes 5, 6 950 ns

Clock Input Low Time Notes 5, 6 950 ns

Data Input Setup Time 300 ns

Data Input Hold Setup Time 300

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

≤ 200ns, t

≤ 20ns, f = 500kHz, 50% ±10% duty cycle.

6. Clock input rise and fall times must not exceed 300ns.

Micrel, Inc. MM5450/5451

February 2006

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(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.

= (V

OUT

) (I

LED

) (No. of segments) (124°C/W) + T

where:

= junction temperature + 150°C max

OUT

= the voltage at the LED driver outputs

LED

= the LED current

124°C/W = thermal resistance of the package

= 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

Figure 9.

Typical Applications

LM324

MM5450

LM317

–

240

RAW DC

> 9 V

I19 =

2N2907

I19

PIN 19

CD4046

(VCO)

MM74HC123

10 µS

MM5450

Q19

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

MM5450

DISPLAY DRIVER

ELECTRONIC

TUNING

CONTROLLER

PLL

SYNTHESIZER

KEYBOARD

STATION DETECT, ETC.

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.

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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

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indemnify Micrel for any damages resulting from such use or sale.