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mm5450

MM5450/5451

LED Display Driver

SuperSwitcher and Super ?eta 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 ? https://www.wendangku.net/doc/8599135.html,

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

RESET

(only available in die form)

BRIGHTNESS

CONTROL

Pin 23 is Output 35 in MM5451

Figure 1.

Connection Diagram: Die

Figure 2.

Connection Diagram: Dual-in-line Package

OUTPUT BIT 18CLOCK IN

V SS

V DD OUTPUT BIT 17OUTPUT BIT 16OUTPUT BIT 15OUTPUT BIT 14OUTPUT BIT 13OUTPUT BIT 12OUTPUT BIT 11OUTPUT BIT 10

OUTPUT BIT 9OUTPUT BIT 8OUTPUT BIT 7OUTPUT BIT 6OUTPUT BIT 5OUTPUT BIT 4OUTPUT BIT 3OUTPUT BIT 2OUTPUT BIT 1BRIGHTNESS CONTROL

DATA IN DATA ENABLE OUTPUT BIT 19OUTPUT BIT 20OUTPUT BIT 21OUTPUT BIT 22OUTPUT BIT 23OUTPUT BIT 24OUTPUT BIT 25OUTPUT BIT 26OUTPUT BIT 27OUTPUT BIT 28OUTPUT BIT 29OUTPUT BIT 30OUTPUT BIT 31OUTPUT BIT 32OUTPUT BIT 33OUTPUT BIT 34

OUTPUT BIT 18CLOCK IN

V SS

V DD OUTPUT BIT 17OUTPUT BIT 16OUTPUT BIT 15OUTPUT BIT 14OUTPUT BIT 13OUTPUT BIT 12OUTPUT BIT 11OUTPUT BIT 10

OUTPUT BIT 9OUTPUT BIT 8OUTPUT BIT 7OUTPUT BIT 6OUTPUT BIT 5OUTPUT BIT 4OUTPUT BIT 3OUTPUT BIT 2OUTPUT BIT 1BRIGHTNESS CONTROL

DATA IN OUTPUT BIT 19OUTPUT BIT 20OUTPUT BIT 21OUTPUT BIT 22OUTPUT BIT 23OUTPUT BIT 24OUTPUT BIT 25OUTPUT BIT 26OUTPUT BIT 27OUTPUT BIT 28OUTPUT BIT 29OUTPUT BIT 30OUTPUT BIT 31OUTPUT BIT 32OUTPUT BIT 33OUTPUT BIT 34OUTPUT BIT 35

Figure 3a, 3b.

Connection Diagram: Plastic Leaded Chip Carrier

OUTPUT BIT 13OUTPUT BIT 12OUTPUT BIT 11

OUTPUT BIT 10OUTPUT BIT 9OUTPUT BIT 8OUTPUT BIT 7OUTPUT BIT 6OUTPUT BIT 5OUTPUT BIT 4OUTPUT BIT 23OUTPUT BIT 24OUTPUT BIT 25OUTPUT BIT 26OUTPUT BIT 27NC

OUTPUT BIT 28OUTPUT BIT 29OUTPUT BIT 30OUTPUT BIT 31OUTPUT BIT 32

NC OUTPUT BIT 13OUTPUT BIT 12OUTPUT BIT 11

OUTPUT BIT 10OUTPUT BIT 9OUTPUT BIT 8OUTPUT BIT 7OUTPUT BIT 6OUTPUT BIT 5OUTPUT BIT 4OUTPUT BIT 23OUTPUT BIT 24OUTPUT BIT 25OUTPUT BIT 26OUTPUT BIT 27NC

OUTPUT BIT 28OUTPUT BIT 29OUTPUT BIT 30OUTPUT BIT 31OUTPUT BIT 32

Figure 4a, 4b.

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

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

Reset Pad Current

die

8 μA

Notes:

1. Output matching is calculated as the percent variation (I MAX + I MIN ) /

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.

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.

Figure 5.

Typical Performance Characteristics

Figure 7.Figure 8.

LED

T U O

Figure 9.

Typical Applications

RAW DC

Figure 10. Typical Application of Constant Current

Figure 11. Brightness Control Varying the Duty Cycle

Brightness Control

Typical Applications

S T A T I O N D E T E C T , E T C.

Figure 12. Basic Electronically Tuned Radio System

TYP.

V 3.0V

C L O

Figure 13. Duplexing 8 Digits with One MM5450

Package Information

40-Pin Plastic DIP (N)

44-Pin PLCC (V)