Electronic Components Datasheet Search |
|
MM5450N Datasheet(PDF) 4 Page - National Semiconductor (TI) |
|
|
MM5450N Datasheet(HTML) 4 Page - National Semiconductor (TI) |
4 / 8 page 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 0001 capacitor should be connect- ed to brightness control pin 19 to prevent possible oscilla- tions 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 400 X 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 LED Figure 3 shows the timing relationships between data clock and DATA ENABLE A max clock frequency of 05 MHz 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 VOUT The following equation can be used for calculations Tj e (VOUT)(ILED) (No of segments)(iJA) a TA where 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 CW iJA (Board Mount) e 49 CW The above equation was used to plot Figure 5 Figure 6 and Figure 7 TLF6136 – 4 FIGURE 3 4 |
Similar Part No. - MM5450N |
|
Similar Description - MM5450N |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.COM |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Datasheet Upload | Contact us | Privacy Policy | Link Exchange | Manufacturer List All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |