Functional Description

The MM5484 is designed to drive LED displays directly Se-

rial data transfer from the data source to the display driver is

accomplished with 3 signals DATA IN CLOCK and EN-

ABLE The signal ENABLE acts as an envelope and only

while this signal is at a logic ‘1’ do the circuits recognize the

clock signal

While ENABLE is high data on the serial data input is trans-

ferred and shifted in the internal shift register on the rising

clock edge ie a logic ‘0’ to logic ‘1’ transition

When the ENABLE signal goes to a low (logic zero state)

the contents of the shift register is latched and the display

will show the new data While new data is being loaded into

the SR the display will continue to show the old data

For the MM5484 data is output from the serial DATA OUT

pin on the falling edge of clock so cascading is made simple

with race hazards eliminated

When the chip first powers on an internal power on reset

signal is generated which resets the SR and latches to zero

so that the display will be off

Timing Diagram

TLF6141 – 5

FIGURE 3

Molded Dual-In-Line Package (N)

Order Number MM5484N

NS Package Number N22A

3