MAX6954ATL(2014) 데이터 시트보기 (PDF) - Maxim Integrated

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MAX6954ATL
(Rev.:2014)

4-Wire Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan

Maxim Integrated 

MAX6954

4-Wire Interfaced, 2.7V to 5.5V LED Display

Driver with I/O Expander and Key Scan

DOUT

CLK

MICROCONTROLLER

CS

DIN

DOUT

CLK MAX6954

CS

DIN

DOUT

CLK MAX6954

CS

DIN

CLK MAX6954 DOUT

CS

DIN

Figure 2. MAX6954 Daisy-Chain Connection

CS

CLK

DIN

DOUT

tCSS

tCL

tCH

tDH

tDS

D15

D14

tCSW

tCSH

tCP

D1

D0

tDO

D15

Figure 3. Timing Diagram

to read. Bits D7 to D0 contain dummy data, which is

discarded.

4) Take CS high (while CLK is still high after clocking

in the last data bit), positions D7 through D0 in the

shift register are now loaded with the register data

addressed by bits D15 through D8.

5) Take CLK low.

6) Issue another read or write command (which can

be a no-op), and examine the bit stream at DOUT;

the second 8 bits are the contents of the register

addressed by bits D14 through D8 in step 3.

Digit Type Registers

The MAX6954 uses 32 digit registers to store the char-

acters that the user wishes to display. These digit regis-

ters are implemented with two planes, P0 and P1. Each

digit is represented by 2 bytes of memory, 1 byte in

plane P0 and the other in plane P1. The digit registers

are mapped so that a digit’s data can be updated in

plane P0, plane P1, or both planes at the same time

(Table 6).

If the blink function is disabled through the Blink Enable

Bit E (Table 19) in the configuration register, then the

digit register data in plane P0 is used to multiplex the

display. The digit register data in P1 is not used. If the

blink function is enabled, then the digit register data in

both plane P0 and plane P1 are alternately used to mul-

tiplex the display. Blinking is achieved by multiplexing

the LED display using data plane P0 and plane P1 on

alternate phases of the blink clock (Table 20).

The data in the digit registers does not control the digit

segments directly for 14- and 16-segment displays.

Instead, the register data is used to address a charac-

ter generator that stores the data for the 14- and 16-

segment fonts (Tables 7 and 8). The lower 7 bits of the

digit data (D6 to D0) select the character from the font.

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