MAX6954
Detailed Description
The MAX6954 is a serially interfaced display driver that
can drive up to 16 digits 7-segment, 8 digits 14-seg-
ment, 8 digits 16-segment, 128 discrete LEDs, or a
combination of these display types. Table 1 shows the
drive capability of the MAX6954 for monocolor and
bicolor displays.
The MAX6954 includes 104-character ASCII font maps
for 14-segment and 16-segment displays, as well as
the hexadecimal font map for 7-segment displays. The
characters follow the standard ASCII font, with the addi-
tion of the following common symbols: £, €, ¥, °, µ, ±,
↑, and ↓. Seven bits represent the 104-character font
map; an 8th bit is used to select whether the decimal
point (DP) is lit. Seven-segment LED digits may be con-
trolled directly or use the hexadecimal font. Direct seg-
ment control allows the MAX6954 to be used to drive
bar graphs and discrete LED indicators.
Tables 2, 3, and 4 list the connection schemes for 16-,
14-, and 7-segment digits, respectively. The letters in
Tables 2, 3, and 4 correspond to the segment labels
shown in Figure 1. (For applications that require mixed
display types, see Tables 37–40.)
Serial Interface
The MAX6954 communicates through an SPI-compati-
ble 4-wire serial interface. The interface has three
4-Wire Interfaced, 2.7V to 5.5V LED Display
Driver with I/O Expander and Key Scan
6 _______________________________________________________________________________________
Pin Description
P0–P4
General-Purpose I/O Ports (GPIOs). GPIO can be configured as logic inputs or
open-drain outputs. Enabling key scanning configures some or all ports P0–P3 as
key-switch matrix inputs with internal pullup and port P4 as IRQ output.
3338CS
Chip-Select Input. Serial data is loaded into the shift register while CS is low. The
most recent 16 bits of data latch on CS’s rising edge.
4 4 39 DOUT
Serial-Data Output. The data into DIN is valid at DOUT 15.5 clock cycles later. Use
this pin to daisy-chain several devices or allow data readback. Output is push-pull.
Clock Output. OSC_OUT is a buffered clock output to allow easy blink
synchronization of multiple MAX6954s. Output is push-pull.
— 16, 25 11, 20 N.C. Not Connected Internally
———EP
Exposed Pad (TQFN package only). Internally connected to GND. Connect to a
large ground plane to maximize thermal performance.