MAX6954 Maxim, MAX6954 Datasheet - Page 6

• Manufacturer Part Number: MAX6954
• Description: 4-Wire Interfaced / 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan
• Manufacturer: Maxim

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
addition of the following common symbols: £,
±, , and . Seven bits represent the 104-character font
4-Wire Interfaced, 2.7V to 5.5V LED Display
Driver with I/O Expander and Key Scan
6
34, 35, 36
16, 18
19, 21
22–31
SSOP
7–15,
1, 2,
_______________________________________________________________________________________
17
20
32
33
—
3
4
5
6
PIN
38, 39, 40
17, 18, 20
21, 23, 24
26–35
16, 25
7–15,
PDIP
1, 2,
19
22
36
37
3
4
5
6
Detailed Description
OSC_OUT
O0–O18
NAME
P0–P4
BLINK
DOUT
GND
ISET
OSC
N.C.
CLK
DIN
CS
V+
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.
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.
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.
Serial-Clock Input. On CLK’s rising edge, data shifts into the internal shift register. On CLK’s
falling edge, data is clocked out of DOUT. CLK is active only while CS is low.
Serial-Data Input. Data from DIN loads into the internal 16-bit shift register on CLK’s rising
edge.
Digit/Segment Drivers. When acting as digit drivers, outputs O0 to O7 sink current from the
display common cathodes. When acting as segment drivers, O0 to O18 source current to the
display anodes. O0 to O18 are high impedance when not being used as digit or segment
drivers.
Ground
Segment Current Setting. Connect ISET to GND through series resistor R
current.
Positive Supply Voltage. Bypass V+ to GND with a 47µF bulk capacitor and a 0.1µF ceramic
capacitor.
Multiplex Clock Input. To use internal oscillator, connect capacitor C
To use external clock, drive OSC with a 1MHz to 8MHz CMOS clock.
Blink Clock Output. Output is open drain.
Clock Output. OSC_OUT is a buffered clock output to allow easy blink synchronization of
multiple MAX6954s. Output is push-pull.
Not Internally Connected
, ¥, °, µ,
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.)
The MAX6954 communicates through an SPI-compati-
ble 4-wire serial interface. The interface has three
FUNCTION
Pin Description
SET
Serial Interface
from OSC to GND.
SET
to set the peak