MAX6955AAX+T Maxim Integrated Products, MAX6955AAX+T Datasheet - Page 11

• Manufacturer Part Number: MAX6955AAX+T
• Description: IC DRVR DSPL LED 36-SSOP
• Manufacturer: Maxim Integrated Products

Specifications of MAX6955AAX+T

• Display Type: LED
• Configuration: 7, 14, 16 Segment
• Interface: I²C
• Current - Supply: 22mA
• Voltage - Supply: 2.7 V ~ 5.5 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 36-SSOP
• Number Of Digits: 16
• Number Of Segments: 128
• Low Level Output Current: 935 mA
• High Level Output Current: 55 mA
• Operating Supply Voltage: 2.7 V to 5.5 V
• Maximum Supply Current: 30 mA
• Maximum Power Dissipation: 941 mW
• Maximum Operating Temperature: + 125 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Digits Or Characters: -
• Lead Free Status / Rohs Status: Details

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 8 and 9). The lower 7 bits of the
digit data (D6 to D0) select the character from the font.
The most significant bit of the register data (D7) con-
trols the DP segment of the digits; it is set to 1 to light
DP, and to zero to leave DP unlit (Table 10).
For 7-segment displays, the digit plane data register
can be used to address a character generator, which
contains the data of a 16-character font containing the
hexadecimal font. The decode mode register can be
used to disable the character generator and allow the
segments to be controlled directly. Table 11 shows the
one-to-one pairing of each data bit to the appropriate
segment line in the digit plane data registers. The hexa-
decimal font is decoded according to Table 12.
The digit-type register configures the display driver for
various combinations of 14-segment digits, 16-segment
digits, and/or pairs, or 7-segment digits. The function of
this register is to select the appropriate font for each
digit and route the output of the font to the appropriate
MAX6955 driver output pins. The MAX6955 has four
digit drive slots. A slot can be filled with various combi-
nations of monocolor and bicolor 16-segment displays,
14-segment displays, or two 7-segment displays. Each
pair of bits in the register corresponds to one of the four
digit drive slots, as shown in Table 13. Each bit also cor-
responds to one of the eight common-cathode digit
drive outputs, CC0 to CC7. When using bicolor digits,
the anode connections for the two digits within a slot are
always the same. This means that a slot correctly drives
two monocolor or one bicolor 14- or 16-segment digit.
The digit type register can be written, but cannot be
read. Examples of configuration settings required for
some display digit combinations are shown in Table 14.
In 7-segment mode, the hexadecimal font can be dis-
abled (Table 15). The decode-mode register selects
between hexadecimal code or direct control for each of
eight possible pairs of 7-segment digits. Each bit in the
register corresponds to one pair of digits. The digit
pairs are {digit 0, digit 0a} through {digit 7, digit 7a}.
Disabling decode mode allows direct control of the 16
LEDs of a dual 7-segment display. Direct control mode
can also be used to drive a matrix of 128 discrete LEDs.
A logic high selects hexadecimal decoding, while a
logic low bypasses the decoder. When direct control is
selected, the data bits D7 to D0 correspond to the seg-
ment lines of the MAX6955. Write x0010000 to blank all
segments in hexadecimal decode mode.
2-Wire Interfaced, 2.7V to 5.5V LED Display
7-Segment Decode-Mode Register
______________________________________________________________________________________
Driver with I/O Expander and Key Scan
The display blinking facility, when enabled, makes the
driver flip automatically between displaying the digit
register data in planes P0 and P1. If the digit register
data for any digit is different in the two planes, then that
digit appears to flip between two characters. To make a
character appear to blink on or off, write the character
to one plane, and use the blank character (0x20) for the
other plane. Once blinking has been configured, it con-
tinues automatically without further intervention.
The blink speed is determined by the frequency of the
multiplex clock, OSC, and by the setting of the Blink
Rate Selection Bit B (Table 19) in the configuration reg-
ister. The Blink Rate Selection Bit B sets either fast or
slow blink speed for the whole display.
On initial power-up, all control registers are reset, the
display is blanked, intensities are set to minimum, and
shutdown is enabled (Table 16).
The configuration register is used to enter and exit shut-
down, select the blink rate, globally enable and disable
the blink function, globally clear the digit data, select
between global or digit-by-digit control of intensity, and
reset the blink timing (Tables 17–20 and 22–25).
The configuration register contains 7 bits:
• S bit selects shutdown or normal operation
• B bit selects the blink rate (read/write).
• E bit globally enables or disables the blink function
• T bit resets the blink timing (data is not stored—tran-
• R bit globally clears the digit data for both planes P0
• I bit selects between global or digit-by-digit control
• P bit returns the current phase of the blink timing
The font is composed of 104 characters in ROM. The
lower 7 bits of the 8-bit digit register represent the char-
acter selection. The most significant bit, shown as x in
the ROM map of Tables 8 and 9, is 1 to light the DP
segment and zero to leave the DP segment unlit.
The character map follows the standard ASCII font for
96 characters in the x0101000 through x1111111
(read/write).
(read/write).
sient bit).
and P1 for ALL digits (data is not stored—transient bit).
of intensity (read/write).
(read only—a write to this bit is ignored).
Character Generator Font Mapping
Configuration Register
Display Blink Mode
Initial Power-Up
Blink Speed
11