MAX6957 MAXIM [Maxim Integrated Products], MAX6957 Datasheet - Page 6

• Manufacturer Part Number: MAX6957
• Description: 4-Wire-Interfaced, 2.5V to 5.5V, 20-Port and 28-Port LED Display Driver and I/O Expander
• Manufacturer: MAXIM [Maxim Integrated Products]

ond driver. The first driver ignores the last 4 bits and
the second driver ignores the first 4 bits.
Two addressing methods are available. Any single port
(bit) can be written (set/cleared) at once; or, any
sequence of eight ports can be written (set/cleared) in
any combination at once. There are no boundaries; it is
equally acceptable to write P0 through P7, P1 through
P8, or P31 through P38 (P32 through P38 are nonexis-
tent, so the instructions to these bits are ignored).
Using 8-bit control, a seven-segment digit with a deci-
mal point can be updated in a single byte-write, a 14-
segment digit with DP can be updated in two
byte-writes, and 16-segment digits with DP can be
updated in two byte-writes plus a bit write. Also, dis-
crete LEDs and GPIO port bits can be lit and controlled
individually without affecting other ports.
Table 2. Port Configuration Matrix
Note: The logic is inverted between the two output modes; a high makes the output go low in LED segment driver mode (0x00) to
turn that segment on; in GPIO output mode (0x01), a high makes the output go high.
4-Wire-Interfaced, 2.5V to 5.5V, 20-Port and
28-Port LED Display Driver and I/O Expander
Table 1. Port Configuration Map
6
Port Configuration for P7, P6, P5, P4
Port Configuration for P11, P10, P9, P8
Port Configuration for P15, P14, P13, P12
Port Configuration for P19, P18, P17, P16
Port Configuration for P23, P22, P21, P20
Port Configuration for P27, P26, P25, P24
Port Configuration for P31, P30, P29, P28
Output
Output
MODE
Input
Input
_______________________________________________________________________________________
GPIO Input with Pullup
LED Segment Driver
Without Pullup
GPIO Output
FUNCTION
GPIO Input
REGISTER
Reading Port
Reading Port
Written High
Written High
Written Low
Written Low
REGISTER
PORT
CODE (HEX)
High impedance
Open-drain current sink, with sink
current (up to 24mA) determined
by the appropriate current register
Active-low logic output
Active-high logic output
Schmitt logic input
Schmitt logic input with pullup
ADDRESS
0x0C
0x0D
0x0A
0x0B
0x0E
0x09
0x0F
PIN BEHAVIOR
When the MAX6957 is in shutdown mode, all ports are
forced to inputs, and the pullup current sources are
turned off. Data in the port and control registers remain
unaltered so port configuration and output levels are
restored when the MAX6957 is taken out of shutdown.
The display driver can still be programmed while in
shutdown mode. For minimum supply current in shut-
down mode, logic inputs should be at GND or V+
potential. Shutdown mode is exited by setting the S bit
in the configuration register (Table 6). Shutdown mode
is temporarily overridden by the display test function.
D7
P11
P15
P19
P23
P27
P31
P7
D6
D5
P10
P14
P18
P22
P26
P30
P6
REGISTER DATA
CODE (HEX)
0x09 to 0x0F
0x09 to 0x0F
0x09 to 0x0F
0x09 to 0x0F
ADDRESS
D4
D3
P13
P17
P21
P25
P29
P5
P9
UPPER
CONFIGURATION
D2
0
0
1
1
BIT PAIR
PORT
D1
Shutdown
LOWER
P12
P16
P20
P24
P28
P4
P8
0
1
0
1
D0