MAX7219_07 Datasheet, PDF (8/16 Pages) Maxim Integrated Products – Serially Interfaced, 8-Digit LED Display Drivers

Serially Interfaced, 8-Digit LED Display Drivers
Table 5. Code B Font
7-SEGMENT
REGISTER DATA
ON SEGMENTS = 1
CHARACTER _{D7* D6–D4 D3 D2 D1 D0 DP* A}
B
C
D
E
F
G
0
1
2
3
4
5
6
7
8
9
—
E
H
L
P
blank
X
0
0
0
0
X
0
0
0
1
X
0
0
1
0
X
0
0
1
1
X
0
1
0
0
X
0
1
0
1
X
0
1
1
0
X
0
1
1
1
X
1
0
0
0
X
1
0
0
1
X
1
0
1
0
X
1
0
1
1
X
1
1
0
0
X
1
1
0
1
X
1
1
1
0
X
1
1
1
1
*The decimal point is set by bit D7 = 1
1
1
1
1
1
1
0
0
1
1
0
0
0
0
1
1
0
1
1
0
1
1
1
1
1
0
0
1
0
1
1
0
0
1
1
1
0
1
1
0
1
1
1
0
1
1
1
1
1
1
1
1
0
0
0
0
1
1
1
1
1
1
1
1
1
1
1
0
1
1
0
0
0
0
0
0
1
1
0
0
1
1
1
1
0
1
1
0
1
1
1
0
0
0
1
1
1
0
1
1
0
0
1
1
1
0
0
0
0
0
0
0
Table 6. No-Decode Mode Data Bits and
Corresponding Segment Lines
A
F
B
G
STANDARD 7-SEGMENT LED
E
C
D
DP
REGISTER DATA
D7 D6 D5 D4 D3 D2 D1 D0
Corresponding
Segment Line
DP
A
B
C
D
E
F
G
Intensity Control
and Interdigit Blanking
The MAX7219/MAX7221 allow display brightness to be
controlled with an external resistor (R_SET) connected
between V+ and ISET. The peak current sourced from
the segment drivers is nominally 100 times the current
entering ISET. This resistor can either be fixed or vari-
able to allow brightness adjustment from the front
panel. Its minimum value should be 9.53kΩ, which typi-
cally sets the segment current at 40mA. Display bright-
ness can also be controlled digitally by using the
intensity register.
Digital control of display brightness is provided by an
internal pulse-width modulator, which is controlled by
the lower nibble of the intensity register. The modulator
scales the average segment current in 16 steps from a
maximum of 31/32 down to 1/32 of the peak current set
by R_SET (15/16 to 1/16 on MAX7221). Table 7 lists the
intensity register format. The minimum interdigit blank-
ing time is set to 1/32 of a cycle.
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