S e ria lly In t e rfa c e d , 8 -Dig it LED Dis p la y Drive rs
9/MAX721
Table 7. Intensity Register Format (Address (Hex) = XA)
DUTY CYCLE
HEX
CODE
D7
D6
D5
D4
D3
D2
D1
D0
MAX7219
MAX7221
1/32
(min on)
1/16
(min on)
X
X
X
X
0
0
0
0
X0
3/32
5/32
2/16
3/16
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
0
0
0
0
0
0
0
1
1
1
1
1
1
1
0
0
0
1
1
1
1
0
0
0
0
1
1
1
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
0
1
0
1
0
X1
X2
X3
X4
X5
X6
X7
X8
X9
XA
XB
XC
XD
XE
7/32
4/16
9/32
5/16
11/32
13/32
15/32
17/32
19/32
21/32
23/32
25/32
27/32
29/32
6/16
7/16
8/16
9/16
10/16
11/16
12/16
13/16
14/16
15/16
15/16
(max on)
31/32
X
X
X
X
1
1
1
1
XF
Table 8. Scan-Limit Register Format (Address (Hex) = XB)
REGISTER DATA
SCAN LIMIT
HEX
CODE
D7
X
X
X
X
X
X
X
X
D6
X
X
X
X
X
X
X
X
D5
X
X
X
X
X
X
X
X
D4
X
X
X
X
X
X
X
X
D3
X
X
X
X
X
X
X
X
D2
0
D1
0
D0
0
Display digit 0 only*
X0
X1
X2
X3
X4
X5
X6
X7
Display digits 0 & 1*
0
0
1
Display digits 0 1 2*
0
1
0
Display digits 0 1 2 3
0
1
1
Display digits 0 1 2 3 4
Display digits 0 1 2 3 4 5
Display digits 0 1 2 3 4 5 6
Display digits 0 1 2 3 4 5 6 7
1
0
0
1
0
1
1
1
0
1
1
1
*See Scan-Limit Register section for application.
scanned. Since the number of scanned digits affects
the display brightness, the scan-limit register should
not be used to blank portions of the display (such as
leading zero suppression). Table 8 lists the scan-limit
register format.
S c a n -Lim it Re g is t e r
The scan-limit register sets how many digits are dis-
played, from 1 to 8. They are displayed in a multiplexed
manner with a typical display scan rate of 800Hz with 8
digits displayed. If fewer digits are displayed, the scan
ra te is 8f
/N, whe re N is the numb e r of d ig its
OSC
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9
MAXIM [ MAXIM INTEGRATED PRODUCTS ]
