MAX1447 Datasheet, PDF (13/24 Pages) Maxim Integrated Products – 3.5- and 4.5-Digit, Single-Chip ADCs with LED Drivers

3.5- and 4.5-Digit, Single-Chip ADCs
with LED Drivers
SEGDP
SEGG
SEGF
SEGE
SEGD
SEGC
SEGB
SEGA
A B C D E F G DP A B C D E F G DP
DIGIT 1
A
F _GB
E
C
DP
D
DIGIT 2
A
FGB
E
C
DP
D
Figure 5. Two-Digit Common-Cathode Configuration
Figure 5 shows a typical common-cathode configura-
tion for two digits. In common-cathode configuration,
the cathodes of all LEDs in a digit are connected
together. Each segment driver of the MAX1447/
MAX1496/MAX1498 connects to its corresponding
LED’s anodes. For example, segment driver SEGA con-
nects to all LED segments designated as A. Similar
configurations are used for other segment drivers.
The MAX1447/MAX1496/MAX1498 use a multiplexing
scheme to drive one digit at a time. The scan rate is fast
enough to make the digits appear to be lit. Figures 6 and
7 show data-timing diagrams for the MAX1447/
MAX1496/MAX1498, where T is the display scan period
(typically around 1/512Hz or 1.9531ms for the
MAX1447/MAX1498, and 1/640Hz or 1.5625ms for the
MAX1496). T_ON in Figures 6 and 7 denotes the amount
of time each digit is on and is calculated as follows:
T_ON =
T ₌ 1.95312ms
5
5
= 390.60µs
(MAX1447 / MAX1498)
T_ON =
T ₌ 1.5625ms _{= 390.60µs}
4
4
(MAX1496)
DIGIT 4 (MSD)
DIGIT 3
DIGIT 2
DIGIT 1
DIGIT 0 (LSD)
DATA
T_ON
T
43210432104
MSD
LSD
Figure 6. LED Voltage Waveform—MAX1447/MAX1498
DIGIT 3 (MSD)
DIGIT 2
DIGIT 1
DIGIT 0 (LSD)
DATA
T_ON
T
32103210321
MSD
LSD
Figure 7. LED Voltage Waveform—MAX1496
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