Datasheet

MAX1447/MAX1496/MAX1498
3.5- and 4.5-Digit, Single-Chip ADCs
with LED Drivers
______________________________________________________________________________________ 13
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
Tms
s MAX MAX
T
Tms
s MAX
ON
ON
== =
== =
5
1 95312
5
390 60 1447 1498
4
1 5625
4
390 60 1496
.
.( / )
.
.( )
µ
µ
A
A
A
DIGIT 1 DIGIT 2
SEGDP
SEGG
SEGF
SEGE
SEGD
SEGC
SEGB
SEGA
DD
EE
GG
FF
BB
CC
DP DP
B C D E F G DP A B C D E F G DP
Figure 5. Two-Digit Common-Cathode Configuration
143210432 04
T
T
ON
DIGIT 4 (MSD)
DIGIT 3
DIGIT 2
DIGIT 1
DIGIT 0 (LSD)
DATA
MSD LSD
Figure 6. LED Voltage Waveform—MAX1447/MAX1498
332103210 21
T
T
ON
DIGIT 3 (MSD)
DIGIT 2
DIGIT 1
DIGIT 0 (LSD)
DATA
MSD LSD
Figure 7. LED Voltage Waveform—MAX1496