Datasheet
MAX1497/MAX1499
3.5- and 4.5-Digit, Single-Chip ADCs with LED
Drivers and µC Interface
14 ______________________________________________________________________________________
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 MAX1497/
MAX1499 connects to its corresponding LEDs anodes.
For example, segment driver SEGA connects to all LED
segments designated as A. Similar configurations are
followed for other segment drivers.
The MAX1497/MAX1499 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 MAX1497/MAX1499 where T
is the display scan period typically around 1/512Hz or
1.9531ms for the MAX1499 and 1/640Hz or 1.5625ms for
the MAX1497. T
ON
in Figures 6 and 7 denotes the amount
of time each digit is on and is calculated as follows:
The MAX1497/MAX1499 allow for full decimal-point
control and feature leading-zero suppression. Use the
DPON, DPSET1, and DPSET2 bits in the control register
to set the value of the decimal point (Tables 2 and 3).
The MAX1497/MAX1499 overrange and underrange
display is shown in Table 4.
T
Tms
s MAX
T
Tms
s MAX
ON
ON
== =
== =
5
1 95312
5
390 60 1499
4
1 5625
4
390 60 1497
.
.( )
.
.( )
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
Table 2. Decimal-Point Control Table—MAX1499
DPON DPSET1 DPSET2 DISPLAY OUTPUT ZERO INPUT READING
00 0 18888 0
00 1 18888 0
01 0 18888 0
01 1 18888 0
10 0 1888.8 0.0
10 1 188.88 0.00
11 0 18.888 0.000
11 1 1.8888 0.0000
Table 3. Decimal-Point Control Table—MAX1497
DPON DPSET1 DPSET2 DISPLAY OUTPUT ZERO INPUT READING
X00 188.8 0.0
X01 18.88 0.00
X10 1888 0
X11 1.888 0.000
X = Don’t care.
Table 4. LED During Overrange and
Underrange Conditions
CONDITION MAX1497 MAX1499
Overrange 1--- 1----
Underrange -1--- -1----