MAX1497 Datasheet, PDF (14/33 Pages) Maxim Integrated Products – 3.5- and 4.5-Digit, Single-Chip ADCs with LED Drivers and μC Interface

3.5- and 4.5-Digit, Single-Chip ADCs with LED
Drivers and µC Interface
Table 2. Decimal-Point Control Table—MAX1499
DPON
0
0
0
0
1
1
1
1
DPSET1
0
0
1
1
0
0
1
1
DPSET2
0
1
0
1
0
1
0
1
DISPLAY OUTPUT
18888
18888
18888
18888
1888.8
188.88
18.888
1.8888
ZERO INPUT READING
0
0
0
0
0.0
0.00
0.000
0.0000
Table 3. Decimal-Point Control Table—MAX1497
DPON
DPSET1
DPSET2
DISPLAY OUTPUT
ZERO INPUT READING
X
0
0
188.8
0.0
X
0
1
18.88
0.00
X
1
0
1888
0
X
1
1
1.888
0.000
X = Don’t care.
Table 4. LED During Overrange and
Underrange Conditions
CONDITION
Overrange
Underrange
MAX1497
1---
-1---
MAX1499
1----
-1----
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
SEGDP
make the digits appear to be lit. Figures 6 and 7 show
SEGG
data timing diagrams for the MAX1497/MAX1499 where T
SEGF
is the display scan period typically around 1/512Hz or
SEGE
1.9531ms for the MAX1499 and 1/640Hz or 1.5625ms for
SEGD
the MAX1497. T_ON in Figures 6 and 7 denotes the amount
of time each digit is on and is calculated as follows:
SEGC
SEGB
SEGA
A B C D E F G DP A B C D E F G DP
T_ON =
T
5
= ^1.95312ms
5
= 390.60µs
(MAX1499)
DIGIT 1
A
F _GB
E
C
DP
D
DIGIT 2
A
FGB
E
C
DP
D
Figure 5. Two-Digit Common-Cathode Configuration
T_ON
=
T
4
=
1.5625ms
4
=
390.60µs
(MAX1497)
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.
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