Rainbow Electronics MAX1367 - Manual (Page 13)

The MAX1365/MAX1367 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. Figure 5 shows the
data-timing diagram for the MAX1365/MAX1367 where
T is the display scan period (typically around 1/512Hz
or 1.9531ms). T
ON in Figure 5 denotes the amount of
time each digit is on and is calculated as follows:
Decimal-Point Control
The MAX1365/MAX1367 allow for full decimal-point
control and feature leading-zero suppression.
Use the DPON, DPSET1, and DPSET2 bits in the con-
trol register to set the value of the decimal point (Tables
2 and 3). The MAX1365/MAX1367 overrange and
underrange display is shown in Table 4.
Leading-Zero Suppression
The MAX1365/MAX1367 include a leading-zero sup-
pression circuitry to turn off unnecessary zeros. For
example, when DPSET1 and DPSET2 = [0,0], 0.0 is dis-
played instead of 000.0 (MAX1365). This feature saves
a substantial amount of power by not lighting unneces-
sary LEDs.
Interdigit Blanking
The MAX1365/MAX1367 also include an interdigit-
blanking circuitry. Without this feature, it is possible to
see a faint digit next to a digit that is completely on.
The interdigit-blanking circuitry prevents ghosting over
into the next digit for a short period of time. The typical
interdigit blanking time is 4µs.
T
T ms
s
ON
= = =
5
1 95312
5
390 60
.
. µ
MAX1365/MAX1367
Stand-Alone, 4.5-/3.5-Digit Panel Meters
with 4–20mA Output
______________________________________________________________________________________ 13
A
B
C
A A A A
D
DIGIT 4 DIGIT 3 DIGIT 2 DIGIT 1 DIGIT 0
D D D D
E
G
F
E E E
G G G G F F F F B B B B
C C C C
DP DP DP DP DP
Figure 2. Segment Connection for the MAX1365 (4.5 Digits)
A
B
A A A
D
DIGIT 4 DIGIT 3 DIGIT 2 DIGIT 1
D D D
E
G
F
E E
G G G F F F B B B
C C C
DP DP DP DP
C
Figure 3. Segment Connection for the MAX1367 (3.5 Digits)
HOLD PEAK DISPLAY VALUES FORM
1 X Hold value
0 1 Peak value
0 0 Latest ADC result
Table 1. LED Priority Table
X = Don’t care.
DPON DPSET1 DPSET2
DISPLAY
OUTPUT
ZERO INPUT
READING
1 0 0 1888. 0.
1 0 1 188.8 0.0
1 1 0 18.88 0.00
1 1 1 1.888 0.000
Table 3. Decimal-Point Control Table—
MAX1367
CONDITION MAX1367 MAX1365
Overrange 1--- 1----
Underrange -1--- -1----
Table 4. LED During Overrange and
Underrange Conditions
DPON DPSET1 DPSET2
DISPLAY
OUTPUT
ZERO INPUT
READING
0 0 0 18888 0
0 0 1 18888 0
0 1 0 18888 0
0 1 1 18888 0
1 0 0 1888.8 0.0
1 0 1 188.88 0.00
1 1 0 18.888 0.000
1 1 1 1.8888 0.0000
Table 2. Decimal-Point Control Table—
MAX1365