MAX1447 Datasheet, PDF (14/24 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
Decimal-Point Control
The MAX1447/MAX1496/MAX1498 allow for full deci-
mal-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 MAX1447/MAX1496/MAX1498 overrange
and underrange display is shown in Table 4.
Leading-Zero Suppression
The MAX1447/MAX1496/MAX1498 include a leading-
zero suppression circuitry to turn off unnecessary zeros.
For example, when DPSET1 and DPSET2 = [0,0], 0.0 is
displayed instead of 000.0. This feature saves a substan-
tial amount of power from being wasted.
Interdigit Blanking
The MAX1447/MAX1496/MAX1498 also include an
interdigit blanking circuitry. Without this feature, it is
possible to see a faint digit next to a digit that is com-
pletely on. The interdigit blanking circuitry prevents
bleeding over into the next digit for a short period of
time. The typical interdigit blanking time is 4µs.
Reference
The MAX1447/MAX1496/MAX1498 reference sets the
full-scale range of the ADC transfer function. With a
nominal 2.048V reference, the ADC full-scale range is
±2V with RANGE = GND. With RANGE = DV_DD
(MAX1447/MAX1498) or V_DD (MAX1496), the full-scale
range is ±200mV. A decreased reference voltage
decreases full-scale range (see the Transfer Functions
section).
The MAX1447/MAX1496/MAX1498 accept either an
external reference or an internal reference (INTREF).
The INTREF logic selects the reference mode.
For internal-reference operation, set INTREF to DV_DD
(MAX1447/MAX1498) or V_DD (MAX1496), connect REF-
to GND, and bypass REF+ to GND with a 4.7µF capaci-
tor. The internal reference provides a nominal 2.048V
source between REF+ and GND. The internal-reference
temperature coefficient is typically 40ppm/°C.
Table 2. Decimal-Point Control Table—MAX1447/MAX1498
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—MAX1496
DPSET1
DPSET2
DISPLAY OUTPUT
0
0
188.8
0
1
1
0
18.88
1888
1
1
X = Don’t care.
1.888
ZERO INPUT READING
0.0
0.00
0
0.000
Table 4. LED During Overrange and
Underrange Conditions
CONDITION
Overrange
Underrange
MAX1496
1---
-1---
MAX1447/MAX1498
1----
-1----
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