MAX1492 Datasheet, PDF (14/35 Pages) Maxim Integrated Products – 3.5- and 4.5-Digit, Single-Chip ADCs with LCD Drivers

3.5- and 4.5-Digit, Single-Chip ADCs
with LCD Drivers
Table 2. Decimal-Point Control Table (MAX1494)
DP_EN
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
1 8 8 8.8
1 8 8.8 8
1 8.8 8 8
1.8 8 8 8
ZERO INPUT READING
0
0
0
0
0.0
0.00
0.000
0.0000
Table 3. Decimal-Point Control Table (MAX1492)
DP_EN
X
X
X
X
DPSET1
0
0
1
1
DPSET2
0
1
0
1
DISPLAY OUTPUT
1 8 8.8
1 8.8 8
1.8 8 8
1888
ZERO INPUT READING
0.0
0.00
0.000
000
X = Don’t care.
Table 4. LCD During Overrange and
Underrange Conditions
CONDITION
OVERRANGE
UNDERRANGE
MAX1492
1– – –
-1– – –
MAX1494
1– – – –
-1– – – –
X
BP1 ^f
BP2 ^e
BP3 ^DP
Y
Z
a
b
g
c
d
DP
Figure 8. Schematic of Display Digit
The MAX1492/MAX1494 allow for full decimal-point con-
trol and feature leading zero suppression. Use the
DP_EN, DPSET1, and DPSET2 bits in the control register
to set the value of the decimal point. Tables 2 and 3 show
the truth tables of the DP_EN, DPSET1, and DPSET2. The
truth tables determine decimal-point usage.
The MAX1492/MAX1494 overrange and underrange
display is shown in Table 4.
Reference
The MAX1492/MAX1494 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
the RANGE bit equal to 0. With the RANGE bit set to 1,
the full-scale range is ±200mV. A decreased reference
voltage decreases full-scale range (see the Transfer
Functions section).
The MAX1492/MAX1494 accept either an external ref-
erence or an internal reference. The INTREF bit selects
the reference mode (see the Control Register
(Read/Write) section).
For internal-reference operation, set INTREF to 1, con-
nect REF- to GND and bypass REF+ to GND with a
4.7µF capacitor. The internal reference provides a nom-
inal 2.048V source between REF+ and GND. The inter-
nal-reference temperature coefficient is typically
40ppm/°C.
The default power-on state sets the MAX1492/
MAX1494 to use the external reference with INTREF
cleared to 0. The external reference inputs, REF+ and
REF-, are fully differential. For a valid external-reference
input, V_REF+ must be greater than V_REF-. Bypass REF+
and REF- with a 0.1µF or greater capacitor to GND in
external-reference mode.
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