MAX1492 Datasheet, PDF (15/35 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
φ1
φ2
φ3
φ1'
φ2'
φ3'
BP1
BP2
BP3
ALL
OFF
a ON
g, d OFF
g ON
a, d OFF
d ON
a, g OFF
V+
VH
VLCD
VL
V-
V+
VH
VL
V-
V+
VH
VL
V-
V+
VH
VL
V-
V+
VH
VL
V-
V+
VH
VL
V-
V+
VH
VL
V-
FREQUENCY = 107Hz
φ1, φ2, φ3 - - BP HIGH WITH RESPECT TO SEGMENT (BP+ TIME)
φ1', φ2', φ3' - - BP LOW WITH RESPECT TO SEGMENT (BP- TIME)
BP1 ACTIVE DURING φ1 AND φ1'
BP2 ACTIVE DURING φ2 AND φ2'
BP3 ACTIVE DURING φ3 AND φ3'
Figure 9. LCD Voltage Waveform—Combinations 1–4 (BP_, SEG2/5/8)
V+ = DVDD, VH = 2/3 DVDD
VL = 1/3 VLCD, V- = GND OR VDISP
VLCD = DVDD - VDISP (MAX1494)
VLCD = DVDD - GND (MAX1492)
Figure 21 shows the MAX1492/MAX1494 operating with
an external single-ended reference. In this mode, REF-
is connected to GND and REF+ is driven with an exter-
nal 2.048V reference. Bypass REF+ to GND with a
0.47µF capacitor.
Figure 20 shows the MAX1492/MAX1494 operating with
an external differential reference. In this mode, REF-
is connected to the top of the strain gauge and REF+
is connected to the midpoint of the resistor-divider of
the supply.
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