CS5520-BSZ Cirrus Logic Inc, CS5520-BSZ Datasheet - Page 35

• Manufacturer Part Number: CS5520-BSZ
• Description: IC ADC 20BIT BRIDGE TRAS 24-SOIC
• Manufacturer: Cirrus Logic Inc

Specifications of CS5520-BSZ

• Number Of Bits: 20
• Sampling Rate (per Second): 60
• Data Interface: Serial
• Number Of Converters: 2
• Power Dissipation (max): 37.5mW
• Voltage Supply Source: Analog and Digital, Dual ±
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 24-SOIC (0.300", 7.50mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 598-1102-5

ample, the board comes with a set of precision
resistors which divide the excitation supply
(nominally 10 volts total) down to 2.5 volts be-
tween the VREF+ and VREF- input pins. This
sets the nominal full scale voltage into the A/D
converter. The input span of the instrumentation
amplifier can be calculated to by knowing the
PGA gain setting, and that the gain of the instru-
mentation amplifier is X25. If the PGA is set for
a gain of 8, then the input span to the instrumen-
tation amplifier will be 2.5 volts (VREF+ -
VREF-) divided by 8 X 25, or 2.5/(200) = 12.5
millivolt nominal in unipolar mode. The device
can be then calibrated with an input voltage
which is as low as 20% less than nominal or up
to 20% greater than nominal. Therefore, with
this VREF+ - VREF- voltage (2.5 volts) and a
PGA gain of 8 the input span can be calibrated
to handle a span from a low of 10 mV to a high
of 15 mV. To modify the input span the user can
either change the PGA gain or modify the resis-
tor divider on the bridge sense voltage to yield
an appropriate value in the range of 2.0 to 3.8
volts. This makes the A/D converter quite flex-
_
DS74DB4
DS74DB3
Figure 4. 4-Wire Bridge Connections
+
SIG +
SIG -
SENSE +
SENSE -
EXC +
EXC -
ible in handling load cells with different output
levels.
transducer device, the CS5516 or the CS5520
A/D converter operates in ratiometric measure-
ment mode. Figures 4 and 5 illustrate how to
connect 4-wire and 6-wire bridge transducers to
the board.
Alternatively, the CS5516 or CS5520 can be
configured for absolute measurement if a preci-
sion reference voltage is supplied between the
VREF+ and VREF- pins of the A/D converter.
The board can be modified to accept a reference
into the voltage reference terminal block; or the
on-board LT1019-2.5 volt reference can be used
as the reference voltage for the A/D converter.
To use either of these inputs will require that
jumper wires be soldered in either 1A-1B to se-
lect the external voltage reference input, or
2A-2B to select the on-board LT1019-2.5. Fig-
ure 6 illustrates the connection of an external
voltage reference to the evaluation board for ab-
solute voltage measurement applications. To
achieve an accurate reference voltage resistor R6
_
Figure 5. 6-Wire Bridge Connections
Whenever configured as a bridge
+
CDB5516/CDB5520
SIG +
SIG -
SENSE +
SENSE -
EXC +
EXC -
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