CDB5374 Cirrus Logic Inc, CDB5374 Datasheet - Page 19

• Manufacturer Part Number: CDB5374
• Description: Audio Modules & Development Tools 2-Ch DS Modulator & Hydrophone Demo Brd
• Manufacturer: Cirrus Logic Inc

Specifications of CDB5374

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

2.2.5
A voltage reference on CDB5374 creates a precision voltage from the regulated analog supplies for the
modulator and test DAC VREF inputs. Because the voltage reference output is generated relative to the
negative analog power supply, VREF+ is near GND potential for bipolar power supplies.
2.2.5.1
The voltage reference output is provided to the CS5374 ∆Σ modulators and the CS4373A test DAC
through separate low-pass RC filters. By separately filtering the voltage reference for each device, signal-
dependent sampling of VREF by one device is isolated from other devices. Each voltage reference signal
is routed as a separate differential pair from the large RC filter capacitor to control the sensitive VREF
source-return currents and keep them out of the ground plane. In addition to the RC filter function, the
100 uF filter capacitor provides a large charge well to help settle voltage reference sampling transients.
2.2.5.2
A buffered version of the voltage reference is created as a low-impedance common mode bias source for
the analog signal inputs. The bias resistors connected between the buffered voltage reference and each
analog signal input half depends on the sensor type and should be modified to match the sensor manu-
facturer recommendations.
DS862DB1
Specification
Precision Reference - Linear Tech
Surface Mount Package Type
Output Voltage Tolerance
Temperature Drift
Quiescent Current
Output Voltage Noise, 10 Hz - 1 kHz
Ripple Rejection, 10 Hz - 200 Hz
Voltage Reference
VREF_MOD12, VREF_MOD34, VREF_DAC
Common Mode Bias
Value
LT1019AIS8-2.5
SO-8
+/- 0.05%
10 ppm / degC
0.65 mA
4 ppm
> 100 dB
RMS
CDB5374
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