CDB5378 Datasheet, PDF (31/72 Pages) Cirrus Logic – Single-channel Seismic Evaluation System

CDB5378
Specification
Negative Analog Supply, -2.5VA
Low Noise Micropower Regulator - Linear Tech
Surface Mount Package Type
Load Regulation, -40 C to +85 C
Quiescent Current, Current @ 100 mA Load
Output Voltage Noise, 10 Hz - 100 kHz
Ripple Rejection, DC - 200 Hz
Value
-2.5 V
LT1964ES5-BYP
SOT-23
+/- 30 mV
30 µA, 1.3 mA
20 µV_RMS
> 45 dB
The VA+ and VA- power supplies to the analog components on CDB5378 can be jumpered to use regu-
lated bipolar power supplies (+2.5 V, -2.5 V), regulated unipolar power supplies (+5 V, GND), or unregu-
lated direct connections (EXT_VA+, EXT_VA-). When using direct connections to EXT_VA+ and
EXT_VA-, extreme care must be taken not to exceed the maximum specified power supply voltages of
the analog components on CDB5378.
Characterization testing has shown the analog components on CDB5378 work best using bipolar analog
power supplies (+2.5 V, -2.5 V) instead of unipolar analog power supplies (+5 V, GND). It is recommend-
ed to always use the regulated bipolar analog power supplies for optimal performance.
The VA+ and VA- power supply nets to the analog components on CDB5378 include reverse-biased
Schottkey diodes to ground to protect against reverse voltages that could latch-up the CMOS analog com-
ponents. Also included on VA+ and VA- are 100 uF bulk capacitors for bypassing and to help settle tran-
sients plus individual 0.1 uF bypass capacitors local to the analog power supply pins of each device.
2.4.2 Digital Voltage Regulators
Linear voltage regulators create the positive digital power supply voltages on CDB5378. Jumper options
select which external power supply input voltage, EXT_VD or EXT_VA+, is supplied to the digital voltage
regulators to create the VD and VCORE power supplies.
Specification
Positive Digital Power Supply
Low Noise Micropower Regulator - Linear Tech
Surface Mount Package Type
Load Regulation, -40 C to +85 C
Quiescent Current, Current @ 100 mA Load
Output Voltage Noise, 10 Hz - 100 kHz
Ripple Rejection, DC - 200 Hz
Value
+2.5 V, +3.3 V
LT1763CS8
SO-8
+/- 25 mV
40 µA, 2 mA
20 µV_RMS
> 50 dB
The VD and VCORE power supplies on CDB5378 can be jumpered to use regulated +3.3 V or +2.5 V
power supplies or an unregulated direct connection to EXT_VD. Extreme care must be taken when using
a direct connection to EXT_VD not to exceed the maximum specified power supply voltages of the digital
components on CDB5378.
DS639DB3
31