CS4373A-ISZ View Datasheet(PDF) - Cirrus Logic

Part Name

Description

MFG CO.

CS4373A-ISZ

Low-power, High-performance ∆Σ Test DAC

Cirrus Logic 

CS4373A

When enabled, attenuation is applied to both

the OUT and BUF differential analog outputs.

The OUT± pins connect directly into the inter-

nal attenuator resistors and so attenuation ac-

curacy is highly sensitive to load impedance

on the OUT± pins. Loading on the BUF± pins

does not affect attenuator accuracy.

The attenuation settings of CS4373A match

the gain ranges of the CS3301A / CS3302A

differential amplifiers to enable full-scale test-

ing at all gain ranges. The

CS3301A / CS3302A amplifier gain settings

(GAIN) are decoded identical to the CS4373A

attenuator settings (ATT) and so can share

GPIO signals from the digital filter.

7.3 OUT± Precision Output

The OUT± pins are precision differential ana-

log outputs for testing the high-performance

electronics measurement channel. These pre-

cision outputs have higher performance spec-

ifications than the BUF outputs, but with a

much higher sensitivity to external loading. Ex-

cessive resistive or capacitive loading on the

OUT± pins will degrade the analog perfor-

mance characteristics of the CS4373A in all

operational modes.

The OUT± precision output is optimized for di-

rect connection to the CS3301A / CS3302A

amplifier differential inputs, which have very

high input impedance. These amplifiers in-

clude a pin-controlled input multiplexer to

switch between an internal differential termina-

tion for noise tests and two external differential

inputs. One external amplifier input is typically

dedicated to sensor measurements and the

other to testing the electronics channel.

The OUT± outputs are enabled in all opera-

tional modes except “AC BUF Only” mode

(MODE 3) and sleep modes (MODE 0, 7). In

AC BUF Only and sleep modes the OUT± pins

are high impedance.

7.4 BUF± Buffered Output

The BUF± pins are buffered differential analog

outputs for testing external sensors such as

geophones or hydrophones. The buffered out-

puts have reduced performance specifications

compared with the OUT outputs, but are less

sensitive to external loading.

The BUF± outputs are enabled in all operation-

al modes except “AC OUT Only” mode

(MODE 2) and sleep modes (MODE 0, 7). In

AC OUT Only and sleep modes the BUF± pins

are high impedance to ensure they do not in-

terfere with sensor operation during normal

data acquisition.

For sensor impedance testing, it is required to

place matched series resistors in between the

BUF± outputs and the differential sensor. With

known series resistors and a known DC differ-

ential source voltage, sensor resistance can

be calculated ratiometrically from the mea-

sured voltage drop across the sensor.

7.5 CAP± Analog Output

The CS4373A requires a 10 nF C0G or NPO-

type capacitor connected differentially across

the CAP± pins. This capacitor creates an inter-

nal anti-alias filter to eliminate high-frequency

signals from the OUT± and BUF± analog out-

puts and helps to maintain the stability of the

low-power ∆Σ circuitry.

A COG, NPO or similar high-quality capacitor

is required for CAP± since other capacitor

types, such as X7R, do not have the required

linearity. Using a poor-quality capacitor on

CAP± will significantly degrade THD perfor-

mance in the AC operational modes.

DS699F2

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