CS5531/32/33/34-AS
16-bit and 24-bit ADCs
with
Ultra-low-noise PGIA
Features
Chopper-stabilized PGIA (Programmable
Gain Instrumentation Amplifier, 1x to 64x)
–
12 nV/√Hz @ 0.1 Hz (No 1/f noise) at 64x
–
1200 pA Input Current with Gains >1
General Description
The CS5531/32/33/34 are highly integrated
∆Σ
Analog-
to-Digital Converters (ADCs) which use charge-balance
techniques to achieve 16-bit (CS5531/33) and 24-bit
(CS5532/34) performance. The ADCs are optimized for
measuring low-level unipolar or bipolar signals in weigh
scale, process control, scientific, and medical
applications.
To accommodate these applications, the ADCs come as
either two-channel (CS5531/32) or four-channel
(CS5533/34) devices and include a very low noise chop-
per-stabilized instrumentation amplifier (6 nV/√Hz @ 0.1
Hz) with selectable gains of 1×, 2×, 4×, 8×, 16×, 32×, and
64×. These ADCs also include a fourth order
∆Σ
modu-
lator followed by a digital filter which provides twenty
selectable output word rates of 6.25, 7.5, 12.5, 15, 25, 30,
50, 60, 100, 120, 200, 240, 400, 480, 800, 960, 1600,
1920, 3200, and 3840 Sps (MCLK = 4.9152 MHz).
To ease communication between the ADCs and a micro-
controller, the converters include a simple three-wire se-
rial interface which is SPI and Microwire compatible with
a Schmitt-trigger input on the serial clock (SCLK).
High dynamic range, programmable output rates, and
flexible power supply options makes these ADCs ideal
solutions for weigh scale and process control
applications.
ORDERING INFORMATION
See
Delta-sigma Analog-to-digital Converter
–
Linearity Error: 0.0007% FS
–
Noise Free Resolution: Up to 23 bits
Two- or Four-channel Differential MUX
Scalable Input Span via Calibration
–
±5 mV to differential ±2.5V
Scalable V
REF
Input: Up to Analog Supply
Simple Three-wire Serial Interface
–
SPI™ and Microwire™ Compatible
–
Schmitt Trigger on Serial Clock (SCLK)
R/W Calibration Registers Per Channel
Selectable Word Rates: 6.25 to 3,840 Sps
Selectable 50 or 60 Hz Rejection
Power Supply Configurations
–
VA+ = +5 V; VA- = 0 V; VD+ = +3 V to +5 V
–
VA+ = +2.5 V; VA- = -2.5 V; VD+ = +3 V to +5 V
–
VA+ = +3 V; VA- = -3 V; VD+ = +3 V
VA+
C1
C2
VREF+
VREF-
VD+
AIN1+
AIN1-
AIN2+
AIN2-
AIN3+
AIN3-
AIN4+
AIN4-
MUX
PGIA
1,2,4,8,16
32,64
DIFFERENTIAL
4
TH
ORDER
∆Σ
MODULATOR
CS
PROGRAMMABLE
SINC FIR FILTER
SERIAL
INTERFACE
SDI
SDO
SCLK
(CS5533/34
SHOWN)
CLOCK
GENERATOR
CALIBRATION
SRAM/CONTROL
LOGIC
LATCH
VA-
A0/GUARD
A1
OSC1
OSC2
DGND
Copyright
©
Cirrus Logic, Inc. 2008
(All Rights Reserved)
OCT ‘08
DS289F5
CIRRUS [ CIRRUS LOGIC ]
