CS5501
CS5503
Low-Cost, 16 & 20-Bit Measurement A/D Converter
Features
Description
The CS5501 and CS5503 are low-cost CMOS A/D con-
verters ideal for measuring low-frequency signals
representing physical, chemical, and biological process-
es. They utilize charge-balance techniques to achieve
16-bit (CS5501) and 20-bit (CS5503) performance with
up to 4 kHz word rates at very low cost.
The converters continuously sample at a rate set by the
user in the form of either a CMOS clock or a crystal. On-
chip digital filtering processes the data and updates the
output register at up to a 4 kHz rate. The converters’ low-
pass, 6-pole Gaussian response filter is designed to al-
low corner frequency settings from 0.1 Hz to 10 Hz in the
CS5501 and 0.5 Hz to 10 Hz in the CS5503. Thus, each
converter rejects 50 Hz and 60 Hz line frequencies as
well as any noise at spurious frequencies.
The CS5501 and CS5503 include on-chip self-calibra-
tion circuitry which can be initiated at any time or
temperature to insure offset and full-scale errors of typi-
cally less than 1/2 LSB for the CS5501 and less than
4 LSB for the CS5503. The devices can also be applied
in system calibration schemes to null offset and gain er-
rors in the input channel.
Each device’s serial port offers two general purpose
modes of operation for direct interface to shift registers
or synchronous serial ports of industry-standard micro-
controllers. In addition, the CS5501’s serial port offers a
third, UART-compatible mode of asynchronous
communication.
ORDERING INFORMATION
See page 33.
I
l
Monolithic CMOS ADC with Filtering
l
Up to 4 kHz Output Word Rates
-
6-Pole, Low-Pass Gaussian Filter
-
On Chip Self-Calibration Circuitry
-
Linearity Error: ±0.0003%
-
Differential Nonlinearity:
CS5501: 16-Bit No Missing Codes
(DNL ±1/8 LSB)
CS5503: 20-Bit No Missing Codes
l
System Calibration Capability
l
Flexible Serial Communications Port
-
µC-Compatible Formats
-
3-State Data and Clock Outputs
-
UART Format (CS5501 only)
l
Pin-Selectable Unipolar/Bipolar Ranges
l
Low Power Consumption: 25 mW
l
Evaluation Boards Available
-
10 µW Sleep Mode for Portable Applications
BP/UPSLEEP
12
11
VREF
10
AIN 9
AGND 8
DGND 5
SC1 SC2
4
13 CAL
Calibration
Calibration
SRAM
Microcontroller
14 VA+
Charge-Balanced A/D Converter
7 VA-
Analog
6-Pole Gaussian
15 VD+
Modulator
Low-Pass Digital Filter
6 VD-
20
SDATA
Clock Generator Serial Interface Logic
2
3
18 16 1
19
CLKOUTCLKIN DRDY CS MODESCLK
Cirrus Logic, Inc.
Crystal Semiconductor Products Division
P.O. Box 17847, Austin, Texas 78760
(512) 445 7222 FAX: (512) 445 7581
http://www.crystal.com
Copyright
©
Cirrus Logic, Inc. 1997
(All Rights Reserved)
MAR ‘95
DS31F2
1
CIRRUS [ CIRRUS LOGIC ]
