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CS5505/06/07/08 Low-Power, 16/20-Bit A/D Converters

CS5505/06/07/08 Low-Power, 16/20-Bit A/D Converters

Product catalog summary

Overview: The CS5505/6/7/8 series are low power CMOS A/D converters designed for measuring low-frequency signals. They offer single and four-channel pseudo-differential versions with 16-bit and 20-bit output options.

Key Features: These converters have very low power consumption, superior performance compared to VFCs and multi-slope integrating ADCs, and a flexible digital interface. They feature a linearity error of ±0.0015% FS for 16-bit and ±0.0007% FS for 20-bit versions, with output update rates up to 100 Sps and on-chip self-calibration.

Specifications: The devices operate over a wide temperature range, with detailed specifications for linearity error, full scale error, noise levels, and input impedance. Recalibration is recommended to remove errors.

Analog Characteristics: They support unipolar and bipolar modes, with specified voltage ranges, common mode rejection, and voltage reference output specifications.

Power and Digital Characteristics: Details include power supply currents, power dissipation, and digital input/output voltage levels for both 5V and 3.3V operations.

Switching Characteristics: Specifications include master clock frequency, timing details for calibration and conversion processes, and serial clock and data output timing.

Conclusion: The CS5505/6/7/8 series provides a versatile and efficient solution for low-frequency signal measurement with robust performance and flexible interfacing options.

General Description: These converters are designed for measuring DC signals, featuring a delta-sigma charge-balance converter, voltage reference, calibration microcontroller, digital filter, and serial interface. They operate optimally with a 32.768 kHz crystal.

Recommended Operating Conditions: The devices operate with positive digital and analog power supplies, with specific ranges for analog reference voltage and input voltage.

Absolute Maximum Ratings: Voltage limits for digital and analog power supplies are specified, with maximum input currents and temperature ranges.

Theory of Operation: The converters have four operating states: start-up, calibration, conversion, and sleep. Calibration ensures accurate conversions, with multiplexer channel selection determined by inputs.

Voltage Reference: The converters use a differential voltage reference input, with an internal reference outputting 2.5V. External references can be used for precision applications.

Analog Input Range: The input range is determined by the reference voltage, with specific modes for unipolar and bipolar signals.

Output Coding: Data is output in binary format for unipolar signals and offset binary format for bipolar signals.

Converter Calibration: Calibration minimizes offset errors and sets the gain slope scale factor, with specific procedures for unipolar and bipolar modes.

Converter Performance: The converters exhibit excellent linearity performance, with calibration minimizing offset and gain errors. Common Mode Rejection is high, and recalibration can eliminate temperature-induced drift.

Analog Input Impedance Considerations: The input can be modeled with capacitors for dynamic sampling, with specific settling time equations provided.

Digital Filter Characteristics: The digital filter is optimized to reject line interference frequencies, with specific rejection and phase characteristics.

Anti-Alias Considerations: Input frequencies should be limited to prevent aliasing, with low-pass filtering recommended.

Crystal Oscillator: The converters are designed to operate with a 32.768 kHz crystal, with specific frequency ranges for operation.

Serial Interface Logic: Data can be read in SSC or SEC mode, with specific timing requirements.

Sleep Mode: Methods are available to enter a sleep condition to conserve power, with calibration words retained in SRAM.

Introduction to Evaluation Board: The CDB5505/6/7/8 evaluation board supports quick testing of the converters, with access to all digital interface pins and configurable operation modes.

Specifications of Evaluation Board: The board supports SSC, SEC, and Sleep modes, with DIP switch selectable modes and on-board precision voltage reference.

Evaluation Board Overview: The board facilitates operation of the A/D converter chip, with pre-configuration for a 32.768 kHz crystal and options for external clock sources.

Configuration and Operation: Users can select serial port mode and operate in bipolar or unipolar mode, with calibration initiated via a button.

Figures and Layouts: The document includes schematic, board layout, and component placement figures.

Revision History: The document has undergone several updates, with the latest removing references to lead-containing devices.

Important Notice: Cirrus Logic provides the information "AS IS" without warranty, and the document is subject to change.

Catalog excerpts

CS5505/06/07/08 Low-Power, 16/20-Bit A/D Converters-1

CS5505/6/7/8 ^^GRRUSLOGIC Very LowPower, 16-bit & 20-bit A/D Converters Features Very Low Power Consumption - Single supply +5 V opթration: 1.7 mW - Dual supply ±5 V operation: 3.2 mW Offers superior performance to VFCs and multi-slope integrating ADCs Օ Differential Inputs - Single-channel (CS5507/8) and Four-channel (CS5505/6) pseudo-differential versions Either 5 V or 3.3 V Digital Interface Օ Linearity Error: - ±0.0015% FS (16-bit CS5505/7) - ±0.0007% FS (20-bit CS5506/8) Output update rates up to 100 Sps Օ Flexible Serial Port Pin-Selectable Unipolar/Bipolar Ranges Descriptiov The CS5505/6/7/8 are a family of low power CMOS A/D converters which are ideal for measuring low-frequency signals representing physical, chemical, and biological processes. The CS 5507/8 have single-channel differential analog and reference inputs while the CS5505/6 have four pseudo-differential analog input channels. The CS5505/7 have a 16-bit output word. The CS5506/8 have a 20-bit output word.The CS5505/6/7/8 sample upon command up to 100 Sps. The on-chip digital filter offers superior line rejection at 50 and 60 Hz when the device is operated from a 32.768 kHz clock (output word rate = 20 Sps). The CS 5505/6/7/8 include on-chip self-calibration cir-cuitry which can be initiated at any time or temperature to ensure minimum offset and full-scale errors. The CS5505/6/7/8 serial port offers two general-purpose modes for the direct interface to shift registers or syn-chronous serial ports of industry-standard microcontrollers. ORDERING INFORMATION See page 30. VA+ VA- VD+ DGND VREFOUT VREF+ VREF- AIN1 + AIN2+ AIN3+ AIN4+ AIN- pգ Voltage Rשfrence 17 18 20 19 2 CS DRDY SCLK SDATA j4_ Differential 4th-Order Digital Delta-Sigma Filter Modulator 23 Ser al Interface Logic 21 1$_ 9 22 10 MUX 2 3 7 M/SLP CAL BP/UP 11 Calibration uC 4 m. 8 Calibration SRAM OSC 1 24 A0 A1 CONV XIN XOUT cs5505 (16-bit) and cs5506 (20-bit) shown CUeRUS LOGIC Copyright © Cirruo Logih, Inc. 2009 nAR '0Q http://www.cirrus.com (All Rights ReseAeR) T^L09 DS59F7

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CS5505/06/07/08 Low-Power, 16/20-Bit A/D Converters-2

CS5505/6/7/8 ANALOG CHARACTERISTICS (Ta = tmin to Tmax; va+ = 5V ± 10%; va- = -5V ± 10%; vd+ = 3.3V ± 5%; VREF+ = 2.5V(external); VREF- = 0V; fCLK = 32.768kHz; Bipolar Mode; Rsource = 1 kQ with a 10nF to AGND at AIN; Analog input channel AIN1+; AIN- = AGND; unless otherwise specified.) (Notes 1, 2) Parameter* CS5505/7-A Min Typ Max Units Specified Temperature Range -40 to +85 °C Accuracy Linearity Error Differential Nonlinearity - 0.0015 0.003 - ±0.25 ±0.5 ±%FS LSB16 Full Scale Error (Note 3) - ±0.25 ±2 LSB16 Full Scale Drift (Note 4) - ±0.5 - LSB16 Unipolar Offset (Note 3) - ±0.5 ±2 LSB16 Unipolar...

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CS5505/06/07/08 Low-Power, 16/20-Bit A/D Converters-3

CS5505/6/7/8 ANALOG CHARACTERISTICS (Ta = tmin to Tmax; va+ = 5 V ± 10%; va- = -5 V ± 10%; vd+ 3.3V ± 5%; VREF+ = 2.5V (external); VREF- = 0V; fCLK = 32.768kHz; Bipolar Mode; Rsource = 1kq with a 10nF to AGND at AIN; Analog input channel AIN1+; AIN- = AGND; unless otherwise specified.) (Notes 1, 2) Parameter* CS5506/8-B Min Typ Max Units Specified Temperature Range -40 to +85 °C Accuracy Linearity Error Differential Nonlinearity (No Missing Codes) - 0.0007 0.0015 20 - - ±%FS Bits Full Scale Error (Note 3) - ±4 ±32 LSB20 Full Scale Drift (Note 4) - ±8 - LSB20 Unipolar Offset (Note 3) - ±8 ±32...

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CS5505/06/07/08 Low-Power, 16/20-Bit A/D Converters-4

CS5505/6/7/8 ANALOG CHARACTERISTICS (Ta = tmin to Tmax; va+ = 5V ± 10%; va- = -5 V ± 10%; vd+ 3.3V ± 5%; VREF+ = 2.5V (external); VREF- = 0V; fCLK = 32.768kHz; Bipolar Mode; Rsource = 1 kQ with a 10nF to AGND at AIN; Analog input channel AIN1+; AIN- = AGND; unless otherwise specified.) (Notes 1, 2) CS5505/7 CS5506/8 Parameter* Min Typ MaxH Units Specified Temperature Range -40 to +85 °C Analog Input Analog Input Range: Unipolar (VAIN+)-(VAIN-) Bi polar (Note 5) 0 to +2.5 ±2.5 Volts Volts Common Mode Rejection: dc 50, 60 Hz (Note 6) - 105 120 - dB dB Off Channel Isolation - 120 dB Input Capacitance...

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CS5505/06/07/08 Low-Power, 16/20-Bit A/D Converters-5

CS5505/6/7/8 5V DIGITAL CHARACTERISTICS (Ta = tmin to Tmax; va+vd+ = 5V ± 10%; va-= -5V ± 10%; DGND = 0.) All measurements below are performed under static conditions. (Note 2) Parameter Symbol Min Typ Max Units High-Level Input Voltage: XIN VIH 3.5 - - V M/SLP VIH 0.9VD+ - - V All Pins Except XIN and M/SLP VIH 2.0 - - V Low-Level Input Voltage: XIN Vil - - 1.5 V M/SLP Vil - - 0.1VD+ V All Pins Except XIN and M/SLP Vil - - 0.8 V M/SLP SLEEP Active Threshold (Note 8) Vslp 0.45VD+ 0.5VD+ 0.55VD+ V High-Level Output Voltage (Note 9) Voh (VD+)-1.0 - - V Low Level Output Voltage Iout = 1.6 mA Vol...

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CS5505/06/07/08 Low-Power, 16/20-Bit A/D Converters-6

CS5505/6/7/8 5V SWITCHING CHARACTERISTICS (TA = TMIN to TMAX; VA+, VD+ = 5V ± 10%; VA- = -5V ± 10%; Input Levels: Logic 0 = 0V, Logic 1 = VD+; Cl = 50 pF.) (Note 2) Parameter Symbol Min Master Clock Frequency: Internal Oscillator: XIN 30.0 External Clock: fclk 30 Master Clock Duty Cycle 40 Rise Times: Any Digital Input Any Digital Output (Note 10) trise - Fall Times: Any Digital Input Any Digital Output (Note 10) tfall - Start-Up Power-On Reset Period (Note 11) tres - Oscillator Start-up Time XTAL=32.768 kHz (Note 12) tosu - Wake-up Period (Note 13) twup - Calibration CONV Pulse Width (CAL =...

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CS5505/06/07/08 Low-Power, 16/20-Bit A/D Converters-7

CS5505/6/7/8 3.3V SWITCHING CHARACTERISTICS (ta = tmin to Tmax va+ = 5V ± 10%; VD+ = 3.3V ± 5%; VA- = -5V ± 10%; Input Levels: Logic 0 = 0V, Logic 1 = VD+ ; CL = 50 pF.) (Note 2) Parameter Symbol Min Typ Max Units Master Clock Frequency: Internal Oscillator: XIN 30.0 32.768 53.0 kHz External Clock: fclk 30 - 163 kHz Master Clock Duty Cycle 40 - 60 % Rise Times: Any Digital Input Any Digital Output (Note 10) trise - 50 1.0 us ns Fall Times: Any Digital Input Any Digital Output (Note 10) tfall - 20 1.0 us ns Start-Up Power-On Reset Period (Note 11) tres - 10 - ms Oscillator Start-up Time XTAL=32.768...

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CS5505/06/07/08 Low-Power, 16/20-Bit A/D Converters-8

CS5505/6/7/8 XIN XIN/2 CAL CONV STATE mm. HT mu Standby [t- tscl tcal Standby Calibration Figure 1. Calibration Timing (Not to Scale) XIN XIN/2 A0, A1 CONV DRDY BP/UP STATE tsac tcpw thca tbuh mm 7777777 mm tscn tbus Standby tcon Conversion Standby Figure 2. Conversion Timing (Not to Scale) 8 DS59F7

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