Sample & Buy Product Folder Support & Community Tools & Software Technical Documents Reference Design ADS8353, ADS7853, ADS7253 SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 ADSxx53 Dual, High-Speed, 16-, 14-, and 12-Bit, Simultaneous-Sampling, Analog-to-Digital Converters 1 Features 2 Applications • • • • 1 • • • • • • 16-, 14-, and 12-Bit, Pin-Compatible Family Simultaneous Sampling of Two Channels Supports Single-Ended and Pseudo-Differential Inputs High Speed: – ADS8353: 16 Bits, 600 kSPS – ADS7853: 14 Bits, 1 MSPS – ADS7253: 12 Bits, 1 MSPS Excellent DC Performance: – ADS8353: – 16-Bit NMC DNL, ±2.5-LSB Max INL – ADS7853: – 14-Bit NMC DNL, ±2-LSB Max INL – ADS7253: – 12-Bit NMC DNL, ±1-LSB Max INL Excellent AC Performance: – ADS8353: – 89-dB SNR, –100-dB THD – ADS7853: – 82-dB SNR, –90-dB THD – ADS7253: – 72-dB SNR, –90-dB THD Dual, Programmable, and Buffered 2.5-V Internal Reference Fully-Specified Over the Extended Industrial Temperature Range: –40°C to 125°C Small Footprint: WQFN-16 (3-mm × 3-mm) and TSSOP-16 • • • • • Motor Control: Position Measurement Using Encoders Optical Networking: EDFA Gain Control Loops Protection Relays Power Quality Measurement Three-Phase Power Controls Programmable Logic Controllers 3 Description The ADS8353, ADS7853, and ADS7253 belong to a family of pin-compatible, dual, high-speed, simultaneous-sampling, analog-to-digital converters (ADCs) that support single-ended and pseudodifferential analog inputs. Each device includes two individually programmable reference sources that can be used for system-level gain calibration. Also, a flexible serial interface that can operate over a wide power-supply range enables easy communication with a large variety of host controllers. Power consumption for a given throughput can be optimized by using the two lowpower modes supported by the device. All devices are fully specified over the extended industrial temperature range (–40°C to 125°C) and are available in pin-compatible, WQFN-16 (3-mm × 3-mm) and TSSOP-16 packages. Device Information(1) PART NUMBER ADSxx53 PACKAGE BODY SIZE (NOM) TSSOP (16) 5.00 mm × 4.40 mm WQFN (16) 3.00 mm × 3.00 mm (1) For all available packages, see the orderable addendum at the end of the datasheet. Typical Application Diagram AVDD VCM AVDD OPA836 + + 1k 4 + AVDD - AINP VIN+ 1.8 nF 1k ADSxx53 AINM GND 4 VDC INPUT DRIVER ADS8353 : 16-bit, 600 kSPS ADS7853 : 14-bit, 1 MSPS ADS7253 : 12-bit, 1 MSPS 1 An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications, intellectual property matters and other important disclaimers. PRODUCTION DATA. ADS8353, ADS7853, ADS7253 SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 www.ti.com Table of Contents 1 2 3 4 5 6 7 Features .................................................................. Applications ........................................................... Description ............................................................. Revision History..................................................... Device Comparison Table..................................... Pin Configurations and Functions ....................... Specifications......................................................... 7.1 7.2 7.3 7.4 7.5 7.6 7.7 7.8 7.9 7.10 7.11 7.12 7.13 7.14 1 1 1 2 3 4 5 Absolute Maximum Ratings ..................................... 5 Handling Ratings....................................................... 5 Recommended Operating Conditions....................... 5 Thermal Information .................................................. 5 Electrical Characteristics: ADS8353 ......................... 6 Electrical Characteristics: ADS7853 ......................... 7 Electrical Characteristics: ADS7253 ......................... 8 Electrical Characteristics: All Devices....................... 9 Timing Requirements: Interface Mode.................... 11 Timing Characteristics: Serial Interface ................ 11 Typical Characteristics: ADS8353 ........................ 13 Typical Characteristics: ADS7853 ........................ 17 Typical Characteristics: ADS7253 ........................ 22 Typical Characteristics: Common to ADS8353, ADS7853, and ADS7253 ......................................... 27 8 Detailed Description ............................................ 28 8.1 8.2 8.3 8.4 8.5 9 Overview ................................................................. Functional Block Diagram ....................................... Feature Description................................................. Device Functional Modes........................................ Register Maps and Serial Interface......................... 28 28 29 35 35 Application and Implementation ........................ 49 9.1 Application Information............................................ 49 9.2 Typical Applications ................................................ 51 10 Power-Supply Recommendations ..................... 59 11 Layout................................................................... 60 11.1 Layout Guidelines ................................................. 60 11.2 Layout Example .................................................... 60 12 Device and Documentation Support ................. 61 12.1 12.2 12.3 12.4 12.5 Related Links ........................................................ Related Documentation......................................... Trademarks ........................................................... Electrostatic Discharge Caution ............................ Glossary ................................................................ 61 61 61 61 61 13 Mechanical, Packaging, and Orderable Information ........................................................... 61 4 Revision History Changes from Revision A (July 2014) to Revision B Page • Made changes to the ADS8353 preview device and moved to Production Data status ........................................................ 1 • Changed document status from Mixed Status to Production Data ........................................................................................ 1 • Corrected cross-reference for Figure 99 .............................................................................................................................. 48 Changes from Original (October 2013) to Revision A • 2 Page Made changes to product preview data sheet........................................................................................................................ 1 Submit Documentation Feedback Copyright © 2013–2014, Texas Instruments Incorporated Product Folder Links: ADS8353 ADS7853 ADS7253 ADS8353, ADS7853, ADS7253 www.ti.com SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 5 Device Comparison Table PRODUCT RESOLUTION (Bits) INPUT CONFIGURATION NMC (Bits) INL (LSB) SNR (dB) ADS8354 16 Fully-differential 16 ±2.5 93 (typ) ADS7854 14 Fully-differential 14 ±1.5 88 (typ) ADS7254 12 Fully-differential 12 ±1 74 (typ) ADS8353 16 Single-ended and pseudo-differential 16 ±2.5 89 (typ) ADS7853 14 Single-ended and pseudo-differential 14 ±2 84 (typ) ADS7253 12 Single-ended and pseudo-differential 12 ±1 73.5 (typ) Copyright © 2013–2014, Texas Instruments Incorporated Product Folder Links: ADS8353 ADS7853 ADS7253 Submit Documentation Feedback 3 ADS8353, ADS7853, ADS7253 SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 www.ti.com 6 Pin Configurations and Functions RTE Package WQFN-16 (Top View) AINM_A AINP_A AVDD GND 16 15 14 13 PW Package TSSOP-16 (Top View) REFIO_A 1 12 SDO_B REFGND_A 2 11 SDO_A REFGND_B 3 10 SCLK REFIO_B 4 9 CS AINP_A 1 16 AVDD AINM_A 2 15 GND REFIO_A 3 14 SDO_B REFGND_A 4 13 SDO_A REFGND_B 5 12 SCLK REFIO_B 6 11 CS AINM_B 7 10 SDI AINP_B 8 9 DVDD 8 SDI 7 DVDD 6 AINP_B AINM_B 5 Thermal Pad Pin Functions PIN NO. NAME TSSOP WQFN I/O AINM_A 2 16 Analog input Negative analog input, channel A AINM_B 7 5 Analog input Negative analog input, channel B AINP_A 1 15 Analog input Positive analog input, channel A Positive analog input, channel B AINP_B 8 6 Analog input AVDD 16 14 Supply CS 11 9 Digital input DESCRIPTION Supply voltage for ADC operation Chip-select signal; active low DVDD 9 7 Digital I/O supply GND 15 13 Supply Digital ground REFGND_A 4 2 Supply Reference ground potential A REFGND_B 5 3 Supply Reference ground potential B REFIO_A 3 1 Analog input/output Reference voltage input/output, channel A REFIO_B 6 4 Analog input/output Reference voltage input/output, channel B SCLK 12 10 Digital input Clock for serial communication SDI 10 8 Digital input Data input for serial communication SDO_A 13 11 Digital output Data output for serial communication, channel A and channel B SDO_B 14 12 Digital output Data output for serial communication, channel B Thermal pad — Thermal pad Supply 4 Submit Documentation Feedback Digital I/O supply Exposed thermal pad (only for WQFN). TI recommends connecting this pin to the printed circuit board (PCB) ground. Copyright © 2013–2014, Texas Instruments Incorporated Product Folder Links: ADS8353 ADS7853 ADS7253 ADS8353, ADS7853, ADS7253 www.ti.com SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 7 Specifications 7.1 Absolute Maximum Ratings (1) over operating free-air temperature range (unless otherwise noted) MIN MAX UNIT –0.3 6 V REFGND_x – 0.3 AVDD + 0.3 V GND – 0.3 DVDD + 0.3 V AVDD to REFGND_x or DVDD to GND Analog (AINP_x and AINM_x) and reference input (REFIO_x) voltage with respect to REFGND_x Digital input voltage with respect to GND Ground voltage difference |REFGND_x-GND| 0.3 V Input current to any pin except supply pins ±10 mA Maximum virtual junction temperature, TJ 150 °C (1) Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. 7.2 Handling Ratings MIN MAX UNIT –65 150 °C Human body model (HBM), per ANSI/ESDA/JEDEC JS-001, all pins (1) –2000 2000 Charged device model (CDM), per JEDEC specification JESD22-C101, all pins (2) –500 500 Tstg Storage temperature range V(ESD) Electrostatic discharge (1) (2) V JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process. JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process. 7.3 Recommended Operating Conditions over operating free-air temperature range (unless otherwise noted) MIN AVDD Analog supply voltage DVDD Digital supply voltage NOM MAX UNIT 5 V 3.3 V 7.4 Thermal Information ADS8353, ADS7853, ADS7253 THERMAL METRIC (1) RTE (WQFN) PW (TSSOP) 16 PINS 16 PINS RθJA Junction-to-ambient thermal resistance 33.3 86.9 RθJC(top) Junction-to-case (top) thermal resistance 29.5 21 RθJB Junction-to-board thermal resistance 7.3 39.1 ψJT Junction-to-top characterization parameter 0.2 0.8 ψJB Junction-to-board characterization parameter 7.4 38.4 RθJC(bot) Junction-to-case (bottom) thermal resistance 0.9 N/A (1) UNIT °C/W For more information about traditional and new thermal metrics, see the IC Package Thermal Metrics application report, SPRA953. Copyright © 2013–2014, Texas Instruments Incorporated Product Folder Links: ADS8353 ADS7853 ADS7253 Submit Documentation Feedback 5 ADS8353, ADS7853, ADS7253 SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 www.ti.com 7.5 Electrical Characteristics: ADS8353 All minimum and maximum specifications are at TA = –40°C to 125°C, AVDD = 5 V, DVDD = 3.3 V, VREF_A = VREF_B = VREF = 2.5 V (internal), and fDATA = 600 kSPS, unless otherwise noted. Typical values are at TA = 25°C, AVDD = 5 V, and DVDD = 3.3 V. PARAMETER TEST CONDITIONS MIN TYP MAX UNIT RESOLUTION Resolution DC ACCURACY 16 Bits (1) NMC No missing codes 32-clock mode 16 INL Integral nonlinearity 32-clock mode –2.5 ±1 2.5 LSB DNL Differential nonlinearity 32-clock mode –0.99 ±0.6 2 LSB EIO Input offset error –1 ±0.5 1 mV –1 ±0.5 1 EIO match ADC_A to ADC_B Bits Input offset thermal drift EG Gain error Referenced to the voltage at REFIO_x –0.1 ±0.05 0.1 EG match ADC_A to ADC_B –0.1 ±0.05 0.1 Gain error thermal drift Referenced to the voltage at REFIO_x dEG/dT mV μV/°C dEIO/dT 1 %FS %FS 1 ppm/°C 83 dB VREF = 2.5 V, 2 × VREF input range, 32-clock mode 83.9 dB VREF = 5 V (external), VREF input range, 32-clock mode 88.7 dB 83 dB VREF = 2.5 V, 2 × VREF input range, 32-clock mode 84 dB VREF = 5 V (external), VREF input range, 32-clock mode 89 dB VREF = 2.5 V, VREF input range, 32-clock mode –100 dB VREF = 2.5 V, 2 × VREF input range, 32-clock mode –100 dB VREF = 5 V (external), VREF input range, 32-clock mode –100 dB VREF = 2.5 V, VREF input range, 32-clock mode 105 dB VREF = 2.5 V, 2 × VREF input range, 32-clock mode 105 dB VREF = 5 V (external), VREF input range, 32-clock mode 105 dB AC ACCURACY (2) VREF = 2.5 V, VREF input range, 32-clock mode SINAD Signal-to-noise + distortion 80.2 VREF = 2.5 V, VREF input range, 32-clock mode SNR THD SFDR (1) (2) 6 Signal-to-noise ratio Total harmonic distortion Spurious-free dynamic range 80.5 LSB = least significant bit. All ac parameters are tested at –0.5 dBFS and a 2-kHz input frequency. Submit Documentation Feedback Copyright © 2013–2014, Texas Instruments Incorporated Product Folder Links: ADS8353 ADS7853 ADS7253 ADS8353, ADS7853, ADS7253 www.ti.com SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 7.6 Electrical Characteristics: ADS7853 All minimum and maximum specifications are at TA = –40°C to 125°C, AVDD = 5 V, DVDD = 3.3 V, VREF_A = VREF_B = VREF = 2.5 V (internal), and fDATA = 1 MSPS, unless otherwise noted. Typical values are at TA = 25°C, AVDD = 5 V, and DVDD = 3.3 V. PARAMETER TEST CONDITIONS MIN TYP MAX UNIT RESOLUTION Resolution DC ACCURACY 14 Bits 32-clock mode 14 Bits 16-clock mode 13 Bits (1) NMC No missing codes INL Integral nonlinearity DNL Differential nonlinearity EIO Input offset error EIO match 32-clock mode –2 ±0.7 2 LSB 16-clock mode –2.5 ±1 2.5 LSB 32-clock mode –0.99 ±0.5 1 LSB 16-clock mode –1 ±0.9 2 LSB –1 ±0.5 1 mV –1 ±0.5 1 ADC_A to ADC_B Input offset thermal drift EG Gain error Referenced to the voltage at REFIO_x –0.1 ±0.05 0.1 EG match ADC_A to ADC_B –0.1 ±0.05 0.1 Gain error thermal drift Referenced to the voltage at REFIO_x dEG/dT mV μV/°C dEIO/dT ±1 ±1 %FS %FS ppm/°C AC ACCURACY (2) SINAD Signal-to-noise + distortion VREF = 2.5 V, VREF input range 32-clock mode 80.9 dB 16-clock mode 80.3 dB VREF = 2.5 V, 2 × VREF input range 32-clock mode 81.4 dB 16-clock mode 80.8 dB = 5 V (external), 32-clock mode input range 16-clock mode 83.9 dB 82.9 dB VREF VREF SNR THD SFDR Signal-to-noise ratio Total harmonic distortion Spurious-free dynamic range VREF = 2.5 V, VREF input range 32-clock mode 81 dB 16-clock mode 80.5 dB VREF = 2.5 V, 2 × VREF input range 32-clock mode 81.5 dB 16-clock mode 81 dB 84 dB 83.5 dB VREF = 2.5 V, VREF input range 32-clock mode –100 dB 16-clock mode –93 dB VREF = 2.5 V, 2 × VREF input range 32-clock mode –98 dB 16-clock mode –94 dB VREF = 5 V (external), 32-clock mode VREF input range 16-clock mode –102 dB –92 dB VREF = 2.5 V, VREF input range 32-clock mode 100 dB 16-clock mode 95 dB VREF = 2.5 V, 2 × VREF input range 32-clock mode 100 dB 16-clock mode 95 dB = 5 V (external), 32-clock mode input range 16-clock mode 102 dB 95 dB –100 dB (1) (2) fIN = 15 kHz at 10 %FS, fNOISE = 25 kHz at FS ADC-to-ADC isolation 78.5 VREF = 5 V (external), 32-clock mode VREF input range 16-clock mode VREF VREF ISOXT 78.4 LSB = least significant bit. All ac parameters are tested at –0.5 dBFS and a 2-kHz input frequency. Copyright © 2013–2014, Texas Instruments Incorporated Product Folder Links: ADS8353 ADS7853 ADS7253 Submit Documentation Feedback 7 ADS8353, ADS7853, ADS7253 SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 www.ti.com 7.7 Electrical Characteristics: ADS7253 All minimum and maximum specifications are at TA = –40°C to 125°C, AVDD = 5 V, DVDD = 3.3 V, VREF_A = VREF_B = VREF = 2.5 V (internal), and fDATA = 1 MSPS, unless otherwise noted. Typical values are at TA = 25°C, AVDD = 5 V, and DVDD = 3.3 V. PARAMETER TEST CONDITIONS MIN TYP MAX UNIT RESOLUTION Resolution DC ACCURACY 12 Bits (1) NMC No missing codes 12 INL Integral nonlinearity –1 ±0.3 1 LSB DNL Differential nonlinearity –0.99 ±0.3 1 LSB EIO Input offset error –2 ±0.5 2 mV –2 ±0.5 2 EIO match ADC_A to ADC_B Bits Input offset thermal drift EG Gain error Referenced to the voltage at REFIO_x –0.2 ±0.05 0.2 EG match ADC_A to ADC_B –0.2 ±0.05 0.2 Gain error thermal drift Referenced to the voltage at REFIO_x dEG/dT ±1 ±1 mV μV/°C dEIO/dT %FS %FS ppm/°C AC ACCURACY (2) VREF = 2.5 V, VREF input range SINAD Signal-to-noise + distortion 71 72.9 dB VREF = 2.5 V, 2 × VREF input range 72.9 dB VREF = 5 V (external), VREF input range 73.4 dB 73 dB 73 dB VREF = 5 V (external), VREF input range 73.5 dB VREF = 2.5 V, VREF input range –90 dB VREF = 2.5 V, 2 × VREF input range –90 dB VREF = 5 V (external), VREF input range –90 dB VREF = 2.5 V, VREF input range 93.5 dB VREF = 2.5 V, 2 × VREF input range 93.5 dB VREF = 5 V (external), VREF input range 93.5 dB fIN = 15 kHz at 10 %FS, fNOISE = 25 kHz at FS –80 dB VREF = 2.5 V, VREF input range SNR THD SFDR ISOXT (1) (2) 8 VREF = 2.5 V, 2 × VREF input range Signal-to-noise ratio Total harmonic distortion Spurious-free dynamic range ADC-to-ADC isolation 71.5 LSB = least significant bit. All ac parameters are tested at –0.5 dBFS and a 2-kHz input frequency. Submit Documentation Feedback Copyright © 2013–2014, Texas Instruments Incorporated Product Folder Links: ADS8353 ADS7853 ADS7253 ADS8353, ADS7853, ADS7253 www.ti.com SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 7.8 Electrical Characteristics: All Devices All minimum and maximum specifications are at TA = –40°C to 125°C, AVDD = 5 V, DVDD = 3.3 V, VREF_A = VREF_B = VREF = 2.5 V, and fDATA = maximum, unless otherwise noted. Typical values are at TA = 25°C, AVDD = 5 V, and DVDD = 3.3 V. PARAMETER TEST CONDITIONS MIN TYP MAX UNIT 0 VREF V –VREF / 2 VREF / 2 V 0 2 × VREF V –VREF VREF V ANALOG INPUT VREF range FSR Full-scale input range (AINP_x – AINM_x) (1) 2 × VREF range VINP Absolute input voltage (AINP_x to REFGND) VINM Ci Input capacitance Ilkg(i) Input leakage current Pseudo-differential input, AINM_x = +VREF / 2 Single-ended input, AINM_x = GND, AVDD ≥ 2 × VREF Pseudo-differential input, AINM_x = +VREF, AVDD ≥ 2 × VREF VREF range 0 VREF V 2 × VREF range, AVDD ≥ 2 × VREF 0 2 × VREF V VREF range Absolute input voltage (AINM_x to REFGND) Single-ended input, AINM_x = GND 2 × VREF range Single-ended input Pseudo-differential input –0.1 VREF / 2 – 0.1 Single-ended input, AVDD ≥ 2 × VREF Pseudo-differential input, AVDD ≥ 2 × VREF VREF / 2 –0.1 VREF – 0.1 In sample mode VREF 0.1 V VREF / 2 + 0.1 V 0.1 V VREF + 0.1 V 40 In hold mode pF 4 pF 0.1 µA INTERNAL VOLTAGE REFERENCE VREFOUT Reference output voltage REFDAC_x = 1FFh (default), at 25°C VREF-match VREF_A to VREF_B matching REFDAC_x = 1FFh (default), at 25°C 2.495 REFDAC_x resolution (2) 2.500 2.505 V ±1 mV 1.1 mV dVREFOUT/dT Reference voltage temperature drift REFDAC_x = 1FFh (default) ±10 ppm/°C dVREFOUT/dt Long-term stability 1000 hours 150 ppm RO Internal reference output impedance 1 Ω IREFOUT Reference output dc current 2 mA CREFOUT Recommended output capacitor 10 µF tREFON Reference output settling time 8 ms For CREF = 10 μF VOLTAGE REFERENCE INPUT VREF Reference voltage (input) IREF Average Reference input current CREF External ceramic reference capacitance Ilkg(dc) DC leakage current (1) (2) VREF range 2.4 2.5 AVDD V 2 × VREF range 2.4 2.5 AVDD / 2 V Per ADC 300 μA 10 μF ±0.1 μA Ideal input span, does not include gain or offset error. Refer to the Reference section for more details. Copyright © 2013–2014, Texas Instruments Incorporated Product Folder Links: ADS8353 ADS7853 ADS7253 Submit Documentation Feedback 9 ADS8353, ADS7853, ADS7253 SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 www.ti.com Electrical Characteristics: All Devices (continued) All minimum and maximum specifications are at TA = –40°C to 125°C, AVDD = 5 V, DVDD = 3.3 V, VREF_A = VREF_B = VREF = 2.5 V, and fDATA = maximum, unless otherwise noted. Typical values are at TA = 25°C, AVDD = 5 V, and DVDD = 3.3 V. PARAMETER TEST CONDITIONS MIN TYP MAX UNIT SAMPLING DYNAMICS tA Aperture delay tA match tAJIT ADC_A to ADC_B Aperture jitter 8 ns 40 ps 50 ps DIGITAL INPUTS (3) VIH High-level input voltage VIL Low-level input voltage DVDD > 2.3 V 0.7 DVDD DVDD + 0.3 V DVDD ≤ 2.3 V 0.8 DVDD DVDD + 0.3 V DVDD > 2.3 V –0.3 0.3 DVDD V DVDD ≤ 2.3 V –0.3 Input current 0.2 DVDD ±10 V nA DIGITAL OUTPUTS (3) VOH High-level output voltage IOH = 500-µA source VOL Low-level output voltage IOH = 500-µA sink 0.8 DVDD DVDD V 0 0.2 DVDD V POWER SUPPLY AVDD Analog supply voltage (AVDD to AGND) ±VREF range ±2 × VREF range DVDD AIDD DIDD PD (3) (4) 10 Internal reference 4.5 5.0 5.5 V External reference: VEXT_REF < 4.5 V 4.5 5.0 5.5 V External reference: VEXT_REF > 4.5 V VEXT_REF 5.0 5.5 V 5.0 5.0 5.5 V 2 × VREF_EXT 5.0 5.5 V 5.5 V 10 mA Internal reference External reference Digital supply voltage (DVDD to AGND) Analog supply current Digital supply current Power dissipation (normal operation) 1.65 AVDD = 5 V, fastest throughput internal reference 8.5 AVDD = 5 V, fastest throughput external reference (4) 7.5 AVDD = 5 V, no conversion internal reference 5.5 AVDD = 5 V, no conversion external reference (4) 4.5 mA AVDD = 5 V, STANDBY mode Internal Reference 2.5 mA AVDD = 5 V, STANDBY mode external reference (4) 1 mA mA 7 μA Power-down mode 10 DVDD = 3.3 V, CLOAD = 10 pF, fastest throughput 0.5 mA 1 mA DVDD = 5 V, CLOAD = 10 pF fastest throughput AVDD = 5V, fastest throughput, internal reference 42.5 50 mA 50 mW Specified by design; not production tested. With internal reference powered down, CFR.B6 = 0. Submit Documentation Feedback Copyright © 2013–2014, Texas Instruments Incorporated Product Folder Links: ADS8353 ADS7853 ADS7253 ADS8353, ADS7853, ADS7253 www.ti.com SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 7.9 Timing Requirements: Interface Mode (1) PARAMETER ASSOCIATED FIGURES tCLK CLOCK period Figure 1, Figure 91, Figure 92, Figure 93, Figure 94 tACQ Acquisition time Figure 91, Figure 92, Figure 93, Figure 94 tCONV Conversion time Figure 91, Figure 92, Figure 93, Figure 94 (1) These parameters are specific to the interface mode of operation. Refer to the Conversion Data Read section for more details. 7.10 Timing Characteristics: Serial Interface PARAMETER TEST CONDITIONS ASSOCIATED FIGURES MIN TYP MAX UNIT TIMING REQUIREMENTS tPH_CK CLOCK high time tPL_CK CLOCK low time fCLK CLOCK frequency tPH_CS CS high time 0.4 Figure 1 Figure 1 ADS8353 tPH_CS_SHRT CS high time after frame abort ADS7853 Figure 99 ADS7253 tSU_CSCK Setup time: CS falling edge to SCLK falling edge tD_CKCS Delay time: Last SCLK falling edge to CS rising edge tSU_CKDI Setup time: DIN data valid to SCLK falling edge tHT_CKDI Hold time: SCLK falling edge to (previous) data valid on DIN tPU_STDBY Power-up time from STANDBY mode tPU_SPD Power-up time from SPD mode 0.4 0.6 tCLK 0.6 tCLK 1 / tCLK MHz 40 ns 150 ns 100 ns 70 ns 15 ns 15 ns 5 ns 5 ns 1 µs 3 ms 1 ms 1.666 µs 1 µs Figure 1 Figure 96 With internal reference With external reference Figure 98 TIMING SPECIFICATIONS ADS8353 tTHROUGHPUT ADS7853 Throughput time ADS7253 32-CLK mode 32-CLK mode Figure 91, Figure 92 16-CLK mode Figure 93, Figure 94 1 µs 32-CLK mode Figure 91, Figure 92 1 µs 16-CLK mode Figure 93, Figure 94 1 µs Figure 91, Figure 92, Figure 93, Figure 94 fTHROUGHPUT Throughput tDV_CSDO Delay time: CS falling edge to data enable tDZ_CSDO Delay time: CS rising edge to data going to 3-state tD_CKDO Delay time: SCLK falling edge to next data valid Figure 1 Copyright © 2013–2014, Texas Instruments Incorporated Product Folder Links: ADS8353 ADS7853 ADS7253 1 / tTHROUGHPUT kSPS 12 ns 12 ns 20 ns Submit Documentation Feedback 11 ADS8353, ADS7853, ADS7253 SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 www.ti.com Figure 1 shows the details of the serial interface between the device and the digital host controller. CS CS tSU_CSCK SCLK 1 2 1 SCLK 2 12 13 14 tSU_CKDI tDV_CSDO SDO B14 B15 SDI 15 16 tHT_CKDI B4 B3 B2 B1 Sample N+1 Sample N tPH_CS CS SCLK 1 2 N9 tSCLK tPL_CK tPH_CK N8 N7 N6 N5 N4 N3 N2 tD_CKDO tD_CKCS N1 N tDZ_CSDO SDOADS8353/4 V V D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 SDOADS7853/4 V V D7 D6 D5 D4 D3 D2 D1 D0 0 0 SDOADS7253/4 V V D5 D4 D3 D2 D1 D0 0 0 0 0 Figure 1. Serial Interface Timing Diagram 12 Submit Documentation Feedback Copyright © 2013–2014, Texas Instruments Incorporated Product Folder Links: ADS8353 ADS7853 ADS7253 ADS8353, ADS7853, ADS7253 www.ti.com SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 7.11 Typical Characteristics: ADS8353 0 0 ±20 ±20 ±40 ±40 Signal Power (dB) Signal Power (dB) At TA = 25°C, AVDD = 5 V, DVDD = 3.3 V, VREF = 2.5 V (internal), and fDATA = 600 kSPS, unless otherwise noted. ±60 ±80 ±100 ±120 ±140 ±60 ±80 ±100 ±120 ±140 ±160 ±160 ±180 ±180 ±200 ±200 0 60 120 180 240 300 Input Frequency (kHz) fIN = 2 kHz 0 60 SNR = 84.2 dB THD = -101.3 dB fIN = 100 kHz Signal-to-Noise and Distortion Ratio (dB) Signal-to-Noise Ratio (dB) 85 84 83 82 81 80 26 59 92 85 84 83 82 81 80 ±40 ±7 26 59 Free-Air Temperature (oC) 92 125 C204 fIN = 2 kHz Figure 4. SNR vs Temperature Figure 5. SINAD vs Temperature Signal-to-Noise and Distortion Ratio (dB) 90 89 Signal-to-Noise Ratio (dB) C202 THD = -99.1 dB 86 C203 fIN = 2 kHz 88 87 86 85 84 83 82 2.5 300 87 125 Free-Air Temperature (oC) 2 240 Figure 3. Typical FFT 86 ±7 180 SNR = 80.8 dB Figure 2. Typical FFT 87 ±40 120 Input Frequency (kHz) C201 3 3.5 4 4.5 Reference Voltage (V) fIN = 2 kHz 5 5.5 90 89 88 87 86 85 84 83 82 2 2.5 3 3.5 4 4.5 5 Reference Voltage (V) C205 5.5 C206 fIN = 2 kHz Figure 6. SNR vs Reference Voltage Figure 7. SINAD vs Reference Voltage Copyright © 2013–2014, Texas Instruments Incorporated Product Folder Links: ADS8353 ADS7853 ADS7253 Submit Documentation Feedback 13 ADS8353, ADS7853, ADS7253 SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 www.ti.com Typical Characteristics: ADS8353 (continued) At TA = 25°C, AVDD = 5 V, DVDD = 3.3 V, VREF = 2.5 V (internal), and fDATA = 600 kSPS, unless otherwise noted. Signal-to-Noise and Distortion Ratio (dB) 85 Signal-to-Noise Ratio (dB) 84 83 82 81 80 79 78 77 76 75 0 60 120 180 240 Input Frequency (kHz) 85 83 81 79 77 75 300 0 180 240 300 C208 VREF = 5 V Figure 8. SNR vs Input Frequency Figure 9. SINAD vs Input Frequency ±70 Total Harmonic Distortion (dB) ±70 Total Harmonic Distortion (dB) 120 Input Frequency (kHz) VREF = 5 V ±80 ±90 ±100 ±110 ±120 ±130 ±80 ±90 ±100 ±110 ±120 ±130 ±40 ±7 26 59 92 Free-Air Temperature (oC) 125 2 2.5 3 3.5 4 4.5 5 Reference Voltage (V) C209 fIN = 2 kHz 5.5 C211 fIN = 2 kHz Figure 10. THD vs Temperature Figure 11. THD vs Reference Voltage ±70 10 9.5 ±80 IAVDD Dynamic (mA) Total Harmonic Distortion (dB) 60 C207 ±90 ±100 ±110 ±120 9 8.5 8 7.5 7 6.5 ±130 6 0 60 120 180 240 Input Frequency (kHz) 300 ±40 ±7 26 59 Free-Air Temperature (oC) C213 92 125 C224 VREF = 5 V Figure 12. THD vs Input Frequency 14 Submit Documentation Feedback Figure 13. Analog Supply Current vs Temperature Copyright © 2013–2014, Texas Instruments Incorporated Product Folder Links: ADS8353 ADS7853 ADS7253 ADS8353, ADS7853, ADS7253 www.ti.com SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 Typical Characteristics: ADS8353 (continued) At TA = 25°C, AVDD = 5 V, DVDD = 3.3 V, VREF = 2.5 V (internal), and fDATA = 600 kSPS, unless otherwise noted. 40000 10 30000 8 Number of Hits IAVDD Dynamnic (mA) 9 7 6 5 20000 10000 4 3 0 2 0 4 8 12 16 SCLK Frequency (MHz) 32771 20 32772 750 75 500 50 Gain Error (m%) 100 0 ±250 32776 32777 C215 VIN-DIFF = 0 V 25 0 ±25 ±500 ±50 ±750 ±75 ±1000 32775 Figure 15. DC Histogram Figure 14. Analog Supply Current vs SCLK Frequency 1000 250 32774 Code 65536 data points Offset Error (uV) 32773 C225 ±100 ±40 ±7 26 59 92 Free-Air Temperature (oC) 125 ±40 26 ±7 59 92 Free-Air Temperature (oC) C216 Figure 16. Offset Error vs Temperature 125 C217 Figure 17. Gain Error vs Temperature 2 2.5 Integral Nonlinearity (LSB) Differential Nonlinearity (LSB) 2 1.5 1 0.5 0 -0.5 1.5 1 0.5 0 -0.5 -1 -1.5 -2 -1 -2.5 0 65535 Code 0 65535 Code C218 Figure 18. Typical DNL C219 Figure 19. Typical INL Copyright © 2013–2014, Texas Instruments Incorporated Product Folder Links: ADS8353 ADS7853 ADS7253 Submit Documentation Feedback 15 ADS8353, ADS7853, ADS7253 SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 www.ti.com Typical Characteristics: ADS8353 (continued) At TA = 25°C, AVDD = 5 V, DVDD = 3.3 V, VREF = 2.5 V (internal), and fDATA = 600 kSPS, unless otherwise noted. 2 2.5 Integral Nonlinearity (LSB) Differential Nonlinearity (LSB) 2 1.5 1 Maximum 0.5 0 -0.5 Minimum 1.5 Maximum 1 0.5 0 -0.5 -1 Minimum -1.5 -2 -1 -2.5 ±40 26 ±7 59 92 125 Free-Air Temperature (oC) ±40 26 ±7 59 92 125 Free-Air Temperature (oC) C220 Figure 20. DNL vs Temperature C221 Figure 21. INL vs Temperature 2 2.5 Integral Nonlinearity (LSB) Differential Nonlinearity (LSB) 2 1.5 1 Maximum 0.5 0 -0.5 Minimum Maximum 1 0.5 0 -0.5 Minimum -1 -1.5 -2 -1 -2.5 2 2.5 3 3.5 4 4.5 5 Reference Voltage (V) Figure 22. DNL vs Reference Voltage 16 1.5 Submit Documentation Feedback 5.5 2 2.5 3 3.5 4 4.5 5 Reference Voltage (V) C222 5.5 C223 Figure 23. INL vs Reference Voltage Copyright © 2013–2014, Texas Instruments Incorporated Product Folder Links: ADS8353 ADS7853 ADS7253 ADS8353, ADS7853, ADS7253 www.ti.com SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 7.12 Typical Characteristics: ADS7853 0 0 ±20 ±20 ±40 ±40 Signal Power (dB) Signal Power (dB) At TA = 25°C, AVDD = 5 V, DVDD = 3.3 V, VREF = 2.5 V (internal), and fDATA = 1 MSPS, unless otherwise noted. ±60 ±80 ±100 ±120 ±140 ±60 ±80 ±100 ±120 ±140 ±160 ±160 ±180 ±180 ±200 ±200 0 100 200 300 400 Input Frequency (kHz) fIN = 2 kHz 16-CLK interface SNR = 81.1 dB 500 0 100 THD = –94.2 dB fIN = 250 kHz 16-CLK interface 400 500 C102 THD = –90.4 dB Figure 25. Typical FFT 0 0 ±20 ±20 ±40 ±40 Signal Power (dB) Signal Power (dB) 300 SNR = 80.2 dB Figure 24. Typical FFT ±60 ±80 ±100 ±120 ±140 ±60 ±80 ±100 ±120 ±140 ±160 ±160 ±180 ±180 ±200 ±200 0 100 200 300 400 Input Frequency (kHz) fIN = 2 kHz 32-CLK interface SNR = 81.9 dB 500 0 100 THD = –98.1 dB fIN = 250 kHz 32-CLK interface Signal-to-Noise and Distortion Ratio (dB) 32 CLK Mode 83.5 83 16 CLK Mode 82.5 82 81.5 81 ±7 26 59 400 500 C152 THD = –92.1 dB Figure 27. Typical FFT 84.5 ±40 300 SNR = 80.8 dB Figure 26. Typical FFT 84 200 Input Frequency (kHz) C151 85 Signal-to-Noise Ratio (dB) 200 Input Frequency (kHz) C101 92 Free-Air Temperature (oC) fIN = 2 kHz 125 84 83.5 32 CLK Mode 83 82.5 82 81.5 16 CLK Mode 81 80.5 80 ±40 ±7 26 59 92 Free-Air Temperature (oC) C103 125 C104 fIN = 2 kHz Figure 28. SNR vs Temperature Figure 29. SINAD vs Temperature Copyright © 2013–2014, Texas Instruments Incorporated Product Folder Links: ADS8353 ADS7853 ADS7253 Submit Documentation Feedback 17 ADS8353, ADS7853, ADS7253 SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 www.ti.com Typical Characteristics: ADS7853 (continued) At TA = 25°C, AVDD = 5 V, DVDD = 3.3 V, VREF = 2.5 V (internal), and fDATA = 1 MSPS, unless otherwise noted. Signal-to-Noise and Distortion Ratio (dB) 85 Signal-to-Noise Ratio (dB) 84.5 84 83.5 83 82.5 82 81.5 81 80.5 80 2 2.5 3 3.5 4 4.5 5 Reference Voltage (V) 84 83.5 83 82.5 82 81.5 81 80.5 80 2 5.5 Figure 30. SNR vs Reference Voltage Signal-to-Noise and Distortion Ratio (dB) Signal-to-Noise Ratio (dB) 4 4.5 5 5.5 C106 Figure 31. SINAD vs Reference Voltage 84.5 84 83.5 83 82.5 82 81.5 81 50 100 150 200 250 Input Frequency (kHz) 85 84.5 84 83.5 83 82.5 82 81.5 81 0 300 50 100 150 200 250 Input Frequency (kHz) C107 VREF = 5 V 300 C108 VREF = 5 V Figure 32. SNR vs Input Frequency Figure 33. SINAD vs Input Frequency ±60 Total Harmonic Distortion (dB) ±60 Total Harmonic Distortion (dB) 3.5 fIN = 2 kHz 85 ±70 ±80 16 CLK Mode ±90 32 CLK Mode ±100 ±110 ±120 ±70 ±80 16 CLK Mode ±90 32 CLK Mode ±100 ±110 ±120 ±40 ±7 26 59 92 Free-Air Temperature (oC) fIN = 2 kHz Submit Documentation Feedback 125 2 2.5 3 3.5 4 4.5 5 Reference Voltage (V) C109 5.5 C111 fIN = 2 kHz Figure 34. THD vs Temperature 18 3 Reference Voltage (V) fIN = 2 kHz 0 2.5 C105 Figure 35. THD vs Reference Voltage Copyright © 2013–2014, Texas Instruments Incorporated Product Folder Links: ADS8353 ADS7853 ADS7253 ADS8353, ADS7853, ADS7253 www.ti.com SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 Typical Characteristics: ADS7853 (continued) At TA = 25°C, AVDD = 5 V, DVDD = 3.3 V, VREF = 2.5 V (internal), and fDATA = 1 MSPS, unless otherwise noted. 10 9.5 ±70 IAVDD Dynamic (mA) Total Harmonic Distortion (dB) ±60 ±80 ±90 ±100 ±110 9 8.5 8 7.5 7 6.5 6 ±120 0 50 100 150 200 250 Input Frequency (kHz) 300 ±40 26 ±7 59 92 Free-Air Temperature (oC) C113 125 C124 VREF = 5 V Figure 36. THD vs Input Frequency Figure 37. Analog Supply Current vs Temperature 10 10 9 IAVDD Dynamic (mA) IAVDD Dynamic (mA) 9 8 7 6 5 7 6 5 4 3 2 4 0 4 8 12 16 SCLK Frequency (MHz) 0 20 8 16 24 32 SCLK Frequency (MHz) C030 40 C125 32-CLK interface 16-CLK interface Figure 39. Analog Supply Current vs SCLK Frequency Figure 38. Analog Supply Current vs SCLK Frequency 70000 70000 60000 60000 50000 50000 Number of Hits Number of Hits 8 40000 30000 40000 30000 20000 20000 10000 10000 0 0 8098 8099 8100 16-CLK interface 8099 8100 C115 Code 65536 data points Figure 40. DC Histogram VIN-DIFF = 0 V 8101 Code 32-CLK interface 65536 data points C155 VIN-DIFF = 0 V Figure 41. DC Histogram Copyright © 2013–2014, Texas Instruments Incorporated Product Folder Links: ADS8353 ADS7853 ADS7253 Submit Documentation Feedback 19 ADS8353, ADS7853, ADS7253 SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 www.ti.com Typical Characteristics: ADS7853 (continued) At TA = 25°C, AVDD = 5 V, DVDD = 3.3 V, VREF = 2.5 V (internal), and fDATA = 1 MSPS, unless otherwise noted. 100 1000 750 75 32 CLK Mode 50 Gain Error (m%) Offset Error (uV) 500 16 CLK Mode 250 0 ±250 16 CLK Mode 25 0 32 CLK Mode ±25 ±500 ±50 ±750 ±75 ±100 ±1000 ±40 ±7 26 59 92 Free-Air Temperature (oC) ±40 125 1 2 0.75 1.5 Integral Nonlinearity (LSB) Differential Nonlinearity (LSB) 92 125 C11 Figure 43. Gain Error vs Temperature 0.5 0.25 0 -0.25 -0.5 -0.75 1 0.5 0 -0.5 -1 -1.5 -1 -2 0 16384 Code 0 16384 Code C118 16-CLK interface C119 16-CLK interface Figure 44. Typical DNL Figure 45. Typical INL 2 2 1.5 1.5 Integral Nonlinearity (LSB) Differential Nonlinearity (LSB) 59 Free-Air Temperature (oC) Figure 42. Offset Error vs Temperature 1 0.5 0 -0.5 1 0.5 0 -0.5 -1 -1.5 -1 -2 0 16384 Code 0 16384 Code C153 32-CLK interface C154 32-CLK interface Figure 46. Typical DNL 20 26 ±7 C116 Submit Documentation Feedback Figure 47. Typical INL Copyright © 2013–2014, Texas Instruments Incorporated Product Folder Links: ADS8353 ADS7853 ADS7253 ADS8353, ADS7853, ADS7253 www.ti.com SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 Typical Characteristics: ADS7853 (continued) At TA = 25°C, AVDD = 5 V, DVDD = 3.3 V, VREF = 2.5 V (internal), and fDATA = 1 MSPS, unless otherwise noted. 2 1.5 1.5 Integral Nonlinearity (LSB) Differential Nonlinearity (LSB) 2 Maximum 16 CLK Mode 1 0.5 Maximum 32 CLK Mode 0 Minimum 32 CLK Mode -0.5 Maximum 16 CLK Mode 1 0.5 Maximum 32 CLK Mode 0 Minimum 32 CLK Mode -0.5 -1 Minimum 16 CLK Mode -1.5 Minimum 16 CLK Mode -1 -2 ±40 26 ±7 59 92 125 Free-Air Temperature (oC) ±40 92 125 C121 Figure 49. INL vs Temperature 2 1.5 1.5 Integral Nonlinearity (LSB) Differential Nonlinearity (LSB) Figure 48. DNL vs Temperature Maximum 16 CLK Mode Maximum 32 CLK Mode 0.5 59 Free-Air Temperature (oC) 2 1 26 ±7 C120 0 Minimum 32 CLK Mode -0.5 Maximum 16 CLK Mode 1 0.5 Maximum 32 CLK Mode 0 Minimum 32 CLK Mode -0.5 Minimum 16 CLK Mode Minimum 16 CLK Mode -1 -1 2 2.5 3 3.5 4 4.5 5 Reference Voltage (V) Figure 50. DNL vs Reference Voltage 5.5 2 2.5 3 3.5 4 4.5 5 Reference Voltage (V) C122 5.5 C123 Figure 51. INL vs Reference Voltage Copyright © 2013–2014, Texas Instruments Incorporated Product Folder Links: ADS8353 ADS7853 ADS7253 Submit Documentation Feedback 21 ADS8353, ADS7853, ADS7253 SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 www.ti.com 7.13 Typical Characteristics: ADS7253 0 0 ±20 ±20 ±40 ±40 ±60 Signal Power (dB) Signal Power (dB) At TA = 25°C, AVDD = 5 V, DVDD = 3.3 V, VREF = 2.5 V (internal), and fDATA = 1 MSPS, unless otherwise noted. ±80 ±100 ±120 ±140 ±60 ±80 ±100 ±120 ±140 ±160 ±160 ±180 ±180 ±200 0 100 200 300 400 Input Frequency (kHz) fIN = 2 kHz 16-CLK interface SNR = 73.2 dB ±200 500 0 100 THD = –90.5 dB fIN = 250 kHz 16-CLK interface 0 0 ±20 ±20 ±40 ±40 Signal Power (dB) Signal Power (dB) 400 500 C002 THD = –90.1 dB Figure 53. Typical FFT ±60 ±80 ±100 ±120 ±140 ±60 ±80 ±100 ±120 ±140 ±160 ±160 ±180 ±180 ±200 ±200 0 100 200 300 400 Input Frequency (kHz) fIN = 2 kHz 32-CLK interface SNR = 73.6 dB 500 0 100 THD = –91.6 dB fIN = 250 kHz 32-CLK interface Signal-to-Noise and Distortion Ratio (dB) 16 CLK Mode 72.5 72 71.5 71 70.5 70 ±40 ±7 26 59 92 Free-Air Temperature (oC) fIN = 2 kHz 500 C052 THD = –90.6 dB 125 74 73.5 73 72.5 72 71.5 71 70.5 70 ±40 ±7 26 59 92 Free-Air Temperature (oC) C003 125 C004 fIN = 2 kHz Figure 56. SNR vs Temperature Submit Documentation Feedback 400 Figure 55. Typical FFT 32 CLK Mode 73 300 SNR = 73.4 dB Figure 54. Typical FFT 73.5 200 Input Frequency (kHz) C051 74 Signal-to-Noise Ratio (dB) 300 SNR = 73.1 dB Figure 52. Typical FFT 22 200 Input Frequency (kHz) C001 Figure 57. SINAD vs Temperature Copyright © 2013–2014, Texas Instruments Incorporated Product Folder Links: ADS8353 ADS7853 ADS7253 ADS8353, ADS7853, ADS7253 www.ti.com SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 Typical Characteristics: ADS7253 (continued) At TA = 25°C, AVDD = 5 V, DVDD = 3.3 V, VREF = 2.5 V (internal), and fDATA = 1 MSPS, unless otherwise noted. 32 CLK Mode 73.5 Signal-to-Noise Ratio (dB) Signal-to-Noise and Distiortion Ratio (dB) 74 73 16 CLK Mode 72.5 72 71.5 71 70.5 70 2 2.5 3 3.5 4 4.5 5 Reference Voltage (V) 74 32 CLK Mode 73 16 CLK Mode 72 71 70 5.5 2 4 4.5 5 5.5 C00 Figure 59. SINAD vs Reference Voltage Signal-to-Noise and Distortion Ratio (dB) 75 74.5 Signal-to-Noise Ratio (dB) 3.5 fIN = 2 kHz Figure 58. SNR vs Reference Voltage 16 CLK Mode 74 73.5 32 CLK Mode 73 72.5 72 71.5 71 50 100 150 200 250 Input Frequency (kHz) 75 74.5 16 CLK Mode 74 73.5 73 72.5 72 71.5 71 300 0 50 100 150 200 250 Input Frequency (kHz) C007 VREF = 5 V 300 C008 VREF = 5 V Figure 60. SNR vs Input Frequency Figure 61. SINAD vs Input Frequency ±60 Total Harmonic Distortion (dB) ±60 Total Harmonic Distortion (dB) 3 Reference Voltage (V) fIN = 2 kHz 0 2.5 C005 ±70 ±80 ±90 ±100 ±110 ±70 ±80 32 CLK Mode ±90 16 CLK Mode ±100 ±110 ±120 ±120 ±40 ±7 26 59 92 Free-Air Temperature (oC) fIN = 2 kHz 125 2 2.5 C009 3 3.5 4 4.5 5 Reference Voltage (V) 5.5 C011 fIN = 2 kHz Figure 62. THD vs Temperature Figure 63. THD vs Reference Voltage Copyright © 2013–2014, Texas Instruments Incorporated Product Folder Links: ADS8353 ADS7853 ADS7253 Submit Documentation Feedback 23 ADS8353, ADS7853, ADS7253 SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 www.ti.com Typical Characteristics: ADS7253 (continued) At TA = 25°C, AVDD = 5 V, DVDD = 3.3 V, VREF = 2.5 V (internal), and fDATA = 1 MSPS, unless otherwise noted. 8 7.5 ±70 ±80 IAVDD Dynamiv (mA) Total Harmonic Distortion (dB) ±60 16 CLK Mode ±90 32 CLK Mode ±100 ±110 7 6.5 6 5.5 5 4.5 4 ±120 0 50 100 150 200 250 Input Frequency (kHz) 300 ±40 ±7 26 59 92 Free-Air Temperature (oC) C013 125 C024 VREF = 5 V Figure 64. THD vs Input Frequency Figure 65. Analog Supply Current vs Temperature 10 10 9 IAVDD Dynamic (mA) IAVDD Dynamic (mA) 9 8 7 6 5 6 5 4 2 0 4 8 12 16 SCLK Frequency (MHz) 0 20 8 16 24 32 SCLK Frequency (MHz) C030 40 C125 32-CLK interface 16-CLK interface Figure 67. Analog Supply Current vs SCLK Frequency Figure 66. Analog Supply Current vs SCLK Frequency 60000 60000 50000 50000 40000 40000 Number of Hits Number of Hits 7 3 4 30000 20000 10000 30000 20000 10000 0 0 2024 2025 2026 Code 16-CLK interface 65536 data points Submit Documentation Feedback 2024 2025 Code C015 Figure 68. DC Histogram 24 8 VIN-DIFF = 0 V 32-CLK interface 65536 data points 2026 C015 VIN-DIFF = 0 V Figure 69. DC Histogram Copyright © 2013–2014, Texas Instruments Incorporated Product Folder Links: ADS8353 ADS7853 ADS7253 ADS8353, ADS7853, ADS7253 www.ti.com SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 Typical Characteristics: ADS7253 (continued) At TA = 25°C, AVDD = 5 V, DVDD = 3.3 V, VREF = 2.5 V (internal), and fDATA = 1 MSPS, unless otherwise noted. 100 2000 32 CLK Mode 1500 75 16 CLK Mode 50 500 Gain Error (m%) Offset Error (uV) 1000 32 CLK Mode 0 ±500 16 CLK Mode 25 0 ±25 ±1000 ±50 ±1500 ±75 ±100 ±2000 ±40 ±7 26 59 92 Free-Air Temperature (oC) 125 ±40 92 125 C01 Figure 71. Gain Error vs Temperature 1 1 0.75 0.75 Integral Nonlinearity (LSB) Differential Nonlinearity (LSB) 59 Free-Air Temperature Figure 70. Offset Error vs Temperature 0.5 0.25 0 -0.25 -0.5 -0.75 0.5 0.25 0 -0.25 -0.5 -0.75 -1 -1 0 4096 Code 0 4096 Code C018 16-CLK interface C019 16-CLK interface Figure 72. Typical DNL Figure 73. Typical INL 1 1 0.75 0.75 Integral Nonlinearity (LSB) Differential Nonlinearity (LSB) 26 ±7 C016 0.5 0.25 0 -0.25 -0.5 -0.75 0.5 0.25 0 -0.25 -0.5 -0.75 -1 -1 0 4096 Code 0 4096 Code C053 32-CLK interface C054 32-CLK interface Figure 74. Typical DNL Figure 75. Typical INL Copyright © 2013–2014, Texas Instruments Incorporated Product Folder Links: ADS8353 ADS7853 ADS7253 Submit Documentation Feedback 25 ADS8353, ADS7853, ADS7253 SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 www.ti.com Typical Characteristics: ADS7253 (continued) 1 1 0.75 0.75 0.5 Differential Nonlinearity (LSB) Differential Nonlinearity (LSB) At TA = 25°C, AVDD = 5 V, DVDD = 3.3 V, VREF = 2.5 V (internal), and fDATA = 1 MSPS, unless otherwise noted. Maximum 16 CLK Mode 0.25 Maximum 32 CLK Mode 0 Minimum 32 CLK Mode -0.25 -0.5 Minimum 16 CLK Mode -0.75 -1 0.5 Maximum 16 CLK Mode 0.25 Maximum 32 CLK Mode 0 Minimum 32 CLK Mode -0.25 Minimum 16 CLK Mode -0.5 -0.75 -1 ±40 26 ±7 59 92 125 Free-Air Temperature (oC) ±40 0.75 0.75 Maximum 16 CLK Mode 0.25 Maximum 32 CLK Mode Minimum 32 CLK Mode -0.25 Minimum 16 CLK Mode -0.5 -0.75 125 C021 0.5 Maximum 16 CLK Mode 0.25 Maximum 32 CLK Mode 0 Minimum 32 CLK Mode -0.25 Minimum 16 CLK Mode -0.5 -0.75 -1 -1 2 2.5 3 3.5 4 4.5 5 Reference Voltage (V) Figure 78. DNL vs Reference Voltage 26 92 Figure 77. DNL vs Temperature 1 Integral Nonlinearity (LSB) Differential Nonlinearity (LSB) Figure 76. DNL vs Temperature 0 59 Free-Air Temperature (oC) 1 0.5 26 ±7 C020 Submit Documentation Feedback 5.5 2 2.5 C022 3 3.5 4 4.5 5 Reference Voltage (V) 5.5 C023 Figure 79. INL vs Reference Voltage Copyright © 2013–2014, Texas Instruments Incorporated Product Folder Links: ADS8353 ADS7853 ADS7253 ADS8353, ADS7853, ADS7253 www.ti.com SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 7.14 Typical Characteristics: Common to ADS8353, ADS7853, and ADS7253 At TA = 25°C, AVDD = 5 V, DVDD = 3.3 V, VREF = 2.5 V (internal), and fDATA = maximum, unless otherwise noted. 200 3 IAVDD Power Down (mA) IAVDD STANDBY (mA) 2.5 16 CLK Mode 2 1.5 32 CLK Mode 1 0.5 160 120 80 40 16 CLK Mode -40 -7 26 59 92 Free-Air Temperature (oC) -40 125 -7 26 59 92 Free- AirTemperature (oC) C027 Figure 80. STANDBY Current vs Temperature 125 C028 Figure 81. Power-Down Current vs Temperature 2.55 2.6 Internal Reference Output (V) Internal Reference Output (V) 32 CLK Mode 0 0 2.53 2.51 2.49 2.47 2.45 -40 -7 26 59 Free-Air Temperature (oC) 92 125 2.55 2.5 2.45 2.4 2.35 2.3 -5 0 C016 5 10 15 Load Current (mA) 20 25 30 C017 ROUT = 0.67 Ω Figure 82. Internal Reference Output vs Temperature Figure 83. Internal Reference Output Impedance Copyright © 2013–2014, Texas Instruments Incorporated Product Folder Links: ADS8353 ADS7853 ADS7253 Submit Documentation Feedback 27 ADS8353, ADS7853, ADS7253 SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 www.ti.com 8 Detailed Description 8.1 Overview These devices belong to a family of pin-compatible, dual, high-speed, simultaneous-sampling, analog-to-digital converters (ADCs). The ADS8353, ADS7853, and ADS7253 support single-ended and pseudo-differential input signals. The devices provide a simple, serial interface to the host controller and operate over a wide range of analog and digital power supplies. These devices have two independently programmable internal references to achieve system-level gain error correction. The Functional Block Diagram section provides a functional block diagram of the device. 8.2 Functional Block Diagram REF_A Comparator S/H CDAC SAR ADC_A ADC_B S/H Serial Interface SAR CDAC Comparator REF_B 28 Submit Documentation Feedback Copyright © 2013–2014, Texas Instruments Incorporated Product Folder Links: ADS8353 ADS7853 ADS7253 ADS8353, ADS7853, ADS7253 www.ti.com SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 8.3 Feature Description 8.3.1 Reference The device has two simultaneous sampling ADCs (ADC_A and ADC_B). ADC_A and ADC_B operate with reference voltages VREF_A and VREF_B present on the REFIO_A and REFIO_B pins, respectively. The REFIO_A and REFIO_B pins should be decoupled with the REFGND_A and REFGND_B pins, respectively, with 10-µF decoupling capacitors. The device supports operation either with an internal or external reference source, as shown in Figure 84. The reference voltage source is determined by setting bit 6 of the configuration register (CFR.B6). Note that this bit is common to ADC_A and ADC_B. AINP_A AINM_A ADC_A REFGND_A REFDAC_A DAC_A 10 PF REFIO_A CFR.B6 Enable INTREF REFIO_B REFDAC_B 10 PF DAC_B REFGND_B AINP_B AINM_B ADC_B Figure 84. Reference Configurations and Connections When CFR.B6 is 0, the device shuts down the internal reference source (INTREF) and ADC_A and ADC_B operate on external reference voltages provided by the user on the REFIO_A and REFIO_B pins, respectively. When CFR.B6 is 1, the device operates with the internal reference source (INTREF) connected to REFIO_A and REFIO_B via DAC_A and DAC_B, respectively. In this configuration, VREF_A and VREF_B can be changed independently by writing to the respective user-programmable registers, REFDAC_A and REFDAC_B, respectively. Refer to the REFDAC Registers (REFDAC_A and REFDAC_B) section for more details. Copyright © 2013–2014, Texas Instruments Incorporated Product Folder Links: ADS8353 ADS7853 ADS7253 Submit Documentation Feedback 29 ADS8353, ADS7853, ADS7253 SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 www.ti.com Feature Description (continued) 8.3.2 Analog Inputs The ADS8353, ADS7853, and ADS7253 support single-ended or pseudo-differential analog inputs on both ADC channels. These inputs are sampled and converted simultaneously by the two ADCs, ADC_A and ADC_B. ADC_A samples and converts (VAINP_A – VAINM_A), and ADC_B samples and converts (VAINP_B – VAINM_B). Figure 85a and Figure 85b show equivalent circuits for the ADC_A and ADC_B analog input pins, respectively. Series resistance, RS, represents the on-state sampling switch resistance (typically 50 Ω) and CSAMPLE is the device sampling capacitor (typically 40 pF). AVDD AVDD RS CSAMPLE AINP_A RS CSAMPLE RS CSAMPLE AINP_B GND GND AVDD AVDD RS CSAMPLE AINM_A AINM_B GND GND a) ADC_A b) ADC_B Figure 85. Equivalent Circuit for the Analog Input Pins 8.3.2.1 Analog Input: Full-Scale Range Selection The full-scale range (FSR) supported at the analog inputs of the device is programmable with bit B9 of the configuration register (CFR.B9). This bit is common for both ADCs (ADC_A and ADC_B). The FSR is given by Equation 1 and Equation 2 : For CFR.B9 = 0, FSR_ADC_A = 0 to VREF_A and FSR_ADC_B = 0 to VREF_B For CFR.B9 = 1, FSR_ADC_A = 0 to 2 × VREF_A and FSR_ADC_B = 0 to 2 × VREF_B (1) where: • VREF_A and VREF_B are the reference voltages going to ADC_A and ADC_B, respectively (as described in the Reference section). (2) Therefore, with appropriate settings of the REFDAC_A and REFDAC_B registers, CFR.B7, and CFR.B9, the maximum dynamic range of the ADC can be used. Note that while using CFR.B9 set to 1, care must be taken so that the ADC analog supply (AVDD) is as in Equation 3 and Equation 4: 2 × VREF_A ≤ AVDD ≤ AVDD(max) 2 × VREF_B ≤ AVDD ≤ AVDD(max) 30 Submit Documentation Feedback (3) (4) Copyright © 2013–2014, Texas Instruments Incorporated Product Folder Links: ADS8353 ADS7853 ADS7253 ADS8353, ADS7853, ADS7253 www.ti.com SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 Feature Description (continued) 8.3.2.2 Analog Input: Single-Ended and Pseudo-Differential Configurations The ADS8353, ADS7853, and ADS7253 can support single-ended or pseudo-differential input configurations. For supporting single-ended inputs, B7 in the configuration register (CFR.B7) must be set to 0 (CFR.B7 = 0) and AINM_A and AINM_B must be externally connected to GND. For supporting pseudo-differential inputs, CFR.B7 must be set to 1 (CFR.B7 = 1) and AINM_A and AINM_B must be externally connected to FSR_ADC_A / 2 and FSR_ADC_B / 2, respectively. Note that CFR.B7 is common to both ADCs. The CFR.B9 and CFR.B7 settings can be combined to select the desired input configuration, as shown in Table 1. Table 1. Input Configurations INPUT RANGE SELECTION AINM SELECTION CONNECTION DIAGRAM VREF_x VREF_x REFIO_x AINP_x CFR.B9 = 0 (FSR_ADC_A = 0 to VREF_A) (FSR_ADC_B = 0 to VREF_B) CFR.B7 = 0 (AINM_A = GND) (AINM_B = GND) 0V Device AINM_x 2 u VREF_x VREF_x REFIO_x AINP_x CFR.B9 = 1 (FSR_ADC_A = 0 to 2 x VREF_A) (FSR_ADC_B = 0 to 2 x VREF_B) CFR.B7 = 0 (AINM_A = GND) (AINM_B = GND) 0V Device AINM_x Copyright © 2013–2014, Texas Instruments Incorporated Product Folder Links: ADS8353 ADS7853 ADS7253 Submit Documentation Feedback 31 ADS8353, ADS7853, ADS7253 SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 www.ti.com Feature Description (continued) Table 1. Input Configurations (continued) INPUT RANGE SELECTION AINM SELECTION CONNECTION DIAGRAM VREF_x VREF_x REFIO_x AINP_x 0V CFR.B9 = 0 (FSR_ADC_A = VREF_A) (FSR_ADC_B = VREF_B) CFR.B7 = 1 (AINM_A = VREF_A/2) (AINM_B = VREF_B/2) Device AINM_x VREF_x / 2 2 u VREF_x VREF_x REFIO_x AINP_x 0V CFR.B9 = 1 (FSR_ADC_A = 2 x VREF_A) (FSR_ADC_B = 2 x VREF_B) CFR.B7 = 1 (AINM_A = VREF_A) (AINM_B = VREF_B) Device AINM_x VREF_x 32 Submit Documentation Feedback Copyright © 2013–2014, Texas Instruments Incorporated Product Folder Links: ADS8353 ADS7853 ADS7253 ADS8353, ADS7853, ADS7253 www.ti.com SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 8.3.3 Transfer Function The device supports two input configurations: 1. Single-ended inputs, CFR.B7 = 0 (default), or 2. Pseudo-differential inputs, CFR.B7 = 1. The device also supports two output data formats: 1. Straight binary output, CFR.B4 = 0 (default), or 2. Twos compliment output, CFR.B4 = 1. Device resolution is calculated by Equation 5: 1 LSB = (FSR_ADC_x) / (2N) where: • • N = 16 (ADS8353), 14 (ADS7853), or 12 (ADS7253) and FSR_ADC_x is the full-scale input range of the ADC (refer to the Analog Input section for more details) (5) Table 2 and Table 3 show the different input voltages and the corresponding output codes from the device. Table 2. Transfer Characteristics for Straight Binary Output (CFR.B4 = 0, Default) AINP_x Single-ended (CFR.B7 = 0, default) Pseudo-differential (CFR.B7 = 1) OUTPUT CODE (Hex) INPUT VOLTAGE INPUT CONFIGURATION AINM_x STRAIGHT BINARY (CFR.B4 = 0, Default) AINP_x - AINM_x CODE ADS8353 ADS7853 ≤ 1 LSB ZC 0000 0000 000 FSR_ADC_x / 2 MC 7FFF 1FFF 7FF ≥ FSR_ADC_x – 1 LSB ≥ FSR_ADC_x – 1 LSB FSC FFFF 3FFF FFF ≤ 1 LSB ≤ –FSR_ADC_x / 2 + 1 LSB ZC 0000 0000 000 0 MC 7FFF 1FFF 7FF ≥ FSR_ADC_x / 2 – 1 LSB FSC FFFF 3FFF FFF ≤ 1 LSB FSR_ADC_x / 2 FSR_ADC_x / 2 0 FSR_ADC_x / 2 ≥ FSR_ADC_x – 1 LSB ADS7253 Table 3. Transfer Characteristics for Twos Compliment Output (CFR.B4 = 1) AINP_x Single-ended (CFR.B7 = 0, default) AINM_x ≤ 1 LSB FSR_ADC_x / 2 0 ≥ FSR_ADC_x – 1 LSB ≤ 1 LSB Pseudo-differential (CFR.B7 = 1) OUTPUT CODE (Hex) INPUT VOLTAGE INPUT CONFIGURATION FSR_ADC_x / 2 FSR_ADC_x / 2 ≥ FSR_ADC_x – 1 LSB TWOS COMPLIMENT (CFR.B4 = 1) AINP_x - AINM_x CODE ADS8353 ADS7853 ADS7253 ≤ 1 LSB NFSC 8000 2000 800 FSR_ADC_x / 2 MC 0000 0000 000 ≥ FSR_ADC_x – 1 LSB PFSC 7FFF 1FFF 7FF ≤ –FSR_ADC_x / 2 + 1 LSB NFSC 8000 2000 800 0 MC 0000 0000 000 ≥ FSR_ADC_x / 2 – 1 LSB PFSC 7FFF 1FFF 7FF Copyright © 2013–2014, Texas Instruments Incorporated Product Folder Links: ADS8353 ADS7853 ADS7253 Submit Documentation Feedback 33 ADS8353, ADS7853, ADS7253 SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 www.ti.com Figure 86 shows the ideal device transfer characteristics for the single-ended analog input. PFSC MC MC ZC NFSC 1 LSB FSR_ADC_x / 2 VIN ADC Code (Hex) Twos Compliment Output Format ADC Code (Hex) Straight Binary Output Format FSC FSR_ADC_x ± 1 LSB Single-Ended Analog Input (AINP_x ± AINM_x) Figure 86. Ideal Transfer Characteristics for a Single-Ended Analog Input Figure 87 shows the ideal device transfer characteristics for the pseudo-differential analog input. PFSC -FSR_ADC_x/2 + 1 LSB MC 0 FSR_ADC_x/2 ± 1 LSB ZC MC ADC Code (Hex) Twos Compliment Output Format ADC Code (Hex) Straight Binary Output Format FSC NFSC Pseudo-Differential Analog Input (AINP_x ± AINM_x) Figure 87. Ideal Transfer Characteristics for a Pseudo-Differential Analog Input 34 Submit Documentation Feedback Copyright © 2013–2014, Texas Instruments Incorporated Product Folder Links: ADS8353 ADS7853 ADS7253 ADS8353, ADS7853, ADS7253 www.ti.com SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 8.4 Device Functional Modes The device provides three user-programmable registers: the configuration register (CFR), the REFDAC_A register, and the REFDAC_B register. These registers support write (refer to the Write to User Programmable Registers section) and readback (refer to the Reading User-Programmable Registers section) operations and allow the user to customize ADC behavior for specific application requirements. The device supports four interface modes (refer to the Conversion Data Read section), two low-power modes (refer to the Low-Power Modes section), and short-cycling/reconversion feature (refer to the Frame Abort, Reconversion, or Short-Cycling section). 8.5 Register Maps and Serial Interface 8.5.1 Serial Interface The device uses the serial clock (SCLK) for synchronizing data transfers in and out of the device. The CS signal defines one conversion and serial transfer frame. A frame starts with a CS falling edge and ends with a CS rising edge. Between the start and end of the frame, a minimum of N SCLK falling edges must be provided to validate the read or write operation. As shown in Table 4, N depends upon the interface mode used to read the conversion result. When N SCLK falling edges are provided, the write operation attempted in the frame is validated and the internal user-programmable registers are updated on the subsequent CS rising edge. This CS rising edge also ends the frame. Table 4. SCLK Falling Edges for a Valid Write Operation INTERFACE MODE MINIMUM SCLK FALLING EDGES REQUIRED TO VALIDATE WRITE OPERATION N 32-CLK, dual-SDO mode (default). See the 32-CLK, Dual-SDO Mode section. 32 32-CLK, single-SDO mode. See the 32-CLK, Single-SDO Mode section. 48 16-CLK, dual-SDO mode. See the 16-CLK, Dual-SDO Mode section. 16 16-CLK, single SDO mode. See the 16-CLK, Single SDO Mode section. 32 If CS is brought high before providing N SCLK falling edges, the write operation attempted in the frame is not valid. Refer to the Frame Abort, Reconversion, or Short-Cycling section for more details. 8.5.2 Write to User Programmable Registers The device features three user-programmable registers: the configuration register (CFR), the REFDAC_A register, and the REFDAC_B register. These registers can be written with the device SDI pin. The first 16 bits of data on SDI are latched into the device on the first 16 SCLK falling edges. However, the new configuration takes effect only when the read or write operation is validated. If these registers are not required to update, SDI must remain low during the respective frames. The first four SDI data bits (B[15:12]) determine what operation is performed (that is, either a read or write operation or no operation), which register address the operation uses, and the function of the next 12 SDI data bits (B[11:0]). Table 5 lists the various combinations supported for B[15:12]. Table 5. Data Write Operation B15 B14 B13 B12 OPERATION FUNCTION OF BITS B[11:0] 0 0 0 0 No operation is performed These bits are ignored 0 0 0 1 REFDAC_A read 000h; see the Reading User-Programmable Registers section 0 0 1 0 REFDAC_B read 000h; see the Reading User-Programmable Registers section 0 0 1 1 CFR read 000h; see the Reading User-Programmable Registers section 1 0 0 0 CFR write See the Configuration Register (CFR) section 1 0 0 1 REFDAC_A write See the REFDAC_A section 1 0 1 0 REFDAC_B write See the REFDAC_B section 1 0 1 1 No operation is performed These bits are ignored X 1 X X No operation is performed These bits are ignored Copyright © 2013–2014, Texas Instruments Incorporated Product Folder Links: ADS8353 ADS7853 ADS7253 Submit Documentation Feedback 35 ADS8353, ADS7853, ADS7253 SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 www.ti.com 8.5.2.1 Configuration Register (CFR) The device operation configuration is controlled by the configuration register (CFR) status. Data written into the CFR in a valid frame (F) determine the device configuration for frame (F+1). The bit functions are outlined in Figure 88. On power-up, all bits in the CFR default to 0. Figure 88. CFR Bit Functions 15 14 13 12 WRITE/READ 0 ADDR1 ADDR0 7 6 5 INM_SEL REF_SEL STANDBY 4 RD_DATA_ FORMAT 11 RD_CLK_ MODE 3 10 RD_DATA_ LINES 2 9 8 INPUT_RANGE 0 1 0 0 0 0 0 Table 6. Configuration Register (CFR) Field Descriptions Bit Field Type Reset 15 WRITE/READ W 0h 14 0 R/W 0h 13 ADDR1 R/W 0h 12 ADDR0 R/W 0h 11 10 RD_DATA_LINES R/W R/W These bits select the user-programmable register. 1000 = Select this combination to write to the CFR register and to enable bits 11:0 0h This bit provides clock mode selection for the serial interface. 0 = Selects 32-CLK mode (default) 1 = Selects 16-CLK mode (Note that the ADS8353 only supports 32-CLK mode. This bit is ignored for the ADS8353.) 0h This bit provides data line selection for the serial interface. 0 = Use SDO_A to output ADC_A data and SDO_B to output of ADC_B data (default) 1 = Use only SDO_A to output of ADC_A data followed by ADC_B data 9 INPUT_RANGE R/W 0h This bit selects the maximum input range for the ADC as a function of the reference voltage provided to the ADC. See the Analog Inputs section for more details. 0 = FSR equals VREF 1 = FSR equals 2 × VREF 8 0 R/W 0h This bit must be set to 0 (default) 7 INM_SEL R/W 0h This bit selects the voltage to be externally connected to the INM pin. 0 = INM must be externally connected to the GND potential (default) 1 = INM must be externally connected to the FSR_ADC_x / 2 potential 6 REF_SEL R/W 0h This bit selects the ADC reference voltage source. Refer to the Reference section for more details. 0 = Use external reference (default) 1 = Use internal reference 5 STANDBY W 0h This bit is used by the device to enter or exit STANDBY mode. Refer to the STANDBY Mode section for more details. 4 RD_DATA_FORMAT R/W 0h This bit selects the output data format. 0 = Output is in straight binary format (default) 1 = Output is in twos compliment format 0 R/W 0h These bits must be set to 0 (default) 3:0 36 RD_CLK_MODE Description Submit Documentation Feedback Copyright © 2013–2014, Texas Instruments Incorporated Product Folder Links: ADS8353 ADS7853 ADS7253 ADS8353, ADS7853, ADS7253 www.ti.com SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 8.5.2.2 REFDAC Registers (REFDAC_A and REFDAC_B) The REFDAC registers, bit functions, and resolution information are described in this section. Figure 89. REFDAC_X Bit Functions 15 WRITE/READ 7 D4 14 0 6 D3 13 ADDR1 5 D2 12 ADDR0 4 D1 11 D8 3 D0 10 D7 2 0 9 D6 1 0 8 D5 0 0 Table 7. REFDAC Registers Field Descriptions Bit Field Type Reset Description 15 WRITE/READ W 0h 14 0 R/W 0h 13 ADDR1 R/W 0h 12 ADDR0 R/W 0h These bits select the configurable register address. 1001 = Select this combination to write to the REFDAC_A register 1010 = Select this combination to write to the REFDAC_B register 11:3 D[8:0] R/W 0h Data to program the individual DAC output voltage. Note: These bits are valid only for bits 15:12 = 1001 or bits 15:12 = 1010. Table 8 shows the relationship between the REFDAC_x programmed value and the DAC_x output voltage. 2:0 0 R/W 0h This bit must be set to 0 (default) Table 8. REFDAC Settings REFDAC_x VALUE (Bits 11:3 in Hex) B[2:0] Typical DAC_x OUPTUT VOLTAGE (V) (1) 1FF (default) 000 2.5000 1FE 000 2.4989 1FD 000 2.4978 — — — 1D7 000 2.45 — — — 1AE 000 2.40 — — — 186 000 2.35 (1) — — — 15D 000 2.30 — — — 134 000 2.25 — — — 10C 000 2.20 — — — 0E3 000 2.15 — — — 0BA 000 2.10 — — — 091 000 2.05 — — — 069 000 2.00 — — — 064 to 000 000 Do not use Actual output voltage may vary by a few millivolts from the specified value. To obtain the desired output voltage, TI recommends starting with the specified register setting and then experimenting with five codes on either side of the specified register setting. Copyright © 2013–2014, Texas Instruments Incorporated Product Folder Links: ADS8353 ADS7853 ADS7253 Submit Documentation Feedback 37 ADS8353, ADS7853, ADS7253 SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 www.ti.com 8.5.3 Data Read Operation The device supports two types of read operations: reading user-programmable registers and reading conversion results. 8.5.3.1 Reading User-Programmable Registers The device supports a readback option for all user-programmable registers: CFR, REFDAC_A, and REFDAC_B. Figure 90 shows a detailed timing diagram for this operation. Frame (F) Frame (F+1) Frame (F+2) Frame (F+3) CS SCLK 1 2 N 1 2 4 3 5 16 48 SDO-A Valid Data Valid data as per device configuration. SDO-B Valid Data Valid data as per device configuration. SDI No change in device configuration B14 B13 B12 B15 X X X 1 2 R15 R14 15 16 47 R1 R0 1 48 2 N Valid Data Valid Data X No change in device configuration Device configuration for frame (F+3) Note that N is a function of the device configuration, as described in Table 4. Figure 90. Register Readback Timing To readback the user-programmable register settings, the appropriate control word should be transmitted to the device during frame (F+1), as shown in Table 9. Frame (F+1) must have at least 48 SCLK falling edges. Table 9. Control Word to Readback User-Programmable Registers CONTROL WORD TO BE PROGRAMMED IN FRAME (F+1) USER-PROGRAMMABLE REGISTER B[15:12] (Binary) B[11:0] (Hex) CFR 0011b 000h REFDAC_A 0001b 000h REFDAC_B 0010b 000h Frame (F+2) must have at least 48 SCLK falling edges. During frame (F+2), SDO_A outputs the contents of the selected user-programmable register on the first 16 SCLK falling edges (as shown in Table 10) and then outputs 0s for any subsequent SCLK falling edges. The SDO_B pin outputs 0s for all the SCLK falling edges. Table 10. Register Data Read Back USERPROGRAMMABLE REGISTER DATA READ ON SDO-A IN FRAME (F+2) R15 R14 R13 R12 CFR 0 0 1 REFDAC_A 0 0 REFDAC_B 0 0 R11 — R3 R2 R1 R0 1 CFG.B11 — CFG.B3 CFG.B2 CFG.B1 CFG.B0 0 1 REFDAC_A.D8 — 1 0 REFDAC_B.D8 — REFDAC_A.D0 0 0 0 REFDAC_B.D0 0 0 0 Register settings programmed during frame (F+2) determine the device configuration in frame (F+3). 38 Submit Documentation Feedback Copyright © 2013–2014, Texas Instruments Incorporated Product Folder Links: ADS8353 ADS7853 ADS7253 ADS8353, ADS7853, ADS7253 www.ti.com SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 8.5.3.2 Conversion Data Read The device provides four different interface modes to the user for reading the conversion result. These modes offer flexible hardware connections and firmware programming. Table 11 shows how to select one of the four interface modes. Table 11. Interface Mode Selection CFR.B11 CFR.B10 INTERFACE MODE MINIMUM SCLK FALLING EDGES REQUIRED TO VALIDATE WRITE OPERATION N 0 0 32-CLK, dual-SDO mode (default) 32 0 1 32-CLK, single-SDO mode 48 1 0 16-CLK, dual-SDO mode 16 1 1 16-CLK, single SDO mode 32 In the 32-CLK interface modes, the device uses an internal clock to convert the sampled analog signal. The conversion is completed during the first 16 periods of SCLK and the conversion result can be read on the subsequent SCLK falling edges. All devices in the family (that is, ADS8353, ADS7853, and ADS7253) support the 32-CLK interface modes. In addition to the 32-CLK interface modes, the ADS7853 and ADS7253 also support the 16-CLK interface modes. By using the 16-CLK interface modes, the same throughput can be achieved at much lower SCLK speeds. The following sections detail the various interface modes supported by the device. 8.5.3.2.1 32-CLK, Dual-SDO Mode (CFR.B11 = 0, CFR.B10 = 0, Default) The 32-CLK, dual-SDO mode is the default mode supported by all devices. This mode can also be selected by writing CFR.B11 = 0 and CFR.B10 = 0. In this mode, the SDO_A pin outputs the ADC_A conversion result and the SDO_B pin outputs the ADC_B conversion result. Figure 91 shows a detailed timing diagram for this mode. Sample N Sample N+1 tTHROUGHPUT tCONV tACQ CS tSCLK SCLK 1 2 14 15 16 ADS8353, ADS8354 SDO_A and SDO_B 17 18 25 26 27 D15 D14 D7 D6 D5 28 29 D4 30 31 32 D3 D2 D1 D0 D1 D0 0 0 0 0 0 0 Data From Sample N ADS7853, ADS7854 SDO_A and SDO_B D13 D12 D5 D4 D3 D2 Data From Sample N ADS7253, ADS7254 SDO_A and SDO_B D11 D10 D3 D2 D1 D0 Data From Sample N SDI B15 B14 B2 B1 B0 X X X X X X X X X X Figure 91. 32-CLK, Dual-SDO Mode Timing Diagram Copyright © 2013–2014, Texas Instruments Incorporated Product Folder Links: ADS8353 ADS7853 ADS7253 Submit Documentation Feedback 39 ADS8353, ADS7853, ADS7253 SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 www.ti.com A CS falling edge brings the serial data bus out of 3-state and also outputs a 0 on the SDO_A and SDO_B pins. The device converts the sampled analog input during the conversion time (tCONV). SDO_A and SDO_B read 0 during this period. After completing the conversion process, the sample-and-hold circuit returns to sample mode. The device outputs the MSBs of ADC_A and ADC_B on SDO_A and SDO_B pins, respectively, on the 16th SCLK falling edge. The subsequent SCLK falling edges are used to shift out the rest of the bits of the conversion result, as shown in Table 12. Table 12. Data Launch Edge LAUNCH EDGE DEVICE ADS8353 ADS7853 ADS7253 PINS CS SCLK ↓ ↓1 — — ↓27 ↓28 ↓29 ↓30 ↓31 ↓32 ... ↑ SDO-A 0 0 — 0 D15_A — D4_A D3_A D2_A D1_A D0_A 0 ... Hi-Z SDO-B 0 0 — 0 D15_B — D4_B D3_B D2_B D1_B D0_B 0 ... Hi-Z SDO-A 0 0 — 0 D13_A — D2_A D1_A D0_A 0 0 0 ... Hi-Z SDO-B 0 0 — 0 D13_B — D2_B D1_B D0_B 0 0 0 ... Hi-Z SDO-A 0 0 — 0 D11_A — D0_A 0 0 0 0 0 ... Hi-Z SDO-B 0 0 — 0 D11_B — D0_B 0 0 0 0 0 ... Hi-Z ↓15 ↓16 CS In this mode, at least 32 SCLK falling edges must be given to validate the read or write frame. A CS rising edge ends the frame and puts the serial bus into 3-state. Refer to Table 13 for timing specifications specific to this serial interface mode. Table 13. 32-CLK, Dual-SDO Interface Specific Timing PARAMETER TEST CONDITIONS MIN TYP MAX UNIT TIMING REQUIREMENTS tCLK CLOCK period tACQ Acquisition time ADS8353 50 ns ADS7853 29.4 ns ADS7253 29.4 ns 33 × tCLK – tCONV ns TIMING SPECIFICATIONS tCONV 40 Conversion time Submit Documentation Feedback ADS8353 730 ns ADS7853 450 ns ADS7253 450 ns Copyright © 2013–2014, Texas Instruments Incorporated Product Folder Links: ADS8353 ADS7853 ADS7253 ADS8353, ADS7853, ADS7253 www.ti.com SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 8.5.3.2.2 32-CLK, Single-SDO Mode (CFR.B11 = 0, CFR.B10 = 1) The 32-CLK, single-SDO mode provides the option of using only one SDO pin (SDO_A) to read conversion results from both ADCs (ADC_A and ADC_B). SDO_B remains in 3-state and can be treated as a no connect (NC) pin. This mode can be selected by writing CFR.B11 = 0 and CFR.B10 = 1. Figure 92 shows a detailed timing diagram for this mode. Sample N Sample N+1 tTHROUGHPUT tCONV tACQ CS SCLK 1 2 14 15 16 17 28 18 ADS8353, ADS8354 SDO_A D1 5-A D1 4-A ADS7853, ADS7854 SDO_A D1 3-A D1 2-A ADS7253, ADS7254 SDO_A D1 1-A D1 0-A 29 D4A 31 30 D3A D2A 33 32 34 45 44 47 46 48 D1A D0A D1 5-B D4B D3B D2B D1B D0B 0 0 D1 3-B D2B D1B D0B 0 0 0 0 D1 1-B D0B 0 0 0 0 X X X X X X Data From Sample N D2A D1A D0A Data From Sample N D0A 0 0 Data From Sample N All Devices SDO_B SDI B15 B14 B3 B2 B1 B0 X X X X X X X Figure 92. 32-CLK, Single-SDO Mode Timing Diagram A CS falling edge brings the serial data bus out of 3-state and also outputs a 0 on the SDO_A pin. The device converts the sampled analog input during the conversion time (tCONV). SDO_A reads 0 during this period. After competing the conversion process, the sample-and-hold circuit goes back into sample mode. The device outputs the MSB of ADC_A on the SDO_A pin on the 16th SCLK falling edge. The subsequent SCLK falling edges are used to shift out the conversion result of ADC_A followed by the conversion result of ADC_B on the SDO_A pin, as shown in Table 14. Table 14. Data Launch Edge LAUNCH EDGE DEVICE PIN CS SCLK ↓ ↓1 — ↓15 ↓16 — ↓27 ↓28 ↓29 ↓30 ↓31 CS ↓32 — ↓43 ↓44 ↓45 ↓46 ↓47 ↓48 ... D15_B — ↑ D4_B D3_B D2_B D1_B D0_B 0 ... Hi-Z ADS8353 SDO-A 0 0 — 0 D15_A — D4_A D3_A D2_A D1_A D0_A ADS7853 SDO-A 0 0 — 0 D13_A — D2_A D1_A D0_A 0 0 0 — D2_B D1_B D0_B 0 0 0 ... Hi-Z ADS7253 SDO-A 0 0 — 0 D11_A — D0_A 0 0 0 0 0 — D0_B 0 0 0 0 0 ... Hi-Z In this mode, at least 48 SCLK falling edges must be given to validate the read or write frame. A CS rising edge ends the frame and puts the serial bus into 3-state. Copyright © 2013–2014, Texas Instruments Incorporated Product Folder Links: ADS8353 ADS7853 ADS7253 Submit Documentation Feedback 41 ADS8353, ADS7853, ADS7253 SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 www.ti.com Refer to Table 15 for timing specifications specific to this serial interface mode. Table 15. 32-CLK, Single-SDO Interface Specific Timing PARAMETER TEST CONDITIONS MIN TYP MAX UNIT TIMING REQUIREMENTS tCLK tACQ CLOCK period ADS8353 50 ns ADS7853 29.4 ns ADS7253 29.4 ns Acquisition time 49 × tCLK – tCONV ns TIMING SPECIFICATIONS tCONV Conversion time ADS8353 730 ns ADS7853 450 ns ADS7253 450 ns 8.5.3.2.3 16-CLK, Dual-SDO Mode (CFR.B11 = 1, CFR.B10 = 0) The 16-CLK, dual-SDO mode is designed to support the maximum throughput at lower SCLK frequencies. This interface mode is not supported by the ADS8353. For the ADS7853 and ADS7253, this interface mode can be selected by writing CFR.B11 = 1 and CFR.B10 = 0. In this mode, the SDO_A pin outputs the ADC_A conversion result and the SDO_B pin outputs the ADC_B conversion result. Figure 93 shows a detailed timing diagram for this mode. Sample N Sample N+1 tTHROUGHPUT tPH_CS CS tSCLK SCLK 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 tCONV ADS7853, ADS7854 SDO_A and SDO_B 0 0 D13 D12 D11 D10 D9 D8 tACQ D7 D6 D5 D4 D3 D2 D1 tCONV ADS7253, ADS7254 SDO_A and SDO_B 0 0 D11 D10 D9 D8 D7 D0 tACQ D6 D5 D4 D3 D2 D1 D0 0 0 Data From Sample N SDI B15 B14 B13 B12 B11 B10 B9 B8 B7 B6 B5 B4 B3 B2 B1 B0 Figure 93. 16-CLK, Dual-SDO Mode Timing Diagram 42 Submit Documentation Feedback Copyright © 2013–2014, Texas Instruments Incorporated Product Folder Links: ADS8353 ADS7853 ADS7253 ADS8353, ADS7853, ADS7253 www.ti.com SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 A CS falling edge brings the serial data bus out of 3-state and also outputs a 0 on the SDO_A and SDO_B pins. The subsequent SCLK falling edges are used for conversion and for data transfer using the serial interface, as shown in Table 16. The sample-and-hold circuit goes back into sample mode as soon as the conversion process is over. Table 16. Data Launch Edge LAUNCH EDGE DEVICE ADS7853 ADS7253 PINS CS SCLK CS ↓ ↓1 ↓2 — ↓13 ↓14 ↓15 ↓16 ... ↑ SDO-A 0 0 D13_A — D2_A D1_A D0_A 0 ... Hi-Z SDO-B 0 0 D13_B — D2_B D1_B D0_B 0 ... Hi-Z SDO-A 0 0 D11_A — D0_A 0 0 0 ... Hi-Z SDO-B 0 0 D11_B — D0_B 0 0 0 ... Hi-Z In this mode, at least 16 SCLK falling edges must be given to validate the read or write frame. A CS rising edge ends the frame and puts the serial bus into 3-state. Refer to Table 17 for timing specifications specific to this serial interface mode. Table 17. 16-CLK, Dual-SDO Interface Specific Timing PARAMETER TEST CONDITIONS MIN TYP MAX UNIT TIMING REQUIREMENTS tCLK tACQ CLOCK period Acquisition time ADS7853 55.5 ADS7253 55.5 ns ns ADS7853 4 × tCLK ns ADS7253 6 × tCLK ns ADS7853 14 × tCLK ns ADS7253 12 × tCLK ns TIMING SPECIFICATIONS tCONV Conversion time Copyright © 2013–2014, Texas Instruments Incorporated Product Folder Links: ADS8353 ADS7853 ADS7253 Submit Documentation Feedback 43 ADS8353, ADS7853, ADS7253 SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 www.ti.com 8.5.3.2.4 16-CLK, Single-SDO Mode (CFR.B11 = 1, CFR.B10 = 1) The 16-CLK, single-SDO mode provides the option of using only one SDO pin (SDO_A) and a lower-speed clock to read the conversion results of both ADCs. This interface mode is not supported by the ADS8353. For the ADS7853 and ADS7253, this mode can be selected by writing CFR.B11 = 1 and CFR.B10 = 1. The SDO_A pin is used to output the conversion results of both ADCs (ADC_A and ADC_B). SDO_B remains in 3state and can be treated as a no connect (NC) pin. Figure 94 shows a detailed timing diagram for this mode. Sample N Sample N+1 tTHROUGHPUT tPH_CS CS tSCLK SCLK 1 2 3 4 5 14 13 15 16 17 18 19 20 21 D13B D12B tCONV ADS7853, ADS7854 SDO_A 0 0 D13A D12A 0 0 D11A 31 32 tACQ D11A D2-A D3-A D1-A D0-A 0 0 tCONV ADS7253, ADS7254 SDO_A 30 D11D2-B B D1-B D0-B D9-B D0-B 0 0 tACQ D10A D9-A D0-A D1-A 0 0 0 D11B 0 D10B Data From Sample N All Devices SDO_B SDI B15 B14 B13 B3 B12 B2 B1 B0 X X X X X X X X Figure 94. 16-CLK, Single-SDO Mode Timing Diagram A CS falling edge brings the serial data bus out of 3-state and also outputs a 0 on the SDO_A pin. The subsequent SCLK falling edges are used for conversion and for data transfer using the serial interface, as shown in Table 18. The sample-and-hold circuit goes back into sample mode as soon as the conversion process is over. Table 18. Data Launch Edge LAUNCH EDGE DEVICE PIN CS SCLK ↓ ↓1 ↓2 — ↓13 ↓14 ↓15 ↓16 ↓17 CS ↓18 — ↓29 ↓30 ↓31 ↓32 ... ↑ ADS7853 SDO-A 0 0 D13_A — D2_A D1_A D0_A 0 0 D13_B — D2_B D1_B D0_B 0 ... Hi-Z ADS7253 SDO-A 0 0 D11_A — D0_A 0 0 0 0 D11_B — D0_B 0 0 0 ... Hi-Z 44 Submit Documentation Feedback Copyright © 2013–2014, Texas Instruments Incorporated Product Folder Links: ADS8353 ADS7853 ADS7253 ADS8353, ADS7853, ADS7253 www.ti.com SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 In this mode, at least 32 SCLK falling edges must be given to validate the read/write frame. A CS rising edge ends the frame and puts the serial bus into 3-state. Refer to Table 19 for timing specifications specific to this serial interface mode. Table 19. 16-CLK, Single-SDO Interface Specific Timing PARAMETER TEST CONDITIONS MIN TYP MAX UNIT TIMING REQUIREMENTS tCLK CLOCK period tACQ Acquisition time ADS7853 55.5 ADS7253 55.5 ns ns ADS7853 19 × tCLK ns ADS7253 21 × tCLK ns ADS7853 14 × tCLK ns ADS7253 12 × tCLK ns TIMING SPECIFICATIONS tCONV Conversion time 8.5.4 Low-Power Modes In normal mode of operation, all internal circuits of the device are always powered up and the device is always ready to commence a new conversion. This mode enables the device to support the rated throughput. The device also supports two low-power modes to optimize the power consumption at lower throughputs: STANDBY mode and software power-down (SPD) mode. 8.5.4.1 STANDBY Mode The device supports a STANDBY mode of operation where some of the internal circuits of the device are powered down. However, if bit 6 in configuration register is set to 1 (CFR.B6 = 1), then the internal reference is not powered down and the contents of the REFDAC_A and REFDAC_B registers are retained to enable faster power-up to a normal mode of operation. As shown in Figure 95, a valid write operation in frame (F) to program the configuration register with B5 set to 1 (CFR.B5 = 1) places the device into a STANDBY mode of operation on the following CS rising edge. While in STANDBY mode, SDO_A and SDO_B output all 1s when CS is low and remain in 3-state when CS is high. To remain in STANDBY mode, SDI must remain low in the subsequent frames. Device enters STANDBY mode Frame (F) Frame (F+1) Device in STANDBY mode CS SCLK 1 2 3 4 SDO-A and SDO-B 5 6 7 8 9 10 11 12 13 14 15 16 N 1 2 Valid Data as per device configuration CFG.B[5] = 1 SDI CFG.B[15:12] = 1000b CFG.B[11:6] CFG.B[4:0] = 00000b Note that N is a function of the device configuration, as described in Table 4. Figure 95. Enter STANDBY Mode Copyright © 2013–2014, Texas Instruments Incorporated Product Folder Links: ADS8353 ADS7853 ADS7253 Submit Documentation Feedback 45 ADS8353, ADS7853, ADS7253 SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 www.ti.com As shown in Figure 96, a valid write operation in frame (F+3) by writing the configuration register with B5 set to 0 (CFR.B5 = 0) brings the device out of STANDBY mode on the following CS rising edge. Frame (F+3) must have at least 48 SCLK falling edges. After exiting the STANDBY mode, a delay of tPU_STDBY must elapse for the internal circuits to fully power-up and resume normal operation in frame (F+4). Device configuration for frame (F+4) is determined by the status of the CFR.B[11:6] bits programmed during frame (F+3). Frame (F+2) CS SCLK Frame (F+3) Device in STANDBY mode tPU_STDBY 1 2 3 4 5 SDO-A and SDO-B SDI Frame (F+4) Device exits STANDBY mode 6 7 8 9 10 11 12 13 14 15 16 48 CFG.B[11:6] 2 15 16 N Valid Data as per device configuration These bits set device configuration for Frame (F+4) CFG.B[5] = 0 CFG.B[15:12] = 1000b 1 CFG.B[4:0] = 00000b CFG settings for Frame (F+5) Note that N is a function of the device configuration, as described in Table 4. Figure 96. Exit STANDBY Mode Refer to the Timing Characteristics: Serial Interface for timing specifications for this operating mode. 46 Submit Documentation Feedback Copyright © 2013–2014, Texas Instruments Incorporated Product Folder Links: ADS8353 ADS7853 ADS7253 ADS8353, ADS7853, ADS7253 www.ti.com SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 8.5.4.2 Software Power-Down (SPD) Mode In software power-down (SPD) mode, all internal circuits (including the internal references) are powered down. However, the contents of the REFDAC_A and REFDAC_B registers are retained. As shown in Figure 97, to enter SPD mode, the device must be selected (by bringing CS low) and SDI must be kept high for a minimum of 48 SCLK cycles during frame (F). The device goes to SPD on the CS rising edge following frame (F). While in SPD mode, SDO_A and SDO_B go to 3-state irrespective of the status of the CS signal. To remain in SPD mode, SDI must remain high in subsequent frames. Device enters SPD mode Frame (F) Frame (F+1) Device in SPD mode CS SCLK 1 2 SDO-A and SDO-B 3 47 1 48 2 Valid Data as per device configuration SDI Figure 97. Enter SPD Mode As shown in Figure 98, to exit SPD mode, the device must be selected (by bringing CS low) and SDI must be kept low for a minimum of 48 SCLK cycles during frame (F+3). The device starts powering-up on a CS rising edge following frame (F+3). After frame (F+3), a delay of tPU_SPD must elapse before programming the configuration register. A valid write operation in frame (F+4) sets the device configuration for frame (F+5). Frame (F+4) must have at least 48 SCLK falling edges. The output data in frame (F+4) should be discarded. Frame (F+2) Frame (F+3) Frame (F+4) Device exits SPD Frame (F+5) tPU_SPD CS SCLK Device in SPD 1 2 47 48 1 2 SDO-A and SDO-B 15 16 48 Invalid Data SDI CFG settings for Frame (F+5) 1 2 15 16 N Valid Data as per device configuration CFG settings for Frame (F+6) Note that N is a function of the device configuration, as described in Table 4. Figure 98. Exit SPD Mode Refer to the Timing Characteristics: Serial Interface for timing specifications for this operating mode. Copyright © 2013–2014, Texas Instruments Incorporated Product Folder Links: ADS8353 ADS7853 ADS7253 Submit Documentation Feedback 47 ADS8353, ADS7853, ADS7253 SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 www.ti.com 8.5.5 Frame Abort, Reconversion, or Short-Cycling As discussed in Figure 99, the minimum number of SCLK falling edges (N) that must be provided between the beginning and end of the frame depends on the serial interface mode. The SCLK falling edges (N) program the device and retrieve the conversion result. If CS is brought high before the expected number of SCLK falling edges are provided, the current frame is aborted and the device starts sampling the new analog input signal. If frame (F) is aborted, then the register write operation attempted in frame (F) is considered invalid and the internal registers are not updated. The device continues to have the same configuration in frame (F+1) from frame (F). The output data bits latched before the CS rising edge are still valid data that correspond to sample N. tPL_CS tPH_CS_SHRT CS 1 SCLK 2 SDO Sample N Sample N+1 tCONV tACQ tPH_CS_SHRT CS SCLK 1 2 SDO 13 14 15 16 17 22 23 24 V V V V V Data From Sample N Figure 99. Frame Abort, Reconversion, or Short-Cycling Feature Refer to the Timing Characteristics: Serial Interface for timing specifications for this operating mode. 48 Submit Documentation Feedback Copyright © 2013–2014, Texas Instruments Incorporated Product Folder Links: ADS8353 ADS7853 ADS7253 ADS8353, ADS7853, ADS7253 www.ti.com SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 9 Application and Implementation 9.1 Application Information The two primary circuits required to maximize the performance of a high-precision, successive approximation register (SAR), analog-to-digital converter (ADC) are the input driver and the reference driver circuits. This section details some general principles for designing these circuits, and some application circuits designed using these devices. The device supports operation either with an internal or external reference source. Refer to the Reference section for details about the decoupling requirements. The reference source to the ADC must provide low-drift and very accurate dc voltage and support the dynamic charge requirements without affecting the noise and linearity performance of the device. The output broadband noise (typically in the order of a few 100 μVRMS) of the reference source must be appropriately filtered by using a low-pass filter with a cutoff frequency of a few hundred hertz. After band-limiting the noise from the reference source, the next important step is to design a reference buffer that can drive the dynamic load posed by the reference input of the ADC. At the start of each conversion, the reference buffer must regulate the voltage of the reference pin within 1 LSB of the intended value. This condition necessitates the use of a large filter capacitor at the reference pin of the ADC. The amplifier selected to drive the reference input pin must be stable while driving this large capacitor and should have low output impedance, low offset, and temperature drift specifications. To reduce the dynamic current requirements and crosstalk between the channels, a separate reference buffer is recommended for driving the reference input of each ADC channel. The input driver circuit for a high-precision ADC mainly consists of two parts: a driving amplifier and a fly-wheel RC filter. The amplifier is used for signal conditioning of the input voltage and its low output impedance provides a buffer between the signal source and the switched capacitor inputs of the ADC. The RC filter helps attenuate the sampling charge injection from the switched-capacitor input stage of the ADC and functions as an antialiasing filter to band-limit the wideband noise contributed by the front-end circuit. Careful design of the front-end circuit is critical to meet the linearity and noise performance of a high-precision ADC. 9.1.1 Input Amplifier Selection Selection criteria for the input amplifiers is highly dependent on the input signal type and the performance goals of the data acquisition system. Some key amplifier specifications to consider while selecting an appropriate amplifier to drive the inputs of the ADC are: • Small-signal bandwidth. Select the small-signal bandwidth of the input amplifiers to be as high as possible after meeting the power budget of the system. Higher bandwidth reduces the closed-loop output impedance of the amplifier, thus allowing the amplifier to more easily drive the low cutoff frequency RC filter at the ADC inputs. Higher bandwidth also minimizes the harmonic distortion at higher input frequencies. In order to maintain the overall stability of the input driver circuit, the amplifier bandwidth should be selected as described in Equation 6: § 1 Unity Gain Bandwidth t 4 u ¨¨ © 2S u ( RFLT RFLT ) u C FLT • · ¸¸ ¹ (6) Noise. Noise contribution of the front-end amplifiers should be as low as possible to prevent any degradation in SNR performance of the system. As a rule of thumb, to ensure that the noise performance of the data acquisition system is not limited by the front-end circuit, the total noise contribution from the front-end circuit should be kept below 20% of the input-referred noise of the ADC. Noise from the input driver circuit is bandlimited by designing a low cutoff frequency RC filter and is calculated by Equation 7: 2 § V 1 _ AM P_ PP · S ¨ ¸ NG u 2 u ¨ f en2 _ RM S u u f3dB ¸ 6.6 2 ¨ ¸ © ¹ d § SNR dB · ¸ 20 ¹ ¨ 1 VREF u u 10 © 5 2 where: • • • • V1 / f_AMP_PP is the peak-to-peak flicker noise in µV, en_RMS is the amplifier broadband noise density in nV/√Hz, f–3dB is the 3-dB bandwidth of the RC filter, and NG is the noise gain of the front-end circuit, which is equal to 1 in a buffer configuration. Copyright © 2013–2014, Texas Instruments Incorporated Product Folder Links: ADS8353 ADS7853 ADS7253 Submit Documentation Feedback (7) 49 ADS8353, ADS7853, ADS7253 SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 www.ti.com Application Information (continued) • Distortion. Both the ADC and the input driver introduce nonlinearity in a data acquisition block. As a rule of thumb, to ensure that the distortion performance of the data acquisition system is not limited by the front-end circuit, the distortion of the input driver should be at least 10 dB lower than the distortion of the ADC, as shown in Equation 8. THD AMP d THD ADC 10 dB • (8) Settling Time. For dc signals with fast transients that are common in a multiplexed application, the input signal must settle to the desired accuracy at the inputs of the ADC during the acquisition time window. This condition is critical to maintain the overall linearity performance of the ADC. Typically, the amplifier data sheets specify the output settling performance only up to 0.1% to 0.001%, which may not be sufficient for the desired accuracy. Therefore, the settling behavior of the input driver should always be verified by TINA™SPICE simulations before selecting the amplifier. 9.1.2 Antialiasing Filter Converting analog-to-digital signals requires sampling an input signal at a constant rate. Any higher frequency content in the input signal beyond half the sampling frequency is digitized and folded back into the low-frequency spectrum. This process is called aliasing. Therefore, an analog, antialiasing filter must be used to remove the harmonic content from the input signal before being sampled by the ADC. An antialiasing filter is designed as a low-pass, RC filter, for which the 3-dB bandwidth is optimized based on specific application requirements. For dc signals with fast transients (including multiplexed input signals), a high-bandwidth filter is designed to allow accurately settling the signal at the ADC inputs during the small acquisition time window. For ac signals, the filter bandwidth should be kept low to band-limit the noise fed into the ADC input, thereby increasing the signal-tonoise ratio (SNR) of the system. A filter capacitor, CFLT, connected across the ADC inputs (as shown in Figure 100), filters the noise from the front-end drive circuitry, reduces the sampling charge injection and provides a charge bucket to quickly charge the internal sample-and-hold capacitors during the acquisition process. As a rule of thumb, the value of this capacitor should be at least 10 times the specified value of the ADC sampling capacitance. For these devices, the input sampling capacitance is equal to 40 pF. Thus, the value of CFLT should be greater than 400 pF. The capacitor should be a COG- or NPO-type because these capacitor types have a high-Q, low-temperature coefficient, and stable electrical characteristics under varying voltages, frequency, and time. Note that driving capacitive loads can degrade the phase margin of the input amplifiers, thus making the amplifier marginally unstable. To avoid amplifier stability issues, series isolation resistors (RFLT) are used at the output of the amplifiers. A higher value of RFLT is helpful from the amplifier stability perspective, but adds distortion as a result of interactions with the nonlinear input impedance of the ADC. Distortion increases with source impedance, input signal frequency, and input signal amplitude. Therefore, the selection of RFLT requires balancing the stability and distortion of the design. For these devices, TI recommends limiting the value of RFLT to a maximum of 22 Ω in order to avoid any significant degradation in linearity performance. The tolerance of the selected resistors can be chosen as 1% because the use of a differential capacitor at the input balances the effects resulting from any resistor mismatch. RFLT 22 f 3 dB 2S u R FLT 1 R FLT u C FLT V + AINP CFLT 400 pF ADS8353 ADS7853 ADS7253 AINM GND RFLT 22 Figure 100. Antialiasing Filter The input amplifier bandwidth should be much higher than the cutoff frequency of the antialiasing filter. TI strongly recommends performing a SPICE simulation to confirm that the amplifier has more than 40° phase margin with the selected filter. If an amplifier has less than a 40° phase margin with 22-Ω resistors, using a different amplifier with higher bandwidth or reducing the filter cutoff frequency with a larger differential capacitor is advisable. 50 Submit Documentation Feedback Copyright © 2013–2014, Texas Instruments Incorporated Product Folder Links: ADS8353 ADS7853 ADS7253 ADS8353, ADS7853, ADS7253 www.ti.com SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 9.2 Typical Applications 9.2.1 DAQ Circuit to Achieve Maximum SINAD for a 10-kHz Input Signal at Full Throughput AVDD VCM AVDD OPA836 + + 1k 10 + AVDD - 8.2 nF COG (NPO) VIN+ 1k AINP ADSxx53 AINM GND 10 VDC Where; VDC = 0 V for CFR.B7 = 0 VDC = FSR_ADC_x/2 for CFR.B7 = 1 VCM = FSR_ADC_x/2 ADS8353 : 16-bit, 600 kSPS ADS7853 : 14-bit, 1 MSPS ADS7253 : 12-bit, 1 MSPS INPUT DRIVER NOTE: Only one ADC channel is shown in this diagram. Replicate the same circuit for other ADC channels. Figure 101. DAQ Circuit: Maximum SINAD for a 10-kHz Input Signal at Full Throughput, 32-CLK Interface AVDD VCM AVDD OPA836 + + 1k 4 + AVDD - 1.8 nF COG (NPO) VIN+ 1k AINP ADSxx53 AINM GND 4 VDC Where; VDC = 0 V for CFR.B7 = 0 VDC = FSR_ADC_x/2 for CFR.B7 = 1 VCM = FSR_ADC_x/2 ADS7853 : 14-bit, 1 MSPS ADS7253 : 12-bit, 1 MSPS INPUT DRIVER NOTE: Only one ADC channel is shown in this diagram. Replicate the same circuit for other ADC channels. Figure 102. DAQ Circuit: Maximum SINAD for a 10-kHz Input Signal at Full Throughput, 16-CLK Interface Copyright © 2013–2014, Texas Instruments Incorporated Product Folder Links: ADS8353 ADS7853 ADS7253 Submit Documentation Feedback 51 ADS8353, ADS7853, ADS7253 SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 www.ti.com Typical Applications (continued) AVDD 10 µF AVDD REF5025, REF5040, REF5050(1) REFGND-A 1k 0.1 + ADC_A AVDD 1 µF REFIN-A - VOUT Device AVDD TRIM 0.22 1k + 1 µF REFIN-B 10 µF 1 µF ADC_B - 0.1 REFGND-B OPA2350 10 µF (1) When using the REF5050, AVDD must be set to 5.5 V. Figure 103. Reference Drive Circuit 9.2.1.1 Design Requirements To design an application circuit optimized to achieve target specifications listed in Table 20. Table 20. Target Specifications TARGET SPECIFICATIONS TEST CONDITIONS SNR THD DEVICE INPUT SIGNAL FREQUENCY THROUGHPUT INTERFACE MODE > 83 dB < -100 dB ADS8353 10 kHz Maximum supported 32-CLK, dual-SDO > 81 dB < –95 dB ADS7853 10 kHz Maximum supported 32-CLK, dual-SDO > 77.5 dB < –85 dB ADS7853 10 kHz Maximum supported 16-CLK, dual-SDO > 71.5 dB < –88 dB ADS7253 10 kHz Maximum supported 32-CLK, dual-SDO > 70.5 dB < –80 dB ADS7253 10 kHz Maximum supported 16-CLK, dual-SDO 9.2.1.2 Detailed Design Procedure Best practice is for the distortion from the input driver to be at least 10 dB less than the ADC distortion. The distortion resulting from variation in the common-mode signal is eliminated by using the amplifier in an inverting gain configuration that establishes a fixed common-mode level for the circuit. This configuration also eliminates the requirement of rail-to-rail swing at the amplifier input. The low-power OPA836, used as an input driver, provides exceptional ac performance because of its extremely low-distortion and high-bandwidth specifications. In addition, the components of the antialiasing filter are such that the noise from the front-end circuit is kept low without adding distortion to the input signal. The application circuit illustrated in Figure 101 is optimized to achieve the lowest distortion and lowest noise for a 10-kHz input signal fed to the ADS8353 or ADS7853 or ADS7253 operating at full throughput with the default 32CLK, dual-SDO interface mode. The input signal is processed through a high-bandwidth, low-distortion amplifier in an inverting gain configuration and a low-pass RC filter before being fed into the device. 52 Submit Documentation Feedback Copyright © 2013–2014, Texas Instruments Incorporated Product Folder Links: ADS8353 ADS7853 ADS7253 ADS8353, ADS7853, ADS7253 www.ti.com SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 The ADS7853 and the ADS7253 also support 16-CLK interface modes that achieve the rated throughput rate at much lower SCLK frequencies. However, when using the 16-CLK interface modes, the device receives less acquisition time when compared to the 32-CLK interface modes. The application circuit illustrated in Figure 102 is optimized to achieve the lowest distortion and lowest noise for a 10-kHz input signal fed to the ADS7853 or ADS7253 operating at full throughput with the 16-CLK, dual-SDO interface mode. The input signal is processed through a high-bandwidth, low-distortion amplifier in an inverting gain configuration and a low-pass RC filter before being fed into the device. Figure 103 illustrates the reference driver circuit when operation with an external reference is desired. The reference voltage is generated by the high-precision, low-noise REF50xx circuit. The output broadband noise of the reference is heavily filtered by a low-pass filter with a 3-dB cutoff frequency of 160 Hz. The decoupling capacitor on each reference pin is selected to be 10 µF. The low output impedance, low noise, and fast settling time makes the OPA2350 a good choice for driving this high capacitive load. 9.2.1.3 Application Curves To minimize external components and to maximize the dynamic range of the ADC, device is configured to operate with internal reference (CFR.B6 = 1) and 2 x VREF_x input full scale range (CFR.B9 = 1). Figure 104, Figure 105, and Figure 106, show the FFT plots and test results obtained with the ADS8353, ADS7853, and ADS7253, respectively, operating at full throughput with a 32-CLK interface and the circuit configuration of Figure 101. 0 0 ±20 ±30 ±60 Power (dB) Signal Power (dB) ±40 ±80 ±100 ±120 ±60 ±90 ±140 ±160 ±120 ±180 ±200 ±150 0 60 120 180 240 300 Input Frequency (kHz) SNR = 83.5 dB THD = –101.2 dB 0 100 200 fIN = 10.1 kHz 300 400 500 Input Frequency (kHz) C301 SNR = 82.1 dB Figure 104. ADS8353 in 32-CLK Interface Mode THD = –98.2 dB C003 fIN = 10.1 kHz Figure 105. ADS7853 in 32-CLK Interface Mode 0 Power (dB) ±30 ±60 ±90 ±120 ±150 0 100 200 300 400 500 Input Frequency (kHz) SNR = 72.5 dB THD = –94.2 dB C001 fIN = 10.1 kHz Figure 106. ADS7253 in 32-CLK Interface Mode Copyright © 2013–2014, Texas Instruments Incorporated Product Folder Links: ADS8353 ADS7853 ADS7253 Submit Documentation Feedback 53 ADS8353, ADS7853, ADS7253 SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 www.ti.com 0 0 ±30 ±30 Power (dB) Power (dB) Figure 107 and Figure 108 show the FFT plots and test results obtained with the ADS7853 and ADS7253, respectively, operating at full throughput with 16-CLK interface and the circuit configuration of Figure 102. ±60 ±90 ±120 ±90 ±120 ±150 0 100 200 300 400 Input Frequency (kHz) SNR = 78.1 dB THD = –89.8 dB Submit Documentation Feedback 500 ±150 0 100 fIN = 10.1 kHz 200 300 400 500 Input Frequency (kHz) C004 Figure 107. ADS7853 in 16-CLK Interface Mode 54 ±60 SNR = 71.2 dB THD = –84.9 dB C002 fIN = 10.1 kHz Figure 108. ADS7253 in 16-CLK Interface Mode Copyright © 2013–2014, Texas Instruments Incorporated Product Folder Links: ADS8353 ADS7853 ADS7253 ADS8353, ADS7853, ADS7253 www.ti.com SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 9.2.2 DAQ Circuit to Achieve Maximum SINAD for a 100-kHz Input Signal at Full Throughput +15 V VCM AVDD THS4032 + 4.7 602 AVDD + - VIN+ -15 V V + AINP 1 nF COG (NPO) 602 ADSxx53 AINM GND 10 pF 4.7 +15 V VDC + THS4032 -15 V ADS8353 : 16-bit, 600 kSPS ADS7853 : 14-bit, 1 MSPS ADS7253 : 12-bit, 1 MSPS Where; VDC = 0 V for CFR.B7 = 0 VDC = FSR_ADC_x/2 for CFR.B7 = 1 VCM = FSR_ADC_x/2 INPUT DRIVER NOTE: Only one ADC channel is shown in this diagram. Replicate the same circuit for other ADC channels. Figure 109. DAQ Circuit: Maximum SINAD for a 100-kHz Input Signal at Full Throughput AVDD AVDD REF5025, REF5040, REF5050(1) 10 µF REFGND-A 1k + 0.1 AVDD 1 µF ADC_A REFIN-A - VOUT Device AVDD TRIM 0.22 1k + 1 µF REFIN-B 10 µF 1 µF - ADC_B 0.1 REFGND-B OPA2350 10 µF (1) When using the REF5050, AVDD must be set to 5.5 V. Figure 110. Reference Drive Circuit Copyright © 2013–2014, Texas Instruments Incorporated Product Folder Links: ADS8353 ADS7853 ADS7253 Submit Documentation Feedback 55 ADS8353, ADS7853, ADS7253 SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 www.ti.com 9.2.2.1 Design Requirements To design an application circuit optimized to achieve target specifications listed in Table 21. Table 21. Target Specifications TARGET SPECIFICATIONS TEST CONDITIONS SNR THD DEVICE INPUT SIGNAL FREQUENCY > 83 dB < -95 dB ADS8353 100 kHz Maximum supported 32-CLK, dual-SDO > 78.5 dB < –88 dB ADS7853 100 kHz Maximum supported 32-CLK, dual-SDO > 77.5 dB < –85 dB ADS7853 100 kHz Maximum supported 16-CLK, dual-SDO > 71.5 dB < –85 dB ADS7253 100 kHz Maximum supported 32-CLK, dual-SDO > 71 dB < –84 dB ADS7253 100 kHz Maximum supported 16-CLK, dual-SDO THROUGHPUT INTERFACE MODE 9.2.2.2 Detailed Design Procedure Best practice is for the distortion from the input driver to be at least 10 dB less than the ADC distortion. The distortion resulting from variation in the common-mode signal is eliminated by using the amplifier in an inverting gain configuration that establishes a fixed common-mode level for the circuit. This configuration also eliminates the requirement of rail-to-rail swing at the amplifier input. The low-power OPA836, used as an input driver, provides exceptional ac performance because of its extremely low-distortion and high-bandwidth specifications. In addition, the components of the antialiasing filter are such that the noise from the front-end circuit is kept low without adding distortion to the input signal. To take full advantage of the pseudo-differential input structure of the ADC, the AINM pin must be driven to the appropriate VDC with the same amplifier and matching source impedance. The application circuit illustrated in Figure 109 is optimized to achieve the lowest distortion and lowest noise for a 100-kHz input signal fed to the ADS8353 or ADS7853 or ADS7253 operating at full throughput. The THS4032, used as an input driver, provides exceptional ac performance because of its extremely low-distortion, low-noise, and high-bandwidth specifications. In addition, the components of the antialiasing filter are such that the noise from the front-end circuit is kept low without adding distortion to the input signal. External clamp circuit may be required to ensure that the inputs to the device do not exceed AVDD. Figure 103 illustrates the reference driver circuit when operation with an external reference is desired. The reference voltage is generated by the high-precision, low-noise REF50xx circuit. The output broadband noise of the reference is heavily filtered by a low-pass filter with a 3-dB cutoff frequency of 160 Hz. The decoupling capacitor on each reference pin is selected to be 10 µF. The low output impedance, low noise, and fast settling time makes the OPA2350 a good choice for driving this high capacitive load. 56 Submit Documentation Feedback Copyright © 2013–2014, Texas Instruments Incorporated Product Folder Links: ADS8353 ADS7853 ADS7253 ADS8353, ADS7853, ADS7253 www.ti.com SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 9.2.2.3 Application Curves To minimize external components and to maximize the dynamic range of the ADC, device is configured to operate with internal reference (CFR.B6 = 1) and 2 x VREF_x input full scale range (CFR.B9 = 1). Figure 111, Figure 112, and Figure 113 show the FFT plots and test results obtained with the ADS8353, ADS7853 and ADS7253, respectively, operating at full throughput with a 32-CLK interface and the circuit configuration of Figure 109. 0 0 ±20 ±30 ±60 ±80 Power (dB) Signal Power (dB) ±40 ±100 ±120 ±60 ±90 ±140 ±160 ±120 ±180 ±200 0 60 120 180 240 Input Frequency (kHz) SNR = 83.1 dB THD = –95.5 dB ±150 300 0 100 C303 200 300 400 500 C007 Input Frequency (dB) fIN = 100.2 kHz SNR = 79.6 dB Figure 111. ADS8353 in 32-CLK Interface Mode THD = –90.9 dB fIN = 100.2 kHz Figure 112. ADS7853 in 32-CLK Interface Mode 0 Power (dB) ±30 ±60 ±90 ±120 ±150 0 100 200 300 400 Input Frequency (kHz) SNR = 72.9 dB THD = –85.8 dB 500 C005 fIN = 100.2 kHz Figure 113. ADS7253 in 32-CLK Interface Mode Copyright © 2013–2014, Texas Instruments Incorporated Product Folder Links: ADS8353 ADS7853 ADS7253 Submit Documentation Feedback 57 ADS8353, ADS7853, ADS7253 SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 www.ti.com 0 0 ±30 ±30 Power (dB) Power (dB) Figure 114 and Figure 115 show the FFT plots and test results obtained with the ADS7853 and ADS7253, respectively, operating with a 16-CLK interface and the circuit configuration of Figure 109. ±60 ±90 ±120 ±90 ±120 ±150 ±150 0 100 200 300 400 500 Input Frequency (kHz) SNR = 78.2 dB THD = –87.2 dB Submit Documentation Feedback 0 100 fIN = 100.2 kHz 200 300 400 Input Frequency (kHz) C008 Figure 114. ADS7853 in 16-CLK Interface Mode 58 ±60 SNR = 72.3 dB THD = –84.3 dB 500 C006 fIN = 100.2 kHz Figure 115. ADS7253 in 16-CLK Interface Mode Copyright © 2013–2014, Texas Instruments Incorporated Product Folder Links: ADS8353 ADS7853 ADS7253 ADS8353, ADS7853, ADS7253 www.ti.com SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 10 Power-Supply Recommendations The devices have two separate power supplies: AVDD and DVDD. The device operates on AVDD; DVDD is used for the interface circuits. AVDD and DVDD can be independently set to any value within the permissible ranges. When using the device with 2 × VREF input range (CFR.B9 = 1), the AVDD supply voltage value defines the permissible voltage swing on the analog input pins. To avoid saturation of output codes, and to use the full dynamic range on the analog input pins, AVDD must be set as shown in Equation 9, Equation 10, and Equation 11: AVDD ≥ 2 × VREF_A AVDD ≥ 2 × VREF_B 4.75 V ≤ AVDD ≤ 5.25 V (9) (10) (11) Decouple the AVDD and DVDD pins with the GND pin using individual 10-µF decoupling capacitors, as shown in Figure 116. AVDD AVDD (pin 14) 10 PF GND (pin 13) 10 PF DVDD DVDD (pin 7) Figure 116. Power-Supply Decoupling Copyright © 2013–2014, Texas Instruments Incorporated Product Folder Links: ADS8353 ADS7853 ADS7253 Submit Documentation Feedback 59 ADS8353, ADS7853, ADS7253 SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 www.ti.com 11 Layout 11.1 Layout Guidelines Figure 117 shows a board layout example for the ADS8353, ADS7853, and ADS7253 with the WQFN package. Use a ground plane underneath the device and partition the PCB into analog and digital sections. Avoid crossing digital lines with the analog signal path and keep the analog input signals and the reference input signals away from noise sources. As shown in Figure 117, the analog input and reference signals are routed on the left side of the board and the digital connections are routed on the right side of the device. The power sources to the device must be clean and well-bypassed. Use 10-μF, ceramic bypass capacitors in close proximity to the analog (AVDD) and digital (DVDD) power-supply pins. Avoid placing vias between the AVDD and DVDD pins and the bypass capacitors. Connect all ground pins to the ground plane using short, low impedance paths. The REFIO-A and REFIO-B reference inputs and outputs are bypassed with 10-μF, X7R-grade, 0805-size, 16-V rated ceramic capacitors (CREF-x). Place the reference bypass capacitors as close as possible to the reference REFIO-x pins and connect the bypass capacitors using short, low-inductance connections. Avoid placing vias between the REFIO-x pins and the bypass capacitors. Small 0.1-Ω to 0.2-Ω resistors (RREF-x) are used in series with the reference bypass capacitors to improve stability. The fly-wheel RC filters are placed immediately next to the input pins. Among ceramic surface-mount capacitors, COG (NPO) ceramic capacitors provide the best capacitance precision. The type of dielectric used in COG (NPO) ceramic capacitors provides the most stable electrical properties over voltage, frequency, and temperature changes. Figure 117 shows CIN-A and CIN-B filter capacitors placed across the analog input pins of the device. 11.2 Layout Example CREF-A AVDD CIN-A GND GND AVDD AINP-A AINM-A RREF-A CAVDD GND SDO-A REFIO-A CIN-B /CS SDI AINM-B RREF-B CREF-B SCLK GND REFIO-B GND SDO-B REFGND-B DVDD GND REFGND-A AINP-B GND CDVDD DVDD GND GND Figure 117. Recommended Layout 60 Submit Documentation Feedback Copyright © 2013–2014, Texas Instruments Incorporated Product Folder Links: ADS8353 ADS7853 ADS7253 ADS8353, ADS7853, ADS7253 www.ti.com SBAS584B – OCTOBER 2013 – REVISED AUGUST 2014 12 Device and Documentation Support 12.1 Related Links The table below lists quick access links. Categories include technical documents, support and community resources, tools and software, and quick access to sample or buy. Table 22. Related Links PARTS PRODUCT FOLDER SAMPLE & BUY TECHNICAL DOCUMENTS TOOLS & SOFTWARE SUPPORT & COMMUNITY ADS8353 Click here Click here Click here Click here Click here ADS7853 Click here Click here Click here Click here Click here ADS7253 Click here Click here Click here Click here Click here 12.2 Related Documentation • • • • • TIPD117 Verified Design Reference Guide: 12 Bit 1 MSPS Single Supply Dual Channel Data Acquisition System for Optical Encoders in Motor Control Application Reference Design, SLAU517. REF5050 Data Sheet, SBOS410. OPA2350 Data Sheet, SBOS099. OPA836, OPA2836 Data Sheet, SLOS712. THS4032 Data Sheet, SLOS224. 12.3 Trademarks TINA is a trademark of Texas Instruments Inc.. All other trademarks are the property of their respective owners. 12.4 Electrostatic Discharge Caution This integrated circuit can be damaged by ESD. Texas Instruments recommends that all integrated circuits be handled with appropriate precautions. Failure to observe proper handling and installation procedures can cause damage. ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more susceptible to damage because very small parametric changes could cause the device not to meet its published specifications. 12.5 Glossary SLYZ022 — TI Glossary. This glossary lists and explains terms, acronyms, and definitions. 13 Mechanical, Packaging, and Orderable Information The following pages include mechanical packaging and orderable information. This information is the most current data available for the designated devices. This data is subject to change without notice and revision of this document. For browser-based versions of this data sheet, refer to the left-hand navigation. Copyright © 2013–2014, Texas Instruments Incorporated Product Folder Links: ADS8353 ADS7853 ADS7253 Submit Documentation Feedback 61 PACKAGE OPTION ADDENDUM www.ti.com 7-Sep-2014 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Pins Package Drawing Qty Eco Plan Lead/Ball Finish MSL Peak Temp (2) (6) (3) Op Temp (°C) Device Marking (4/5) ADS7253IPW ACTIVE TSSOP PW 16 90 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR -40 to 125 ADS7253 ADS7253IPWR ACTIVE TSSOP PW 16 2000 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR -40 to 125 ADS7253 ADS7253IRTER ACTIVE WQFN RTE 16 3000 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR -40 to 125 7253 ADS7253IRTET ACTIVE WQFN RTE 16 250 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR -40 to 125 7253 ADS7853IPW ACTIVE TSSOP PW 16 90 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR -40 to 125 ADS7853 ADS7853IPWR ACTIVE TSSOP PW 16 2000 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR -40 to 125 ADS7853 ADS7853IRTER ACTIVE WQFN RTE 16 3000 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR -40 to 125 7853 ADS7853IRTET ACTIVE WQFN RTE 16 250 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR -40 to 125 7853 ADS8353IPW ACTIVE TSSOP PW 16 90 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR -40 to 125 ADS8353 ADS8353IPWR ACTIVE TSSOP PW 16 2000 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR -40 to 125 ADS8353 ADS8353IRTER ACTIVE WQFN RTE 16 3000 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR -40 to 125 8353 ADS8353IRTET ACTIVE WQFN RTE 16 250 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR -40 to 125 8353 (1) The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design. PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device. (2) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability information and additional product content details. TBD: The Pb-Free/Green conversion plan has not been defined. Addendum-Page 1 Samples PACKAGE OPTION ADDENDUM www.ti.com 7-Sep-2014 Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes. Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above. Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material) (3) MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature. (4) There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device. (5) Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation of the previous line and the two combined represent the entire Device Marking for that device. (6) Lead/Ball Finish - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead/Ball Finish values may wrap to two lines if the finish value exceeds the maximum column width. Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals. TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release. In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis. Addendum-Page 2 PACKAGE MATERIALS INFORMATION www.ti.com 19-Mar-2016 TAPE AND REEL INFORMATION *All dimensions are nominal Device Package Package Pins Type Drawing SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant ADS7253IPWR TSSOP PW 16 2000 330.0 12.4 6.9 5.6 1.6 8.0 12.0 Q1 ADS7253IRTER WQFN RTE 16 3000 330.0 12.4 3.3 3.3 1.1 8.0 12.0 Q2 ADS7253IRTET WQFN RTE 16 250 180.0 12.4 3.3 3.3 1.1 8.0 12.0 Q2 ADS7853IPWR TSSOP PW 16 2000 330.0 12.4 6.9 5.6 1.6 8.0 12.0 Q1 ADS7853IRTER WQFN RTE 16 3000 330.0 12.4 3.3 3.3 1.1 8.0 12.0 Q2 ADS7853IRTET WQFN RTE 16 250 180.0 12.4 3.3 3.3 1.1 8.0 12.0 Q2 ADS8353IPWR TSSOP PW 16 2000 330.0 12.4 6.9 5.6 1.6 8.0 12.0 Q1 ADS8353IRTER WQFN RTE 16 3000 330.0 12.4 3.3 3.3 1.1 8.0 12.0 Q2 ADS8353IRTET WQFN RTE 16 250 180.0 12.4 3.3 3.3 1.1 8.0 12.0 Q2 Pack Materials-Page 1 PACKAGE MATERIALS INFORMATION www.ti.com 19-Mar-2016 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) ADS7253IPWR ADS7253IRTER TSSOP PW 16 2000 367.0 367.0 35.0 WQFN RTE 16 3000 367.0 367.0 35.0 ADS7253IRTET WQFN RTE 16 250 210.0 185.0 35.0 ADS7853IPWR TSSOP PW 16 2000 367.0 367.0 35.0 ADS7853IRTER WQFN RTE 16 3000 367.0 367.0 35.0 ADS7853IRTET WQFN RTE 16 250 210.0 185.0 35.0 ADS8353IPWR TSSOP PW 16 2000 367.0 367.0 35.0 ADS8353IRTER WQFN RTE 16 3000 367.0 367.0 35.0 ADS8353IRTET WQFN RTE 16 250 210.0 185.0 35.0 Pack Materials-Page 2 IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, enhancements, improvements and other changes to its semiconductor products and services per JESD46, latest issue, and to discontinue any product or service per JESD48, latest issue. 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