8-Channel, 1.5 MSPS, 12-Bit and 10-Bit Parallel ADCs with a Sequencer Data Sheet AD7938/AD7939 FEATURES FUNCTIONAL BLOCK DIAGRAM V AGND DD Throughput rate: 1.5 MSPS Specified for V of 2.7 V to 5.25 V DD AD7938/AD7939 V REFIN/ Power consumption V REFOUT 2.5V 6 mW maximum at 1.5 MSPS with 3 V supplies VREF 13.5 mW maximum at 1.5 MSPS with 5 V supplies V 0 IN CLKIN 12-/10-BIT 8 analog input channels with a sequencer SAR ADC I/P CONVST T/H AND MUX Software-configurable analog inputs CONTROL BUSY V 7 IN 8-channel single-ended inputs 4-channel fully differential inputs 4-channel pseudo differential inputs SEQUENCER 7-channel pseudo differential inputs Accurate on-chip 2.5 V reference V PARALLEL INTERFACE/CONTROL REGISTER DRIVE 0.2% maximum 25C, 25 ppm/C maximum 69 dB SINAD at 50 kHz input frequency No pipeline delays DB0 DB11 CS RD WR W/B DGND High speed parallel interfaceword/byte modes Full shutdown mode: 2 A maximum Figure 1. 32-lead LFCSP and TQFP packages GENERAL DESCRIPTION The AD7938/AD7939 are 12-bit and 10-bit, high speed, low These parts use advanced design techniques to achieve very power, successive approximation (SAR) analog-to-digital low power dissipation at high throughput rates. They also converters (ADCs). The parts operate from a single 2.7 V to feature flexible power management options. An on-chip 5.25 V power supply and feature throughput rates up to control register allows the user to set up different operating 1.5 MSPS. The parts contain a low noise, wide bandwidth, conditions, including analog input range and configuration, differential track-and-hold amplifier that can handle input output coding, power management, and channel sequencing. frequencies up to 50 MHz. PRODUCT HIGHLIGHTS The AD7938/AD7939 feature eight analog input channels with 1. High throughput with low power consumption. a channel sequencer that allows a preprogrammed selection of 2. Eight analog inputs with a channel sequencer. channels to be converted sequentially. These parts can operate 3. Accurate on-chip 2.5 V reference. with either single-ended, fully differential, or pseudo 4. Single-ended, pseudo differential, or fully differential differential analog inputs. analog inputs that are software selectable. 5. Single-supply operation with V function. The V DRIVE DRIVE The conversion process and data acquisition are controlled function allows the parallel interface to connect directly to using standard control inputs that allow easy interfacing with 3 V or 5 V processor systems independent of V . DD microprocessors and DSPs. The input signal is sampled on the 6. No pipeline delay. CONVST falling edge of and the conversion is also initiated at 7. Accurate control of the sampling instant via a CONVST this point. input and once-off conversion control. The AD7938/AD7939 have an accurate on-chip 2.5 V reference Table 1. Related Devices that can be used as the reference source for the analog-to- Device No. of Bits No. of Channels Speed digital conversion. Alternatively, this pin can be overdriven to AD7933/AD7934 12/10 4 1.5 MSPS provide an external reference. AD7938-6 12 8 625 kSPS AD7934-6 12 4 625 kSPS Rev. F Document Feedback Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. rights of third parties that may result from its use. Specifications subject to change without notice. Tel: 781.329.4700 20042020 Analog Devices, Inc. All rights reserved. No license is granted by implication or otherwise under any patent or patent rights of Analog Technical Support www.analog.com Devices. Trademarks and registered trademarks are the property of their respective owners. 03715-001AD7938/AD7939 Data Sheet TABLE OF CONTENTS Features .............................................................................................. 1 Circuit Information ....................................................................... 19 Functional Block Diagram .............................................................. 1 Converter Operation ................................................................. 19 General Description ......................................................................... 1 ADC Transfer Function ............................................................ 19 Product Highlights ........................................................................... 1 Typical Connection Diagram ................................................... 20 Revision History ............................................................................... 2 Analog Input Structure ............................................................. 20 Specifications .................................................................................... 4 Analog Inputs ............................................................................. 21 AD7938 Specifications ................................................................. 4 Analog Input Selection .............................................................. 23 AD7939 Specifications ................................................................. 6 Reference ..................................................................................... 24 Timing Specifications .................................................................. 8 Parallel Interface ......................................................................... 26 Absolute Maximum Ratings ........................................................... 9 Power Modes of Operation ....................................................... 29 ESD Caution.................................................................................. 9 Power vs. Throughput Rate ...................................................... 30 Pin Configuration and Function Descriptions .......................... 10 Microprocessor Interfacing ...................................................... 30 Typical Performance Characteristics ........................................... 12 Application Hints ........................................................................... 32 Terminology .................................................................................... 14 Grounding and Layout .............................................................. 32 On-Chip Registers .......................................................................... 16 PCB Design Guidelines for Chip Scale Package .................... 32 Control Register ......................................................................... 16 Evaluating AD7938/AD7939 Performance ............................ 32 Sequencer Operation ................................................................. 17 Outline Dimensions ....................................................................... 33 Shadow Register ......................................................................... 18 Ordering Guide .......................................................................... 34 REVISION HISTORY 11/2020Rev. E to Rev. F 10/2011Rev. B to Rev. C Changed CP-32-2 to CP-32-7 ...................................... Throughout Changes to SINAD Specification in Features Section .................. 1 Changes to Figure 2 ........................................................................ 10 Changes to AD7938 Specifications Section ................................... 3 Updated Outline Dimensions ....................................................... 32 Updated Outline Dimensions ...................................................... 32 Changes to Ordering Guide .......................................................... 33 Changes to Ordering Guide .......................................................... 33 1/2018Rev. D to Rev. E 2/2007Rev. A to Rev. B Changed CP-32-7 to CP-32-2 ...................................... Throughout Updated Format ................................................................. Universal Updated Outline Dimensions ....................................................... 32 Changes to Sequencer Operation Section ................................... 16 Changes to Ordering Guide .......................................................... 33 Updated Outline Dimensions ...................................................... 32 10/2016Rev. C to Rev. D 7/2005Rev. 0 to Rev. A Changed to CP-32-7 ...................................................... Throughout Changes to Specifications ................................................................. 3 Changes to Figure 2 .......................................................................... 9 Added Figure 3 ..................................................................................9 Updated Outline Dimensions ....................................................... 32 Changes to Table 5 ......................................................................... 10 Changes to Ordering Guide .......................................................... 33 Updated Typical Performance Characteristics .......................... 13 Changes to Table 11 ....................................................................... 16 Rev. F Page 2 of 37