8-Channel, 1 MSPS, 8-/10-/12-Bit ADCs with Sequencer in 20-Lead TSSOP Data Sheet AD7908/AD7918/AD7928 FEATURES FUNCTIONAL BLOCK DIAGRAM AV Fast throughput rate: 1 MSPS DD Specified for AVDD of 2.7 V to 5.25 V REF IN Low power V 0 IN 6.0 mW max at 1 MSPS with 3 V supply T/H 8-/10-/12-BIT 13.5 mW max at 1 MSPS with 5 V supply SUCCESSIVE APPROXIMATION Eight (single-ended) inputs with sequencer ADC Wide input bandwidth I/P MUX AD7928, 70 dB min SINAD at 50 kHz input frequency Flexible power/serial clock speed management No pipeline delays High speed serial interface SPI/QSPI/ V 7 IN MICROWIRE/DSP compatible SCLK Shutdown mode: 0.5 A max DOUT SEQUENCER CONTROL LOGIC DIN 20-lead TSSOP package CS Qualified for automotive applications AD7908/AD7918/AD7928 V DRIVE GENERAL DESCRIPTION GND The AD7908/AD7918/AD7928 are, respectively, 8-bit, 10-bit, and Figure 1. 12-bit, high speed, low power, 8-channel, successive approximation PRODUCT HIGHLIGHTS ADCs. The parts operate from a single 2.7 V to 5.25 V power supply and feature throughput rates up to 1 MSPS. The parts 1. High Throughput with Low Power Consumption. The AD7908/ contain a low noise, wide bandwidth track-and-hold amplifier that AD7918/AD7928 offer up to 1 MSPS throughput rates. At the can handle input frequencies in excess of 8 MHz. maximum throughput rate with 3 V supplies, the AD7908/ AD7918/AD7928 dissipate just 6 mW of power maximum. The conversion process and data acquisition are controlled using CS and the serial clock signal, allowing the device to easily interface 2. Eight Single-Ended Inputs with a Channel Sequencer. with microprocessors or DSPs. The input signal is sampled on the A sequence of channels can be selected, through which CS falling edge of and conversion is also initiated at this point. the ADC cycles and converts on. There are no pipeline delays associated with the part. 3. Single-Supply Operation with VDRIVE Function. The AD7908/ The AD7908/AD7918/AD7928 use advanced design techniques to AD7918/AD7928 operate from a single 2.7 V to 5.25 V supply. achieve very low power dissipation at maximum throughput rates. The VDRIVE function allows the serial interface to connect directly At maximum throughput rates, the AD7908/AD7918/AD7928 to either 3 V or 5 V processor systems independent of AV . DD consume 2 mA maximum with 3 V supplies with 5 V supplies, the 4. Flexible Power/Serial Clock Speed Management. The conversion current consumption is 2.7 mA maximum. rate is determined by the serial clock, allowing the conversion Through the configuration of the control register, the analog input time to be reduced through the serial clock speed increase. The range for the part can be selected as 0 V to REF or 0 V to 2 IN parts also feature various shutdown modes to maximize power REF , with either straight binary or twos complement output IN efficiency at lower throughput rates. Current consumption is coding. The AD7908/AD7918/AD7928 each feature eight single- 0.5 A max when in full shutdown. ended analog inputs with a channel sequencer to allow a 5. No Pipeline Delay. The parts feature a standard successive preprogrammed selection of channels to be converted sequentially. approximation ADC with accurate control of the sampling The conversion time for the AD7908/AD7918/AD7928 is instant via a CS input and once off conversion control. determined by the SCLK frequency, which is also used as the master clock to control the conversion. Rev. E 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. No Tel: 781.329.4700 20062014 Analog Devices, Inc. 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Technical Support www.analog.com 03089-001AD7908/AD7918/AD7928 Data Sheet TABLE OF CONTENTS Features .............................................................................................. 1 Control Register .............................................................................. 15 General Description ......................................................................... 1 Sequencer Operation ................................................................. 16 Functional Block Diagram .............................................................. 1 SHADOW Register .................................................................... 17 Product Highlights ........................................................................... 1 Circuit Information .................................................................... 18 Revision History ............................................................................... 2 Converter Operation .................................................................. 18 Specifications ..................................................................................... 3 ADC Transfer Function ............................................................. 19 AD7908 Specifications ................................................................. 3 Handling Bipolar Input Signals ................................................ 19 AD7918 Specifications ................................................................. 5 Typical Connection Diagram ................................................... 19 AD7928 Specifications ................................................................. 7 Modes of Operation ................................................................... 21 Timing Specifications .................................................................. 9 Power vs. Throughput Rate ....................................................... 23 Absolute Maximum Ratings .......................................................... 10 Serial Interface ............................................................................ 23 ESD Caution ................................................................................ 10 Microprocessor Interfacing ....................................................... 24 Pin Configuration and Function Descriptions ........................... 11 Application Hints ....................................................................... 27 Terminology .................................................................................... 12 Outline Dimensions ....................................................................... 28 Typical Performance Characteristics ........................................... 13 Ordering Guide .......................................................................... 28 Performance Curves ................................................................... 13 Automotive Products ................................................................. 28 REVISION HISTORY 1/14Rev. D to Rev. E 11/08Rev. B to Rev. C Changes to Ordering Guide .......................................................... 28 Changes to ESD Parameter, Table 5 ............................................. 10 12/10Rev. C to Rev. D 6/06Rev. A to Rev. B Changes to Features Section............................................................ 1 Updated Format .................................................................. Universal Added Automotive SINAD and SNR Parameters (Table 1)........ 3 Changes to Reference Section ....................................................... 21 Added Automotive SINAD and SNR Parameters (Table 2)........ 5 9/03Rev. 0 to Rev. A Added Automotive SINAD and SNR Parameters (Table 3)........ 7 Changes to Figure 3 ........................................................................ 15 Added Automotive Temperature Range (Table 5) ....................... 7 Changes to Reference section ....................................................... 18 Added Automotive Products Section........................................... 28 Changes to Ordering Guide .......................................................... 28 Rev. E Page 2 of 28