2 8-Channel, 10- and 12-Bit ADCs with I C- Compatible Interface in 20-Lead TSSOP AD7997/AD7998 FEATURES FUNCTIONAL BLOCK DIAGRAM V AGND REF CONVST DD IN 10- and 12-bit ADC with fast conversion time: 2 s typ 8 single-ended analog input channels AD7997/AD7998 Specified for V of 2.7 V to 5.5 V DD 10-/12-BIT V 1 IN SUCCESSIVE CONTROL Low power consumption T/H 8:1 APPROXIMATION LOGIC I/P ADC Fast throughput rate: up to 188 kSPS MUX Sequencer operation V 8 OSCILLATOR IN Automatic cycle mode 2 I C-compatible serial interface supports standard, fast, CONVERSION DATA LIMIT LOW RESULT and high speed modes REGISTER REGISTER CH1CH4 Out-of-range indicator/alert function CONFIGURATION ALERT/BUSY Pin-selectable addressing via AS REGISTER DATA LIMIT HIGH REGISTER CH1CH4 Shutdown mode: 1 A max ALERT STATUS REGISTER Temperature range: 40C to +85C HYSTERESIS 20-lead TSSOP package CYCLE TIMER REGISTER CH1CH4 REGISTER See the AD7992 and AD7994 for 2-channel and 4-channel AS SCL equivalent devices, respectively 2 I C INTERFACE SDA AGND GENERAL DESCRIPTION Figure 1. The AD7997/AD7998 are 8-channel, 10- and 12-bit, low power, 2 On-chip limit registers can be programmed with high and successive approximation ADCs with an I C-compatible low limits for the conversion result, and an open-drain, out-of- interface. The parts operate from a single 2.7 V to 5.5 V power range indicator output (ALERT) becomes active when the supply and feature a 2 s conversion time. The parts contain an programmed high or low limits are violated by the conversion 8-channel multiplexer and track-and-hold amplifier that can result. This output can be used as an interrupt. handle input frequencies up to 11 MHz. PRODUCT HIGHLIGHTS The AD7997/AD7998 provide a 2-wire serial interface that is 2 1. 2 s conversion time with low power consumption. compatible with I C interfaces. Each part comes in two versions, AD7997-0/AD7998-0 and AD7997-1/AD7998-1, and each 2 2. I C-compatible serial interface with pin-selectable 2 2 version allows at least two different I C addresses. The I C addresses. Two AD7997/AD7998 versions allow five interface on the AD7997-0/AD7998-0 supports standard and AD7997/AD7998 devices to be connected to the same 2 2 fast I C interface modes. The I C interface on the AD7997-1/ serial bus. 2 AD7998-1 supports standard, fast, and high speed I C interface 3. The parts feature automatic shutdown while not converting modes. to maximize power efficiency. Current consumption is 1 A The AD7997/AD7998 normally remain in a shutdown state max when in shutdown mode at 3V. while not converting, and power up only for conversions. The 4. Reference can be driven up to the power supply. conversion process can be controlled using the pin, CONVST 2 by a command mode where conversions occur across I C write 5. Out-of-range indicator that can be software disabled or operations or an automatic conversion interval mode selected enabled. through software control. 6. One-shot and automatic conversion rates. The AD7997/AD7998 require an external reference that should 7. Registers store minimum and maximum conversion be applied to the REFIN pin and can be in the range of 1.2 V to results. VDD. This allows the widest dynamic input range to the ADC. Rev. 0 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 rights of third parties that may result from its use. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Specifications subject to change without notice. No license is granted by implication Tel: 781.329.4700 www.analog.com or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners. Fax: 781.326.8703 2004 Analog Devices, Inc. All rights reserved. 03473-0-001AD7997/AD7998 TABLE OF CONTENTS AD7997 Specifications..................................................................... 3 Serial Bus Address ...................................................................... 23 AD7998 Specifications..................................................................... 5 Writing to the AD7997/AD7998 .................................................. 24 2 I C Timing Specifications................................................................ 7 Writing to the Address Pointer Register for a Subsequent Read.............................................................................................. 24 Absolute Maximum Ratings............................................................ 9 Writing a Single Byte of Data to the Alert Status Register or ESD Caution.................................................................................. 9 Cycle Register.............................................................................. 24 Pin Configuration and Pin Function Descriptions.................... 10 Writing Two Bytes of Data to a Limit, Hysteresis, or Configuration Register .............................................................. 24 Terminology .................................................................................... 11 Reading Data from the AD7997/AD7998................................... 26 Typical Performance Characteristics ........................................... 12 ALERT/BUSY Pin .......................................................................... 27 Circuit Information........................................................................ 15 SMBus ALERT ............................................................................ 27 Converter Operation.................................................................. 15 BUSY............................................................................................ 27 Typical Connection Diagram ................................................... 16 Placing the AD7997-1/AD7998-1 into High Speed Mode ... 27 Analog Input ............................................................................... 16 The Address Select (AS) Pin ..................................................... 27 Internal Register Structure ............................................................ 18 Modes of Operation ....................................................................... 28 Address Pointer Register ........................................................... 18 Mode 1Using the CONVST Pin ........................................... 28 Configuration Register .............................................................. 19 Mode 2 COMMAND MODE ............................................... 29 Conversion Result Register ....................................................... 20 Mode 3Automatic Cycle Interval Mode.............................. 30 Limit Registers ............................................................................ 20 Outline Dimensions ....................................................................... 31 Alert Status Register (CH1 to CH4) ........................................ 21 Ordering Guide .......................................................................... 31 Cycle Timer Register.................................................................. 22 2 Related Parts in I C-Compatible ADC Product Family........ 31 Sample Delay and Bit Trial Delay............................................. 22 Serial Interface ................................................................................ 23 REVISION HISTORY 9/04Revision 0: Initial Version Rev. 0 Page 2 of 32