Datasheet AD7997, AD7998 (Analog Devices)

8-Channel, 10- and 12-Bit ADCs with I2C- Compatible Interface in 20-Lead TSSOP AD7997/AD7998 FEATURES FUNCTIONAL BLOCK DIAGRAM 10- and 12-bit ADC with fast conversion time: 2 µs typ VDD AGND REF CONVST IN 8 single-ended analog input channels AD7997/AD7998 Specified for VDD of 2.7 V to 5.5 V 10-/12-BIT V Low power consumption IN1 SUCCESSIVE CONTROL T/H 8:1 APPROXIMATION LOGIC Fast throughput rate: up to 188 kSPS I/P ADC MUX Sequencer operation V OSCILLATOR IN8 Automatic cycle mode I2C®-compatible serial interface supports standard, fast, CONVERSION and high speed modes DATALOWLIMIT RESULT REGISTER CH1–CH4 REGISTER Out-of-range indicator/alert function CONFIGURATION Pin-selectable addressing via AS ALERT/BUSY REGISTER DATAHIGHLIMIT Shutdown mode: 1 µA max REGISTER CH1–CH4 ALERT STATUS Temperature range: −40°C to +85°C REGISTER HYSTERESIS 20-lead TSSOP package CYCLE TIMER REGISTER CH1–CH4 See the AD7992 and AD7994 f or 2-channel and 4-channel REGISTER AS equivalent devices, respectively SCL I2C INTERFACE SDA
001 0-
GENERAL DESCRIPTION AGND
03473- The AD7997/AD7998 are 8-channel, 10- and 12-bit, low power, Figure 1. successive approximation ADCs with an I2C-compatible On-chip limit registers can be programmed with high and interface. The parts operate from a single 2.7 V to 5.5 V power low limits for the conversion result, and an open-drain, out-of- supply and feature a 2 µs conversion time. The parts contain an range indicator output (ALERT) becomes active when the 8-channel multiplexer and track-and-hold amplifier that can programmed high or low limits are violated by the conversion handle input frequencies up to 11 MHz. result. This output can be used as an interrupt.
PRODUCT HIGHLIGHTS
The AD7997/AD7998 provide a 2-wire serial interface that is compatible with I2C interfaces. Each part comes in two versions, 1. 2 µs conversion time with low power consumption. AD7997-0/AD7998-0 and AD7997-1/AD7998-1, and each 2. I2C-compatible serial interface with pin-selectable version allows at least two different I2C addresses. The I2C 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 fast I2C interface modes. The I2C interface on the AD7997-1/ serial bus. AD7998-1 supports standard, fast, and high speed I2C interface modes. 3. The parts feature automatic shutdown while not converting to maximize power efficiency. Current consumption is 1 µA 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 conversion process can be controlled using the CONVST pin, 4. Reference can be driven up to the power supply. by a command mode where conversions occur across I2C 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.
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Document Outline FEATURES GENERAL DESCRIPTION FUNCTIONAL BLOCK DIAGRAM PRODUCT HIGHLIGHTS AD7997 SPECIFICATIONS AD7998 SPECIFICATIONS I2C TIMING SPECIFICATIONS ABSOLUTE MAXIMUM RATINGS ESD CAUTION PIN CONFIGURATION AND PIN FUNCTION DESCRIPTIONS TERMINOLOGY TYPICAL PERFORMANCE CHARACTERISTICS CIRCUIT INFORMATION CONVERTER OPERATION TYPICAL CONNECTION DIAGRAM ANALOG INPUT INTERNAL REGISTER STRUCTURE ADDRESS POINTER REGISTER CONFIGURATION REGISTER CONVERSION RESULT REGISTER LIMIT REGISTERS DATAHIGH Register CH1/CH2/CH3/CH4 DATALOW Register CH1/CH2/CH3/CH4 Hysteresis Register (CH1/CH2/CH3/CH4) Using the Limit Registers to Store Min/Max Conversion Result ALERT STATUS REGISTER (CH1 TO CH4) CYCLE TIMER REGISTER SAMPLE DELAY AND BIT TRIAL DELAY SERIAL INTERFACE SERIAL BUS ADDRESS WRITING TO THE AD7997/AD7998 WRITING TO THE ADDRESS POINTER REGISTER FOR A SUBSEQUENT REA WRITING A SINGLE BYTE OF DATA TO THE ALERT STATUS REGISTER O WRITING TWO BYTES OF DATA TO A LIMIT, HYSTERESIS, OR CONFIGU READING DATA FROM THE AD7997/AD7998 ALERT/BUSY PIN SMBus ALERT BUSY PLACING THE AD7997-1/AD7998-1 INTOHIGH SPEED MODE THE ADDRESS SELECT (AS) PIN MODES OF OPERATION MODE 1—USING THE PIN MODE 2 – COMMAND MODE MODE 3—AUTOMATIC CYCLE INTERVAL MODE OUTLINE DIMENSIONS ORDERING GUIDE RELATED PARTS IN I2C-COMPATIBLE ADC PRODUCT FAMILY