Datasheet AD7291 (Analog Devices)

8-Channel, I2C, 12-Bit SAR ADC with Temperature Sensor Data Sheet AD7291 FEATURES FUNCTIONAL BLOCK DIAGRAM 12-bit SAR ADC VDD GND 8 single-ended analog input channels Analog input range: 0 V to 2.5 V VREF 12-bit temperature-to-digital converter REF BUF Temperature sensor accuracy of ±1°C typical Channel sequencer operation 12-BIT VIN0 SUCCESSIVE Specified for V T/H DD of 2.8 V to 3.6 V APPROXIMATION ADC Logic voltage VDRIVE = 1.65 V to 3.6 V Internal 2.5 V reference INPUT V MUX AD7291 IN7 I2C-compatible serial interface supports standard and fast speed modes SEQUENCER SCL Out of range indicator/alert function SDA CONTROL LOGIC I2C INTERFACE AS1 Autocycle mode TEMP AS0 Power-down current: 12 μA maximum SENSOR V Temperature range: −40°C to +125°C DRIVE
1 00 1-
20-lead LFCSP package PD/RST
1
ALERT
87 0 Figure 1.
GENERAL DESCRIPTION
On-chip limit registers can be programmed with high and low The AD7291 is a 12-bit, low power, 8-channel, successive limits for the conversion results; an out-of-range indicator approximation analog-to-digital converter (ADC) with an output (ALERT) becomes active when the programmed high internal temperature sensor. or low limits are violated by the conversion result. This output can be used as an interrupt. The device operates from a single 3.3 V power supply and features an I2C-compatible interface. The device contains a 9-
PRODUCT HIGHLIGHTS
channel multiplexer and a track-and-hold amplifier than can 1. Ideally suited to monitoring system variables in a variety handle frequencies up to 30 MHz. The device has an on-chip of systems including telecommunications, process control, 2.5 V reference that can be disabled to allow the use of an and industrial control. external reference. 2. I2C-compatible serial interface, which supports standard The AD7291 provides a 2-wire serial interface compatible with and fast modes. I2C interfaces. The I2C interface supports standard and fast I2C 3. Automatic partial power-down while not converting to interface modes. The AD7291 normally remains in a partial maximize power efficiency. power-down state while not converting and powers up for 4. Channel sequencer operation. conversions. The conversion process can be controlled by a 5. Integrated temperature sensor with 0.25°C resolution. command mode where conversions occur across I2C write 6. Out of range indicator that can be software disabled or operations or an autocycle mode selected through software enabled. control.
Table 1. AD7291 and Related Products
The AD7291 includes a high accuracy band gap temperature
Device Resolution Interface Features
sensor, which is monitored and digitized by the 12-bit ADC to AD7291 12-bit I2C 8-channel, I2C, 12-bit SAR give a resolution of 0.25°C. ADC with temperature sensor AD7298 12-bit SPI 8-channel, 1 MSPS, 12-bit SAR The AD7291 offers a programmable sequencer, which enables ADC with temperature sensor the selection of a preprogrammable sequence of channels for conversion.
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Document Outline FEATURES FUNCTIONAL BLOCK DIAGRAM GENERAL DESCRIPTION PRODUCT HIGHLIGHTS REVISION HISTORY SPECIFICATIONS I2C TIMING SPECIFICATIONS ABSOLUTE MAXIMUM RATINGS THERMAL RESISTANCE ESD CAUTION PIN CONFIGURATION AND FUNCTION DESCRIPTIONS TYPICAL PERFORMANCE CHARACTERISTICS TERMINOLOGY CIRCUIT INFORMATION CONVERTER OPERATION ANALOG INPUT ADC TRANSFER FUNCTION TEMPERATURE SENSOR OPERATION TEMPERATURE SENSOR AVERAGING Temperature Value Format VDRIVE THE INTERNAL OR EXTERNAL REFERENCE RESET INTERNAL REGISTER STRUCTURE ADDRESS POINTER REGISTER COMMAND REGISTER (0x00) Sample Delay and Bit Trial Delay VOLTAGE CONVERSION RESULT REGISTER (0x01) Temperature Value Format TSENSE CONVERSION RESULT REGISTER (0x02) TSENSE AVERAGE RESULT REGISTER (0X03) LIMIT REGISTERS (0X04 TO 0X1E) DATAHIGH Register DATALOW Register HYSTERESIS REGISTER ALERT STATUS REGISTER A AND ALERT STATUS REGISTER B (0x1F AND 0x20) I2C INTERFACE SERIAL BUS ADDRESS BYTE GENERAL I2C TIMING WRITING TO THE AD7291 WRITING TWO BYTES OF DATA TO A 16-BIT REGISTER WRITING TO MULTIPLE REGISTERS READING DATA FROM THE AD7291 READING TWO BYTES OF DATA FROM A 16-BIT REGISTER MODES OF OPERATION COMMAND MODE AUTOCYCLE MODE OUTLINE DIMENSIONS ORDERING GUIDE