The AD7745/AD7746 are a high resolution, Σ-Δ capacitance-to-digital converter (CDC). The capacitance to be measured is connected directly to the device inputs. The architecture fea-tures inherent high resolution (24-bit no missing codes, up to 21-bit effective resolution), high linearity (±0.01%), and high accuracy (±4 fF factory calibrated). The AD7745/AD7746 capacitance input range is ±4 pF (changing), while it can accept up to 17 pF common-mode capacitance (not changing), which can be balanced by a programmable on-chip, digital-to-capacitance converter (CAPDAC).

The AD7745 has one capacitance input channel, while the AD7746 has two channels. Each channel can be configured as single-ended or differential. The AD7745/AD7746 are designed for floating capacitive sensors. For capacitive sensors with one plate connected to ground, the AD7747 is recommended.

The parts have an on-chip temperature sensor with a resolution of 0.1°C and accuracy of ±2°C. The on-chip voltage reference and the on-chip clock generator eliminate the need for any external components in capacitive sensor applications. The parts have a standard voltage input, which together with the differential reference input allows easy interface to an external temperature sensor, such as an RTD, thermistor, or diode.

The AD7745/AD7746 have a 2-wire, I²C-compatible serial interface. Both parts can operate with a single power supply from 2.7 V to 5.25 V. They are specified over the automotive temperature range of –40°C to +125°C and are housed in a 16-lead TSSOP package.

Applications

Automotive, Industrial and Medical Systems for:

• Pressure Measurement
• Position Sensors
• Level Sensors
• Flowmeters
• Humidity Sensors
• Impurity Detection

Part#	Resolution (Bits)	T-Put Rate	# Chan	Supply V	Pwr Diss (max)	Input Base C (pF Max)	Cin Range (pF)	Pkg Type	Price* (1000-4999)	Product Description	Interface
AD7142	16	27.8SPS	14	Single(+2.6 to +3.6), Single(+2.7), Single(+3), Single(+3.3)	3.6mW	20	±2	CSP	$1.35	CAPTouch (TM) Programmable Controller for 2-Electrode Capacitance Sensor with SPI or I2C Interface	I²C/Ser 2-Wire, Ser, SPI
AD7143	16	43.5SPS	8	Single(+2.6 to +3.6)	3.6mW	20	±2	CSP	$1.24	CAPTouch (TM) Programmable Controller for 2-Electrode Capacitance Sensor with I2C Interface	I²C/Ser 2-Wire, Ser
AD7147	16	111SPS	13	Single(+3), Single(+3.3)	3.6mW	20	±8	CSP	$1.30	CAPTouch (TM) Programmable Controller w/ SPI or I2C Interface for Single-Electrode Cap Sensors	I²C/Ser 2-Wire, Ser, SPI
AD7150	12	100SPS	2	Single(+2.7 to +3.6)	0.43mW	10	±4	SOP	$1.35	Ultra-Lo Pwr, 2-Ch Capacitance Converter for Proximity Sensing Applications	I²C/Ser 2-Wire, Ser
AD7151	12	100SPS	1	Single(+2.7 to +3.6)	0.3mW	10	±4	SOP	$1.35	Ultra-Low Power, 1-Ch, Capacitance Converter for Proximity Sensing Applications	I²C/Ser 2-Wire, Ser
AD7745	24	90SPS	1	Single(+2.7 to +5.25)	4.25mW	17	±4	SOP	$4.60	24-Bit, Cap-to-Dig Conv. w/ 1 SE/Diff Capacitive Input Ch for Interface to Dual Electrode Cap Sensor	I²C/Ser 2-Wire, Ser
AD7746	24	90SPS	2	Single(+2.7 to +5.25)	4.25mW	17	±4	SOP	$4.95	24-bit, Cap-to-Dig Conv. w/ 2 SE/Diff Capacitive Input Ch for interface to Dual Electrode Cap Sensor	I²C/Ser 2-Wire
AD7747	24	45.5SPS	1	Single(+2.7 to +5.25)	4.25mW	17	±8	SOP	$4.60	24-bit, Cap-to-Dig Conv w/1 SE/Diff Capacitive Input Ch for interface to Single Electrode Cap Sensor	I²C/Ser 2-Wire, Ser

* The pricing listed here is provided only for budgetary purposes as recommended list price in U.S. Dollars in the United States ex factor per unit for the stated volume. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.
** Pricing is currently unavailable. Click on the product number to see the Product Page for additional information.

The model number is a specific version of a generic that can be purchased or sampled.

Status indicates the current lifecycle of the product. This can be one of 4 stages:

• Pre-Release: The model has not been released to general production, but samples may be available.
• Production: The model is currently being produced, and generally available for purchase and sampling.
• Last Time Buy: The model has been scheduled for obsolescence, but may still be purchased for a limited time.
• Obsolete: The specific part is obsolete and no longer available. Other models listed in the table may still be available (if they have a status that is not obsolete).

The package for this IC (i.e. DIP, SOIC, BGA). An Evaluation Board is a board engineered to show the performance of the model, the part is included on the board.

For detailed drawings and chemical composition please consult our  Package Site

Pin Count is the number of pins, balls, or pads on the device. Pin-out diagrams & pin function descriptions may be found in the datasheet.

This is the acceptable operating range of the device. The various ranges specified are as follows:

• Commercial: 0 to +70 degrees Celsius
• Military : -55 to +125 degrees Celsius
• Industrial: Temperature ranges may vary by model. Please consult the datasheet for more information.
• Automotive: -40 to +125 degrees Celsius

The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Analog Devices, Inc. sales office or authorized distributor. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.

This is the date Analog Devices, Inc. anticipates that the product will ship from the warehouse. Most orders ship within 48 hours of this date.Once an order has been placed, Analog Devices, Inc. will send an Order Acknowledgement email to confirm your delivery date. It is important to note the scheduled dock date on the order entry screen. We do take orders for items that are not in stock, so delivery may be scheduled at a future date. Also, please note the warehouse location for the product ordered. We have warehouses in the United States, Europe and Southeast Asia. Transit times from these sites may vary.

Due to environmental concerns, ADI offers many of our products in lead-free versions. For more information about lead-free parts, please consult our Pb (Lead) free information page.