AD7745/AD7746

Rev. 0| Page 7 of 28

PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS

16

15

14

13

12

11

10

9

1

2

3

4

5

6

7

8

AD7745

TOP VIEW

(Not to Scale)

SCL

EXCA

EXCB

REFIN(+)

REFIN(–)

CIN1(–)

CIN1(+)

RDY

SDA

VDD

GND

VIN(–)

VIN(+)

NC

NC

NC

NC = NO CONNECT

Figure 4. AD7745 Pin Configuration (16-Lead TSSOP)

16

15

14

13

12

11

10

9

1

2

3

4

5

6

7

8

AD7746

TOP VIEW

(Not to Scale)

SCL

EXCA

EXCB

REFIN(+)

REFIN(–)

CIN1(–)

CIN1(+)

RDY

SDA

VDD

GND

VIN(–)

VIN(+)

CIN2(–)

CIN2(+)

NC

NC = NO CONNECT

Figure 5. AD7746 Pin Configuration (16-Lead TSSOP)

Table 4. Pin Function Descriptions

Pin No.

Mnemonic

Description

1

SCL

Serial Interface Clock Input. Connects to the master clock line. Requires pull-up resistor if not already

provided in the system.

2

RDY

Logic Output. A falling edge on this output indicates that a conversion on enabled channel(s) has been

finished and the new data is available. Alternatively, the status register can be read via the 2-wire serial

interface and the relevant bit(s) decoded to query the finished conversion. If not used, this pin should be left

as an open circuit.

3, 4

EXCA, EXCB

CDC Excitation Outputs. The measured capacitance is connected between one of the EXC pins and one of the

CIN pins. If not used, these pins should be left as an open circuit.

5, 6

REFIN(+),

REFIN(–)

Differential Voltage Reference Input for the Voltage Channel (ADC). Alternatively, the on-chip internal

reference can be used for the voltage channel. These reference input pins are not used for conversion on

capacitive channel(s) (CDC). If not used, these pins can be left as an open circuit or connected to GND.

7

CIN1(–)

CDC Negative Capacitive Input in Differential Mode. This pin is internally disconnected in single-ended CDC

configuration. If not used, this pin can be left as an open circuit or connected to GND.

8

CIN1(+)

CDC Capacitive Input (in Single-Ended Mode) or Positive Capacitive Input (in Differential Mode). The

measured capacitance is connected between one of the EXC pins and one of the CIN pins. If not used, this pin

can be left as an open circuit or connected to GND.

9, 10

(AD7745)

NC

Not Connected. This pin should be left as an open circuit.

9

(AD7746)

CIN2(+)

CDC Second Capacitive Input (in Single-Ended Mode) or Positive Capacitive Input (in Differential Mode). If not

used, this pin can be left open circuit or connected to GND.

10

(AD7746)

CIN2(–)

CDC Negative Capacitive Input in Differential Mode. This pin is internally disconnected in a single-ended CDC

configuration. If not used, this pin can be left as an open circuit or connected to GND.

11, 12

VIN(+), VIN(–)

Differential Voltage Input for the Voltage Channel (ADC). These pins are also used to connect an external

temperature sensing diode. If not used, these pins can be left as an open circuit or connected to GND.

13

GND

Ground Pin.

14

VDD

Power Supply Voltage. This pin should be decoupled to GND, using a low impedance capacitor, for example

in combination with a 10 µF tantalum and a 0.1 µF multilayer ceramic.

15

NC

Not Connected. This pin should be left as an open circuit.

16

SDA

Serial Interface Bidirectional Data. Connects to the master data line. Requires a pull-up resistor if not provided

elsewhere in the system.