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AD7294

Data Sheet

Rev. I | Page 12 of 47

Table 7. Pin Function Descriptions

TQFP Pin No.

LFCSP Pin No.

Mnemonic

Description

2, 61

1, 54

RS2(−), RS1(−)

Connection for External Shunt Resistor.

3, 60

2, 53

RS2(+), RS1(+)

Connection for External Shunt Resistor.

1, 4, 16, 17, 32,

33, 59, 64

3, 52

No Connection. Do not connect these pins.

5, 8, 14, 25, 56, 57

4, 7, 13, 22, 50

AVDD1 to AVDD6

for TQFP; AVDD1

to AVDD4 for

LFCSP

Analog Supply Pins. The operating range is 4.5 V to 5.5 V. These pins provide

the supply voltage for all the analog circuitry on the AD7294. Connect the

AVDD and DVDD pins together to ensure that all supply pins are at the same

potential. This supply should be decoupled to AGND with one 10 µF tantalum

capacitor and a 0.1 µF ceramic capacitor for each AVDD pin.

6, 7, 13, 24, 34,

55, 58

5, 6 12, 21, 29, 49,

AGND1 to

AGND7

Analog Ground. Ground reference point for all analog circuitry on the AD7294.

Refer all analog input signals and any external reference signal to this AGND

voltage. Connect all seven of these AGND pins to the AGND plane of the

system. Note that AGND5 is a DAC ground reference point and should be used

as a star ground for circuitry being driven by the DAC outputs. Ideally, the

AGND and DGND voltages should be at the same potential and must not be

more than 0.3 V apart, even on a transient basis.

9, 12

8, 11

D2(−), D1(−)

Temperature Sensor Analog Input. These pins are connected to the external

temperature sensing transistor. See Figure 46 and Figure 47.

10, 11

9, 10

D2(+), D1(+)

Temperature Sensor Analog Input. These pins are connected to the external

temperature sensing transistor. See Figure 46 and Figure 47.

REFOUT/REFIN DAC

DAC Reference Output/Input Pin. The REFOUT/REFIN DAC pin is common to all

four DAC channels. On power-up, the default configuration of this pin is

external reference (REFIN). Enable the internal reference by writing to the

power-down register; see Table 27. Decoupling capacitors (220 nF

recommended) are connected to this pin to decouple the reference buffer.

Provided the output is buffered, the on-chip reference can be taken from this

pin and applied externally to the rest of a system. A maximum external

reference voltage of AVDD − 2 V can be supplied to the REFOUT portion of the

REFOUT/REFIN DAC pin.

18, 23, 26, 31

15, 20 23,28

OFFSET IN A to

OFFSET IN D

DAC Analog Offset Input Pins. These pins set the desired output range for each

DAC channel. The DACs have an output voltage span of 5 V, which can be

shifted from 0 V to 5 V to a maximum output voltage of 10 V to 15 V by

supplying an offset voltage to these pins. These pins can be left floating, in

which case decouple them to AGND with a 100 nF capacitor.

19, 22, 27, 30

16, 19, 24, 27

VOUT A to VOUT D

Buffered Analog DAC Outputs for Channel A to Channel D. Each DAC analog

output is driven from an output amplifier that can be offset using the OFFSET

IN x pin. The DAC has a maximum output voltage span of 5 V that can be level

shifted to a maximum output voltage level of 15 V. Each output is capable of

sourcing and sinking 10 mA and driving a 10 nF load.

20, 29

17, 26

DAC OUT GND

AB, DAC OUT

GND CD

Analog Ground. Analog ground pins for the DAC output amplifiers on VOUTA

and VOUTB, and VOUTC and VOUTD, respectively.

21, 28

18, 25

DAC OUTV+ AB,

DAC OUTV+ CD

Analog Supply. Analog supply pins for the DAC output amplifiers on VOUTA and

VOUTB, and VOUTC and VOUTD, respectively. The operating range is 4.5 V to 16.5 V.

ALERT/BUSY

Digital Output. Selectable as an alert or busy output function in the

configuration register. This is an open-drain output. An external pull-up

resistor is required.

When configured as an alert, this pin acts as an out-of-range indicator and

becomes active when the conversion result violates the DATAHIGH or DATALOW

When configured as a busy output, this pin becomes active when a conversion

is in progress.

38, 37, 36

33, 32, 31

AS0, AS1, AS2

Digital Logic Input. Together, the logic state of these inputs selects a unique

I2C address for the AD7294. See Table 34 for details.

SDA

Digital Input/Output. Serial bus bidirectional data; external pull-up resistor

required.

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