0.1 µF (typical)

VDD

VDD

SDA

SCL

Microcontroller or

Microprocessor

with I C Port

2

5

14

1

2

9

4

GND

CH3

CH4

SCL

15

16

7

6

SDA

VDD

CH6

CH5

ADS7828-Q1

Inputs Selected

from Configuration

Register

Pullup Resistors

1 k

to 10 k

(typical)

CH0

CH1

ADS7828-Q1

SBAS456B – DECEMBER 2008 – REVISED JANUARY 2016

www.ti.com

8 Application and Implementation

NOTE

Information in the following applications sections is not part of the TI component

specification, and TI does not warrant its accuracy or completeness. TI’s customers are

responsible for determining suitability of components for their purposes. Customers should

validate and test their design implementation to confirm system functionality.

8.1 Application Information

The following sections give example circuits and suggestions for using the ADS7828-Q1 device in various

situations.

8.1.1 Basic Connections

For many applications, connecting the ADS7828-Q1 device is simple. Figure 21 shows a basic connection

diagram for the ADS7828-Q1 device.

The fully differential voltage input of the ADS7828-Q1 device is ideal for connection to differential sources with

moderately low source impedance, such as thermocouples and thermistors. Although the ADS7828-Q1 device

can read bipolar differential signals, they cannot accept negative voltages on either input. It may be helpful to

think of the ADS7828-Q1 positive voltage input as noninverting, and of the negative input as inverting.

When the ADS7828-Q1 device converts data, it draws current in short spikes. The 0.1-

μF bypass capacitor

supplies the momentary bursts of extra current needed from the supply.

The ADS7828-Q1 device interfaces directly to standard mode, fast mode, and high-speed mode I2C controllers.

Any microcontroller I2C peripheral, including master-only and non-multiple-master I2C peripherals, can operate

with the ADS7828-Q1 device. The ADS7828-Q1 device does not perform clock-stretching (that is, it never pulls

the clock line low), so it is not necessary to provide for this function unless other clock-stretching devices are on

the same I2C bus.

Pullup resistors are required on both the SDA and SCL lines because I2C bus drivers are open-drain. The size of

these resistors depends on the bus operating speed and capacitance of the bus lines. Higher-value resistors

consume less power, but increase the transition times on the bus, limiting the bus speed. Lower-value resistors

allow higher speed at the expense of higher power consumption. Long bus lines have higher capacitance and

require smaller pullup resistors to compensate. The resistors should not be too small; if they are, the bus drivers

may not be able to pull the bus lines low.

Figure 21. Typical Connections of the ADS7828-Q1

22

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