ADS1113 datasheet(12/38 Pages) TI1

12 / 38 page

VDD

GND

AIN0

VDD

GND

AIN1

VDD

GND

AIN2

VDD

GND

AIN3

AIN

GND

ADS1115

SAMPLE

OFF

ADS1113

ADS1114

ADS1115

SBAS444B – MAY 2009 – REVISED OCTOBER 2009

www.ti.com

MULTIPLEXER

If it is possible that the voltages on the input pins may

violate these conditions, external Schottky clamp

The ADS1115 contains an input multiplexer, as

diodes and/or series resistors may be required to limit

shown in Figure 24. Either four single-ended or two

the input current to safe values (see the Absolute

differential signals can be measured. Additionally,

Maximum Ratings table).

AIN0 and AIN1 may be measured differentially to

AIN3. The multiplexer is configured by three bits in

Also, overdriving one unused input on the ADS1115

the Config register. When single-ended signals are

may affect conversions taking place on other input

measured, the negative input of the ADC is internally

pins. If overdrive on unused inputs is possible, again

connected to GND by a switch within the multiplexer.

it is recommended to clamp the signal with external

Schottky diodes.

ANALOG INPUTS

The ADS1113/4/5 use a switched-capacitor input

stage where capacitors are continuously charged and

then discharged to measure the voltage between

AINP and AINN. The capacitors used are small, and to

external

circuitry

the

average

appears

resistive. This structure is shown in Figure 26. The

resistance is set by the capacitor values and the rate

at which they are switched. Figure 25 shows the

on/off setting of the switches illustrated in Figure 26.

During the sampling phase, S1 switches are closed.

This event charges CA1 to AINP, CA2 to AINN, and CB

to (AINP – AINN). During the discharge phase, S1 is

first opened and then S2 is closed. Both CA1 and CA2

then

discharge

approximately

0.7V

and

discharges to 0V. This charging draws a very small

transient

current

from

the

source

driving

the

Figure 24. ADS1115 MUX

ADS1113/4/5 analog inputs. The average value of

this current can be used to calculate the effective

The

ADS1113

and

ADS1114

not

have

impedance (Reff) where Reff = VIN/IAVERAGE.

multiplexer.

Either

one

differential

one

single-ended signal may be measured with these

devices. For single-ended measurements, connect

the AIN1 pin to GND. Note that in subsequent

sections of this data sheet, AINP refers to AIN0 and

AINN refers to AIN1 for the ADS1113 and ADS1114.

When measuring single-ended inputs it is important to

note that the negative range of the output codes are

not used. These codes are for measuring negative

Figure 25. S1 and S2 Switch Timing for Figure 26

differential signals such as (AINP – AINN) < 0. ESD

diodes to VDD and GND protect the inputs on all

three devices (ADS1113, ADS1114, and ADS1115).

To prevent the ESD diodes from turning on, the

absolute voltage on any input must stay within the

following range:

GND – 0.3V < AINx < VDD + 0.3V

Submit Documentation Feedback

Product Folder Link(s): ADS1113 ADS1114 ADS1115

ADS1113 Datasheet(PDF) 12 Page - Texas Instruments

ADS1113 Datasheet(HTML) 12 Page - Texas Instruments

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38

Datasheet Download

Link URL