ADS8860IDRCR datasheet(21/53 Pages) TI2

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0001

FFFF

8000

VREF

VREF/2

1 LSB

Single-Ended Analog Input

(AINP ± AINN)

7FFF

VIN

0000

ADS8860

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SBAS569B – MAY 2013 – REVISED FEBRUARY 2019

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Feature Description (continued)

9.3.4 ADC Transfer Function

The ADS8860 is a unipolar, single-ended input device. The device output is in straight binary format.

Figure 47 shows ideal characteristics for the device. The full-scale range for the ADC input (AINP – AINN) is

equal to the reference input voltage to the ADC (VREF). One LSB is equal to [(VREF / 2

16)].

Figure 47. Single-Ended Transfer Characteristics

9.4 Device Functional Modes

The ADS8860 is a low pin-count device. However, the device offers six different options for interfacing with the

digital host.

These options can be broadly classified as being either CS mode (in either a 3- or 4-wire interface) or daisy-

chain mode. The device operates in CS mode if DIN is high at the CONVST rising edge. If DIN is low at the

CONVST rising edge, or if DIN and CONVST are connected together, the device operates in daisy-chain mode.

In both modes, the device can either operate with or without a busy indicator, where the busy indicator is a bit

preceding the output data bits that can be used to interrupt the digital host and trigger the data transfer.

The 3-wire interface in CS mode is useful for applications that need galvanic isolation on-board. The 4-wire

interface in CS mode allows the user to sample the analog input independent of the serial interface timing and,

therefore, allows easier control of an individual device while having multiple, similar devices on-board. The daisy-

chain mode is provided to hook multiple devices in a chain similar to a shift register and is useful in reducing

component count and the number of signal traces on the board.

9.4.1 CS Mode

CS mode is selected if DIN is high at the CONVST rising edge. There are six different interface options available

in this mode: 3-wire CS mode without a busy indicator, 3-wire CS mode with a busy indicator, 4-wire CS mode

without a busy indicator, and 4-wire CS mode with a busy indicator. The following sections discuss these

interface options in detail.

ADS8860IDRCR Datasheet(PDF) 21 Page - Texas Instruments