ADS8862_14 Datasheet, PDF (19/46 Pages) Texas Instruments – 16-Bit, 680-kSPS, Serial Interface, microPower, Miniature Single-Ended Input, SAR Analog-to-Digital Converter

ADS8862
www.ti.com
SBAS570A – MAY 2013 – REVISED DECEMBER 2013
ADC TRANSFER FUNCTION
The ADS8862 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 (V_REF). 1 LSB is equal to [(V_REF / 2¹⁶)].
FFFF
8000
7FFF
0001
0000
V_IN
1 LSB
VREF/2
VREF
Single-Ended Analog Input
(AINP ± AINN)
Figure 47. Single-Ended Transfer Characteristics
DIGITAL INTERFACE
The ADS8862 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.
CS Mode
CS mode is selected if DIN is high at the CONVST rising edge. There are four 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.
Copyright © 2013, Texas Instruments Incorporated
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