ADS8860IDRCT Datasheet, PDF (26/45 Pages) Texas Instruments – 16-Bit 1-MSPS Serial Interface microPower Miniature Single-Ended Input SAR Analog-to-Digital Converter

ADS8860
SBAS569A – MAY 2013 – REVISED DECEMBER 2013
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At the end of conversion, every ADC in the chain loads its own conversion result into the internal, 16-bit, shift
register and also outputs the MSB bit of this conversion result on its own DOUT pin. All ADCs enter an
acquisition phase and power-down. On every subsequent SCLK falling edge, the internal shift register of each
ADC latches the data available on its DIN pin and shifts out the next bit of data on its DOUT pin. Therefore, the
digital host receives the data of ADC N, followed by the data of ADC N–1, and so on (in MSB-first fashion). A
total of 16 x N SCLK falling edges are required to capture the outputs of all N devices in the chain. Data are valid
on both SCLK edges. Data are valid on both edges of SCLK and can be captured on either edge. However, a
digital host capturing data on the SCLK falling edge can achieve a faster reading rate (provided t_{h_CK_DO} is
acceptable).
Daisy-Chain Mode With a Busy Indicator
This interface option is most useful in applications where multiple ADC devices are used but the digital host has
limited interfacing capability and an interrupt-driven data transfer is desired. Figure 60 shows a connection
diagram with N ADCs connected in the daisy-chain. The CONVST pins of all ADCs in the chain are connected
together and are controlled by a single pin of the digital host. Similarly, the SCLK pins of all ADCs in the chain
are connected together and are controlled by a single pin of the digital host. The DIN pin for ADC 1 is connected
to its CONVST. The DOUT pin of ADC 1 is connected to the DIN pin of ADC 2, and so on. The DOUT pin of the
last ADC in the chain (ADC N) is connected to the SDI and IRQ pins of the digital host.
CNV
CONVST
CONVST
CONVST
CONVST
IRQ
DIN
DOUT
DIN
DOUT
} DIN
DOUT
DIN
DOUT
SDI
SCLK
SCLK
SCLK
SCLK
ADC 1
ADC 2
}
ADC N1
ADC N
CLK
Digital Host
Figure 60. Connection Diagram: Daisy-Chain Mode With a Busy Indicator (DIN = 0)
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