AD4693 datasheet(40/77 Pages) AD

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Data Sheet

AD4693/AD4694

MODES OF OPERATION

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MANUAL MODE

Manual mode differs from the other operating modes by bypassing

the configuration registers, channel sequencer, and averaging filters

to enable faster data readback and direct SPI control over the

multiplexer channel sequencing. The manual mode SPI protocol

does not follow the register access format described in the Register

Access section. ADC results are read out on SDO without a register

access instruction phase on SDI. The SDI data instead consist of a

5-bit command code (CMD) used for selecting the next multiplexer

channel.

Table 21 lists the valid manual mode CMD codes. CMD codes are

sent in the first five bits of SDI input data. The code values written

in the CMD[4:0] column represent the 5-bit CMD values, while the

SDI[15:0] column translates these 5-bit values to a 16-bit equivalent

value (with padded zeros) to align with the 16-bit ADC data on

SDO. All other 5-bit values of CMD are treated as no operation,

where the multiplexer remains on the current channel for the next

conversion.

Setting the MANUAL_MODE bit to 1 puts the AD4693/AD4694 into

manual mode. The device remains in manual mode until the exit

command is sent on SDI. Upon receiving the exit command, the

MANUAL_MODE bit is cleared and the device exits manual mode.

Figure 73 shows a timing diagram of exiting manual mode with the

exit command.

In manual mode, the CNV input functions as the ADC sampling

clock source. Each rising edge of the CNV signal triggers a single

conversion. The digital host reads the conversion result via the SPI

before sending the next CNV rising edge.

Figure 70 shows a typical connection diagram for the digital host,

and Figure 71 shows a timing diagram of the CNV signal and SPI

frames containing the CMD codes on SDI and the ADC data on

SDO. Manual mode is backwards compatible with the AD4696 two

cycle command mode. There is a two cycle delay between sending

an SDI CMD and when the resulting ADC sample is read on SDO.

Manual mode includes optional status bits which contain the chan-

nel identification for the ADC data, and an OV_ERR bit which

indicates if any of the overvoltage protection clamps are active.

The status bits are enabled by setting the STATUS_EN bit in

the DEVICE_SETUP bit to 1. When the status bits are enabled,

the 16-bit SDO data packets are extended to 24-bits. Figure 72

shows the SDO data packet format in manual mode with status bits

disabled and enabled.

Figure 97 illustrates the step-by-step configuration flow for AD4693/

AD4694 in manual mode.

Table 21. Manual Mode CMD Code Functions

CMD[4:0]

SDI[15:0]

Function

0x0A

0x5000

Exit command

0x0F

0x7000

Temperature sensor

0x10 to 0x17

0x8000 to 0xB800

IN0 to IN7 channel selection

Figure 70. Manual Mode Example Connection Diagram

Figure 71. Manual Mode Timing Diagram

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