Datasheet

ADS8634

ADS8638

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SBAS541A –MAY 2011– REVISED AUGUST 2011

Auto: Auto-Scan Mode Register (Address = 05h; Page 0)

7 6 5 4 3 2 1 0

Sel Temp

Reset-Seq 0 0 0 Range Select[2:0]

Sensor

This register selects device operation in auto-scan mode, allows the preselected signal range for the next

conversion to be temporarily overriden, and enables the device temperature to be read.

Bit 7 Reset-Seq

This bit resets the auto-mode sequence counter. The counter is reset to the lowest channel number in the selected

sequence.

For example, if the Auto-Md Ch-Sel register is programmed to 01101100 (auto-mode sequence channels 2, 3, 5, 6,

2, 3, 5, 6…2, 3, 5, 6) and, if the auto register bit 7 is programmed to '1' in frame n while channel 3 is sampled, then

the auto-mode sequence counter resets to channel 2 in frame n + 1. This setting means channel 2 is sampled

instead of channel 5 in frame n + 1.

0 = No reset (continue sequence from the present channel number)

1 = Reset channel sequncing counter

Bits[6:4] Must always be set to '0'

Bits[3:1] Range Select[2:0]

These bits select the signal range for the channel acquired in the next frame.

For example, if this register is written in frame number n, then the selected range is applicable for frame number n

+ 1. This is a dynamic range selection and overrides selection through the configuration registers (address 10h to

13h, page 0) only for the next frame.

000 = Ranges as selected through the configuration registers (addresses 10h to 13h)

001 = Range is set to ±10V

010 = Range is set to ±5V

011 = Range is set to ±2.5V

100 = Reserved; do not use this setting

101 = Range is set to 0V to 10V

110 = Range is set to 0V to 5V

111 = Powers down the device immediately after the 16th SCLK falling edge

Bit 0 Sel Temp Sensor

This bit selects the temperature sensor for acquisition in the next frame.

This selection overrides channel selection through the auto sequence only for the next frame. The auto sequence

continues from where it was interrupted after the temperature sensing frame.

For example, if the programmed auto sequence is channels 0, 1, 3, 0, 1, 3…0, 1, 3 and, if the temperature sensor

is selected in frame number n while channel 0 is sampled, then the temperature sensor is sampled in frame n + 1.

The auto sequence resumes from frame n + 2 sampling channel 1. Range selection is not applicable for the

temperature sensor.

0 = Next conversion as per selection through bits[3:1]

1 = The temperature sensor is selected for acquisition in the next frame

Product Folder Link(s): ADS8634 ADS8638