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 to be temporarily

overriden for the next conversion, 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 (the auto-mode sequence channels are 2,

3, 5, 6, 2, 3, 5, 6…2, 3, 5, 6), and, if the Reset-Seq bit is programmed to '1' in frame n while channel 3 is sampled,

then the auto-mode sequence counter is reset to channel 2 in frame n + 1. This setting means that channel 2 is

sampled instead of channel 5 in frame n + 1.

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

1 = Reset the 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 (address 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 the channel selection through the auto sequence only for the next frame. The auto-mode

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 selected through bits[3:1]

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

Product Folder Link(s): ADS8634 ADS8638