Datasheet

ADS8634
ADS8638
SBAS541A –MAY 2011– REVISED AUGUST 2011 www.ti.com
PAGE 0 REGISTER DESCRIPTIONS: ADS8638
This section provides bit-by-bit descriptions of each page 0 register.
Channel Sequencing Control Registers for the ADS8638
There are two modes for channel sequencing: auto and manual mode. In auto-scan mode, the device
automatically scans the preselected channels in sequential order with a new channel selected for every
conversion. In manual mode, the channel is manually selected for the next conversion. In both modes, the
preselected signal range is considered for each channel independently. Note that the range can be temporarily
overriden.
Manual: Manual Mode Register (Address = 04h; Page 0)
7 6 5 4 3 2 1 0
Sel Temp
0 Channel Select[2:0] Range Select[2:0]
Sensor
This register selects device operation in manual scan mode, selects the channel for the next conversion, allows
the preselected signal range to be temporarily overriden for the next conversion, and enables the device
temperature to be read.
Bit 7 Must always be set to '0'
Bits[6:4] Channel Select[2:0]
These bits select the channel for acquisition during the next frame.
For example, if this register is written in frame number n, then the addressed channel signal is acquired in frame
number n + 1 and the conversion result is available in frame number n + 2.
000 = Channel 0
001 = Channel 1
010 = Channel 2
011 = Channel 3
100 = Channel 4
101 = Channel 5
110 = Channel 6
111 = Channel 7
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, page 0)
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 bits[6:4]. 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
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