Datasheet ADT7411 (Analog Devices) - 2

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ADT7411 Silicon Anomaly ANOMALIES Table 1. Averaging Function [er001] Background
Averaging mode may output incorrect measurements before giving a final result.
Issue
Averaging mode enabled (for any channel) may output incorrect results.
Workaround
Disable the averaging function by setting C5 = 1 in the Control Configuration 2 register. The user may still accomplish averaging by reading back 16 conversions and averaging all 16 readings to get a value that has reduced noise levels.
Related Issues
None.
Table 2. Round Robin (Fast Clock Mode Only) [er002] Background
Erroneous results can be read intermittently in round robin fast clock mode (SPI and I2C).
Issue
As the temperature of the device is ramped from cold to hot, irregular temperature and/or voltage measurements may be obtained.
Workarounds
Enable slow clock mode by setting C0 = 0 in the Control Configuration 3 register.
Related Issues
None.
Table 3. Single Channel (Continuous Monitoring Mode Only) [er003] Background
Changing a channel in single channel continuous monitoring mode during a conversion can result in data being written into the new channel register instead of the previous register (SPI and I2C).
Issue
An error can be obtained where the data read back appears from the previous converted channel instead of the current channel.
Workaround
Disable continuous monitoring before changing a channel. Once a channel is selected, turn monitoring on, wait for a conversion and then turn monitoring off. Wait one conversion period to allow any in progress conversion to complete before changing the channel; then take a measurement. The recommended list of steps are described in the Workaround Steps for the er003 section.
Related Issues
None.
Workaround Steps for the er003
1. Enable single channel mode by setting C4 = 1 in the Control Configuration 2 register. 2. Set monitoring off (Set C0 = 0 in the Control Configuration 1 register). 3. Select a channel, for example, the channel for internal temperature (write 0x71 to Control Configuration 2 register). 4. Set monitoring on (Bit C0 = 1 in the Control Configuration 1 register). 5. Wait 2x the typical conversion time for the channel selected (depending on which one is being measured, the power supply [VDD] or the analog input [AIN]) and 3x the typical conversion time for the temperature conversion. 6. Set monitoring off (Bit C0 = 0 in the Control Configuration 1 register). 7. Wait 1x the typical conversion time to allow any in progress conversion to complete before changing the channel. 8. Take a measurement. 9. Select the next channel (go back to Step 3).
Table 4. Software Reset (Round Robin Only) [er004] Background
Erroneous results can be read if resetting the part repeatedly in round robin mode.
Issue
Resetting the part repeatedly by setting Bit C7 = 1 in Control Configuration 2, can cause all data registers to read back 00 after several software resets.
Workaround
Power down the part by setting Bit D7 (PD) = 1 in Control Configuration 1 and power up the part again by clearing Bit D7 = 0 in Control Configuration 1, just before asserting the software reset bit in Control Configuration 2.
Related Issues
None.
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Document Outline ADT7411 Functionality Issues Anomalies Workaround Steps for the er003