Revision Affected:

A and B

Details:

When the CC1310 device enters standby, a time interval must be set for the initial period between VDDR recharges based on temperature and certain device-specific trims. However, if the Sensor Controller wakes and returns the device to standby without waking the CM3, the initial recharge period programmed by the CM3 is used again by the hardware. If the temperature has increased sufficiently between the time the CM3 put the device into standby and the time the Sensor Controller put the device into standby, the recharge period programmed may be too long. VDDR may drop below the permitted minimum threshold due to the temperature-induced increased leakage. This may cause an inconsistent internal state in the device or cause the device to hang, forcing a pin reset.

Workaround:

If the device is put in standby while using the Sensor Controller, the user must ensure that the initial recharge period programmed by the CM3 is more conservative than what is strictly necessary at the current temperature. The longest duration that the CM3 sleeps at a specific temperature gradient, defines a maximum limit for temperature increase between recalculations of the initial recharge period. The sleep duration can be altered such that a decrease in the converged recharge period matches the margin subtracted from the initial recharge period.

The following parameters are needed for the workaround:

• The user’s maximum expected temperature gradient in °C/s
• The upper bound of the user’s expected operating temperature range in °C
• The initial recharge period set at the upper bound of the expected operating temperature range in SCLK_LF clock periods
• A table of converged recharge periods in SCLK_LF clock periods at varying temperatures decreasing from the upper bound of the expected operating temperature
• The margin in SCLK_LF clock periods that the user wants to subtract from the regular initial recharge period. The higher this value, the longer the device can sleep before requiring a wakeup to recalculate the initial recharge period. However, higher values will lead to slower convergence of the recharge algorithm towards the ideal recharge period at a given temperature.

Based on the parameters above, make the following calculations to determine the maximum duration the CM3 can sleep before waking up to recalculate the initial recharge period:

• Add the margin to the converged recharge period at the upper bound of your operating temperature.
• Find the value in the table of converged recharge periods that comes closest to this value and determine the temperature this value occurs at.
• Find the temperature difference between that temperature and the upper bound of your expected operating temperature range.
• Divide this temperature delta by your maximum expected temperature gradient.

The result of the calculations above is a time value in seconds. This value is the longest time the device can safely stay in standby before a CM3 wakeup must be forced if the Sensor Controller is active.

To apply the workaround, convert this duration from seconds to system ticks. When using SIMPLELINK-CC13X0-SDK_1.60.00.21 or later, apply this value into PowerCC26XX_Config.maxStandbyDuration, set PowerCC26XX_Config. enableMaxStandbyDuration to true, and set PowerCC26XX_Config.vddrRechargeMargin to the value chosen earlier.