User's Manual l TQMa335xL UM 0101 l © 2019, TQ-Systems GmbH
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3.2.7.3
Adaptive Voltage Scaling (AVS)
The combination of AM335x and PMIC TPS65910A31 supports Adaptive Voltage Scaling (AVS) based on Smart Reflex.
The function is very limited due to several errata!
3.2.7.4
Voltage supervision
The TQMa335xL is available with several voltage supervision options.
On the primarily manufactured version of the TQMa335xL a MAX803 with a trigger level of 3.08 V monitors the supply voltage.
Below 3.08 V a PORESET# is triggered at the AM335x.
On a second version of the TQMa335xL all voltages, except the DVS-capable voltages VDDS_MPU and VDDS_CORE are
monitored. If one of these voltages falls below the permitted level a PORESET# is triggered at the AM335x.
On a third version of the TQMa335xL undervoltage and overvoltage of the supply voltages are monitored.
If one of these voltages fall below or exceed the permitted level a PORESET# is triggered at the AM335x.
3.2.7.5
TQMa335xL / carrier board Power-Up sequence
Since the AM335x is very sensitive to cross-supply it has to be ensured that the components on the carrier board are not supplied
by the I/O-voltages (VDDSHV) during power-up.
Switch
TQMa335x
VCC3V3
VDDSHV
3.3 V components
on carrier board
3.3 V DC/DC
on carrier board
Illustration 11: Block diagram power supply carrier board
With the procedure described above it is certified that the pull-ups on the carrier board are already supplied with voltage when
the boot-configuration pins are read.
Attention: Power-Up sequence
To avoid cross-supply and errors in the power-up sequence, no I/O pins may be driven by external
components until the power-up sequence has been completed.
The end of the power-up sequence is indicated by a high level of signal VDDSHV.
