VPP pin can be left floating (HiZ) or terminated
to ground during power-up/power-down sequences and during normal device operation.
This supply is only sourced while programming the eFuse. The following hardware
requirements must be met when programming keys in the OTP eFuses:
- The VPP power supply must be
ramped up after completion of proper device power-up sequence.
- The VPP supply has high
current transients and local bulk capacitors are likely needed near the VPP
pin to assist the LDO transient response.
- Select the power supply with
quick discharge capability or use a discharge resistor. A Maximum current of
400 mA is required for programming. It is recommended to use an LDO for
power the VPP.
- If an external power supply
is used, the supply is applied after the processor power supplies are
stable.
- The VPP power supply must be
disabled (left floating (HiZ) or grounded) when not programming the OTP
registers.
For more information, see the VPP Specifications for One-Time Programmable (OTP)
eFuses section in the Specifications chapter of the device-specific
data sheet.