AN4440 datasheet(33/36 Pages) STMICROELECTRONICS

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AN4440

USID modification

•

Send value 40d (00101000) for 4 V to HVDAC1

Figure 59. Send data to HVDAC1 with AUT

•

Send value 112d (00100000) for 20.4 V to HVDAC2

Figure 60. Send data to HVDAC2 with AUT

5.3

N HVDACs on the same RFFE bus

For more than 2 HVDACs (N) on the same RFFE bus, the recommendation is to connect

one HVDAC SELSID to GND and other ones to the MCU GPIOs (N-1).

This will allow reprogramming each HVDAC USID in order to transmit commands

independently to each.

For USID reprogramming, the task of the MCU is to set GPIO polarity in order to have a

unique couple "USID + SELSID" on the HVDAC in the USID reprogramming phase.

–

HVDAC with SELSID to GND reprogramming while all GPIOs are high level (it is

unique with SELSID = 0)

–

Set the next HVDAC SELSID to GND using GPIO (as the previous HVDAC USID

is no longer 0111, it is unique with USID = 0111 AND SELSID=0)

–

Repeat for all HVDACs (N-2 times)

–

Then each HVDAC has a unique USID.

AN4440 Datasheet(PDF) 33 Page - STMicroelectronics