Hi!
I have a PCB that (among other electronics) contains a EM250 ZigBee module connected over the UART interface with a FT232 FTDI IC, as shown in the second attached figure.
The problem is that due to this connection the power consumption of the PCB is higher than I expected. The FTDI is power from the USB bus (and not from the power supply of the PCB) which is however not all the time present. Thus, I assume that the high power consumption that is measured only when the USB supply power is not present comes from current throwing from/to the pins of the EM250 to/from the pins of the FT232. I have tried all possible states of the pins of the uC but could not go too low in the power consumption (the best is around 700uA, while around 200uA was expected).
To reduce the power consumption further, I was thinking of making the modification shown in the first attached figure, thus adding some buffers between the two ICs that are going to be activated only when communication is required (when the USB supply power is actually present) and remain deactivated otherwise.
Do you think that this will work? Do you have any other alternative to propose me?
nikos
I have a PCB that (among other electronics) contains a EM250 ZigBee module connected over the UART interface with a FT232 FTDI IC, as shown in the second attached figure.
The problem is that due to this connection the power consumption of the PCB is higher than I expected. The FTDI is power from the USB bus (and not from the power supply of the PCB) which is however not all the time present. Thus, I assume that the high power consumption that is measured only when the USB supply power is not present comes from current throwing from/to the pins of the EM250 to/from the pins of the FT232. I have tried all possible states of the pins of the uC but could not go too low in the power consumption (the best is around 700uA, while around 200uA was expected).
To reduce the power consumption further, I was thinking of making the modification shown in the first attached figure, thus adding some buffers between the two ICs that are going to be activated only when communication is required (when the USB supply power is actually present) and remain deactivated otherwise.
Do you think that this will work? Do you have any other alternative to propose me?
nikos
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