I have been looking for a problem where my production units use more power than the prototypes. The production units have a BGX13S with flow control enabled and use several more µA than the prototype.
The RTS and CTS pins of the BGX are connected to pins of an EFM8SB2 MCU. I am using flow control to force the BGX13 to wake and sleep. This does not work perfectly.
The RTS pin of the BGX13S is held high when the BGX13S is asleep. This seems to cause power leakage of about 5 µA during sleep. I have tried using a pull-up resistor, connected to the main supply, but this made no difference. The I have found that a pull-up resistor connected to a slightly higher voltage than the supply (3.4 volts vs. 3.3 volts) will cause the BGX13S to sleep and consume current in accordance with the manual.
Is this a recognised behaviour of the BGX13S or a bug?
Thanks in advanced,
Generally there is some small leakage for leaving any pin enabled in sleep, but it should be on the order of tens of of nA. if the pin is logic high and it is consuming current I think the first thing to check is what the connection is on the RTS pin. Is the other end configured as open drain and does it have an internal pullup as well?
For some context, Internally the BGX13S uses the same 41KOhm pullup as BGM13S devices if enabled. If your configuration has enabled the pullups, try disabling them when using an external pullup. Current draw through the internal pullup may be why raising the external pullup voltage to 3.4V resolved the issue. Commands for changing the internal pullup configuration may be found below.