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TPS2546: TPS2546: Propagation delay

ptm
Intellectual 270 points
Part Number: TPS2546
Other Parts Discussed in Thread: AM3356,
Hi,
 In one of my design I am using TPS2546 USB controller and it is interfaced to AM3356. We configured USB1 as host but when we connect the thumb drive it is not detecting. Below is the configuration we are using
USB1_ID is NC, USB1_DRVVBUS is connected to TPS2546 enable pin, and USB1_VBUS is connected to TPS2546 output and to the pin1 of USB A connector.
The software used is same as beagle bone EVM. When we probed the USB1_DRVVBUS signal it is not going HIGH always it is showing LOW. When we did read-back of register related to USB1 it is showing correctly (configured for HOST).
When we connect USB1_ID to LOW then also we are seeing USB1_DRVVBUS always LOW.
Later we modified the schematic then we are able to detect the thumb drive, below is the circuit
When we measured the output of the TPS2546 with respect to USB1_DRVVBS signal (i.e. enable signal of the TPS2546) we observed that 5V is appearing at the TPS2546 output (USB1_PWR) after 200ms.
But As per TPS2546 datasheet Propagation delay is 0.25ns (TYP).  
Can anyone tell me from where 200 ms delay is getting added / introduced?
By default i am setting CTL1 = 0, CTL2 = 1, CTL3 = 1, ILIM = 0 and Target current is 1.5 A, any of the BC1.2
Hi,
 
In one of my design I am using TPS2546 USB controller and it is interfaced to AM3356. We configured USB1 as host but when we connect the thumb drive it is not detecting. Below is the configuration we are using
USB1_ID is NC, USB1_DRVVBUS is connected to TPS2546 enable pin, and USB1_VBUS is connected to TPS2546 output and to the pin1 of USB A connector.
The software used is same as beagle bone EVM. When we probed the USB1_DRVVBUS signal it is not going HIGH always it is showing LOW. When we did read-back of register related to USB1 it is showing correctly (configured for HOST).
When we connect USB1_ID to LOW then also we are seeing USB1_DRVVBUS always LOW.
Later we modified the schematic then we are able to detect the thumb drive, below is the circuit
When we measured the output of the TPS2546 with respect to USB1_DRVVBS signal (i.e. enable signal of the TPS2546) we observed that 5V is appearing at the TPS2546 output (USB1_PWR) after 200ms.
But As per TPS2546 datasheet Propagation delay is 0.25ns (TYP).  
Can anyone tell me from where 200 ms delay is getting added / introduced?
By default i am setting CTL1 = 0, CTL2 = 1, CTL3 = 1, ILIM = 0 and Target current is 1.5 A, any of the BC1.2
 

  • 0
    TI__Mastermind 32661 points
    I am not able to see your schematic, so I cannot comment as to why the change altered the functionality of your system.

    The 200ms delay you are describing is part of the PPM functionality of the part described in section 8.3.72 of the specification. There is a 200ms delay after current draw exceeds ILIM_LO+60mA before the part is fully enabled.

    If this delay is not desirable in your system, then I suggest using mode 0111 (CTL1,2,3,ILIM_SEL) or 0110. These modes will not have the 200mS delay.

    Please feel free to ask any further questions you have or if I have fully answered your questions, then please click the customer thinks resolve button.

    Regards,
    Chuck
  • 0 in reply to Chuck Branch
    TI__Mastermind 32661 points
    I am changing this thread to TI thinks resolved.

    Please feel free to ask any further questions you have or if I have fully answered your questions, then please click the customer thinks resolve button.

    Regards,
    Chuck