Other Parts Discussed in Thread: TUSB4041I
Tool/software:
Hello,
We are using the TUSB4041I in an on-board USB switch application for a power consumption sensitive (automotive) environment. During testing, we have noticed anomalously high current consumption by the TUSB4041 and a seeming lack of impact by the GRSTz pin. I have attached the relevant portions of our board schematic for your reference.
We are unfortunately unable to readily measure the power consumption of the 3.3V and 1.1V USB power supplies separately from rest of the board during operation, but we did isolate them in order to take a baseline measurement. The following are my observations:
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Total Board Current Consumption @ 12V Input (mA) |
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Condition |
GRSTz Not Asserted |
GRSTz Asserted |
|
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USB Supplies Physically Disconnected |
< 1 |
N/A |
|
|
USB 1.1V Supply Disabled (3.3V only active) |
35 |
35 |
|
|
Both Supplies Active |
As Shown in Schematic |
45 |
45 |
|
GRSTz cap removed |
45 |
45 |
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Previous + PWRCTLx pins shorted to Ground |
64 |
64 |
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|
Previous + FULLPWRMGMTz resistor removed |
78 |
78 |
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Previous + PWRCTLx ground jumpers removed |
43 |
43 |
|
In all cases, there were no upstream or downstream devices connected to the switch.
The switch itself seems to function properly when an upstream device (our compute module) or downstream device is connected, but this current consumption is untenable in the case where we put our upstream device into sleep/shutdown.
Our questions:
- Are we using the reset functionality correctly? We know our 3.3V supply is sequenced before the 1.1V supply but, based on our reading of the datasheet, an active reset assertion should take care of this; however, reset assertion appears to not have any effect on power consumption.
- What could be causing our high current consumption across the board? These values seem high, even setting aside the reset issue.
Thank you for any help you can provide!TUSB4041I_circuit_schematic.pdf
