Dear Team
Some questions about TPS25830AQ1 need to be consulted
MFI OCP test, when current limit is 3.5A , should add capacitance 330uf, please help confirm below schematic whether the placement is correct？
Meanwhile help review RLIMIT and parallel RC circuit （current limit 3.5A)
Hello Shan,
The TPS25830A-Q1's orderable part number is TPS25830AQWRHBRQ1, so the names refer to the same device.
TPS25830QWRHBTQ1 is the orderable part number of TPS25830-Q1.
The TPS25830-Q1 is the previous gen of TPS25830A-Q1 and the table below highlights the difference.
As the table shows, the TPS25830-Q1 is not MFI OC compliant; a 330uF capacitor has to be added to CSP in order to pass MFI OCP with a 3A USB port. The TPS25830A-Q1 was designed so that the 330uF cap is no longer needed to pass MFI OCP, thus making it MFI OC compliant, and this was done by raising the high-side peak current limit to 6.8A (characterized to typical 7.1A as stated in the datasheet).
From the TPS25830-Q1 datasheet:
From the TPS25830A-Q1 datasheet.
No, the current limit doesn't need to be set to the peak current limit, typical 7.1A. Let's take a look Figures 10-18, 10-19, and 10-20 in Section 10.3.10.2 of the TPS25830A-Q1 datasheet. When using an external MOSFET for current limit, there are two current limit thresholds that must be implemented to meet the MFI OC requirement. In your system design, ILIMIT1 is set to 3.5A. The second threshold ILIMIT2 equals to 1.6 times ILIMIT1, or 5.6A. This would be a problem if you were using TPS25830-Q1 because the high-side peak current limit is typ 5.4A, so the 330uF is required. For the TPS25830A-Q1, 5.6A is under its high-side peak current limit.
The R_limit value is good. For designs using an external MOSFET for current limit, with 300Ω R_set and 0.015Ω R_sns, R_limit should be 11.3kΩ to set ILIMIT1 to 3.5A.
Hope this helps,
Seong
