TEA1721BT Buck User Guide Doubt

Nishant2 — Thu, 12 Jun 2025 12:55:28 GMT

There is a user guide UM10521 related to TEA1721BT which explains Non-isolated buck and buck/boost converter demo board.
In the buck design is the IC GND and system GND are different same or different.

If the both GNDs are different in this design I have the following doubt:
1. How is the FB going from the output (referenced to system ground) is going to FB pin (which is referenced to IC ground), because both grounds has to be same for this case ?
2. How this IC is in CV mode. Is R4 resistor is the Source current sense resistor or snubber ?

If the both GNDs are same in this design I have the following doubt:
1. Then Vsource cannot be in the range of (100mV to 555mV) for CV mode as source pin will have voltage from drain pin when mosfet will be ON ?
2. Then how the FB and Vsource are sensed in this case ?
https://www.nxp.com/docs/en/user-guide/UM10522.pdf

https://www.nxp.com/docs/en/data-sheet/TEA1721BT.pdf

Re: TEA1721BT Buck User Guide Doubt

ErikaC — Thu, 12 Jun 2025 16:46:31 GMT

Hello,

In the non-isolated buck configuration described in the demo board IC GND and system GND are the same.

The IC uses the FB pin to sense output voltage through a resistor divider, and the Source pin to measure current via a low-side sense resistor (R4), but only during the MOSFET’s OFF-time when the inductor current is near zero. CV mode begins at a switching frequency of 22.5 kHz and a Vsource of 100 mV, and as output power increases, both Vsource and switching frequency rise, up to 555 mV and 50.5 kHz respectively. Once the IC reaches its start-up voltage, the internal start-up current source is disabled

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TEA1721BT Buck User Guide Doubt

Re: TEA1721BT Buck User Guide Doubt