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INT- TPS65320-Q1 application

Rocson He
Intellectual 1830 points
Other Parts Discussed in Thread: TPS65320-Q1

Hi, team,

For TPS65320-Q1, is it designed only for BUCK output higher than LDO application when both are on, as below operation mode ‘’EN1=1, EN2=1’’ ?

Now customer want to set the LDO output at 5V, and the DCDC output is 4V, but it seems the LDO output is only right when BUCK is disable. When both BUCK and LDO are enable, the LDO would follow the output voltage of BUCK ?

Also, in the spec of page 18, it mentions there is one charge pump for LDO, but I don’t see it in the block diagram and what is its function?

Besides, do we have another one Buck+ one LDO part that have completely independent enable signal to realize the application above, not like TPS65320-Q1?

Thanks.

  • 0
    TI__Mastermind 20580 points

    Hi Rocson,

    This was answered off line already in an e-mail.  Summary below for other E2E searches:

    The device TPS65320 is not designed to do what the customer is attempting.  There is a device on the roadmap, TPS65321, where the LDO and buck will have independent control.   

    For the TPS65320 you cannot run the LDO at a higher voltage than the Buck.  The main application case for this device is something like running  the buck at 5V and the LDO at 3.3V and using the buck as a sort of efficient pre-regulator for higher current loads and when for example the MCU is in low power state and not drawing much current switching the buck off and using only the LDO so the system quiescent current is the lowest possible during low power state.

     Figure 22 shows the typical application where depending on KL15 and 30 the device will change where the supply for the LDO is taken.

    As for the charge pump on the LDO it is needed to ensure proper Vgs on the gate of the output device for the LDO especially when the input voltage (VIN) is low. 

    - Scott