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TIDM-1003: what are the power supplies requirements for this design: 12v, 5v, 3.3v ?

Vlad Blanshey
Intellectual 690 points
Other Parts Discussed in Thread: TIDM-1003

Note: TIDM-1003 is TI design "Low-Voltage 50-A Sensorless FOC for BLDC or PMSM ref design"  - this posting window does not recognize this entered number, probably because it is new design.

What is the current output requirements for each DC-DC converter in this design:12v, 5, 3.3v ? Assuming that converters are not chained but all convert from Vdc input range. If they are chained as in this design - each stage should in addition produce current needed for all down stages. Key system specification does not mention requirements even for the external feed Vdc.

Also related: What is the benefit of making a chain: each converter is a step-down buck of the previous ? 12v converter has to have enough power to also include current for the lower converters - probably more power dissipation (even though step-down voltage differences are lower)?

  • 0
    TI__Guru** 109690 points
    3.3V LDO is for controller which needs about 120mA current consumption for 60MHz CPU frequency.
    5V LDO will be converted to 3.3V and for Hall sensor or other interface, it's better to have more than 200mA current output capacity.
    12V DC/DC will be converted to 5V for all devices, include controller FET driver, interface, so need more than 250mA current output capacity.
    You can calculate the power consumption with voltage, current and power device efficiency. Only a DC-DC converter is used for dc-bus voltage (54V) to 12V power supply, other two use LDO., and you can use DC-DC also, the current output is the same, and DC-DC will have better power converter efficiency than LDO.