Servo signals and power

[ReikoR]

Are Palli_H and Palli_S servo PWM signals?

If they are, then 5V switching regulator would also be needed to power the servos, since linear regulators are inefficient for higher currents.

[ReikoR]

NCV8730 regulator is only rated for 150 mA output current, which is not enough for servos. Linear regulators in general are inefficient for higher currents.

We have bought XTPS62933DRLR switching regulators and SRP6060FA-5R6M inductors for powering the servos: https://ut-robotics.github.io/picr22-home/basketball_robot_guide/electronics/components.html

Texas Instruments Webench can be used to help with the design: https://webench.ti.com/power-designer/switching-regulator?powerSupply=0

[ReikoR]

1. RT pin should be left floating, connected to GND or to resistor. \ \ From TPS62933 datasheet:

2. 130k and 22k feedback resistors set the output voltage to about 5.5V, not 5V.

[ReikoR]

1. 100k RT resistor results in switching frequency of 225 kHz. \ When using this frequency in https://webench.ti.com/power-designer/switching-regulator, it says: This design is not stable due phase margin either smaller than 35 or greater than 120. \ Also lower switching frequency requires inductor with higher inductance. \ Either lower resistor value needs to be used to set switching frequency higher or RT pin should be left unconnected to set frequency to 500 kHz.

2. Feedback resistors should be changed, not the power port value: \ 5.5V is too close to maximum recommended supply voltage for isolators. From datasheet:

[ReikoR]

100k and 22k feedback resistors set the output voltage to 4.436 V.

If you don't know how to select the resistor values, then see sections 9.3.4 Output Voltage Setting and 10.2.2.2 Output Voltage Resistors Selection in the TPS62933 datasheet.