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OPA544: About "FIGURE 5. Digitally Programmable Power Supply"

Junya Kato
Expert 1635 points
Part Number: OPA544


Hello Team,

I have a question about the reference circuit of "FIGURE 5".
Is not it necessary to have a capacitor for phase compensation in the circuit?

Best regards,
Kato

  • 0
    TI__Guru* 93105 points

    Hello Kato,

    The compensation method applied in a paticular circuit varies with the op amp being used and the application circuit design. The compensation required depends on the op amp open-loop gain/phase (Aol) and output impedance (Zo) characteristics, and the load the op amp must drive. The OPA544 programmable power supply circuit in this case has been compensated for high capacitive loads. Compensation wouldn't be necessary for a purely resistive load.

    The OPA544 compensation applied in this power supply application consists of the series RC from the summing node to ground (4.7 k + 470 pF), the parallel RL in series with output pin (10 ohms || 1 uH), and the series snubber (1 ohm + 10 nF) from the output to ground.

    No doubt this circuit was constructed and fully tested to assure stability with high capacitive loads as the note in Figure 5 indicates.

    Regards, Thomas

    Precision Amplifiers Applications Engineering