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TLC5925 / 59025

Jan Volkering
Expert 8190 points
Other Parts Discussed in Thread: TLC59025, TLC5925

Two questions:

1: Is the only difference between the TLC59025 and the TLC5925 the matching of the ourput currents?

2: What happens if you set the current at such a level that the product of current and load impedance is higher that the avaliable voltage, e.g.

If I set the current at 20mA , connect my load that has an impedance of 500Ohms at 5Vcc.

Will the driver saturate at 0.4V and deliver no more than ~9.2mA but stay stable (no oscillations)?

Reason I am asking is that I want to combine driving  7 LEDs, that need 20mA constant current and 8 Reed relais that are 500Ohms but need 5V drive voltage.

Using the unused outputs of the TLC5925 to power the reed relais saves me additional drive logic.

Will the TLC5925 be able to drive an inductive load?

 

  • 0
    TI__Guru 61175 points

    Hello Jan,

    1. TLC59025 also uses the industry standard for Iout to external resistor ratio.

    2. We never tested the parts with other loads than LEDs. In general I would say that the impedance limits the current, even if the IC wants to draw more current. I do not expect the drivers to oscillate.

    An inductive loads, I think you just get into trouble during turn off of the current sink. If the current sink turns off, the current in the inductor tries to flow and if you do not add a free wheeling diode in parallel to the inductor (cathode to positive voltage and anode to output of the TLC59x25), the current will destroy the IC. But please keep in mind, this is not tested.

    Best regrads,
    Brigitte