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TPS61158's VOUT PIN sink current

Pokkun
Genius 4695 points
Other Parts Discussed in Thread: TPS61158

Hello.

My customer is currently in using TPS61158, now.

I have gotten a question about this product .

So, please teach me about TPS61158.

＜Question＞

I want to know the sink current of VOUT pin (IOUT_sink) when "CTRL = Low".

What Ω is feedback resistance value of the OVP (ROVP).

Could you help us?

Best Regards,

Masumi Sekiguchi

  • 0
    Genius 4695 points
    Excuse me.
    We'd like a reply .
  • 0 in reply to Pokkun
    TI__Intellectual 2140 points

    Hi,

    I will need some time to gather details on the information you requested.

    The datasheet Iq max spec of 1uA includes the current into the OVP voltage divider. Therefore, the total resistor value should be in the mega-ohm range.

  • 0 in reply to Angelos Tsiros
    Genius 4695 points

    Thanks for the answer .

    I want to know the time until VOUT Pin voltage = VIN(CTRL = L)

    So, please continue to check the specific resistance value.(what MΩ ??)

    Waiting for the answer, thank you.

  • 0 in reply to Pokkun
    TI__Intellectual 2140 points
    Hi,
    We cannot predict the time it takes VOUT to drop to VIN after CTRL = low. As explained previously, in shutdown mode there is no active discharge for VOUT. The rate of discharging of the output capacitor depends on the value of the capacitor and any impedance to ground that is present. This does not only include the path through the OVP voltage divider but also the leakage through the LEDs. Initially, as VOUT is high, the LEDs glow and dissipate power rapidly. As VOUT drops, the LED forward voltage is suppressed and the current through the LEDs is reduced rapidly, until there is no current flow at all. The time it takes for VOUT = VIN will also depend on the starting VOUT and VIN. We cannot predict the profile of this discharge mechanism because it depends on the characteristics of the LEDs and the number of LEDs used.
    The OVP voltage dividing resistors are disconnected from the output when CTRL = low. There is however some very high impedance path to ground through a circuit that is turned on to protect other internal circuits from being damaged when the boost is disabled.
    In short, the exact profile of VOUT discharging is not readily predictable.

    Regards,
    Angelos Tsiros