According to datasheet, zero duty cycle condition is "Vout<Vin<Vout+0.24V and Vout>Vout_nom".
How does the device operate if Vin voltage becomes higher than Vout+0.24V?
Best Regards,
Kohei Sasaki
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According to datasheet, zero duty cycle condition is "Vout<Vin<Vout+0.24V and Vout>Vout_nom".
How does the device operate if Vin voltage becomes higher than Vout+0.24V?
Best Regards,
Kohei Sasaki
Hi Sasaki,
When Vin is higher than programmed Vout, the device works at zero duty cycle mode. High side switch is always on so Vout will rises higher than programmed Vout too. That's the meaning of zero duty cycle definition: Vout< Vin< Vout+0.24V and Vout> Vout_nom.
The voltage drop between Vin and Vout depends on the high side switch on resistance. So maximum voltage drop will be Vin-Vo=Io*Rdson= 2A*100mohm=0.2V if the Io_max=2A.
Hi Sasaki-san,
Precharge current limit detection works when Vout < Vout_nom and Vout < Vin. For zero duty cycle condition, current limit is the same with Ilim_sw.
Liu-san,
TPS61230 ILIM_sw is 4A min.
When Iout is 4A in Zero duty mode, I think Vin-Vout drop becomes 0.3V. (Rdson is 75m ohm)
This is out of range of Zero duty condition.
In this case, how does the device operate? Is it keep zero duty mode?
Best Regards,
Kohei Sasaki
Hi Sasaki-san,
The 0.24V is a typical value to help designer understand zero duty mode definition. In extreme condition, the voltage drop may be higher than 0.24V.