PTN78020W: 100% duty cycle

Dear Jimmy,

Thank you for your feedback. Actually I would like to use this converter to step down voltage from a battery. The battery voltage range is 16.8V to 10.5V (10.5V is the cut off voltage of the battery). From your explanation, when the Vin almost equal to Vout, there still output voltage but it just not regulated. The output voltage will directly follow the input voltage. Is my understanding correct?  

Thank you.

Best regards,

Fariz

Hi Jimmy,

Can you advise me which IC or power module (buck or buck-boost) should I use in order to meet my requirement as below:

Vin: 10.5V to 17V (battery supply)

Vout: 12V 

Iout: 4A

Thank you.

Best regards,

Fariz

Hi Muhammad,

The TPS62136 supports your Vin, Vout, and Iout with true 100% duty cycle mode.

Hi Chris,

Thank you for the suggestion. But the Vin and Vout spec is quiet marginal to my requirement (Vin=16.8V, Vout=12V). Any consideration should I take to use this IC with my current spec (eg: thermal, performance, life cycle)?

Thank you.

Best regards,

Fariz

Hi Fariz,

Yes, the device limits are close to your maximums. Another way to look at it is that the design is not over-designed with too much margin. 16.8Vin and 12Vout is perfectly fine.

Assuming you have a 4S supply, you would need to consider if there would be any transients that would create a voltage higher than 16.8V. If you use an accurate TI charger, with 1% charge voltage accuracy or better, your battery voltage will always be below 17V.

For thermals, we need to consider if there is airflow, what the ambient temperature range is, and how long the 4A would be present (DC or some short peak time in the msec). What type of system are you designing?