TPS563201: The transition point to the light load operation

Ryo Akashi

Part Number: TPS563201
Other Parts Discussed in Thread: TPS563208

Hello experts,

I got question about the transition point to the light load operation from customer.
From equation of IOUT(LL) in datasheet P10, we can calculate the transition point.

For this equation, we need frequency value.

Can we figure out the frequency value from WEBENCH's chart?

Or should we utilize figure 7 in datasheet?

Are these correct way?

Thanks and best regards,

Ryo Akashi

over 4 years ago

0 JohnTucker over 4 years ago

TI__Guru**** 191445 points

Akashi-san,

You can use datasheet figure 8 or we bench to estimate the efficiency during light load operation. Figure 7 is for TPS563208 which operates in forced PWM mode where the frequency does not reduce in light load conditions.

0 Ryo Akashi over 4 years ago in reply to JohnTucker

TI__Expert 8980 points

Hello Tucker-san,

Thank you for your reply.

I'm sorry, I misunderstood about figure 7. It shows about fSW vs Vin for TPS563208.

Let me ask additional question.

From figure 8, we can estimate the transition point (IOUT(LL) and fSW). Is it correct?

My customer wants to know the switching frequency value which we can apply for equation (1) in datasheet.

The customer's condition (Vin, Vout, Iout) is different from datasheet shows. It's difficult to apply the data from figure 8 directly.

Could you give me advise how to estimate switching frequency for equation (1)?

Thanks and best regards,

Ryo Akashi

0 Ryan Hu (BSR-MV) over 4 years ago in reply to Ryo Akashi

TI__Expert 4035 points

Hi Ryo,

Use typical center frequency of 580kHz to calculate the transition point through eq1. Attached a calculator as below to calculate the real fsw under light load conditions.

Fsw_ECO_DCAP2.xlsx

0 Ryo Akashi over 4 years ago in reply to Ryan Hu (BSR-MV)

TI__Expert 8980 points

Hello Ryan,

Thank you for your reply.

I understand the frequency value.

Also, thank you for sharing calculator.

Thanks and best regards,

Ryo Akashi

Power management

Power management forum

TPS563201: The transition point to the light load operation