TPS61043 for 2cell application

tateo yamashiro

Other Parts Discussed in Thread: TPS61043

Hi,

My customer has question about TPS61043.
Could you tell me about questoin?

[Question]
- My customer considers to use TPS61043 for 2cell application.
So my customer consider the design separating Vin from power stage.
Can TPS61043 be used with higher input voltage as long as the control circuitry is kept separate from the power stage?
Please see figure below.

- How is the condition of soft-start function is enabled?
Is it only when device is start-up or every time PWM High signal is inputted for CTRL pin?
My customer is concerned about rush current.
Is there waveform of LED current at rising edge of PWM signal?

- Pulling the CTRL pin to GND for more than 32 ms or 10 ms disables the device.
What is the difference between 32 ms and 10 ms?
Does 10 ms be accepted only at Duty cycle below 1%?

Best Regards,
tateo

over 7 years ago

0 Helen chen over 7 years ago

TI__Mastermind 40080 points

We will check with the designer and will reply the question tomorrow!

0 Helen chen over 7 years ago in reply to Helen chen

TI__Mastermind 40080 points

Hi,

Here's my answer:

1. It is not suggest to make Vin seperated, because control Vin will change the operation frequency of the device, which makes the average current flow into the LED changes a little because of different ripple frequency. But if you didn't care about the regulation, then it is OK. But make sure, the control Vin is 2.7-3.6V, don't make this range larger.
2. There's no inrush at the rising edge of the PWM signal, please refer to Figure 26 in the datasheet.
3. When duty >1%, toff should >32ms, when duty <1%, toff should >10ms.

BR,

Helen

0 tateo yamashiro over 7 years ago in reply to Helen chen

Guru 10890 points

Thank you for your reply.
If Vin is fixed 3.3V, the switching frequency is fixed?

Best Regards,
tateo

0 Helen chen over 7 years ago in reply to tateo yamashiro

TI__Mastermind 40080 points

If both control Vin and power Vin is fixed, then frequency is fixed.

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TPS61043 for 2cell application