TPS61170: quadruple circuit

Given Ding

Part Number: TPS61170

Hi Team,

Here is a question from customer.

Customer use TPS61170 to do a boost+ quadruple circuit ( using diode and cap, similar with the double circuit shown in fig 20 in datasheet) to achieve 90Vout. But they find issue that Vout cannot be above 77V and SW is changing between Dmax to small duty cycle regularly. Then they change the quadruple circuit to triple circuit and it can works but since Vout is high, SW spike is beyond spec.

So just want to get some suggestions on why the quadruple circuit cannot work. Thanks.

BRs

Given

over 5 years ago

0 Helen chen over 5 years ago

TI__Mastermind 40080 points

Hi Given,

What is the Vin, Vout and the Iout in the application?

Could you please post the schematic?

0 Given Ding over 5 years ago in reply to Helen chen

TI__Genius 10205 points

61170 sch and waveforms.xlsx

0 Given Ding over 5 years ago in reply to Given Ding

TI__Genius 10205 points

Hi Helen,

please kindly see attached file. looking forward to your reply and thanks.

BRs

Given

0 Given Ding over 5 years ago in reply to Given Ding

TI__Genius 10205 points

Hi Helen,

In addition, Iout=1mA. Thanks.

BRs
Given

0 Helen chen over 5 years ago in reply to Given Ding

TI__Mastermind 40080 points

Hi Given,

Not sure if they need very high output precision, if the precision is not high. Then can use two stage charge pump circuit. Like the below circuit.

0 Helen chen over 5 years ago in reply to Given Ding

TI__Mastermind 40080 points

By the way, is their input voltage a stable 5V? What is the precision of the 5Vin? Actually, for the 5Vin, the single stage output voltage can reach 35V, two stage charge pump can reach 70V and the three stage can reach 105V.

0 Given Ding over 5 years ago in reply to Helen chen

TI__Genius 10205 points

Hi Helen,

customer has chosen 40V rating diode ( considering 80% derating), so they use a quadruple circuit.

I have suggested them to use a triple charge pump but they consist on quadruple circuit. So please kindly add some comments on the issue they met. Thanks.

BRs

Given

0 Helen chen over 5 years ago in reply to Given Ding

TI__Mastermind 40080 points

Hi Given,

As what we discussed just now, the customer can choose a controller to make the circuit easy to be controlled.

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TPS61170: quadruple circuit