TPS61170-Q1: TPS61170 Bandwith/stability improvement

Stijn Bosmans

Part Number: TPS61170-Q1
Other Parts Discussed in Thread: TPS61170

Hi all,

In our design, we are using the TPS61170 to convert 12V input voltage to 27V. The feedback is controlled by a PWM signal that is used to ramp up the output voltage(to limit the inrush current to the high output capacitance)

Due to a high output capacitance(and ESR) on the output, I need to add a small capacitor in the compensation circuit.
We also want to improve the bandwidth of the system, we want to recalculate the compensation resistor and capacitor.
For this, we are using SLVA913C application report of this boost converter.

In the Se formula(I think this is for the Slope compensation ramp), there are 3 variables mentioned where I can't find a value for; A F and D.

I also have another question; this added capacitor, how can this be implemented in the transfer function Gt(s)?

Can you please help me to find these variables?

Thanks,

Stijn

over 6 years ago

0 Helen chen over 6 years ago

TI__Mastermind 40080 points

Dear Sir,

Could you please share the Vin, Vout , Iout and the output capacitance value, its ESR with us first?

0 Stijn Bosmans over 6 years ago in reply to Helen chen

Prodigy 225 points

Hi Helen,

Vin=9V
Vout=27V
Iout=0.15mA
Cout=300uF
Cap_ESR=30mOhm

Thanks,
Stijn

0 Helen chen over 6 years ago in reply to Stijn Bosmans

TI__Mastermind 40080 points

Dear Sir,

you can choose Rcomp=51k, Ccomp=330nF, Cp=100pF in your design. And suggest you add a 0.1-1uF ceramic cap as close to the TPS61170's output side as possible.

0 Stijn Bosmans over 6 years ago in reply to Helen chen

Prodigy 225 points

Hi Helen,

Thank you for this quick response, according to Matlab calculations the stability and bandwidth of the system are indeed optimised with these values.

I want to compare the GT(s)(page 3 of SLVA319) transfer function with T(s)=GPW(s)*Hea(s)(page5 of SLVA319). But for this, I need to know what the A, F and D are standing for(in the slope compensation ramp)

Thanks,
Stijn

0 Helen chen over 6 years ago in reply to Stijn Bosmans

TI__Mastermind 40080 points

Dear Stijn-San,

I'm on holiday. I'll give the data to you within the two days. Please wait in patience.

0 Stijn Bosmans over 6 years ago in reply to Helen chen

Prodigy 225 points

Hi Helen,

Do you have any update about this?

There is also another question showing up when gathering more information about this;
Is there a way to determine if the boost converter is in CCM mode during the full output voltage range(9V-30V) with a load of 125mA?

Thanks,
Stijn

0 Helen chen over 6 years ago in reply to Stijn Bosmans

TI__Mastermind 40080 points

Dear Sir,

This is an old part, I con't know exactly what is the writer mean. But per datasheet, A is the DC gain, F is the frequency, D is the duty cycle.

To know whether it is in the CCM mode, it is based on the inductor selection. Low inductance and high ripple current will results in DCM operation.

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TPS61170-Q1: TPS61170 Bandwith/stability improvement