TPS61390: Can the boost converter output supply powers to an Op Amp?

David__

Part Number: TPS61390
Other Parts Discussed in Thread: OPA552, , TPS61175, TPS55340

Hi, I'm using +-30V high voltage OPA552 Op Amp from TI. I have used this Op Amp with an external power supply until now.

However, I have to make this as a battery powered product with CC3320 Wi-Fi chip.

I'm using a Lithium Ion Polymer Battery - 3.7v 500mAh.

https://www.adafruit.com/product/1578

The only idea I had was to use a boost converter and enable the boost converter's output for a short time to save the battery life.

Later, I will be changing the Op Amp to another one that supports more higher voltage.

These are my questions;

Q0. I cannot find TPS61390 from Digikey or Mouser. Since this is a new product, can't I buy this online now?

Q1. For now, I have to generate +30V and -30V with the TPS61390.

Just like this connection, is it possible to create +30V and -30V with two TPS61390?

Q2. To extend the battery life, I will toggle the EN (Enable pin) really shortly.

How fast am I allowed to toggle the EN pin? I just need to enable the boost converter for 1μs so I hope the EN pin can detect this sudden change.

Or I'm worried whether the boost converter needs more time to turn on.

Q3. Lastly, for battery-powered applications, is using two boost converter to power the Op Amp a good idea?

My desired power supply is +70V -70V so this output surely meets my desire.

However, the boost converter draws many currents so I'm curious whether there is a better way.

Thanks for your help.

over 5 years ago

0 Helen chen over 5 years ago

TI__Mastermind 40080 points

Dear Sir,
What is your target supply voltage, +-30V or +-70V? And what will be the current consumption of the OPA?
And what is the 1us mean? Is it mean you need to make the boost converter enabled to work within 1us?

0 David__ over 5 years ago in reply to Helen chen

Genius 3585 points

Hi, Helen.

Helen chen said:
And what is the 1us mean? Is it mean you need to make the boost converter enabled to work within 1us?

Yes. like a PWM, I wish to enable the boost converter for a short time, minimum 1μs, if possible since this is a battery powered device.

Helen chen said:
What is your target supply voltage, +-30V or +-70V?

For now, it is +-30V. After testing my prototype PCB, I will change this to +- 70V and use a different Op Amp.

Helen chen said:
what will be the current consumption of the OPA?

Max 80mA.

0 Helen chen over 5 years ago in reply to David__

TI__Mastermind 40080 points

Dear Sir,
In order to enable the IC to work, the EN should last at least around 1ms, 1us is far too less.
TPS61390 can't support +-30V, 80mA. for +-30V, 80mA application, you need to use TPS61175 with charge pump circuit. And for the +-70V, 80mA, at least you need to use TPS555340 with charge pump circuit.

0 David__ over 5 years ago in reply to Helen chen

Genius 3585 points

Thanks, Helen!

Q0. I cannot find TPS555340 on Google nor TI's webpage.

Is this a new product as well? How can I look at the details and buy this?

Q2. For both the TPS61175 and TPS555340,

Helen chen said:
you need to use TPS61175 with charge pump circuit. And for the +-70V, 80mA, at least you need to use TPS555340 with charge pump circuit.

I don't see any description about this "charge pump" circuit.

From this application, can I ask what part is the "charge pump" circuit and what's the rolt of it, please?

0 Helen chen over 5 years ago in reply to David__

TI__Mastermind 40080 points

Dear Sir,

Sorry I made a mistake. It is TPS55340.

The charge pump circuit is like the attached circuit. charge pump+-30V.pdf

0 David__ over 5 years ago in reply to Helen chen

Genius 3585 points

Oh, Wow. I'm truly surprised!

Q0. Just to double check, this circuit with diodes create -30V right, which is the charge pump circuit?

Q1. Does that -30V has a lot of ripples or voltage drop? If so, I might consider adding two Boost converters.

Q2. Can I add that charge pump circuit with the same diode parts to TPS55340 as well in order to generate -70V?

Hope those diodes can be used for 70V applications.

Q3. About TPS55340,

Helen chen said:
Sorry I made a mistake. It is TPS55340.

The datasheet says the VOut voltage range is 38V max. How can I create +-70V output with this?

0 Helen chen over 5 years ago in reply to David__

TI__Mastermind 40080 points

Hi David,

Please check the red block in the attached picture. It is a negative charge pump cell.

What is the ripple requirement and the Vout accuracy? if you need good accuracy, then you need to add more ceramic caps and even a linear regulator .

For the TPS55340, in order to get -70V. You need to make the Vo=35V, then use two cell negative charge pump and one cell positive charge pump.

0 David__ over 5 years ago in reply to Helen chen

Genius 3585 points

Helen chen said:
you need to add more ceramic caps and even a linear regulator .

Thanks! Few last things, please.

Q0. Is there a way to calculate the capacitance to add? Adding random 100uF seems not okay but I cannot find how many to add using the datasheet, depending on the output voltage.

Q1. Can I simulate Vout using TI TINA 9?

Since I have to add diodes and other components, I wish to take a look at Vout before creating a PCB.

0 Helen chen over 5 years ago in reply to David__

TI__Mastermind 40080 points

Before begin simulation, please tell me what is the +30V -30V precision and the voltage ripple? usually, the charge pump is not fit for the very low ripple and tight regulation application.Because for example, if you feedback +30V, then -30V will change with the load and the +30V load condition. The worst case will be +30V no load while the -30V full load.

0 David__ over 5 years ago in reply to Helen chen

Genius 3585 points

Thanks, Helen.

Helen chen said:
please tell me what is the +30V -30V precision and the voltage ripple?

For instance, if 30V is created I wish Vpp less than 1V, please. I wish to guarantee least -29 ~ 29 V.

Helen chen said:
Because for example, if you feedback +30V, then -30V will change with the load and the +30V load condition. The worst case will be +30V no load while the -30V full load.

Can you explain more about this, please? For my case, I'm using both +30V and -30V to supply voltage to the Op Amp OPA552.

Except the power supply pins, the boost converter output and the charge pump output will not be connected to other loads.

Also, I'm gonna add decoupling capacitors to the Op Amp's power supply (0.1u ~ 1uF).

0 Helen chen over 5 years ago in reply to David__

TI__Mastermind 40080 points

What will be the effect if it is +31, -30V? is it OK?

0 David__ over 5 years ago in reply to Helen chen

Genius 3585 points

Hi, Helen. Yes, that is acceptable. Also, when uploading your schematic, can you explain the math how you get +31V, -30V?

I'm curious what diode (with part number) and capacitor you will choose for generating -30V

0 Helen chen over 5 years ago in reply to David__

TI__Mastermind 40080 points

PMP9770 reference board.PDFOK. Then it looks the charge pump ckt is fit for your application.

Please take a look at the below circuit. The concept is the same.

0 David__ over 5 years ago in reply to Helen chen

Genius 3585 points

Deeply appreciated, Helen! Just a few more things before closing this.

Q0. In your schematic, the pins show the corresponding voltages as

VGL: -30V

VGH: 30V

AVDD: 31V

right?

Q1. I have asked about the +70, -70V solution as well. For that case, how should I set the schematic?

Q2. Also, we talked about running simulations using the TI TINA9.

Can you elaborate on how to test the boost converters using TINA?

0 David__ over 5 years ago in reply to Helen chen

Genius 3585 points

Hi, Helen. How are you? Deeply appreciated for your work, Helen! Just a few more things before closing this.

Q0. In your schematic, the pins show the corresponding voltages as

VGL: -30V

VGH: 30V

AVDD: 31V

right?

Q1. I have asked about the +70, -70V solution as well. For that case, how should I set the schematic?

Q2. Also, we talked about running simulations using the TI TINA9.

Can you elaborate on how to test the boost converters using TINA?

0 Helen chen over 5 years ago in reply to David__

TI__Mastermind 40080 points

We'll try to reply you tomorrow, sorry for the late.

0 David__ over 5 years ago in reply to Helen chen

Genius 3585 points

It's okay. I deeply appreciate your endeavor for hepling my custom PCB. Take your time, please.

0 Helen chen over 5 years ago in reply to David__

TI__Mastermind 40080 points

Hi David,

Please check the attached sch. You just need to replace the TPS61175 with TPS55340.

I'm draw the sch in rush because I'm busy with many new projects.

Sorry for the late !charge pump2.pdf

Power management

Power management forum

TPS61390: Can the boost converter output supply powers to an Op Amp?