Part Number: TPS61390
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.
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.
-Best Regards, David
Boost DC/DC Solution
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In reply to Helen chen:
Helen chenAnd 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 chenWhat 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 chenwhat will be the current consumption of the OPA?
In reply to David__:
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 chenyou 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?
Sorry I made a mistake. It is TPS55340.
The charge pump circuit is like the attached circuit. charge pump+-30V.pdf
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 chenSorry 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?
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.
Helen chenyou 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.
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.
Helen chenplease 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 chenBecause 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).
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