TPS2330: TPS2330 as a power switch

Carl Olen

Part Number: TPS2330

I’m attempting to use the TPS2330 as a power switch. I have a 12V battery-powered system. I want to control the overall power (about 3A) on/off by toggling the enable pin the TPS2330. Then, I want to do the same on another current leg (about 1A) of the system downstream from the overall power. I’m having trouble getting this to work. Has anyone done any similar application with this device?

over 5 years ago

0 Praveen GD over 5 years ago

TI__Guru 57737 points

Hi Olen,

Hotswap controllers are not suitable for Switching applications. When the device is enabled, internal charge-pump circuitry pulls the gate pin up by sourcing approximately 15 μA. The turnon slew rates depends on the capacitance present at the GATE terminal. Switching applications require much higher Source Currents.
We have not seen anyone use Hotswap Controllers for this kind of applications. Can you explain what problems are you facing while working on this circuit ?

0 Carl Olen over 5 years ago in reply to Praveen GD

Expert 1160 points

Praveen, thanks for your reply. I have attached a simplified block diagram and description of what I'm trying to get working...

Power Switch Application Block Diagram.pdf

0 Carl Olen over 5 years ago in reply to Carl Olen

Expert 1160 points

Also, here are the spreadsheets (using TI tools) that I developed for U500 and U501. I'm about to hook up the scope to start looking at waveforms.

U501_HotSwap_tps23xx_tool.xls

0 Carl Olen over 5 years ago in reply to Carl Olen

Expert 1160 points

I guess I can only upload one file attachment at a time...U500_HotSwap_tps23xx_tool .xls

0 Carl Olen over 5 years ago in reply to Carl Olen

Expert 1160 points

I captured the following waveform pairs. I am measuring 4.1V at the VREG pin, after the TPS2330 is enabled. There is 470pF of capacitance across the gate. Yet I see no voltage rise charging this capacitor once the chip is enabled. These waveforms were captured with a no-load condition. Then, captured again with a 2A load and 94uF of load capacitance at the main system output of Q500.

EnableSwitchedON_GATE (no load):

0 Carl Olen over 5 years ago in reply to Carl Olen

Expert 1160 points

EnableSwitchTransition to Low (enabled) with GATE signal (including a 2A load and 94uF of load capacitance):

0 Carl Olen over 5 years ago in reply to Carl Olen

Expert 1160 points

EnableSwitchedON_Timer (no load):

0 Carl Olen over 5 years ago in reply to Carl Olen

Expert 1160 points

EnableSwitchTransition to Low (enabled) with Timer signal (including a 2A load and 94uF of load capacitance):

0 Carl Olen over 5 years ago in reply to Carl Olen

Expert 1160 points

Any thoughts or ideas on how to get this working? Also, if there are other solutions to the basic power switch application I have outlined, I would welcome any suggestions. Thanks! Carl

0 Praveen GD over 5 years ago in reply to Carl Olen

TI__Guru 57737 points

Hi Carl,

Thanks for sharing the Power Switch Application Block Diagram, design calculator and waveforms. From you design calculator, I don't find any reason why the Hotswap shouldn't turn the FET ON. Can you please share the schematic of this section ?
Also, can you share a snapshot of Vin, EN/, GATE and Vout in the same waveform?

0 Carl Olen over 5 years ago in reply to Praveen GD

Expert 1160 points

Praveen, thanks. Here is the schematic. Note that there is a mechanical switch between pins 1 & 2 of J500 (not shown) that switches on the Q502 transistor to enable the TPS2330.

SystemPowerHotSwapCircuit.pdf

0 Carl Olen over 5 years ago in reply to Carl Olen

Expert 1160 points

Also, the U510 device simply controls an LED pilot light based on PWRGD from the TPS2330. But of course, it never comes on. Here is the waveform of the Enable Signal being switched to low ("ON") along with Vin, which never changes from 11.97V.

0 Carl Olen over 5 years ago in reply to Carl Olen

Expert 1160 points

And finally, here is the Enable Signal switching to low ("ON") along with Vout, which never changes from 0V. I'm sorry I couldn't get all four waveforms on the same plot. I don't have enough break-out cables for my scope probes. Please let me know your thoughts. Thanks, Carl

0 Praveen GD over 5 years ago in reply to Carl Olen

TI__Guru 57737 points

Hi Carl,

The schematics look fine as well. You can add a Schottky Diode across the output to freewheel the load, when the FET is turned OFF.
It is surprising to see that neither Timer nor Gate ramping up. There is a typical 'Turnon delay time, ENABLE' of 85us. So, the gate should start ramping up at least after the last EN Low.
Can you please check continuity of the circuit on your board?
Also, please try replacing the IC just to be sure that the IC on board is not damaged.

0 Praveen GD over 5 years ago in reply to Praveen GD

TI__Guru 57737 points

Hi Carl,

Can you update us on this issue ? Were you able to solve this issue ?

0 Praveen GD over 5 years ago in reply to Praveen GD

TI__Guru 57737 points

Hi Carl,

I haven’t heard back from you, I’m assuming you were able to resolve your issue. If not, just post a reply below (or create a new thread if the thread has locked due to time-out)

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TPS2330: TPS2330 as a power switch