TPS2660: Current Limiting in PoE System

Hi Akash,

Yes you can use TPS26600 variant for current limiting 0.5A at 48V input. What is the max voltage seen after bridge rectifier at TPS2660 input?

For 0.5A current limit, connect 24Kohm resistor from ILIM pin to RTN.

TPS26600 variant can be configured to work in two modes:

1. Current Limit with Auto-Retry: Connect MODE pin to RTN pin.

2. Current Limit with Latchoff: Connect a 402Kohm resistor between MODE and RTN pin.

After a over current event, TPS26600 limits the current to 0.5A. If device is in current limit for long time it enters thermal shutdown.

In Auto-Retry, after thermal shutdown, device attempts to restart after 512ms.

In Latchoff, device remains turned off (OUT off) until recycled by SHDNb or input.

If over current is removed before device enters thermal shutdown, device recovers.

TPS26600PWP (TSSOP) and TPS26600RHF (QFN) are the two package variants available.

Regards,
Kari.

Hi Kari,

Thanks for the detailed response. The max voltage after the bridge rectifier is 53.3V which is below the 60V rating for the device so I believe that should be good?

Regards,
Akash

Yes Akash.

Regards,
Kari.

Hi Kari,

By looking at the Latchoff condition.

2) Current Limit with Latchoff: Connect a 402Kohm resistor between MODE and RTN pin.

How does the value of the resistor 402Kohm been defined? Can you share the calculation of it? Can we use other values instead of 402Kohm?

Thanks in advance.

Hi,

10% variation of 402Kohm resistor is allowed for current limit in latchoff operation.

Regards,
Kari.

Thanks Kari,

Another condition is that if it's output is connected in reverse polarity, will the IC burn.

Hi
TPS2660 does not support reverse polarity on the output. Input reverse polarity protection is supported.

Regards,
Kari.