TPS25927: efuse connection with MCU

Hi Carlo,

Customer need wants to change current limit from MCU ? What is the range of current limit needed?

Regards

Kunal Goel

Hello Kunal,

The current limit needed is from 0-500mA only and if it goes beyond 500mA, this limit has to be determined from MCU and the current limit should be fixed by MCU.

Regards,
Carlo

Hi Carlo,

I think I am not understanding. See , current limit means that if load tries to draw current more than set current limit then efuse will limit current through it as equal to current limit. 

Now you have to choose a particular resistor value at ILIM pin of eFuse to set a current limit. 

Every eFuse device has some minimum current limit and maximum current limit you can set. Minimum current limit is not zero.

So in customer application how much is the minimum current limit they want and how much max current limit?

Using TPS25927 device you can set minimum current limit as 1A and maximum current limit as 5A.

Regards

Kunal Goel

Hello Kunal,

The customer would like to communicate an efuse with MCU to prompt the MCU when it is in over-current state, is this possible with any efuse? The maximum current limit they need is 500mA.

Regards,
Carlo

Hi Carlo,

Based on current limit requirement we have TPS2596 and TPS25200.

1. TPS2596 has ILIM pin. This pin gives voltage proportional to current through device. May be this can be used.

2. TPS25200 has active low FLT pin that goes low when overcurrent is there .

Regards

Kunal Goel

Hello Kunal,

For these two devices, can this be connected to an MCU?

Regards,
Carlo

Hi Carlo,

1. TPS25200 FLT pin is giving a digital signal so MCU can read this.

2. TPS2596 ILIM pin is giving a analog signal  ,it can be connected to an ADC. I think it can be connected to MCU analog pin as long as it does not load this pin.

Regards

Kunal Goel

Hello Kunal,

For the TPS25200, if we place a 150k ohm resistor on ILIM pin to set 600mA, it will work in between 0-600mA? if it exceeds the 710mA current consumption, then it will break the circuit and provide an active low at Fault pin?

Regards,
Carlo

Hi Carlo,

When you use 150K then it means that typical value of current limit is 647mA. When current goes above this 647mA then device will quickly turn off and again start land limit current to 647mA. FLT will go low after an 8ms timer when device enter overcurrent.

Also as you mentioned customer wants max current limit as 500mA and they can also change current limit so they can also set it to a a lower value like 200mA?

Regards

Kunal Goel

Hello Kunal,

Our customers do not want to set a minimum current limit only the maximum. Considering a case where our customer has set 150k ohm for limiting up to 647mA, will it run even in 200mA? Is it possible to run in till 647mA for TPS25200? It is correct that we can set only 5 current limiting values by 5 different resistor values?

Regards,
Carlo

Okay . Earlier I thought from your explanation that customer want to change current limit so I recommended TPS25200 as it can also set lower current limit.

We have latest device TPS259470 which has FLT pin that goes low in current limit. Please check this device. You can set 500mA current limit using this device.

When you set a current limit, device will allow all current level below current limit to pass without any blocking. When current goes above current limit then only limiting or blocking happen. You can set any current limit value using any resistor value within recommended range for any eFuse device.

For eg for TPS259470:

You can choose any resistor between 6.65k and 549 ohm.

Regards

Kunal Goel