Hi Team,
My customer has few questions of TPS25924.
1. If IoL is set to 2.8A. How many voltage drop at Vout when load current is over 2.8A? When load current back to under 2.8A, how fast the Vout will back to normal voltage?
2. Below is the current waveform of a fan, the max. current is 4.76A, could team help to suggest the value of RLIM?
Thanks very much.
Vincent Chen
Hi Vincent,
For Q1>>
In current limit mode, the device maintains constant current value which was set at Rilim. The power dissipation across the device is (VIN-VOUT)*I_limit. As VOUT value depends on amount of overload, the power dissipation and hence the duration the device operates before thermal shutdown depends on amount of overload.
For example Vin=5V and current limit value is 2A. When the output is loaded with 1ohm, it is an overload event and output voltage VOUT becomes 2A*1ohm=2V. The power dissipation across the device is (5-2)*2=6W. The device operates for 400ms at 25deg before thermal shutdown.
For example Vin=12V and current limit value is 3.5A. when output is shorted VOUT=0, the power dissipation is (12V-0)*3.5A = 42W. The device should operate for 2ms at 25deg before thermal shutdown.
For Q2>>
If the max. current is 4.76A, you can check with RLIM = 162kOhm. What is your average load current? If it is close to max. current, I suggest to switch to TPS24751 device.
Best Regards,
Rakesh
Hi Rakesh,
The customer's application is a fan and the spin up current as below waveform. You can find the max. current is 5.04A.
1. Do you think TPS25924 is a suitable solution since the recommended max. continue output current is 5A?
2. If yes, what is the recommended resistance of RLIM?
Thanks very much.
Vincent Chen
