Hi,
I am using the tps24751 and I have implemented it as a simple 12A load switch as outlined in Figure 48 of the data sheet. I have all the signals tied as shown and Cgate is a 47 nF cap and Rgate is a 1K resistor. Cload in 470 uF. Vin is 12V.
With no load connected, when the enable is sent to 3.3V, the switch operates as expected and 12V in outputted. However, if I connect up either a 12V fan, which has a nominal 2 amp draw (inrush could be around 7 amps or a known circuit card that draws 4 amps (no inrush) the tps24751 either A) goes int a mode where the output is around 3.3V or B) starts to spin up the fan and gets to about 9 volts and then shuts down to about 3.3V and then about 10 seconds later tries again and does the same thing. I probed the gate pin and the pin is doing a sawtooth pattern at about 9 volts if I remember correctly.
I have been reading the datasheet and I looked at the excel spreadsheet, but it makes no provisions for the load switch design.
I am going to look at modifying Cgate to see if that makes any difference, but also in reading the datasheet, it seems like maybe I should have a cap (47nF) on the timer even though the datasheet doesn't indicate I need one.
What I am trying to do is just have a simple load switch on / off. I do not need inrush control or overvoltage / over current protection, so Im not sure what I am doing wrong in the design. Any guideance or tips would be very appreciated.
Thank you,
Will
