TPS746: slew rate

Hi Gareth, 

When we benchmark parts for the data sheet, Load Transients typically have a slew rate of 1A/us. 

Best,

Juliette

Hi Gareth, 

It would be hard to approximate a slew rate without knowing the setup of the application. 

Figure 30, in the data sheet would help with this calculation. The start-up time will be correlated with the amount of input capacitance (and the inrush current it produces) and the load at the output. 

if the inrush current along with the output load exceed the foldback current (figure 23), the slew rate seen in figure 30 would be slower for your application. 

You can approximate your inrush current using I = C x (dV/dT). Then you can add your output current to see where it lies on the foldback current graph. If the calculated value exceeds foldback current limit, the current limiting feature of the part will engage and your output voltage slew rate will be slower than what is presented in figure 30. 

Foldback current is explained in section 7.3.3 Foldback Current Limit in the datasheet. 

Best,

Juliette

Hi Gareth,

It does not seem like your setup will trigger foldback current; if your VIN is already on and the impedance to your supply is low, the slew rate should be similar to Figure 30 (~10mV/us).

Best,

Juliette