Hi.
Implementing 3 buck using 2 TPS65252, buck1 is 3.3V, buck2 is 1.2V, buck3 is 1.8V.
And max requirement delay time is 1.5ms, 2ms between each sources as 3.3->1.2->1.8 sequence.
So, I set EN capacitor value like buck1:4.7nF, buck2:5.6nF, buck3:6.8nF.
calculated delayed time as below.
buck1: 12+1.67*4.7=19.8ms
buck2: 12+1.67*5.6=21.3ms
buck3: 12+1.67*6.8=23.3ms
But, VOUT2 start timming is delayed 1.8ms than VOUT1, VOUT3 start timming is delayed just 0.5ms than VOUT2.
so, I tried changing EN1 cap. value as 5nF using two parallel cap. because it isn't standard cap. value, then buck1&buck2 are enabled same time and buck3 is delayed almost 2ms than before. I have to set under 1.5ms between each buck, but, that can't set, just min. delay is 1.8ms.
I wonder why delay timming dosen't work as calculated timming with formula in datasheet.
attached figure is captured timming graph of buck1. yellow is VIN, blue is EN, purple is VOUT.
