In the datasheet of the L7987L there is an application schematic for a negative converter (p36), here the VCC is connected to VIN with a 10 Ohm resistor and a capacitor to the generated negative rail (I guess is to filter the power for the low power parts of the IC), but the 'ground' this capacitor is connected to (C4) will (probably) be more noisy than the 'real' ground, can be better to connect it to the input ground?
I think that side should be more stable and can provide a better filtering source, if this is the purpose of this capacitor.
The system works as is, I made a few of them and I can have over 1A at -12V, I'm just wondering if this can be a better option.
