TPS65580: PG pin current

Part Number:TPS65580

Hi,

I'm interfacing the PG pin of the TPS65580 with a microcontroller. To do so, I use the 5.5 V regulator and a zener in order to obtain the desired voltage (2 Vhigh). The zener uses 5 mA.

The PG pin is an open drain. However, I can't find in the datasheet any information regarding the maximum input current it can sink. Do you have the info? 

Thanks,

Federico