ADC 'ADS1130' Wiring Problem
In commercial board, Pin number 4 is connected to Pin nummber 1 i.e 4
  is connected to VCC. But datasheet indicates that pin number 4 is
  DGND.


Then it can't be the chip you think it is. The data sheet is clear about pins 2, 3 and 4 - they are DGND: -



Of course you could have read the part number incorrectly when in fact it was an ADS1131 with pin 4 as an input: -



If you are trying to design something, the most important information you will get is the data sheet. Forget trying to hack a design and read the data sheet.