Hi, John,
I do not think there is the lpc_chip_11A0x directory, in other words, there is not software package based on LPC11Axx family in LPCOpen. I think the peripheral register address are the same for LPC11U68 and LPC11Axx, so I think you can use the code for LPC11U68 for the LPC11Axx.
Hope it can help you
BR
XiangJun Rong