Using the ADS7828 with the Beagleboard

Does anyone have experience of using an ADC based on the ADS7828 chip?

I have connected an ADC module to the I2C port and when I run
i2cdetect I see a new device at location 0x48. The thing is the
ADS7828 datasheet and the module documentation both say that the
default device address is 0x90. Which seem to be a bit shift for 0x48.
What is not clear is how to read the internal device registers? Does
the device only have 2 bytes to read which are always the result of
the last conversion for the last channel requested or can the request
of all the channels be read in one go?

It would be useful if anyone could give some guidance.