Thanks for the infirmation.

It seems that the pins are NOT 5 Volt tolerant and I either:

1. Use the bi-directional level converting circuit given in the Philips application note, or
2. Run the MCU at 3 Volts.

Thanks for the idea of using the HPWM signal for the A/D clock.

The HP03 chip (mounted on a carrier with 0.1 inch pins) is available from Ocean Controls here in Australia for about $AUS 25 ($US 20): http://www.oceancontrols.com.au

Thanks Bill Legge