N900 Hardware Chipset

The TWL4030 (to be precise the TWL5030B, see aka TPS65950) has USB PHY, power managment and audio codec.

The USB PHY isn't used and is handled by the nxp1707a See more information on USB

It seems to be documented - not under this part number - at TIs website

A quick check indicates the I2C bus addresses match - see 13.3 in above datasheet.

If this is the correct part, the following description applies:

The TPS65950 contains;
 * Power management
 * Several regulators - switched mode and LDO.
 * Audio codec
 * Five DACs, two ADCs
 * Several power amplifiers.
 * Microphone amplifiers
 * USB tranciever
 * Highspeed OTG compatible with integrated charge pump, and carkit support, designed for direct connection to the SoC.
 * an ac/USB charger
 * LED drivers
 * ADC
 * ADC can measure both input voltages to device, or voltages connected externally.
 * RTC
 * GPIO
 * This can support switches, keypads, ...