Recommended alternative: UCD9090A is the recommended alternative to the UCD9090 device.
The most current UCD90xxx PMBus™ Command Reference is available at http://www.ti.com/fusiondocs
The UCD9090 is a 10-rail PMBus/I2C addressable power-supply sequencer and monitor. The device integrates a 12-bit ADC for monitoring up to 10 power-supply voltage inputs. Twenty-three GPIO pins can be used for power supply enables, power-on reset signals, external interrupts, cascading, or other system functions. Ten of these pins offer PWM functionality. Using these pins, the UCD9090 offers support for margining, and general-purpose PWM functions.
Specific power states can be achieved using the pin-selected rail states feature. This feature allows with the use of up to 3 GPIs to enable and disable any rail. This is useful for implementing system low-power modes and the Advanced Configuration and Power Interface (ACPI) specification that is used for hardware devices.
The TI Fusion Digital Power™ designer software provides device configuration. This PC-based user interface (UI) offers an intuitive interface for configuring, storing, and monitoring all system operating parameters.