VL82C322A Power Management Unit (PMU)

The VL82C322A PMU dramatically reduces overall system power consumption and provides special features for laptop/notebook AT-compatible computers. The power reduction is accomplished via an activity monitor which detects inactivity in the system and slows or stops the CPU clock and/or removes power from peripheral devices.

The PMU has five operational modes, ON, DOZE, SLEEP, SUSPEND, and OFF. By monitoring the system activity, the PMU will switch between the states to achieve power saving without impacting the system performance. The PMU also provides independent timers for LCD backlight and display and an auto power-on feature to turn on the system power via a push-button switch, modem ring indicator, or real-time clock time of day alarm.

The VL82C322A can control power to eight external devices independently in all five operational modes. It can be used to maintain system DRAM during SUSPEND mode by generating CAS-before-RAS refresh cycles or it can enable self-refresh in DRAM which supports this mode. Full system leakage current control is provided in SUSPEND mode. Several general purpose I/O ports have useful secondary features. One can be used to generate programmable tones or blink an LED, and several are capable of directly driving LEDs. Two can be used to add more levels of low battery detection.

Features:

• Provide 3.3V, 5.0V, or mixed voltage operation without external level shifters
• Very low power operation from 32 kHz clock source
• Supports ON, DOZE, SLEEP, SUSPEND, and OFF operational modes
• Activity detectors and timers allow automatic transition between power management states or via interrupt generation under firmware control
• Programmable to generate NMI, IRQx, or SMI for use as power management interrupt
• Programmable to provide CAS-before-RAS or self refresh during suspend mode
• Provides eight general purpose auto-sequencing power control signals plus dedicated LCD power sequencing controls
• Provides 10 general purpose I/O signals