Voltage Regulator Controller (VRC) and POR ModuleMPC5566 Microcontroller Reference Manual, Rev. 223-2 Freescale Semiconductor23.2 External Signal DescriptionTable 23-1 describes the VRC signals.23.3 Memory Map and Register DefinitionThe VRC and POR module have no memory-mapped registers.23.4 Functional DescriptionThe VRC portion of the module contains a voltage regulator controller, and the POR portion containscircuits to monitor the voltage levels of the 1.5 V and VDDSYN power supplies, as well as circuits tomonitor the power supply for the RESET pad. The PORs indicate whether each supply monitored is abovethe specified voltage threshold. The PORs ensure that the device is correctly powered up during apower-on reset. POR holds the device in reset when any of the monitored supplies fall below the specifiedminimum voltage.23.4.1 Voltage Regulator ControllerThe VRC circuit has a control current for use with an external NPN transistor and an external resistor topower the 1.5 V VDD supply. The control current is output on the V RCCTL pin. The voltage regulatorcontroller slowly turns on the pass transistor while the 3.3 V POR is asserted. The pass transistor iscompletely turned on by the time the 3.3 V POR negates.Table 23-1. Voltage Regulator Controller and POR Block External SignalsSignal Type Signal Level DescriptionVRC33 Supply pin 3.3 V Regulator supply input. 3.3 V VRC supply input.VDDSYN Supply pin 3.3 V FMPLL supply input. This is the 3.3 V supply input for the frequencymodulated phase lock loop (FMPLL) module.VDDEH6 Supply pin 3.3–5.0 V RESET pin supply input. Power supply input for padring segment thatcontains the RESET pad.VRCVSS Supply pin 0.0 V Regulator supply ground. VRCVSS is the 3.3 V ground reference for theon-chip 1.5 V regulator control circuit.VRCSNS 1.5 V sense 1.5 V 1.5 V sense used by VRC. Pad connected to V DD plane in package—not apackage ball. This is the 1.5 V sense from the external 1.5 V supply outputof NPN transistor. This input is monitored by the VRC to determine the valuefor VRCCTL. VRCSNS is a pad on the die that is connected to a VDD planeinside the package. It is not a package ball.VRCCTL Current output — Regulator control output. The V RCCTL sources base current to the externalbypass transistor. The VRCCTL signal is used with internal and externaltransistors to provide VDD, which is the MCU 1.5 V power supply.VDD Supply pin 1.5 V Internal 1.5 V power supply input.
