NXP Semiconductors freescale K51 Series Reference Manual

Table 53-37. LCD power supply configuration options (continued)VSUPPLY[1:0] Configuration powersw1 powersw211 Drive VLL3 externally from VDDorDrive VLL1 internally from VIREG0 0NoteThe charge pump is optimized for 1/3 bias mode operationonly.The charge pump requires external capacitance for itsoperation. To provide this external capacitance, the Vcap1 andVcap2 external pins are provided. It is recommended that aceramic capacitor be used. Proper orientation is imperativewhen using a polarized capacitor. The recommended value forthe external capacitor is 0.1 μF.53.4.4.1 LCD power supply configurationThe LCD bias voltages can be internally derived from VDD, internally derived from avoltage source (should never be externally driven to any level other than VDD) connectedto VLL3, internally derived from a regulated voltage source that can be configured tosupply 1.0 or 1.67 V (VIREG). The following table provides a more detailed description ofthe power state of the LCD controller that depends on the configuration of theVSUPPLY[1:0], CPSEL and RVEN bits. The table shows all possible configurations ofthe LCD power supply. All other combinations of the configuration bits above are notpermissible LCD power supply modes and should be avoided.Table 53-38. LCD power supply optionsLCD operational state LCD power supply configurationVSUPPLY[1:0]HREFSELCPSELRVENVLL2 connected to VDDinternally for 3 V or 5 Vglass operation.For 3 V glass operation, VDD must beequal to 2 V.For 5 V glass operation, VDD must beequal to 3.33 V.Charge pump is used to generate VLL1and VLL3.00 X 1 0Table continues on the next page...Functional descriptionK51 Sub-Family Reference Manual, Rev. 6, Nov 20111564 Freescale Semiconductor, Inc.