求教各位大侠，咨询下。我用ICD2.5仿真或者烧写PIC18F66K80这个芯片的时候，MPLAB里选取Programmer-ICD2，跳出如下信息：
ICDWarn0068:  This device has a VPP(max) below the minimum ICD2 VPP level of 12V.  Please ensure that external protection for MCLR is in place.  (Press the Help button for an example circuit or use AC164112 available from microchipDIRECT.com.)
Connecting to MPLAB ICD 2
...Connected
Setting Vdd source to MPLAB ICD 2
Target Device PIC18F66K80 found, revision = Rev 0x0
...Reading ICD Product ID
Running ICD Self Test
...Passed
MPLAB ICD 2 ready for next operation

我看到有警告信息ICDWarn0068，意思好像说是18F66K80这个芯片烧写仿真时候VPP的电压要低于12V才可以。然后我查看了HELP信息，写道：

ICDWarn0068: This device has a Vpp(max) below the minimum ICD 2 Vpp level of 12V. Please ensure that external protection for MCLR is in place. (Press the Help button for an example circuit.)

The MPLAB ICD 2 Vpp voltage generator is capable of driving from 12V to 14 V. The currently selected device has a Vpp (max) rating less than 12V. Protection circuitry is needed to step down the 12V Vpp generated by the MPLAB ICD2 to a level acceptable by the current device. For example:


但是我的ICD2.5输出电压是13V的，好像标准要求就是13V的。各位大侠，我该怎么弄下？？？万分感谢！！