ETN33 Engineering Technical Note Modification for MCLV (DM330021) and MCSM (DM330022) boards Problem: Some of the dsPIC and PIC24 devices do not function on the MCLV and MCSM boards. Symptoms: This problem is relevant only to the MCLV boards which have a 220µf capacitor at C12 (marked on the top of the capacitor as “220”) and the MCSM boards which have a 100µf capacitor at C20 (marked on the top of the capacitor as “100”). When the board is powered up, the dsPIC / PIC24 device (U9/U12 on MCLV board; U2/U3 on MCSM board) locks up and does not begin executing code. Also, when a programming / debugging tool is connected to the development board, the MPLAB IDE will show a device mismatch dialog box - “Target Device ID (00000000) does not match expected Device ID (xxxxxxxx)”. Once the dsPIC / PIC24 device enters this state, it is not possible to program, debug or use the device. If left in this „locked‟ state for an extended period of time, the device could potentially get damaged. Cause: Value of the filtering capacitor (C12 on MCLV board and C20 on MCSM board) connected to the AVdd pin is higher-than-required. At power-up, this is causing the voltage on AVDD pin to ramp up at a slower rate than the voltage on VDD pin. This slow voltage ramp rate at power-up can cause the voltage difference between VDD and AVDD pin to exceed 300mV, thus causing the on-chip voltage regulator to malfunction. Solution: This ETN provides instructions to modify the MCLV and MCSM boards. Materials Required: 1. 33uf, 50V Radial Can-SMD electrolytic capacitor. Steps: For MCLV board: 1. De-solder the capacitor C12 (220µf). Capacitor C12 2. Solder a 33µf capacitor at C12. Verify the polarity of the capacitor. Microchip Technology, Inc. 06/30/2011 Page 1 of 2 ETN33 Engineering Technical Note For MCSM board: 1. De-solder the capacitor C20 (100µf). Capacitor C20 2. Solder a 33µf capacitor at C20. Verify the polarity of the capacitor. Important Note: Please exercise caution while re-working the MCLV and MCSM boards. The solder pads underneath the capacitor (C12 / C20) can get damaged if the soldering / de-soldering process is not performed carefully. Microchip Technology, Inc. 06/30/2011 Page 2 of 2