ETN #28 Engineering Technical Note PIC16C5x 28P DIP/28P SOIC MPLAB® PM3 socket modules AC164301/AC164302 modification for current limit Vpp/MCLR during programming Problem: There are some cases in which PIC16C5x devices fail to program due to excessive current sink at the Vpp/MCLR pin. To stay within spec and limit the current to 100mA max at the Vpp/MCLR pin during programming, you can modify the AC164301(28P DIP)/AC164302(28P SOIC) MPLAB PM3 socket module. Symptoms: During the programming operation, the MPLAB PM3 screen will turn off and a power-cycle will be required to power up the programmer again. Cause: PIC16C5x devices require 100mA limit current during programming at the Vpp/MCLR pin. Solution: This ETN will provide instructions to modify the 28P DIP socket module AC164301 and 28 SOIC AC164302 to support PIC16C5x devices that exhibit these symptoms. IMPORTANT NOTE: Once AC164301/AC164302 are modified, the socket modules must not be used to program any other devices outside the PIC16C5x family indicated in the programming spec. Materials: 1. 150ohm 0805 SMT resistor 2. 390pF thru-hole capacitor 3. 40-DIP socket module AC164301 or the AC164302, MPLAB PM3 socket module 28P SOIC. 4. Soldering tools. 5. SuperGlue 6. Wire and wire-wrap tool. Steps for modifying the AC164301 40P DIP module: To start, here is a pinout for both 28P DIP and 28P SOIC as a reference: The goal is to isolate and bypass the connection to the socket pin using a 150 ohm resistor and to add a cap to the Vss pin of the DUT (DIP socket pin 4). 1. 2. Remove the top cover from the socket module. To isolate the device pin, cut the socket module at the bottom as indicated Microchip Technology, Inc. 10/30/2015 Page 1 of 4 ETN #28 Engineering Technical Note 3. Glue a 150ohm 0805 resistor as indicated in the picture below. 4. Solder one end of the wire to PIN40 at the P2 connector as indicated in the picture, and solder the other end to the glued resistor. Solder the wire to the other end of the resistor and pass the wire to Socket Pin 40 as indicated in the pictures below (note the cuts as well). 5. 6. Place the plastic back carefully and with the tip of a soldering iron, heat up the corners to secure the socket module plastic cover against the board. Microchip Technology, Inc. 10/30/2015 Page 2 of 4 ETN #28 Engineering Technical Note 7. Solder the 390pF capacitor to the Vpp pin (socket pin 40) and the other end to the Vss pin (socket pin 4) as shown in the picture below. Steps for modifying the AC164302 28P SOIC module: The goal is to isolate the connection to the MCLR (socket pin 28) and bypass this connection with a 150 ohm resistor; then add a 390pf cap between the MCLR pin and the Vss pin (socket pin 4). 1. Remove the top cover from the socket module. 2. To isolate socket pin 28, cut the trace as indicated in the drawing below. Microchip Technology, Inc. 10/30/2015 Page 3 of 4 ETN #28 Engineering Technical Note 3. Now, solder one end of the 150ohm 0805 resistor at socket pin 28. 4. Solder the other end of the wire to the P2 connector pin, as indicated in the picture, and solder the other end to the resistor. 5. Place the plastic back carefully and with the tip of a soldering iron, heat up the corners to secure the socket module plastic cover against the board. Solder the 390pF capacitor to the Vpp pin (socket pin 28) and the other end to the Vss pin (socket pin 4) as shown in the picture below the No. 3 step. 6. Microchip Technology, Inc. 10/30/2015 Page 4 of 4