12/16/96 This directory contains a PCB pattern and component placement diagram for a dual H-bridge "expansion" board originally intended for the MIT Handy Board. The board is based on the LMD18200 from National Semiconductor. The motor battery can be from 12V to 55V. The H-bridge can supply a constant current of 3 amps and a peak current of 6 amps. The file PCB18200.PDF is the actual PCB pattern. There are two images provided, one is the mirror image of the other. One is for people who use iron-on transfers and the other is for those who use photo sensitive board. For iron-on use the pattern with writing reversed. The file PLACEMNT.PDF is the placement diagram. The file 18200.TXT is this file. Component List U1, U2- LMD18200 TO-220 case D1,D3- Green LED T1 case D2,D4- Red LED T1 case R1,R2, R3,R4- 560 ohm 1/4W R5,R6- 2.2k 1/4W C1,C2, C3,C4- 0.01uF Header 2x5 male Screw Terminals 0.2 inch centers Assembly Instruction There is nothing really difficult involved. The 18200's should go in last, R5 goes under U1. The capacitors are optional, but are recommended. They help the H-bridges handle higher frequency PWM rates. The LED's are the user's choice. They only indicate direction of motion. They can be any color you want, but anything bigger than a T1 case may be a tight fit. The values for R1 through R4 may need to be changed if you use a battery greater than 12V. They only limit the current to the LEDs so adjust accordingly for bigger batteries. The screw terminals are stackable two terminal blocks with 0.2 inch centers. They are available at Radio Shack, four 2 terminal blocks for $3 or something close. The battery polarity is indicated on the solder side of the board. J1 should be installed after C3 and U2. It needs to be routed around them. Some insulated hook-up wire is fine. A heat sink is a must. There is enough room for a 1/8 inch thick heat sink behind the 18200's and two marks for mounting holes. I used a piece of aluminum and some home made angle brackets. The tabs on the 18200's are connected to _GROUND_. If the heat sink is not _GROUND_ an insulator must be used. The header is a 10 pin, 2x5 male header for connection with an IDC ribbon cable connector. 10 pin header pin-out 10 9 8 7 6 0 0 0 0 0 [] 0 0 0 0 1 2 3 4 5 square pad is pin 1 pin 1 - direction motor 1 pin 2 - brake motor 1 pin 3 - thermal flag motor 2 pin 4 - current sense motor 2 pin 5 - PWM motor 2 pin 6 - direction motor 2 pin 7 - brake motor 2 pin 8 - thermal flag motor 1 pin 9 - current sense motor 1 pin 10 - PWM motor 1 Using with the Handy Board The motor control routines in IC are completely compatible with the 18200's. The enable lines for the HB motor chips go to the PWM line on the 18200's. The direction lines from the HB go to the direction line on the 18200's. HB pin 1 to PWM motor 1 HB pin 2 to direction motor 1 HB pin 9 to PWM motor 2 HB pin 10 to direction motor 2 The brake lines must be grounded for the motors to work. You can either use a digital out for this or directly connect the brakes to ground. The current sense lines provide a provide a 0-5V signal based on current through the motor. 5V equals 6A through the motor. The 18200 puts out 377 micro amps per amp sent to the motor (0.000377 A/A). R5 and R6 control the scaling of this signal. With the 2.2k resistors indicated, the scaling is about 830mV/A. The thermal flag is an open collector output to signal over heating. The flag will be set before internal protection shuts down the 18200. Make sure the supply ground for the 18200's is connected to the HB ground. You'll get some very strange results if you don't. Use the motor supply header on the HB for this connection. You can take advantage of the noise filtering of the HB that way. The tech docs. on the 18200 are available on the National Semiconductor web site. Questions and comments are welcome. This document and any art work can be reproduced freely. Any fees charged for PCB production using my art work are limited to compensation for materials used, and any postage used for distribution. This information is freeware and intended for use by hobbyists. It is not to be used for profit. If you plan to distribute this information, just let me know you're actually interested in my stuff. Happy 'botting Matt Harlan Cornell University Electrical Engineering mjh10@cornell.edu