Migrating Designs from MCP201 to MCP2021-500 Author: Chuck Simmers Microchip Technology Inc. DEVICE MIGRATIONS The original MCP201 LIN (Local Interconnect Network) transceiver was designed to comply with LIN 1.2 and 1.3 physical layer specifications The MCP2021-500 is designed to be pin- and functionally-compatible with the earlier MCP201, and to meet the latest LIN 2.0 and 2.1 specifications. For most applications, the MCP2021-500 can be dropped in place of a MCP201 in an existing design without printed circuit board or firmware modifications. Note: The MCP2021/2/3/4 family of devices support both LIN and K-line (ISO-9141) buses, 5.0V and 3.3V system voltages, and a new RESET output. The MCP2021500 is the drop-in replacement for the MCP201. down function. If the TXE function is not required, this pin may be left floating. Refer to Section 1.3.5 or the “MCP202x LIN Transceiver” data sheet, DS22018, for more information on the TXE function. The FAULT output definition is the same. Bus contention detect has been debounced. Voltage Regulator There is no longer a need for input filter capacitor to be 8-10 times larger than output load capacitor In fact they can both be 1.0 µF and the regulator will be stable over the whole temperature range if the output capacitor has a couple ohms of ESR. Quiescent current of the regulator is, typically, 20% that of the MCP201 With transmitter off, this drops an additional 10 µA. Output voltage is 4.85V to 5.15V from 6.5V to 18V over full load range and temperature range. Time to VREG ready after POR is less than 400 µs instead of 2.5 ms. Thermal shutdown temperature is 165°C. The following are some considerations to be made when evaluating the upgrade to MCP2021-500. All of the turn on points and turn off points are the same. VREG turns on between 5.5V and 6V on VBAT and shuts down when VBAT is 4V. HARDWARE DIFFERENCES SOFTWARE DIFFERENCES The only difference exists on two pins of the MCP2021500. The internal state-machine of the MCP2021-500 has been simplified. The device will enter the ‘Operational’ as soon as the VREG output has stabilsed and CS/ LWAKE and FAULT/TXE are both high (‘1’). No low-tohigh edge is necessary. CS/LWAKE The CS/LWAKE input is now level sensitive rather than edge-triggered. A low-to-high transition is no longer necessary to enter the ‘Operational’ mode on powerup, or to toggle CS/LWAKE to clear a fault condition. Any existing firmware that implements toggling will work in a MCP2021-500 without modification. FAULT/TXE On the MCP201, this pin was designated FAULT/ SLPS. During power-on this pin was sampled to select between fast and slow voltage slope rate control. This function is not required in the MCP2021-500 due to its time-based slew-rate waveshaping. The Transmit Enable (TXE) function has taken its place. REFERENCES MCP201 Data Sheet, “LIN Transceiver with Voltage Regulator”, DS21730 MCP202X Data Sheet, “LIN Transceiver with Voltage Regulator”, DS22018 Note: For additional information, please contact your Microchip Automotive Products Representative. Existing designs that utilized this function with a external pull-up or pull-down resistor, need to remove the resistor. The pin should be routed to a microcontroller port pin to take advantage of the new TXE power- © 2007 Microchip Technology Inc. DS01075A-page 1 NOTES: DS01075A-page 2 © 2007 Microchip Technology Inc. Note the following details of the code protection feature on Microchip devices: • Microchip products meet the specification contained in their particular Microchip Data Sheet. • Microchip believes that its family of products is one of the most secure families of its kind on the market today, when used in the intended manner and under normal conditions. • There are dishonest and possibly illegal methods used to breach the code protection feature. All of these methods, to our knowledge, require using the Microchip products in a manner outside the operating specifications contained in Microchip’s Data Sheets. Most likely, the person doing so is engaged in theft of intellectual property. • Microchip is willing to work with the customer who is concerned about the integrity of their code. • Neither Microchip nor any other semiconductor manufacturer can guarantee the security of their code. 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Analog-for-the-Digital Age, Application Maestro, CodeGuard, dsPICDEM, dsPICDEM.net, dsPICworks, ECAN, ECONOMONITOR, FanSense, FlexROM, fuzzyLAB, In-Circuit Serial Programming, ICSP, ICEPIC, Mindi, MiWi, MPASM, MPLAB Certified logo, MPLIB, MPLINK, PICkit, PICDEM, PICDEM.net, PICLAB, PICtail, PowerCal, PowerInfo, PowerMate, PowerTool, REAL ICE, rfLAB, rfPICDEM, Select Mode, Smart Serial, SmartTel, Total Endurance, UNI/O, WiperLock and ZENA are trademarks of Microchip Technology Incorporated in the U.S.A. and other countries. SQTP is a service mark of Microchip Technology Incorporated in the U.S.A. All other trademarks mentioned herein are property of their respective companies. © 2007, Microchip Technology Incorporated, Printed in the U.S.A., All Rights Reserved. Printed on recycled paper. Microchip received ISO/TS-16949:2002 certification for its worldwide headquarters, design and wafer fabrication facilities in Chandler and Tempe, Arizona, Gresham, Oregon and Mountain View, California. The Company’s quality system processes and procedures are for its PIC® MCUs and dsPIC® DSCs, KEELOQ® code hopping devices, Serial EEPROMs, microperipherals, nonvolatile memory and analog products. In addition, Microchip’s quality system for the design and manufacture of development systems is ISO 9001:2000 certified. © 2007 Microchip Technology Inc. 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