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MCP2022T Datasheet(PDF) 3 Page - Microchip Technology |
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MCP2022T Datasheet(HTML) 3 Page - Microchip Technology |
3 / 46 page © 2009 Microchip Technology Inc. DS22018E-page 3 MCP2021/2 1.0 DEVICE OVERVIEW The MCP2021/2 provides a physical interface between a microcontroller and a LIN half-duplex bus. It is intended for automotive and industrial applications with serial bus speeds up to 20 Kbaud. The MCP2021/2 provides a half-duplex, bidirectional communications interface between a microcontroller and the serial network bus. This device will translate the CMOS/TTL logic levels to LIN level logic, and vice versa. The LIN specification 2.0 requires that the transceiver of all nodes in the system be connected via the LIN pin, referenced to ground and with a maximum external termination resistance of 510 Ω from LIN bus to battery supply. The 510 Ω corresponds to 1 Master and 16 Slave nodes. The MCP2021-500 provides a +5V 50 mA regulated power output. The regulator uses a LDO design, is short-circuit-protected and will turn the regulator output off if it falls below 3.5V. The MCP2021/2 also includes thermal shutdown protection. The regulator has been specifically designed to operate in the automotive environment and will survive reverse battery connec- tions, +43V load dump transients and double-battery jumps. The other members of the MCP2021-330 family output +3.3V at 50 mA with a turn-off voltage of 2.5V. (see Section 1.6 “Internal Voltage Regulator”). 1.1 Optional External Protection 1.1.1 REVERSE BATTERY PROTECTION An external reverse-battery-blocking diode should be used to provide polarity protection (see Example 1-1). 1.1.2 TRANSIENT VOLTAGE PROTECTION (LOAD DUMP) An external 43V transient suppressor (TVS) diode, between VBB and ground, with a 50 Ω transient protection resistor (RTP) in series with the battery supply and the VBB pin serve to protect the device from power transients (see Example 1-1) and ESD events. While this protection is optional, it should be considered as good engineering practice. EQUATION 1-1: 1.2 Internal Protection 1.2.1 ESD PROTECTION For component-level ESD ratings, please refer to the maximum operation specifications. 1.2.2 GROUND LOSS PROTECTION The LIN Bus specification states that the LIN pin must transition to the recessive state when ground is disconnected. Therefore, a loss of ground effectively forces the LIN line to a hi-impedance level. 1.2.3 THERMAL PROTECTION The thermal protection circuit monitors the die temperature and is able to shut down the LIN transmitter and voltage regulator. There are three causes for a thermal overload. A thermal shut down can be triggered by any one, or a combination of, the following thermal overload conditions. • Voltage regulator overload • LIN bus output overload • Increase in die temperature due to increase in environment temperature Driving the TXD and checking the RXD pin makes it possible to determine whether there is a bus contention (Rx = low, Tx = high) or a thermal overload condition (Rx = high, Tx = low). FIGURE 1-1: THERMAL SHUTDOWN STATE DIAGRAMS RTP <= (VBBmin - 5.5) / 250 mA. 5.5V = VUVLO + 1.0V, 250 mA is the peak current at power-on when VBB = 5.5V Operation Mode Transmitter Shutdown LIN bus Voltage Shutdown Regulator Output Temp < SHUTDOWNTEMP shorted to VBB Overload Temp < SHUTDOWN TEMP |
Similar Part No. - MCP2022T |
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Similar Description - MCP2022T |
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