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MCP2022 bảng dữ liệu(PDF) 4 Page - Microchip Technology |
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MCP2022 bảng dữ liệu(HTML) 4 Page - Microchip Technology |
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4 / 46 page  MCP2021/2 DS22018E-page 4 © 2009 Microchip Technology Inc. 1.3 Modes of Operation For an overview of all operational modes, please refer to Table 1-1. 1.3.1 POWER-ON-RESET MODE Upon application of VBB, the device enters Power-On- Reset mode (POR). During this mode, the part maintains the digital section in a reset mode and waits until the voltage on pin VBB rises above the “ON” threshold (Typ. 5.75V) to enter to the Ready mode. If during the operation, the voltage on pin VBB falls below the “OFF” threshold (Typ. 4.25V), the part comes back to the Power-On-Reset mode. 1.3.2 POWER-DOWN MODE In the Power-down mode, the transmitter and the voltage regulator are both off. Only the receiver section, and the CS/LWAKE pin wake-up circuits are in operation. This is the lowest power mode. If any bus activity (e.g. a BREAK character) or CS/ LWAKE going to a high level should occur during Power-down mode, the device will immediately enter the Ready mode, enable the voltage regulator, and once the output has stabilized (approximately 0.3 ms to 1.2 ms), go to the Operation mode. The part will also enter the Ready mode, followed by the Operation mode, if the CS/LWAKE pin should become active true (‘1’). The part may only enter the Power-down mode after going through an Operation mode step. 1.3.3 READY MODE Upon entering the Ready mode, the voltage regulator and receiver threshold detect circuit are powered up. The transmitter remains in power down mode. The device is ready to receive data but not to transmit. If a microcontroller is being driven by the voltage regulator output, it will go through a Power-on Reset and initial- ization sequence. The LIN pin is in the recessive state. The device will stay in the Ready mode until the output of the voltage regulator has stabilized and CS/LWAKE pin is true (‘1’). After VREG is OK and CS/LWAKE pin is true, the transmitter is enabled and the part enters the Operation mode. On Power-on of the VBB supply pin, the component will stay in the Ready mode if CS/LWAKE is low. If CS/ LWAKE is high, the device will immediately enter the Operation mode. 1.3.4 OPERATION MODE In this mode, all internal modules are operational. The MCP2021/2 will go into the Power-down mode on the falling edge of CS/LWAKE. 1.3.5 TRANSMITTER OFF MODE Whenever the FAULT/TXE signal is low and the LBUS transmitter is off. The transmitter may be re-enabled whenever the FAULT/TXE signal returns high, either by removing the internal fault condition or the CPU returning the FAULT/ TXE high. The transmitter will not be enabled if the FAULT/TXE pin is brought high when the internal fault is still present. The transmitter is also turned off whenever the voltage regulator is unstable or recovering from a fault. This prevents unwanted disruption of the bus during times of uncertain operation. 1.3.5.1 Wake-up The Wake-up sub module observes the LBUS in order to detect bus activity. Bus activity is detected when the voltage on the LBUS stays below a threshold of approximately 3V for at least a typical duration of 10 µs. Such a condition causes the device to leave the Power- down mode. FIGURE 1-2: OPERATIONAL MODES STATE DIAGRAMS Note: The above time interval < 1.2 ms assumes 12V VBB input and no thermal shutdown event. Note: While the MCP2021/2 is in shutdown, TXD should not be actively driven high or it may power internal logic through the ESD diodes and may damage the device. Operation Mode Power-down Mode Ready Mode Bus Activity VREGOK = true POR CS/LWAKE VBBOK = true Start Transmitter Mode Off FAULT/TXE = true = false FAULT/TXE = false CS/LWAKE = false OR CS/LWAKE = true AND CS/LWAKE = true |
Số phần tương tự - MCP2022 |
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Mô tả tương tự - MCP2022 |
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