công cụ tìm kiếm bảng dữ liệu linh kiện điện tử |
|
MCP2021T-500E/SL bảng dữ liệu(PDF) 7 Page - Microchip Technology |
|
MCP2021T-500E/SL bảng dữ liệu(HTML) 7 Page - Microchip Technology |
7 / 54 page 2005-2014 Microchip Technology Inc. DS20002018H-page 7 MCP2021/2/1P/2P 1.3.5 TRANSMITTER-OFF MODE Whenever the FAULT/TXE signal is low, or permanent dominant on TXD/LBUS is detected, 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 when the CPU returns 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. If TX-OFF mode is caused by TXD/LBUS permanent dominant level, the transmitter can recover when the permanent dominant status disappears. 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. 1.3.6 REMOTE WAKE-UP The Remote 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 0.4 VBB for a typical duration of at least 20 µs. The MCP2021/2 device is level sensitive to LBUS. Dominant level longer than 20 µs will cause the device to leave the Power-Down mode. The MCP2021P/2P device is falling-edge sensitive to LBUS. Only the LBUS transition from recessive to dominant, followed by at least 20 µs dominant level, can wake up the device. Putting CS/LWAKE to high level also wakes up the device. Refer to Figure 1-2 and Figure 1-3. 1.3.7 DIFFERENCE DETAILS BETWEEN MCP2021/2 AND MCP2021P/2P The MCP202XP is a minor variation of the MCP202X device that adds improved state machine control, as well as the ability to disconnect the internal 30kΩ pull-up between LIN and VBB in all modes except nor- mal operation. These changes allow the system designer to better handle Fault conditions and reduce the overall system current consumption. The differ- ences between the two device versions are as follows: 1. Switchable LIN-VBB Pull-Up Resistor: On the MCP202XP device, the internal 30kΩ pull-up resistor is disconnected in all modes except Operation mode. On the MCP202X device, this pull-up resistor is always connected. (See the MCP2021/2 Block Diagram and the MCP2021P/2P Block Diagram for details.) 2. Power-Down Wake-up on LIN Traffic: The MCP202XP device requires a LIN falling edge to generate a valid Wake condition, due to bus traffic. The MCP202X device will generate a Wake anytime LIN is at a valid dominant level. Because of this, if the LIN bus becomes perma- nently shorted, it becomes impossible to place the MCP202X in a low-power state. 3. State Machine Options: The MCP202XP device is able to enter Transmitter Off mode from Ready mode without transitioning through Operation mode. The MCP202X device must enter Operation mode from Ready mode. (see State Machine Diagrams, Figure 1-2 and Figure 1-3 for details). This capability allows the system designer to monitor the bus in Ready mode to determine if the system should transition to normal operation and connect the internal pull-up, or if Ready mode was reached due to an invalid condition. In the case of an invalid condition, the MCP202XP device can be placed into Power-Down mode without connecting the internal pull-up and waking other nodes on the LIN Bus network. To properly take advantage of the device differences, the system designer is required to implement some microcontroller code to the power-up routine. This code will monitor the status of the LIN bus to determine how to respond to the dominant signal. It will also determine if the local LIN node needs to respond or can ‘Listen Only’. If the local LIN node does not need to respond, it can enter Transmitter Off mode, disconnecting the 30 kΩ pull-up, reducing module current while still maintaining the ability to properly receive all valid LIN messages. Note: To enter Transmitter Off, the system must set TXE ‘low’ before pulling CS high (see Figure 1-5). Otherwise, if CS is pulled high first, the MCP202XP will enter Operation mode due to the internal pull-up on TXE. |
Số phần tương tự - MCP2021T-500E/SL |
|
Mô tả tương tự - MCP2021T-500E/SL |
|
|
Link URL |
Chính sách bảo mật |
ALLDATASHEET.VN |
Cho đến nay ALLDATASHEET có giúp ích cho doanh nghiệp của bạn hay không? [ DONATE ] |
Alldatasheet là | Quảng cáo | Liên lạc với chúng tôi | Chính sách bảo mật | Trao đổi link | Tìm kiếm theo nhà sản xuất All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |