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MCP2025-330E/P bảng dữ liệu(PDF) 7 Page - Microchip Technology |
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MCP2025-330E/P bảng dữ liệu(HTML) 7 Page - Microchip Technology |
7 / 38 page 2012-2014 Microchip Technology Inc. DS20002306B-page 7 MCP2025 1.2.7 RESET Reset output pin. This is an open-drain output pin. It indicates the internal voltage has reached a valid, stable level. As long as the internal voltage is valid (above 0.8 VREG), this pin will present high impedance; otherwise, the RESET pin switches to ground. 1.2.8 POSITIVE SUPPLY VOLTAGE REGULATOR OUTPUT (VREG) Positive Supply Voltage Regulator Output pin. An on-chip Low Dropout Regulator (LDO) gives +5.0 or +3.3V at 70 mA regulated voltage on this pin. 1.2.9 EXPOSED THERMAL PAD (EP) There is an internal electrical connection between the Exposed Thermal Pad (EP) and the VSS pin; they must be connected to the same potential on the Printed Circuit Board (PCB). This pad can be connected to a PCB ground plane to provide a larger heat sink. This improves the package thermal resistance ( JA). 1.3 Fail-Safe Features 1.3.1 GENERAL FAIL-SAFE FEATURES • An internal pull-down resistor on the CS/LWAKE pin disables the transmitter if the pin is floating. • An internal pull-up resistor on the TXD pin places TXD in high and the LBUS in recessive if the TXD pin is floating. • High-Impedance and low-leakage current on LBUS during loss of power or ground. • The current limit on LBUS protects the transceiver from being damaged if the pin is shorted to VBB. 1.3.2 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 shutdown 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 The recovery time from the thermal shutdown is equal to adequate cooling time. Driving the TXD and checking the RXD pin make it possible to determine whether there is a bus contention (TXD = high, RXD = low) or a thermal overload condition (TXD =low, RXD = high). FIGURE 1-2: THERMAL SHUTDOWN STATE DIAGRAMS 1.3.3 TXD/LBUS TIME-OUT TIMER The LIN bus can be driven to a dominant level, either from the TXD pin or externally. An internal timer deactivates the LBUS transmitter if a dominant status (low) on the LIN bus lasts longer than Bus Dominant Time-Out Time, tTO(LIN) (approximately 20 milliseconds). At the same time, the RXD output is put in recessive (high) and the internal pull-up resistor between LBUS and VBB is disconnected. The timer is reset on any recessive LBUS status or POR mode. The recessive status on LBUS can be caused either by the bus being externally pulled-up or by the TXD pin being returned high. 1.4 Internal Voltage Regulator The MCP2025 has a positive regulator capable of supplying +5.00 or +3.30 VDC ±3% at up to 70 mA of load current over the entire operating temperature range of -40°C to +125°C. The regulator uses an LDO design, is short-circuit-protected and will turn the regulator output off if its output falls below the shutdown voltage threshold, VSD. With a load current of 70 mA, the minimum input-to-output voltage differential required for the output to remain in regulation is typically +0.5V (+1V maximum over the full operating temperature range). Quiescent current is less than 100 µA with a full 70 mA load current when the input-to-output voltage differential is greater than +3.00V. Regarding the correlation between VBB, VREG and IDD, please refer to Figures 1-4 and 1-5. When the input voltage (VBB) drops below the differential needed to provide stable regulation, the voltage regulator output, VREG, will track the input down to approximately VOFF, at which point the regulator will turn off the output. This will allow PIC® microcontrollers with internal POR circuits to generate a clean arming of the POR trip point. The MCP2025 will then monitor VBB and turn on the regulator when VBB is above the threshold of regulator turn-on voltage, VON. In Power-Down mode, the VBB monitor is turned off. Voltage Regulator Shutdown Operation Mode Transmitter Shutdown Output Overload LIN Bus Shorted to VBB Temp < SHUTDOWNTEMP Temp < SHUTDOWNTEMP |
Số phần tương tự - MCP2025-330E/P |
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Mô tả tương tự - MCP2025-330E/P |
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