công cụ tìm kiếm bảng dữ liệu linh kiện điện tử |
|
MC33390DDR2 bảng dữ liệu(PDF) 11 Page - Freescale Semiconductor, Inc |
|
MC33390DDR2 bảng dữ liệu(HTML) 11 Page - Freescale Semiconductor, Inc |
11 / 15 page Analog Integrated Circuit Device Data Freescale Semiconductor 11 33390 TYPICAL APPLICATIONS TYPICAL APPLICATIONS Class B Module Inputs Transmitter Data from the MCU (Tx) The Tx input is a push-pull (N-channel/P-channel FETs) buffer with hysteresis for noise immunity purposes. This pin is a 5.0 V CMOS logic level input from the MCU following a true logic protocol. A logic [0] input drives the BUS output to 0 V (via the external pull-down resistor to ground on each node), while a logic [1] input produces a high voltage at the BUS output. A logic [0] input level is guaranteed when the Tx input pin is open-circuited by virtue of an internal 40 k Ω pull- down resistor. No external resistor is required for its operation. Waveshaping and 4X/Loop This input is a tristateable input: 0 V = normal waveshaping, 5.0 V = waveshaping is disabled for 4X transmitting, and high impedance = loopback mode of operation. This is a logic level input used to select whether waveshaping for the Class B output is enabled or disabled. A logic [0] enables waveshaping, while a logic [1] disables waveshaping. In the 4X mode, the BUS output rise time is less than 2.0 µs and the fall time is less than 5.0 µs (owing to the external RC pull-down to ground). In the loopback condition, the Tx signal is fed back to the Rx output after waveshaping without being transmitted onto the BUS. This mode of operation is useful for system diagnostic purposes. Class B Module Outputs Transceiver Output (BUS) This is the output driver stage that sources current to the bus. Its output follows the waveshaped waveform input. Its output voltage is limited to 6.25 V to 8.0 V under normal battery level conditions. The limited level is controlled by an internal regulator/clamp circuit. Once the battery voltage drops below 9.0 V, the regulator/clamp circuit saturates, causing the bus voltage to track the battery voltage. A 1.5 k Ω ±5% external resistor (as well as any 10.6 k Ω pull-down resistors of any secondary nodes) sinks the current to discharge the capacitors during high-to-low transitions. This sourcing output is short circuit-protected (60 mA to 170 mA) against a short to -2.0 V and sinks less than 1.0 mA when shorted to VBAT. If a short occurs, the overtemperature shutdown circuit protects the source driver of the device. In the event battery power is lost to the assembly, the bus transmitter's output stage will be disabled and the leakage current from the BUS output will not source or sink more than 100 µA of current. The transceiver will operate with a remote ground offset of ±2.0 V, but the lower corners of transmission will not be rounded during this condition. Receiver Output to the Microcontroller (Rx) This is a 5.0 V CMOS compatible push-pull output used to send received data to the microcontroller. It does not require an external pull-up resistor to be used. The receiver is always enabled and draws less than 65 µA of current from VBAT. The receive threshold is dependent on the state of the SLEEP pin. The receiver circuitry is able to operate with VBAT voltages as low as 4.25 V and still remains capable of “waking up” the 33390 when remote Class B activity is detected. When the SLEEP pin is 0 V and message activity occurs on the bus, the receiver passes the bus message through to the microcontroller. The 33390 does not automatically “wake up” from a sleep state when bus activity occurs: the microcontroller must tell it to do so. In the Static Electrical Characteristics table, the maximum voltage for Rx is specified as 4.75 V over an operating range of -40 °C to 125°C temperature and 7.0 V to 16 V V BAT. This maximum Rx voltage is compatible with the minimum VDD voltage of microcontrollers to prevent the 33390 from sourcing current to the microcontroller's output. Switched Ground Output (LOAD) Normally this output is a saturated switch to ground, which pulls down the external resistor between the BUS and LOAD outputs. In the event ground is lost to the assembly, the LOAD output will bias itself “off” and will not leak more than 100 µA of current out of this pin. Overtemperature Shutdown If the BUS output becomes shorted to ground for any duration, an overtemperature shutdown circuit “latches off” the output source transistor whenever the die temperature exceeds 150 °C to 190°C. The output transistor remains latched off until the Tx input is toggled from a logic [0] to a logic [1]. The rising edge provides the clearing function, provided the locally sensed temperature is 10 °C to 15°C below the latch-off temperature trip temperature. Waveshaping Waveshaping is incorporated into the 33390 to minimize radiated EMI emissions. Receiver Protocol The Class B communication scheme uses a variable pulse width (VPW) protocol. The microcontroller provides the VPW decoding function. Once the receiver detects a transition on Rx, it starts an internal counter. The initial “start of frame” bit is a logic [1] and lasts 200 µs. For subsequent bits, if there is a bus transition before 96 µs, one logic state is inferred. If there is a bus transition after 96 µs, the other logic state is inferred. The “end of data” bit is a logic [0] and lasts 200 µs. If there is no activity on the bus for 280 µs to 320 µs following a broadcast message, multiple unit nodes may arbitrate for control of the next message. During an arbitration, after the |
Số phần tương tự - MC33390DDR2 |
|
Mô tả tương tự - MC33390DDR2 |
|
|
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 |