MCP2551-I/P データシートの表示（PDF） - Microchip Technology

部品番号

コンポーネント説明

メーカー

MCP2551-I/P

High-Speed CAN Transceiver

Microchip Technology 

1.5 TXD Permanent Dominant

Detection

If the MCP2551 detects an extended Low state on the

TXD input, it will disable the CANH and CANL output

drivers in order to prevent the corruption of data on the

CAN bus. The drivers are disabled if TXD is Low for

more than 1.25 ms (minimum). This implies a

maximum bit time of 62.5 µs (16 kb/s bus rate),

allowing up to 20 consecutive transmitted Dominant

bits during a multiple bit error and error frame scenario.

The drivers remain disabled as long as TXD remains

Low. A rising edge on TXD will reset the timer logic and

enable the CANH and CANL output drivers.

1.6 Power-on Reset

When the device is powered on, CANH and CANL

remain in a high-impedance state until VDD reaches the

voltage-level VPORH. In addition, CANH and CANL will

remain in a high-impedance state if TXD is Low when

VDD reaches VPORH. CANH and CANL will become

active only after TXD is asserted High. Once powered

on, CANH and CANL will enter a high-impedance state

if the voltage level at VDD falls below VPORL, providing

voltage brown-out protection during normal operation.

1.7 Pin Descriptions

The 8-pin pinout is listed in Table 1-3.

TABLE 1-3: MCP2551 PINOUT

Pin

Pin

Number Name

Pin Function

1

TXD Transmit Data Input

2

VSS Ground

3

VDD Supply Voltage

4

RXD Receive Data Output

5

VREF Reference Output Voltage

6

CANL CAN Low-Level Voltage I/O

7

CANH CAN High-Level Voltage I/O

8

RS Slope-Control Input

MCP2551

1.7.1 TRANSMITTER DATA INPUT (TXD)

TXD is a TTL-compatible input pin. The data on this pin

is driven out on the CANH and CANL differential output

pins. It is usually connected to the transmitter data

output of the CAN controller device. When TXD is Low,

CANH and CANL are in the Dominant state. When TXD

is High, CANH and CANL are in the Recessive state,

provided that another CAN node is not driving the CAN

bus with a Dominant state. TXD has an internal pull-up

resistor (nominal 25 kΩ to VDD).

1.7.2 GROUND SUPPLY (VSS)

Ground supply pin.

1.7.3

SUPPLY VOLTAGE (VDD)

Positive supply voltage pin.

1.7.4 RECEIVER DATA OUTPUT (RXD)

RXD is a CMOS-compatible output that drives High or

Low depending on the differential signals on the CANH

and CANL pins and is usually connected to the receiver

data input of the CAN controller device. RXD is High

when the CAN bus is Recessive and Low in the

Dominant state.

1.7.5 REFERENCE VOLTAGE (VREF)

Reference Voltage Output (defined as VDD/2).

1.7.6 CAN LOW (CANL)

The CANL output drives the Low side of the CAN

differential bus. This pin is also tied internally to the

receive input comparator.

1.7.7 CAN HIGH (CANH)

The CANH output drives the high-side of the CAN

differential bus. This pin is also tied internally to the

receive input comparator.

1.7.8 SLOPE RESISTOR INPUT (RS)

The RS pin is used to select High-Speed, Slope-Control

or Standby modes via an external biasing resistor.

© 2010 Microchip Technology Inc.

DS21667F-page 5

Share Link: