MCP2561 datasheet(4/30 Pages) MICROCHIP

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MCP2561/2

DS25167B-page 4

 2013 Microchip Technology Inc.

1.5

Permanent Dominant Detection

The MCP2561/2 device prevents two conditions:

• Permanent dominant condition on TXD

• Permanent dominant condition on the bus

In Normal mode, if the MCP2561/2 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 will

remain disabled until TXD goes High.

In Standby mode, if the MCP2561/2 detects an

extended dominant condition on the bus, it will set the

RXD pin to Recessive state. This allows the attached

controller to go to Low-Power mode until the dominant

issue is corrected. RXD is latched High until a

Recessive state is detected on the bus, and the

wake-up function is enabled again.

Both conditions have a time-out of 1.25 ms (typical).

This

implies

a maximum

bit

time of 69.44 µs

(14.4 kHz), allowing up to 18 consecutive dominant bits

on the bus.

1.6

Power-On Reset (POR) and

Undervoltage Detection

The MCP2561/2 has undervoltage detection on both

supply pins: VDD and VIO. Typical undervoltage thresh-

olds are 1.2V for VIO and 4V for VDD.

When the device is powered on, CANH and CANL

remain in a high-impedance state until both VDD and

VIO exceed their undervoltage levels. In addition,

CANH and CANL will remain in a high-impedance state

if TXD is Low when both undervoltage thresholds are

reached. 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 volt-

age level at VDD or VIO drop below the undervoltage

levels, providing voltage brown-out protection during

normal operation.

In Normal mode, the receiver output is forced to

Recessive state during an undervoltage condition. In

Standby mode, the low-power receiver is only enabled

when both VDD and VIO supply voltages rise above

their respective undervoltage thresholds. Once these

threshold voltages are reached, the low-power receiver

is no longer controlled by the POR comparator and

remains operational down to about 2.5V on the VDD

supply (MCP2561/2). The MCP2562 transfers data to

the RXD pin down to 1V on the VIO supply.

1.7

Pin Descriptions

Table 1-2 describes the pinout.

TABLE 1-2:

MCP2561/2 PINOUT

MCP2561

3x3 DFN

MCP2561

PDIP, SOIC

MCP2562

3x3 DFN

MCP2562

PDIP, SOIC

Symbol

Pin Function

TXD

Transmit Data Input

VSS

Ground

VDD

Supply Voltage

RXD

Receive Data Output

—

SPLIT

Common Mode Stabilization - MCP2561 only

——

VIO

Digital I/O Supply Pin - MCP2562 only

CANL

CAN Low-Level Voltage I/O

CANH

CAN High-Level Voltage I/O

STBY

Standby Mode Input

—

Exposed Thermal Pad

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