MCP2025-500ESLASHP datasheet(6/38 Pages) MICROCHIP

6 / 38 page

MCP2025

DS20002306B-page 6

 2012-2014 Microchip Technology Inc.

1.2

Pin Descriptions

The descriptions of the pins are listed in Table 1-2.

1.2.1

BATTERY POSITIVE SUPPLY

VOLTAGE (VBB)

Battery Positive Supply Voltage pin. An external diode

is connected in series to prevent the device from being

reversely powered (refer to Figure 1-7).

1.2.2

CHIP SELECT AND LOCAL

WAKE-UP INPUT (CS/LWAKE)

Chip Select and Local Wake-Up Input pin (TTL level,

high-voltage tolerant). This pin controls the device state

transition. Refer to Figure 1-1.

An internal pull-down resistor will keep the CS/LWAKE

pin low to ensure that no disruptive data will be present

on the bus while the microcontroller is executing a

Power-On Reset and I/O initialization sequence. When

CS/LWAKE is ‘1’, a weak pull-down (~600 kΩ) is used

to reduce current. When CS/LWAKE is ‘0’, a stronger

pull-down (~300 kΩ) is used to maintain the logic level.

This pin may also be used as a local wake-up input

(see Figure 1-7). The microcontroller will set the I/O pin

to control the CS/LWAKE. An external switch or

another source can then wake up both the transceiver

and the microcontroller.

1.2.3

GROUND (VSS)

Ground pin.

1.2.4

LIN BUS (LBUS)

LIN Bus pin. LBUS is a bidirectional LIN bus interface

pin and is controlled by the signal TXD. It has an open

collector output with a current limitation. To reduce

electromagnetic emission, the slopes during signal

changes are controlled and the LBUS pin has

corner-rounding control for both falling and rising

edges.

The internal LIN receiver observes the activities on the

LIN bus and generates the output signal RXD that

follows the state of the LBUS. A 1st degree 160 kHz

low-pass

input

filter

optimizes

electromagnetic

immunity.

1.2.5

RECEIVE DATA OUTPUT (RXD)

Receive Data Output pin. The RXD pin is a standard

CMOS output pin and it follows the state of the LBUS

pin.

1.2.6

TRANSMIT DATA INPUT (TXD)

Transmit Data Input pin (TTL level, HV-compliant,

adaptive pull-up). The transmitter reads the data

stream on the TXD pin and sends it to the LIN bus. The

LBUS pin is low (dominant) when TXD is low, and high

(recessive) when TXD is high.

TXD is internally pulled-up to approximately 4.2V. When

TXD is ‘0’, a weak pull-up (~900 kΩ) is used to reduce

current. When TXD is ‘1’, a stronger pull-up (~300 kΩ)

is used to maintain the logic level. A series

reverse-blocking diode allows applying TXD input

voltages greater than the internally generated 4.2V and

renders the TXD pin HV-compliant up to 30V (see

MCP2025 Block Diagram).

TABLE 1-2:

PIN FUNCTION TABLE

Pin Name

Pin Number

Pin Type

Description

8-lead PDIP

4x4 DFN

VBB

Power

Battery

CS/LWAKE

TTL input, HV-tolerant

Chip Select and Local Wake-up Input

VSS

Power

Ground

LBUS

I/O, HV

LIN Bus

RXD

Output

Receive Data Output

TXD

Input, HV-tolerant

Transmit Data Input

RESET

Open-drain output, HV-tolerant

Reset Output

VREG

Output

Voltage Regulator Output

—

Exposed Thermal Pad

Note:

CS/LWAKE should NOT be tied directly to

the VREG pin, as this could force the

MCP2025 into Operation mode before the

microcontroller is initialized.

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