MCP2140A 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

一致するリスト

MCP2140A

IrDA® Standard Protocol Stack Controller With Fixed 9600 Baud Communication Rate

Microchip Technology 

2.8 Minimizing Power

During IR communication between a Primary Device

and the MCP2140A, the MCP2140A is in an opera-

tional mode. In this mode, the MCP2140A consumes

the operational current (Parameter D010A).

For many applications, the time that IR communication

is occurring is a small percentage of the applications

operational time. The ability for the IR controller to be

in a low power mode during this time will save on the

applications power consumption. The MCP2140A will

automatically enter a low power mode once IR activity

has stopped and will return to operational mode once

IR activity is detected on the RXPD and RXPDREF

pins. The PHACT pin indicates if the Protocol Handler

is Active or inactive (low power mode).

Another way to minimize system power is to use an I/O

pin of the Host Controller to enable power to the IR

circuity

MCP2140A

2.8.1 AUTOMATIC LOW POWER MODE

The Automatic Low Power mode allows the system to

achieve the lowest possible operating current.

When the IR link has been “closed”, the protocol

handler state machine returns to the Normal

Disconnect Mode (NDM). During NDM, if no IR activity

occurs for about 10 seconds, the device is disabled and

enters into Low Power mode. In this mode, the device

oscillator is shut down and the PHACT pin will be low

(Parameter D010B).

Table 2-3 shows the MCP2140A current. These are

specified in Parameter D010A and Parameter D010B.

TABLE 2-3: DEVICE MAXIMUM

OPERATING CURRENT

Mode Current

Comment

PHACT = H 407 µA IR communications is

occurring (or waiting for

timeout).

PHACT = L 23 µA No IR communications.

Note:

Additional system current is from the

Receiver/Transmitter and the RXPDREF

voltage reference circuitry.

2.8.2

RETURNING TO DEVICE

OPERATION

The device will exit the Low Power mode when the

RXPD pin voltage crosses the REPDREF pin reference

voltage.

A device reset will also cause the MCP2140A to exit

Low Power mode. After device initialization, if no IR

activity occurs for about 10 seconds, the device returns

to the Low Power mode.

Note:

For proper operation, the device oscillator

must be within oscillator specification in

the time frame specified in Parameter

IR140.

2.9 PHACT Signal

The PHACT signal indicates that the MCP2140 Proto-

col Handler is active. This output pin is an open

collector, so when interfacing to the Host Controller, a

pull-up resistor is required.

© 2007 Microchip Technology Inc.

DS22050A-page 15

Share Link: