FDC37N958FR Ver la hoja de datos (PDF) - SMSC -> Microchip

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FDC37N958FR

Notebook I/O Controller with Enhanced Keyboard and System Control

SMSC -> Microchip 

UART Power Management

Direct power management is controlled by CR22.

Refer to CR22 in the Configuration Section for

more information.

Auto power management is enabled by CR23 bit

4 and bit 5. When set, these bits allow the

following auto power management operations:

1. The transmitter enters auto powerdown when

the transmit buffer and shift register are

empty.

2. The receiver enters powerdown when the

following conditions are all met:

A. Receive FIFO is empty

B. The receiver is waiting for a start bit.

Note: While in powerdown the Ring Indicator

interrupt is still valid.

Exit Auto Powerdown

The transmitter exits powerdown on a write to the

transmit buffer. The receiver exits auto

powerdown when RXD changes state.

Parallel Port Power Management

Direct power management is controlled by CR22.

Refer to CR22 in the Configuration Section for

more information.

Auto power management is enabled by CR23 bit

3. When set, this bit allows the ECP or EPP

logical parallel port blocks to be placed into

powerdown when not being used.

The EPP logic is in powerdown under any of the

following conditions:

1. EPP is not enabled in the configuration

registers.

2. EPP is not selected through ecr while in ECP

mode.

The ECP logic is in powerdown under any of the

following conditions:

1. ECP is not enabled in the configuration

registers.

2 SPP, PS/2 Parallel port or EPP mode is

selected through ecr while in ECP mode.

Exit Auto Powerdown

The parallel port logic can change powerdown

modes when the ECP mode is changed through

the ecr register or when the parallel port mode is

changed through the configuration registers.

SMSC DS – FDC37N958FR

Page 22

Rev. 09/01/99

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