LPC47S457-NC SMSC [SMSC Corporation], LPC47S457-NC Datasheet - Page 96

• Manufacturer Part Number: LPC47S457-NC
• Description: Advanced I/O with X-Bus Interface
• Manufacturer: SMSC [SMSC Corporation]

All pins in the FDD interface which can be connected directly to the floppy disk drive itself are either DISABLED or
TRISTATED.
Pins used for local logic control or part programming are unaffected. Table 44 depicts the state of the floppy disk drive
interface pins in the powerdown state.
6.8.2
Direct power management is controlled by CR22. Refer to CR22 for more information.
Auto Power Management is enabled by CR23-B4 and B5. When set, these bits allow the following auto power
management operations:
1.
2.
Note:
Exit Auto Powerdown
The transmitter exits powerdown on a write to the XMIT buffer. The receiver exits auto powerdown when RXDx
changes state.
6.8.3
Direct power management is controlled by CR22. Refer to CR22 for more information.
Auto Power Management is enabled by CR23-B3. 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:
The ECP logic is in powerdown under any of the following conditions:
Exit Auto Powerdown
SMSC DS – LPC47S45x
The transmitter enters auto powerdown when the transmit buffer and shift register are empty.
The receiver enters powerdown when the following conditions are all met:
A.
B.
1.
2.
1.
2.
Receive FIFO is empty
The receiver is waiting for a start bit.
While in powerdown the Ring Indicator interrupt is still valid and transitions when the RI input changes.
PARALLEL PORT
EPP is not enabled in the configuration registers.
EPP is not selected through ecr while in ECP mode.
ECP is not enabled in the configuration registers.
SPP, PS/2 Parallel port or EPP mode is selected through ecr while in ECP mode.
UART POWER MANAGEMENT
Table 44 − State of Floppy Disk Drive Interface Pins in Powerdown
DRVDEN[0:1]
nWRTPRT
nDSKCHG
FDD PINS
nWDATA
nWGATE
nRDATA
nHDSEL
nINDEX
nMTR0
nSTEP
nTRK0
nDS0
nDIR
DATASHEET
OUTPUT PINS
Page 96 of 259
INPUT PINS
STATE IN AUTO POWERDOWN
Tristated
Tristated
Tristated
Tristated
Active
Active
Active
Active
Input
Input
Input
Input
Input
Rev. 07/09/2001