FDD PINS
nTRK0
STATE IN AUTO POWERDOWN
Input
Input
nINDEX
nDSKCHG
Input
OUTPUT PINS
Tristated
Tristated
Active
nMTR0
nDS0
nDIR
nSTEP
Active
nWDATA
nWGATE
nHDSEL
DRVDEN[0:1]
Tristated
Tristated
Active
Active
UART Power Management
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. 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 and transitions when the RI input
changes.
Exit Auto Powerdown
The transmitter exits powerdown on a write to the XMIT buffer. The receiver exits auto powerdown when
RXDx changes state.
MPU-401 Power Management
Direct power management is controlled by CR22. Refer to CR22 for more information.
Auto Power Management is enabled by CR23-B6. When set, this bit allows 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.
Exit Auto Powerdown
The transmitter exits powerdown on a write to the XMIT buffer. The receiver exits auto powerdown when
MIDI_IN changes state.
Parallel Port
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:
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:
SMSC LPC47B27x
- 96 -
Rev. 08-10-04
DATASHEET
SMSC [ SMSC CORPORATION ]
