LPC47N237-MD SMSC [SMSC Corporation], LPC47N237-MD Datasheet - Page 66

• Manufacturer Part Number: LPC47N237-MD
• Description: 3.3V I/O CONTROLLER FOR PORT REPLICATORS AND DOCKING STATIONS
• Manufacturer: SMSC [SMSC Corporation]

Chapter 10 Power Management
10.1
Note:
10.1.1 Exit Auto Powerdown
10.2
Revision 0.3 (10-26-04)
Power management capabilities are provided for the following logical devices: UART and the parallel port.
For each logical device, two types of power management are provided: direct powerdown and auto
powerdown.
UART Power Management
Direct power management is controlled by CR02. Refer to the Configuration section for more information.
Auto Power Management is enabled by the UART enable bit in CR07. When set, the bit allow the following
auto power management operations:
1.
2.
While in powerdown the Ring Indicator interrupt is still valid and transitions when the RI input changes.
The transmitter exits powerdown on a write to the XMIT buffer. The receiver exits auto powerdown when
RXDx changes state.
Parallel Port Power Management
Direct power management is controlled by Bit[2] in CR01. Refer to the Configuration section for more
information.
Auto Power Management is enabled by Bit[4] in CR07 . 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.
2.
The ECP logic is in powerdown under any of the following conditions:
1.
2
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:
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.
a)
b)
Receive FIFO is empty
The receiver is waiting for a start bit.
DATASHEET
Page 66
3.3v I/O Controller for Port Replicators and Docking Stations
SMSC DS – LPC47N237