LPC47M182 SMSC Corporation, LPC47M182 Datasheet - Page 136

• Manufacturer Part Number: LPC47M182
• Description: ADVANCED I/O CONTROLLER WITH MOTHERBOARD GLUE LOGIC
• Manufacturer: SMSC Corporation

7.30.2 Yellow and Green Power LED Pins
Note:
Revision 1.8 SMSC/Non-SMSC Register Sets (02-24-05)
NPRIMARY_HD
GRN_LED
YLW_LED
nSLP_S5
NAME
The nHD_LED pin is used at the system’s front panel header to drive the hard drive activity LED. Note that
external LEDs should be driven such that the voltage at the nHD_LED pin does not exceed 5V. The output
is open-drain and should be externally pulled to VCC through a resistor.
The LEDs require external pull-up to VTR.
The green and yellow LED outputs are controlled by the LED register accessible via the LPC bus. The
GRN_YLW bit controls which output is asserted. In addition, the SDY_BLK bit indicates whether the
selected LED is steady or blinking. The LED register is located at offset 10h in the Power Control Logical
Device (LD_NUM=O) or the Runtime Register Block Logical Device (LD_NUM=1).
These LED outputs are also controlled by the nSLP_S5 sleep input pin. The functionality is shown in the
table below.
The green and yellow LED outputs are powered by VTR.
X
X
0
1
NSECONDARY_HD
INPUTS
BUFFER
OD24
OD24
SMSC I/O
X
X
1
0
I
Table 7.21 – nHD_LED Truth Table
Figure 7.6 – NHD_LED Circuit
DATASHEET
Table 7.22-- LED Pins
nHD_LED
POWER WELL
136
NSCSI
X
X
0
1
VTR
VTR
VTR
220 ohms
RED
VCC
Advanced I/O Controller with Motherboard GLUE Logic
Green Power LED Open-Drain Output
Yellow Power LED Open-Drain
Output
Input from South Bridge for
Transitioning to the S5 Power State
nHD_LED
OUTPUT
Hi-Z
0
0
0
DESCRIPTION
LED Off
SMSC LPC47M182
NOTES
LED On
LED On
LED On
Datasheet