LPC47M182 datasheet(136/223 Pages) SMSC

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Advanced I/O Controller with Motherboard GLUE Logic

Datasheet

Revision 1.8 SMSC/Non-SMSC Register Sets (02-24-05)

136

SMSC LPC47M182

DATASHEET

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.

Table 7.21 – nHD_LED Truth Table

INPUTS

OUTPUT

NPRIMARY_HD

NSECONDARY_HD

NSCSI

nHD_LED

NOTES

LED On

Hi-Z

LED Off

SMSC I/O

RED

VCC

nHD_LED

220 ohms

Figure 7.6 – NHD_LED Circuit

7.30.2 Yellow and Green Power LED Pins

Table 7.22-- LED Pins

NAME

BUFFER

POWER WELL

DESCRIPTION

GRN_LED

OD24

VTR

Green Power LED Open-Drain Output

YLW_LED

OD24

VTR

Yellow Power LED Open-Drain

Output

nSLP_S5

VTR

Input from South Bridge for

Transitioning to the S5 Power State

Note:

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.

LPC47M182 Datasheet(PDF) 136 Page - SMSC Corporation

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