LPC47M172 SMSC Corporation, LPC47M172 Datasheet - Page 134

• Manufacturer Part Number: LPC47M172
• Description: ADVANCED I/O CONTROLLER WITH MOTHERBOARD GLUE LOGIC
• Manufacturer: SMSC Corporation

Advanced I/O Controller with Motherboard GLUE Logic
Datasheet
Notes:
7.31
7.31.1 Reference Pins
SMSC/Non-SMSC Register Sets (Rev. 02-27-04)
REF5V
REF5V_STBY
*** Default state
The LED is ON in the Hi-Z state. The LED is blinking at 0.67 Hz in the 0.67 Hz state.
NAME
nSLP_S5
The 32.768 kHz clock input is used to control the blink rate and duty cycle of the LEDs. The blink rate is
0.67Hz, and the duty cycle is 39.6%. This corresponds to a LED low output of exactly 0.90625 seconds
(depending on the accuracy of the 32.768 kHz clock).
YLW_LED and GRN_LED require external pull-ups to power the LEDs. A value of 220ohms to VTR is
recommended. These are open drain active high outputs. When the LEDs are off, the open drain output is
sinking the current from VTR through the 220ohm resistor to ground. When the LEDs are on, they are
powered through the 220ohm resistor.
The following figure shows the recommended external LED circuit.
Power Generation (5V)
O
See DC characteristics see the “Electrical Characteristics” section.
AN
1
1
: Analog Output, 5V level.
AO
AO
BUFFER
GRN_YLW Bit
INPUTS
SMSC I/O
1
1
Figure 7.7 - YLW_LED/GRN_LED Circuit
Table 7.24 - Reference Generation Pins
3.3mA
3.3mA
CURRENT
MAX OUT
DATASHEET
SDY_BLK Bit
GRN_LED
YLW_LED
Page 134
VCC
VTR
0
1
POWER
WELL
220 ohms
Green
VTR
5V Reference Output
Highest System Standby Voltage
GRN_LED
0.67 Hz
Hi-Z***
220 ohms
Yellow
OUTPUTS
DESCRIPTION
YLW_LED
0
0
SMSC LPC47M172