
7.18 Hardware Monitoring Interface 
SMSC DS – LPC47M192 
Page 129 
Rev. 03/30/05 
DATASHEET 
The Hardware Monitoring Block is a standalone block in the 2.  It can be accessed using SMBus interface.  This block 
is used to monitor +1.5, +1.8, +2.5V, +3.3V, +5V, +12V and Vccp (core processor) voltages.  It can also monitor its 
own internal HVCC or HVSB.  The block can be used to measure internal temperature and two external temperatures 
and diode faults.  It can indicate out-of-limit temperature and voltage conditions.  The block has an ability to output 
20ms low pulse. 
7.18.1 HARDWARE MONITORING INTERFACE SIGNAL DEFINITION 
The following table shows the pins required for the Hardware Monitoring Block. 
PIN NAME 
TYPE 
SDA 
Digital I/O 
(Open Drain) 
output. 
SCLK 
Digital Input 
HVSS 
Analog Ground 
Internally connected to all of the Hardware Monitoring Block 
circuitry. 
HVCC 
Power 
+3.3V VCC pin dedicated to the Hardware Monitoring block.  
Can be powered by +3.3V Standby power if monitoring in low 
power states is required. 
VID0 
Digital Input 
Voltage supply readout from the processor. This value is read 
in the VID Register. 
VID1 
Digital Input 
Voltage supply readout from the processor. This value is read 
in the VID Register. 
VID2 
Digital Input 
Voltage supply readout from the processor. This value is read 
in the VID Register. 
VID3 
Digital Input 
Voltage supply readout from the processor. This value is read 
in the VID Register. 
D0-/XNOR_IN 
Analog Input/ 
Digital Input 
thermal diode. This serves as the negative input into the A/D.
If held high at power-up, initiates XNOR chain test mode. 
D0+ 
Analog Input 
This is the positive input (current source) from the remote 
thermal diode. This serves as the positive input into the A/D.  
D1- 
Analog Input 
See D0- pin description. 
D1+ 
Analog Input 
See D0+ description. 
12V_IN/VID4 
Analog 
Input/ 
Digital Input 
configured to read the VID4 pin, a voltage supply readout from 
the processor. This value is read in the VID4 Register. 
+5V_IN 
Analog Input 
Analog input for +5V 
+3.3V_IN 
Analog Input 
Analog input for +3.3V 
+2.5V_IN 
Analog Input 
Analog input for +2.5V 
+1.8V_IN 
Analog Input 
Analog input for +1.8V 
+1.5V_IN 
Analog Input 
Analog input for +1.5V 
+Vccp_IN 
Analog Input 
Analog input for +Vccp (processor voltage: 0 to 3.0V). 
A0/RESET#/ 
THERM#/XNOR_OUT 
(Open Drain) 
Can also be configured to be a minimum 20msec low Reset 
output pulse, or as an interrupt output for temperature and 
voltage interrupts.  This pin functions as an output when the 
Hardware Monitor Block is in XNOR-Chain test mode. 
7.18.2 SMBUS INTERFACE 
The host processor communicates with the Hardware Monitor Block through a series of read/write registers via the 
SMBus interface.  SMBus is a serial communication protocol between a computer host and its peripheral devices.  
The SMBus protocol includes a physical layer based on the I
C
 serial bus. 
DESCRIPTION 
System Management Bus bi-directional Data.  Open Drain 
System Management Bus Clock. 
This is the negative input (current sink) from the remote 
Defaults to Analog Input for +12V. Optionally, can be 
Digital I/O 
The lowest order programmable bit of the SMBus Address.