LM93CIMT/NOPB National Semiconductor, LM93CIMT/NOPB Datasheet - Page 13

• Manufacturer Part Number: LM93CIMT/NOPB
• Description: IC HARDWARE MONITOR 56-TSSOP
• Manufacturer: National Semiconductor

Specifications of LM93CIMT/NOPB

• Applications: Monitors
• Interface: 2-Wire SMBus
• Voltage - Supply: 3 V ~ 3.6 V
• Package / Case: 56-TSSOP
• Mounting Type: Surface Mount
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: *LM93CIMT; *LM93CIMT/NOPB; LM93CIMT

AD_IN10
AD_IN11
AD_IN12
AD_IN13
AD_IN14
AD_IN15
AD_IN16
AD_IN1
AD_IN2
AD_IN3
AD_IN4
AD_IN5
AD_IN6
AD_IN7
AD_IN8
AD_IN9
12.0 Functional Description
provide a nominal
should be scaled to provide a nominal
thevenin resistance at the pin should be kept between 1 kΩ
and 7 kΩ.
The −12V monitoring is particularly challenging. It is required
that an external offset voltage and external resistors be used
Application Note: The nominal voltages listed in this table are only typical values. Voltage rails with different nominal voltages can be monitored, but the register
reading at the nominal value is no longer C0h. For example, a Mem_Core rail at 2.5V nominal could be monitored with AD_IN12, or a Mem_Vtt rail at 1.2V could
be monitored with AD_IN13.
12.5 RECOMMENDED EXTERNAL SCALING RESISTORS FOR +12V POWER RAILS
The +12V inputs require external scaling resistors. The re-
sistors need to scale 12V down to 0.927V.
To calculate the required ratio of R1 to R2 use this equation:
It is recommended that the equivalent thevenin resistance of
the divider be between 1k and 7k to minimize errors caused
by leakage currents at extreme temperatures. The best val-
ues for the resistors are: R1=13.7 kΩ and R2=1.15 kΩ. This
(Continued)
Pin
SCSI_Core
Mem_Core
+3.3V S/B
Gbit_Core
ICH_Core
Mem_Vtt
FSB_Vtt
Normal
Resistors for +12V Power Input
+12V1
+12V2
+12V3
Vccp1
Vccp2
+3.3V
3GIO
−12V
Use
+5V
Required External Scaling
3
⁄
4
full scale reading, while the −12V
Nominal
Voltage
0.927V
0.927V
0.927V
1.969V
0.984V
0.984V
0.309V
1.20V
1.20V
1.20V
3.30V
1.5V
1.5V
5.0V
2.5V
3.3V
Register
Reading
Nominal
Voltage
1
⁄
C0h
C0h
C0h
C0h
C0h
C0h
C0h
C0h
C0h
C0h
C0h
C0h
C0h
C0h
C0h
4
40h
at
20068208
scale reading. The
Voltage vs Register Reading
Maximum
Voltage
1.236V
1.236V
1.236V
6.667V
3.333V
2.625V
1.312V
1.312V
1.236V
1.60V
1.60V
1.60V
4.40V
3.6V
2V
2V
Reading at
13
Maximum
Register
Voltage
FFh
FFh
FFh
FFh
FFh
FFh
FFh
FFh
FFh
FAh
FFh
FFh
FFh
FFh
FFh
D1h
to bring the −12V rail into the positive input voltage region of
the A/D input. It is suggested that the supply rail for the LM93
device be used as the offset voltage. This voltage is usually
derived from the P/S 5V stand-by voltage rail via a
accurate linear regulator. In this fashion we can always
assume that the offset voltage is present when the −12V rail
is present as the system cannot be turned on without the
3.3V stand-by voltage being present.
yields a ratio of 11.94498, which has a +0.27% deviation
from the theoretical. It is also recommended that the resis-
tors have
Each LSB in the voltage value registers has a weight of 12V
/ 192 = 62.5 mV. To calculate the actual voltage of the +12V
power input, use the following equation:
12.6 RECOMMENDED EXTERNAL SCALING CIRCUIT
FOR −12V POWER INPUT
The −12V input requires external resistors to level shift the
nominal input voltage of −12V to +0.309V.
V
IN
Minimum
±
Voltage
= (8-bit value register code) x (62.5 mV)
1% tolerance or better.
3.0V
0V
0V
0V
0V
0V
0V
0V
0V
0V
0V
0V
0V
0V
0V
0V
Reading at
Minimum
Register
Voltage
AEh
00h
00h
00h
00h
00h
00h
00h
00h
00h
00h
00h
00h
00h
00h
00h
−0.3V to (V
−0.3V to (V
−0.3V to (V
−0.3V to (V
Maxmum Range
−0.3V to +6.0V
−0.3V to +6.0V
−0.3V to +6.0V
−0.3V to +6.0V
−0.3V to +6.0V
−0.3V to +6.0V
−0.3V to +6.5V
−0.3V to +6.0V
−0.3V to +6.0V
−0.3V to +6.0V
−0.3V to +6.0V
−0.3V to +6.0V
Absolute
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DD
DD
DD
DD
+ 0.05V)
+ 0.05V)
+ 0.05V)
+ 0.05V)
±
1%