LM96000EVAL/NOPB National Semiconductor, LM96000EVAL/NOPB Datasheet - Page 28

• Manufacturer Part Number: LM96000EVAL/NOPB
• Description: BOARD EVALUATION LM96000
• Manufacturer: National Semiconductor
• Series: PowerWise®r

Specifications of LM96000EVAL/NOPB

• Sensor Type: Temperature, Fan Controller
• Sensing Range: 0°C ~ 125°C
• Interface: SMBus (2-Wire/I²C)
• Sensitivity: ±1°C
• Voltage - Supply: 3 V ~ 3.6 V
• Embedded: No
• Utilized Ic / Part: LM96000
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: LM96000EVAL

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Register
Address
6Dh
6Eh
Register
Address
6Fh
74h
Register
Address
4.20 Registers 6D-6Eh: Zone Hysteresis Registers
If the temperature is above Fan Temp Limit, then drops below Fan Temp Limit, the following will occur:
These registers become Read Only when the Ready/Lock/Start/Override register Lock bit is set. Any further attempts to write to
thses registers shall have no effect. After power up the default value is used whenever the Ready/Lock/Start/Override register Start
bit is cleared even though modifications to this register are possible.
4.21 Register 6Fh: Test Register
If the XEN bit is set high, the part will be placed into XOR tree test mode. Clearing the bit (writing a 0 to the XEN bit) brings the
part out of XOR tree test mode.
This register becomes Read Only when the Ready/Lock/Start/Override register Lock bit is set. Any further attempts to write to this
registers shall have no effect. After power up the default value is used whenever the Ready/Lock/Start/Override register Start bit
is cleared even though modifications to this register are possible.
4.22 Registers 70-7Fh: Vendor Specific Registers
These registers are for vendor specific features, including test registers. They will not default to a specific value on power up.
4.22.1 Register 74h: Tachometer Monitor Mode
Each fan TACH input has 4 possible modes of operation when using the low frequency range for the PWM outputs. Mode 0 is the
only mode that is available when using the high frequecy range for the PWM outputs. The modes for TACH3 and TACH4 share
control bits T3/4-[1:0]; TACH2 is controlled by T2-[1:0]; TACH1 is controlled by T1-[1:0]. The result reported in all modes is based
on 2 pulses per revolution. In order for modes 2 and 3 to function properly it is required that the:
PWM1 output must control the fan that has it's tachometer output connected to the TACH1 LM96000 input.
PWM2 output must control the fan that has it's tachometer output connected to the TACH2 LM96000 input.
PWM3 output must control the fans that have their tachometer outputs connected to the TACH3 or TACH4 LM96000 inputs.
– The fan will remain on, at Fan PWM Minimum, until the temperature goes a certain amount below Fan Temp Limit.
– The Hysteresis registers control this amount. See below table for details.
Read/
Write
R/W
R/W
R/W
Read/
Write
Read/
Write
R/W
Register
Name
Zone1 and Zone2 Hysteresis
Zone3 Hysteresis
Tach Monitor Mode
Register
Name
Test Register
Register
Name
Setting
Bit 7
(MSB)
RES
RES
(MSb)
Bit 7
0h
5h
Fh
TABLE 12. Hysteresis Settings
.
.
.
.
.
.
Bit 7
(MSB)
H1-3
H3-3
RES
Bit 6
Bit 6
RES
T3/4-1
Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
H1-2 H1-1 H1-0 H2-3 H2-2 H2-1 H2-0
H3-2 H3-1 H3-0 RES
Bit 5
28
Bit 5
RES
HYSTERESIS
T3/4-0
Bit 4
Bit 4
RES
15°C
0°C
5°C
.
.
.
.
.
.
T2-1
Bit 3
Bit 3
RES
T2-0
Bit 2
RES
Bit 2
RES
T1-1
Bit 1
RES
Bit 1
RES
T1-0
(LSb)
Bit 0
(LSB)
RES
Bit 0
(LSB)
XEN
00h
Default
Default
Value
44h
40h
Value
Default
Value
00h
Lock?
✓
✓
Lock?