LM85 National Semiconductor, LM85 Datasheet - Page 13

• Manufacturer Part Number: LM85
• Description: Hardware Monitor with Integrated Fan Control
• Manufacturer: National Semiconductor

Bit
1
2
3
4–7
Bit
0
1
2
3
4
5
Register
Address
41h
Functional Description
4.8 Register 41h: Interrupt Status Register 1
The Interrupt Status Register 1 bits will be automatically set, by the LM85, whenever a fault condition is detected. A fault condition
is detected whenever a measured value is outside the window set by its limit registers. ZN3 and ZN1 bits will be set when a diode
fault condition, such as a disconect or short, is detected. More than one fault may be indicated in the interrupt register when read.
This register will hold a set bit(s) until the event is read by software. The contents of this register will be cleared (set to 0)
automatically by the LM85 after it is read by software, if the fault condition is no longer exists. Once set, the Interrupt Status
Register 1 bits will remain set until a read event occurs, even if the fault condition no longer exists
This register is read only — a write to this register has no effect.
Name
LOCK
READY
OVRID
Reserved
Name
2.5V_Error
V
3.3V_Error
5V_Error
Zone 1 Limit
Exceeded
Zone 2 Limit
Exceeded
CCP
Read/
Write
R
_Error
Register
Name
Interrupt Status 1
R/W
R/W
R
R/W
R
R/W
R
R
R
R
R
R
Default
0
0
0
Default
0
0
0
0
0
0
(Continued)
Bit 7
(MSB)
ERR
Description
Setting this bit to 1 locks specified limit and parameter registers. Once this bit
is set, limit and parameter registers become read only and will remain locked
until the device is powered off. This register bit becomes read only once it is
set.
The LM85 sets this bit automatically after the part is fully powered up, has
completed the power-up-reset process, and after all A/D converters are
properly functioning.
If this bit is set to 1, all PWM outputs will go to 100% duty cycle regardless of
whether or not the lock bit is set. For the LM85C only, when a PWM is
programmed in the disabled mode (Fan Configuration registers 5C-5Eh, bits
fan_config[7:5] = ZON[2:0]=100) the PWM stays in the disabled mode for this
case. Override bit works in all other cases (zone1-3, hottest ...). For the
LM85B the OVRID bit has precedence over the disabled mode. Therefore,
when OVRID is set the PWM will go to 100% even if the PWM is in the
disabled mode.
Reserved
Description
The LM85 automatically sets this bit to 1 when the 2.5V input voltage is
less than or equal to the limit set in the 2.5V Low Limit register or greater
than the limit set in the 2.5V High Limit register.
The LM85 automatically sets this bit to 1 when the V
less than or equal to the limit set in the V
than the limit set in the V
The LM85 automatically sets this bit to 1 when the 3.3V input voltage is
less than or equal to the limit set in the 3.3V Low Limit register or greater
than the limit set in the 3.3V High Limit register.
The LM85 automatically sets this bit to 1 when the 5V input voltage is less
than or equal to the limit set in the 5V Low Limit register or greater than
the limit set in the 5V High Limit register.
The LM85 automatically sets this bit to 1 when the temperature input
measured by the Remote1− and Remote1+ inputs is less than or equal to
the limit set in the Processor (Zone1) Low Temp register or more than the
limit set in the Processor (Zone1) High Temp register. This bit will be set
when a diode fault is detected.
The LM85 automatically sets this bit to 1 when the temperature input
measured by the internal temperature sensor is less than or equal to the
limit set in the Internal (Zone2) Low Temp register or greater than the limit
set in the Internal (Zone2) High Temp register.
Bit 6
ZN3
13
Bit 5
ZN2
Bit 4
ZN1
CCP
Bit 3
5V
High Limit register.
Bit 2
3.3V
CCP
Low Limit register or greater
Bit 1
V
CCP
CCP
Bit 0
(LSB)
2.5V
input voltage is
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Default
Value
00h