ADM1033ARQZ-REEL7 ON Semiconductor, ADM1033ARQZ-REEL7 Datasheet - Page 25

• Manufacturer Part Number: ADM1033ARQZ-REEL7
• Description: IC THERM/FAN SPEED CTRLR 16-QSOP
• Manufacturer: ON Semiconductor

Specifications of ADM1033ARQZ-REEL7

• Function: Fan Control, Temp Monitor
• Topology: ADC, Comparator, Multiplexer, Register Bank
• Sensor Type: External & Internal
• Sensing Temperature: -40°C ~ 125°C, External Sensor
• Output Type: SMBus™
• Output Alarm: Yes
• Output Fan: Yes
• Voltage - Supply: 3 V ~ 3.6 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 16-QSOP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

0x3A. A hysteresis value of between 0°C and 15°C can be
programmed with a resolution of 1°C and applied to all the
temperature thresholds. Table 28 gives examples of values
for programming.
Programming the THERM Limit for Temperature
Channels
on a temperature channel. Above this temperature, a
component such as the CPU or VRM may be operating
beyond its safe operating limit. When the temperature
measured exceeds THERM, all fans are driven at full speed
to provide critical system cooling. The fans remain running
at full speed until the temperature drops below THERM –
Hysteresis. The hysteresis value is programmable; its
default is 5°C. If the Boost Disable bit (Bit 1) is set in
Configuration Register 2, the fan do not run to full speed.
worst−case operating temperature of the system. Exceeding
any THERM limit runs the fan at full speed, a condition with
very negative acoustic effects. This limit should be set up as
a fail−safe and not exceeded under normal system operating
conditions. The THERM temperature limit registers are
listed in Table 29.
hysteresis value is programmed and applied to all two
temperature channels; Local and Remote 1. A THERM
hysteresis value of between 0°C and 15°C can be programmed
with a resolution of 1°C. Table 33 gives some examples.
Table 28. Programming the Hysteresis
Table 29. THERM Hysteresis Registers
The look−up table’s hysteresis register is at Address
THERM is the absolute maximum temperature allowed
The THERM limit is considered the maximum
The THERM hysteresis register is at Address 0x1A. A
Address
0x0D
0x10
0000 0000
0000 0001
0000 0010
0000 0101
0000 1000
0000 1111
Code
Local THERM Limit
Remote 1 THERM Limit
Description
Hysteresis Value
15°C
0°C
1°C
2°C
5°C
8°C
0x95 (85°C)
0x95 (85°C)
Default
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25
XOR Tree Test Mode
useful for in circuit test equipment at board level testing. By
applying stimulus to the pins included in the XOR test, it is
possible to detect opens or shorts on the system board.
Figure 43 shows the signals that are exercised in the XOR
tree test mode. The XOR tree test is enabled by setting the
XOR bit (Bit 3) in Configuration 4 Register (0x04).
Lock Bit
(Address 0x01) makes all the lockable registers read−only.
These registers remain read−only until the ADM1033 is
powered down and back up again. For more information on
which registers are lockable, see Table 31.
SW Reset
Register 2 (Address 0x02) resets all software resettable bits
to their default value. For more information on resetting
registers and their default values, see Table 31 to Table 65.
Table 30. Programming THERM Hysteresis
DRIVE2
TACH1
The ADM1033 includes an XOR tree test mode. This is
Setting the Lock bit (Bit 6) of Configuration Register 1
Setting the Software Reset bit (Bit 0) of Configuration
0000 0000
0000 0001
0000 0010
0000 0101
0000 1000
0000 1111
THERM
FAN_FAULT/REF
Code
Figure 43. XOR Tree Test
LOCATION
ALERT
Hysteresis Value
5°C = Default
15°C
0°C
1°C
2°C
8°C
DRIVE1