ADM1034ARQZ-R7 ON Semiconductor, ADM1034ARQZ-R7 Datasheet - Page 26

• Manufacturer Part Number: ADM1034ARQZ-R7
• Description: IC THERM/FAN SPEED CTLR 16-QSOP
• Manufacturer: ON Semiconductor

Specifications of ADM1034ARQZ-R7

• 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 ~ 5.5 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 16-QSOP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Setting Which Temperature Channel Controls a Fan
can be controlled by either the local temperature, or by the
Remote 1 or Remote 2 temperatures.
controls Fan 2. If the ADM1034 is in single−channel mode
and one of the fans is set up to run from a temperature
channel that is not being measured, the drive X BHVR bits
are set to 11 and the fan is run at full speed.
Look−Up Table Hysteresis
look−up table. The advantage of this is apparent if the
temperature is cycling around one of the threshold
temperatures and causing the fan speed to switch between
the two speeds, particularly when the look−up table is
configured in discrete mode. It would not be as important in
the linear mode.
Programming the Look−Up Table Hysteresis
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.
Table 27. Drive X BHVR Bits
Table 28. Programming the Hysteresis
Fan Behavior Register (Address 0x07)
Bits <1:0> = DRIVE1 Behavior (D1B)
Bits <3:2> = DRIVE2 Behavior (D2B)
The ADM1034 can be configured so that Fan 1 or Fan 2
By default, Remote 1 controls Fan 1, and Remote 2
The user can program a hysteresis to be applied to the
The look−up table’s hysteresis register is at Address
Bits
00
01
10
11
0000 0000
0000 0001
0000 0010
0000 0101
0000 1000
0000 1111
Code
Local Temperature Controls Fan x
Remote 1 Temperature Controls Fan x
Remote 2 Temperature Controls Fan x
Fan x Runs at Full Speed
DRIVE x BHVR
Hysteresis Value
5°C = Default
15°C
0°C
1°C
2°C
8°C
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Programming the THERM Limit for Each Temperature
Channel
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 fans do not run to full speed.
worst−case operating temperature of the system. Exceeding
any THERM limit runs all fans 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.
Table 29.
hysteresis value is programmed and applied to all three
temperature channels; Local, Remote 1, and Remote 2. 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 29. THERM Hysteresis Registers
Table 30. Programming THERM Hysteresis
THERM is the absolute maximum temperature allowed
The THERM limit is considered the maximum
The THERM temperature limit registers are listed in
The THERM hysteresis register is at Address 0x1A. A
Address
0x0D
0x10
0x13
0000 0000
0000 0001
0000 0010
0000 0101
0000 1000
0000 1111
Code
Local THERM Limit
Remote 1 THERM Limit
Remote 2 THERM Limit
Description
Hysteresis Value
5°C = Default
15°C
0°C
1°C
2°C
8°C
0x95 (85°C)
0x95 (85°C)
0x95 (85°C)
Default