ADM1034ARQZ-R7 ON Semiconductor, ADM1034ARQZ-R7 Datasheet - Page 20

• 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

Conversion Rate Register
However, for the sake of reduced power consumption and
better noise immunity, users may run the ADM1034 at a
slower conversion rate. Better noise immunity results from
the averaging that occurs at the slower conversion rates.
Averaging does not occur at rates of 16, 32, or 64
conversions per second. Table 20 lists the available
conversion rates. Note that the current round−robin loop
must be finished for conversion rates changes to take effect.
THERM I/O Timer and Limits
output it is asserted low to signal that the measured
temperature has exceeded preprogrammed temperature
limits. The output is automatically pulled high again when
the temperature falls below the THERM – Hys limit. The
value of hysteresis is programmable in Register 0x1A.
THERM is enabled as an output by default on powerup.
boosted to full speed, that is, as long as the Boost Disable Bit
(Bit 1) is not set in Configuration Register 2 (Address 0x02).
Table 20. Conversion Rates
THERM−HYST,
THERM, 85°C
The ADM1034 makes up to 64 measurements per second.
Pin 7 can be configured as either an input or output. As an
Once the THERM limits are exceeded, the fans are
TEMPERATURE
0x0B to 0xFF
THERM
80°C
LIMITS
Code
0x0A
0x00
0x01
0x02
0x03
0x04
0x05
0x06
0x07
0x08
0x09
Figure 32. THERM Behavior
Conversion Rate
Reserved
0.0625
0.125
0.25
0.5
16
32
64
1
2
4
8
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TIME
20
THERM timer bit (Bit 2) of Configuration Register 1
(Address 0x01) to 1. (It no longer operates as an output.) The
ADM1034 can then detect when the THERM input is
asserted low. This may be connected to a trip point
temperature sensor or to the FAN_FAULT PROCHOT
output of a CPU. With processor core voltages reducing all
the time, the threshold for the AGTL + PROCHOT output
also reduces down as new processors become available. The
default threshold on the input is the normal CMOS
threshold. However, Pin 8 (FAN_FAULT/REF) can also be
reconfigured as a REF input. This is done by setting Bit 7
(FAN_FAULT/REF) in Configuration Register 4 (Address
0x04). Connect the processor V
a reference for the THERM input. The resulting THERM
threshold is 0.75xV
AGTL+ signal.
THERM input as a percentage of a time window. This time
window is programmable in Configuration Register 4
(Address 0x04) by using Bits <6:4> (THERM % Time
Window). Values between 0.25 seconds and 8 seconds are
programmable. The assertion time as a percentage of the
time window is stored in the THERM % On−Time Register
(Address 0x4E).
the measured percentage exceeds the percentage limit, the
THERM % Exceeded Bit (Bit 4) in Status Register 2 (Address
0x50) is asserted and an ALERT is generated, that is, if the
mask bit is not set. If the limit is set to 0x00, an ALERT is
generated on the first assertion. If the limit is set to 0xFF, an
ALERT is never generated. This is because 0xFF corresponds
to the THERM input, which is asserted continuously.
Enable THERM Events bits in Configuration Register 4
allows Pin 7 to operate as an I/O.
as an output whenever the local temperature exceeds the
local THERM limit. To do this, set the Enable Local
THERM events bit (Bit 0) of Configuration Register 4
(Address 0x04).
Table 21. Conversion Rates
To configure THERM as an input, the user must set the
The ADM1034 also measures assertion times on the
A THERM % limit is also associated with this register. Once
When THERM is configured as an input only, setting the
The user can configure the THERM pin to be pulled low
Code
000
001
010
011
100
101
110
111
CCP
, which is the correct threshold for an
THERM % On−Time Window
CCP
0.25 s
to this input to provide
0.5 s
1 s
2 s
4 s
8 s
8 s
8 s