ADM1030ARQ-REEL ON Semiconductor, ADM1030ARQ-REEL Datasheet - Page 9

• Manufacturer Part Number: ADM1030ARQ-REEL
• Description: IC SNSR TEMP/FAN PWM CTRL 16QSOP
• Manufacturer: ON Semiconductor

Specifications of ADM1030ARQ-REEL

• Rohs Status: RoHS non-compliant
• Function: Fan Control, Temp Monitor
• Topology: ADC, Comparator, Multiplexer, Register Bank
• Sensor Type: External & Internal
• Sensing Temperature: 0°C ~ 100°C, External Sensor
• Output Type: SMBus™
• Output Alarm: Yes
• Output Fan: Yes
• Voltage - Supply: 3 V ~ 5.5 V
• Operating Temperature: 0°C ~ 100°C
• Mounting Type: Surface Mount
• Package / Case: 16-QSOP

ALERT RESPONSE ADDRESS
Alert Response Address (ARA) is a feature of SMBus devices
that allows an interrupting device to identify itself to the host
when multiple devices exist on the same bus.
The INT output can be used as an interrupt output or can be used
as an SMBALERT. One or more INT outputs can be connected
to a common SMBALERT line connected to the master. If a
device’s INT line goes low, the following procedure occurs:
1. SMBALERT pulled low.
2. Master initiates a read operation and sends the Alert
3. The device whose INT output is low responds to the Alert
4. If more than one device’s INT output is low, the one with
5. Once the ADM1030 has responded to the Alert Response
TEMPERATURE MEASUREMENT SYSTEM
Internal Temperature Measurement
The ADM1030 contains an on-chip bandgap temperature sen-
sor. The on-chip ADC performs conversions on the output of
this sensor and outputs the temperature data in 10-bit two’s
complement format. The resolution of the local temperature
sensor is 0.25 C. The format of the temperature data is shown
in Table II.
External Temperature Measurement
The ADM1030 can measure the temperature of an external
diode sensor or diode-connected transistor, connected to Pins
9 and 10.
These pins are a dedicated temperature input channel. The
function of Pin 7 is as a THERM input/output and is used to
flag overtemperature conditions.
The forward voltage of a diode or diode-connected transistor,
operated at a constant current, exhibits a negative temperature
coefficient of about –2 mV/ C. Unfortunately, the absolute
value of V
calibration is required to null this out, so the technique is
unsuitable for mass production.
The technique used in the ADM1030 is to measure the change
in V
This is given by:
where:
K is Boltzmann’s constant.
q is charge on the carrier.
T is absolute temperature in Kelvins.
N is ratio of the two currents.
REV. A
Response Address (ARA = 0001 100). This is a general call
address that must not be used as a specific device address.
Response Address, and the master reads its device address.
The address of the device is now known and can be interro-
gated in the usual way.
the lowest device address will have priority, in accordance
with normal SMBus arbitration.
Address, it will reset its INT output; however, if the error
condition that caused the interrupt persists, INT will be
reasserted on the next monitoring cycle.
BE
when the device is operated at two different currents.
BE
, varies from device to device, and individual
DV
BE
= KT/q ¥ ln (N)
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Figure 3 shows the input signal conditioning used to measure
the output of an external temperature sensor. This figure shows
the external sensor as a substrate transistor, provided for tempera-
ture monitoring on some microprocessors, but it could equally
well be a discrete transistor.
If a discrete transistor is used, the collector will not be grounded,
and should be linked to the base. If a PNP transistor is used, the
base is connected to the D– input and the emitter to the D+
input. If an NPN transistor is used, the emitter is connected to
the D– input and the base to the D+ input.
One LSB of the ADC corresponds to 0.125 C, so the ADM1030
can theoretically measure temperatures from –127 C to +127.75 C,
although –127 C is outside the operating range for the device.
The extended temperature resolution data format is shown in
Tables III and IV.
Table II. Temperature Data Format (Local Temperature and
Remote Temperature High Bytes)
TRANSISTOR
SENSING
REMOTE
Temperature (�C)
–128 C
–125 C
–100 C
–75 C
–50 C
–25 C
–1 C
0 C
+1 C
+10 C
+25 C
+50 C
+75 C
+100 C
+125 C
+127 C
D+
D–
Figure 3. Signal Conditioning
I
DIODE
BIAS
N � I
I
BIAS
LOW-PASS
f
C
FILTER
= 65kHz
Digital Output
1000 0000
1000 0011
1001 1100
1011 0101
1100 1110
1110 0111
1111 1111
0000 0000
0000 0001
0000 1010
0001 1001
0011 0010
0100 1011
0110 0100
0111 1101
0111 1111
V
DD
ADM1030
V
V
OUT+
OUT–
ADC
TO