ADM1033ARQZ-REEL7 ON Semiconductor, ADM1033ARQZ-REEL7 Datasheet - Page 21

• 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

Fan Inputs
This input is open−drain.
slow rise and fall time of typical tachometer outputs. The
maximum input signal range is from 0 V to 5.0 V, even when
V
supplied from fan outputs exceeding 0 V to 5.0 V, either
resistive attenuation of the fan signal or diode clamping
must be used to keep the fan inputs within an acceptable
range.
input circuits. If the fan TACH has a resistive pullup to V
it can be connected directly to the fan output.
voltage greater than 5.0 V), the fan output can be clamped
with a Zener diode, as shown in Figure 36. The Zener
voltage should be chosen so that it is greater than V
than 5.0 V. Allowing for the voltage tolerance of the Zener,
a value of between 3.0 V and 5.0 V is suitable.
CC
Pin 2 is a TACH input intended for fan speed measurement.
Signal conditioning on the ADM1033 accommodates the
Figure 35 to Figure 38 show examples of possible fan
If the fan output has a resistive pullup to 12 V (or another
ACTUAL TACH
5.0 V OR 12 V
is less than 5.0 V. In the event that these inputs are
IDEAL TACH
FAN
Figure 35. Fan with TACH Pullup to +V
DRIVE
PULLUP
4.7kΩ
TYP
OUTPUT
TACH
V
CC
100kΩ
TYP
Figure 34. Drive Signal by Using Synchronous Control
t
TACH X
POLE
t
OFF
DASH = TACH FLOATS HIGH BY PULL-UP RESISTOR
SOLID = TRUE TACH WHEN FAN IS POWERED
POLE TRANSITION POINTS
ADM1033
FAN SPEED
COUNTER
DRIVE X
V
CC
CC
IH
but less
http://onsemi.com
CC
,
21
a totem−pole output, a series resistor can be added to limit
the Zener current, as shown in Figure 37. Alternatively, a
resistive attenuator may be used, as shown in Figure 38.
160 kW to ground. This should be taken into account when
calculating resistor values.
1 kW, suitable values for R1 and R2 would be 100 kW and
47 kW. This gives a high input voltage of 3.83 V.
Totem−Pole Output, Clamped with Zener and Resistor
2.0 V t V
Figure 36. Fan with TACH Pullup to Voltage > 5.0 V,
If the fan has a strong pullup (less than 1 kW to +12 V) or
R1 and R2 should be chosen such that
The fan inputs have an input resistance of nominally
With a pullup voltage of 12 V and pullup resistor less than
Figure 37. Fan with Strong TACH. Pullup to >V
5.0 V OR 12 V
12 V
FAN
PULLUP
PULLUP TYP
<1 kΩ OR
TOTEM POLE
* CHOOSE ZD1 VOLTAGE APPROXIMATELY 0.8 × V
*CHOOSE ZD1 VOLTAGE APPROXIMATELY 0.8 × V
PULLUP
4.7kΩ
Clamped with Zener Diode
TYP
R2 (R
OUTPUT
TACH
V
CC
100kΩ
TYP
PULLUP
ZD1*
TACH X
FAN(0–7)
) R1 ) R2) t 5.0 V
ADM1033
FAN SPEED
COUNTER
FAN SPEED
DRIVE X
ADM1033
COUNTER
V
CC
V
CC
CC
CC
CC
(eq. 3)
or