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MIC502_11 Datasheet, PDF (1/15 Pages) Micrel Semiconductor – Fan Management IC | |||
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MIC502
Fan Management IC
General Description
Features
The MIC502 is a thermal and fan management IC which
supports the features for NLX/ATX power supplies and
other control applications.
Fan speed is determined by an external temperature
sensor, typically a thermistor-resistor divider, and (option-
ally) a second signal, such as the NLX âFanCâ signal. The
MIC502 produces a low-frequency pulse-width modulated
output for driving an external motor drive transistor. Low-
frequency PWM speed control allows operation of
standard brushless dc fans at low duty cycle for reduced
acoustic noise and permits the use of a very small power
transistor. The PWM time base is determined by an
external capacitor.
An open-collector overtemperature fault output is asserted
if the primary control input is driven above the normal
control range.
The MIC502 features a low-power sleep mode with a user-
determined threshold. Sleep mode completely turns off the
fan and occurs when the system is asleep or off (both
control inputs very low). A complete shutdown or reset can
also be initiated by external circuitry as desired.
The MIC502 is available as 8-pin plastic DIP and SOIC
packages in the â40°C to +85°C industrial temperature
range.
Data sheets and support documentation can be found on
Micrelâs web site at www.micrel.com.
⢠Temperature-proportional fan speed control
⢠Low-cost, efficient PWM fan drive
⢠4.5V to 13.2V IC supply range
⢠Controls any voltage fan
⢠Overtemperature detection with fault output
⢠Integrated fan startup timer
⢠Automatic user-specified sleep mode
⢠Supports low-cost NTC/PTC thermistors
⢠8-pin DIP and SOIC packages
Applications
⢠NLX and ATX power supplies
⢠Personal computers
⢠File servers
⢠Telecom and networking hardware
⢠Printers, copiers, and office equipment
⢠Instrumentation
⢠Uninterruptible power supplies
⢠Power amplifiers
___________________________________________________________________________________________________________
Typical Application
12V
T1 R1
R3 R2
R4
CF
Secondary
Fan-contro l
Input
MIC502
1 VT1 VDD 8
2 CF
OUT 7
3 VSLP OTF 6
4 GND VT2 5
Fan
RBASE
Q1
Overtemperature
Fault Output
Micrel Inc. ⢠2180 Fortune Drive ⢠San Jose, CA 95131 ⢠USA ⢠tel +1 (408) 944-0800 ⢠fax + 1 (408) 474-1000 ⢠http://www.micrel.com
November 2006
1
M9999-112206
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