MIC502 Datasheet, PDF (1/11 Pages) Micrel Semiconductor – Fan Management IC Advance Information

MIC502
MIC502
Fan Management IC
Advance Information
Micrel
General Description
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 (optionally) a sec-
ond signal, such as the NLX “FanC” 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 –40°C to +85°C industrial temperature
range.
Features
• 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
• Uninterruptable power supplies
• Power amplifiers
Ordering Information
Part Number
MIC502BN
MIC502BM
Temperature Range
–40°C to +85°C
–40°C to +85°C
Package
8-pin Plastic DIP
8-pin SOIC
Typical Application
12V
T1 R1
R3 R2
R4
C_F
Secondary
Fan-control
Input
MIC502
1 _{VT1 VDD} 8
2 _CF
OUT ⁷
3 _{VSLP OTF} 6
4 _{GND VT2} 5
R_BASE
Fan
Q1
Overtemperature
Fault Output
May 1999
163
MIC502