MIC502 Micrel Semiconductor, MIC502 Datasheet
MIC502
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MIC502 Summary of contents
Page 1
... 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) ...
Page 2
... Driver Output: Asymmetical-drive active-high complimentary PWM output. Typically connect to base of external NPN motor control transistor. Power Supply (Input): IC supply input; may be independent of fan power supply. 164 and V T1 the MIC502 enters sleep mode until Grounding VSLP SLP HYST DD > when active. ...
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... Min Typ 0.5 DD 240 = 0 TBD TBD 0 –2 guarantee reset 0 64/f Micrel DD Max Units 1.2 mA 400 0 MIC502 ...
Page 4
... Note E. Both V and V decrease below Note F. The PWM ‘wakes up’ because one of the control inputs (V high for 64 clock periods. (V WAKE Note G. Following the startup interval, the PWM duty-cycle is the higher of V MIC502 Condition I = 2mA /OTF and 12V, respectively. . ...
Page 5
... Figure 2. MIC502 Typical Power-Up System Behavior Note H. At power-on, the startup timer forces OUT on for 64 PWM cycles of the internal timebase (t dead stop. Note I. The PWM duty-cycle follows the higher of V Note J. The PWM duty-cycle follows increases. ...
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... MIC502 Typical Characteristics Functional Diagram VT2 5 VT1 VSLP 3 VDD 8 MIC502 PWM Frequency vs. Timing Capacitor Value 3000 1000 100 10 1 0.001 0.01 0.1 1 CAPACITANCE ( F) PWM CLK Start-Up Timer RESET Oscillator Sleep Power-On Reset Reset V IL Overtemperature 4 GND 168 Driver OUT 7 OUT Sleep Control ...
Page 7
... Characteristics”). It is optimized for directly driving an NPN transistor switch in the fan’s ground-return. See “Applications Information” for circuit details. Shutdown/Reset Internal circuitry automatically performs a reset of the MIC502 when power is applied. The MIC502 may be shut down at any time by forcing V below its V threshold. This is typically T1 ...
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... MIC502 Sleep Mode During normal operation and V . Exceptions to device will go into sleep mode and fan operation will stop. The T2 MIC502 will exit sleep mode when overtemperature by the hysteresis voltage initiating a device operation will resume. The resumption of normal operation IL ...
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... Making use of the Overtemperature Fault Output. Temperature Sensor Selection Temperature sensor negative temperature coefficient (NTC) thermistor. The MIC502 can be interfaced with either a negative or positive tempco thermistor; however, a nega- tive temperature coefficient thermistor typically costs less than its equivalent positive tempco counterpart. While a ...
Page 10
... FanC 12V. This FanC signal can be applied directly to the for VT2 input of the MIC502, but only when its V signal is required when the MIC502 V divider is necessary to reduce this input voltage so it does not is about 30% ...
Page 11
... BASE triggering a power supply crowbar circuit MIC502 is 5V the output should not be pulled to a higher voltage. This output can sink up to 2mA and remain compat- ible with the TTL logic-low level. – exist for 5V vs. ...