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TC649VUA Fiches technique(PDF) 6 Page - Microchip Technology |
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TC649VUA Fiches technique(HTML) 6 Page - Microchip Technology |
6 / 28 page TC649 DS21449C-page 6 2002 Microchip Technology Inc. FIGURE 3-1: TC649 Nominal Operation. 3.7 Shutdown Mode (RESET) If an unconditional shutdown and/or device reset is desired, the TC649 may be placed in shutdown mode by forcing VIN to a logic low (i.e., VIN < VSHDN) (see Figure 3-1). In this mode, all functions cease and the FAULT output is unconditionally inactive. The TC649 should not be shut down unless all heat producing activ- ity in the system is at a negligible level. The TC649 exits shutdown mode when VIN becomes greater than VREL, the release voltage. Entering shutdown mode also performs a complete device reset. Shutdown mode resets the TC649 into its power-up state. The Start-up and Fault Timers and any current faults are cleared. FAULT is unconditionally inactive in shutdown mode. Upon exiting shutdown mode (VIN > VREL), the Start-up Timer will be triggered and normal operation will resume, assuming no fault conditions exist and VIN > (VAS + VHAS). If a fan fault has occurred and the device has latched itself into shutdown mode, performing a reset will not clear the fault unless VIN > (VAS + VHAS). If VIN is not greater than VAS + VHAS upon exiting shutdown mode, the fan will not be restarted, and there will be no way to establish that the fan fault has been cleared. To ensure that a complete reset takes place, the user’s circuitry must ensure that VIN > (VAS + VHAS) when the device is released from shutdown mode. A recommended algorithm for management of the TC649 by a host microcontroller or other external circuitry is given in Section 5.0, “Typical Applications”. A small amount of hysteresis, typically one percent of VDD (50mV at VDD = 5.0V), is designed into the VSHDN/VREL threshold. The levels specified for VSHDN and VREL in Section 1.0, “Electrical Characteristics”, include this hysteresis plus adequate margin to account for normal variations in the absolute value of the threshold and hysteresis. 2.6V VAS + VHAS VIN tRESET VREL VSHDN VAS 1.2V TC649 Status Normal Operation Auto-Shutdown Mode Normal Operation Shut- Down Normal Operation GND TIME TEMP. HI LO Note: If VIN < VAS when the device exits shut- down mode, the fan will not restart, but will be in auto-shutdown mode. CAUTION: The fan will remain off as long as the VIN pin is being held low or VIN < VAS+ VHAS. |
Numéro de pièce similaire - TC649VUA |
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Description similaire - TC649VUA |
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