TC643

TC643 INTEGRATED FAN / MOTOR DRIVER FEATURES s Integrates Current Limited Power Driver and Diagnostic/Monitoring Circuits in a Single IC s Works with Standard DC Brushless Fans/Motors s Supports Efficient PWM Drive with Logic-Level Input s Supply Range ........................................ 2.7V to 5.5V s Motor Voltage Independent of TC643 Supply Voltage; Supports 3V-15V Fans! s Logic-Level Output Provides RPM Data s Optimized For Use as a Microcontroller Peripheral s Eliminates Discrete Components and Analog Circuit Design Effort s Internal Thermal Shutdown For Fail-safe Operation s Available in 8-Pin PDIP, SOIC, and MSOP Packaging APPLICATIONS s General Purpose Fan or Motor Speed Control s Power Supplies s Portable and Desktop Computers s Telecom Equipment, Servers s UPS’s, Power Amps, etc. FUNCTIONAL BLOCK DIAGRAM RPM CEXT 0.002µF DRV ONESHOT dV/dt DRIVER VFAN +5V VCC FAN FAN – + ILMT I-LIMIT TC643 VREF GNDFAN GND GENERAL DESCRIPTION The TC643 is a switchmode brushless DC fan/motor speed driver with diagnostic circuits. External components are kept to a minimum by integrating the power transistor on chip. Any logic-level signal can be used to drive the on-chip Power Driver. The output is current limited and a logic-level indication, ILMT, is provided to indicate an over-current condition. The RPM output gives an indication of motor RPM. Each time the motor current is interrupted by commutation, a logic pulse occurs on RPM. The fundamental frequency of the...