Abstract: A protection system for an integrated circuit is disclosed. A detection system detects an overvoltage condition and provides an overvoltage condition signal to indicate a condition in which overvoltage protection may be desired. In response to the overvoltage condition signal, one or more variable resistance devices in the system, such as power devices of associated driver circuitry, are controlled to limit the voltage across such devices.

Abstract: A circuit combination (16,86) is presented for providing digital signals indicative of slew rates of drive signals (112,140) provided to H-bridge power drive transistors (60,62,64) of motor windings (66) of a mass data storage device (10). The circuit combination includes a plurality of predriver circuits (53-55) producing predrive signals according to a commutation sequence for connection to respective the power drive transistors (60,62,64). A multiplexer (40) is connected to selectively direct at least some of the drive signals to a multiplexer output port, and a digital comparison circuit (86) receives the at least some drive signals from the multiplexer output port and produces a digital outputs (120,158) having state time changes in dependence upon rise and fall times of the predriver output signals.

Abstract: A circuit (16,86) provides digital signals indicative of slew rates of phase signals (220) of H-bridge power drive transistors (60,62,64) of motor windings (66) of a mass data storage device (10). The circuit uses up and down phase control signals (UP,DN) to initiate up and down voltage changes in the motor phase signals. A portion of the circuit (180) produces a state change in a phase status output signal (196) when the phase signal (220) is less than a supply voltage (186). A digital comparison circuit (210) compares the phase status output signal (196) and the up and down control signals (UP,DN), and produces respective rise and fall digital outputs (216,217) when the up and down phase control signals and the phase status output signal are the same. The respective rise and fall digital outputs (222,224) have state change timings that indicate rise and fall times of said motor phase signals (220).

Abstract: A circuit combination (16,86) is presented for providing digital signals indicative of slew rates of drive signals (112,140) provided to H-bridge power drive transistors (60,62,64) of motor windings (66) of a mass data storage device (10). The circuit combination includes a plurality of predriver circuits (53-55) producing predrive signals according to a commutation sequence for connection to respective the power drive transistors (60,62,64). A multiplexer (40) is connected to selectively direct at least some of the drive signals to a multiplexer output port, and a digital comparison circuit (86) receives the at least some drive signals from the multiplexer output port and produces a digital outputs (120,158) having state time changes in dependence upon rise and fall times of the predriver output signals.

Abstract: A control circuit for motor current including a circuit to generate a voltage to indicate the actual motor current, a first convert circuit to convert the voltage indicative of the motor current to a current, a compare circuit to compare the current indicating the motor current with a reference current and generate a difference current between the current indicating the motor current and the reference current, and a second convert circuit to convert the difference current to a voltage to indicate a difference in motor current from the reference current.

Abstract: A voltage to current conversion circuit is described. The circuit comprises a first differential amplifier for receiving an input voltage and producing an output voltage, and a second amplifier for converting the output voltage of the first amplifier to a current. The transfer function of the voltage to current conversion circuit is proportional to an exponential function that depends on the input voltage. The circuit is temperature and process independent. In a first preferred embodiment, the first amplifier comprises a first transistor for receiving an input voltage at its base terminal, a temperature dependent current source coupled to the emitter of the first transistor, and a positive voltage supply coupled to the collector through a diode coupled transistor, and a second transistor paired with the first transistor and having a base terminal coupled to an input voltage terminal, an emitter coupled to a temperature dependent current source, and a collector coupled to a voltage supply.

Abstract: A monolithic light-to-digital signal converter (1.10) includes a photodiode array (1.24) having a plurality of sections with each section producing a current signal in response to incident light, a current-to-digital signal converter circuit (1.28) for converting selected ones of the current signals to a digital signal, and a control circuit (1.26) for scaling the digital signal in response to user supplied programming signals. The control circuit (1.26) also responds to user supplied programming signals to supply control signals to current-to-digital signal converter circuit (1.28). Current-to-digital signal converter circuit (1.28) is responsive to the control signals for combining selected ones of the current signals into a composite current signal and converting the composite current signal to a digital signal.

Abstract: A system for driving a hard disk drive spindle motor is disclosed. The system comprises a spindle motor control circuit (120) and a spindle motor power circuit (220). The system also includes at least one disk (22) attached to a rotatable spindle (21) and a spindle motor (400) which receives power signals from the spindle motor power circuit (220) and controls the rotation of the spindle (21). The spindle motor control circuit (120) comprises a multiplexor (127) which transmits either a pulse width modulation signal or a current control signal in response to a mode selection signal, and a spindle predriver (125) which receives the multiplexor output signal and transmits spindle motor control signals to the spindle motor power circuit (220).