Abstract: Fault detection circuitry is provided for a PWM driver responsive to a PWM input signal to produce a PWM output signal, and includes a first circuit producing a scaled switching signal as a scaled representation of the PWM input signal. A second circuit is configured to produce a combined switching signal as a combination of the PWM output signal and the scaled switching signal, and a third circuit is configured to convert the combined switching signal to an analog output signal indicative of one or more fault conditions associated with the PWM driver. A number of comparators may be included with each responsive to the analog output signal and to a different one of a corresponding number of different references voltages, to produce a fault signal indicative of a particular one of the one or more fault conditions.

Abstract: Fault detection circuitry is provided for a PWM driver responsive to a PWM input signal to produce a PWM output signal, and includes a first circuit producing a scaled switching signal as a scaled representation of the PWM input signal. A second circuit is configured to produce a combined switching signal as a combination of the PWM output signal and the scaled switching signal, and a third circuit is configured to convert the combined switching signal to an analog output signal indicative of one or more fault conditions associated with the PWM driver. A number of comparators may be included with each responsive to the analog output signal and to a different one of a corresponding number of different references voltages, to produce a fault signal indicative of a particular one of the one or more fault conditions.

Abstract: A boost supply has an inductor coupled to supply voltage and connected to ground through a charging switch and connected through a diode to charge a storage capacitor when the switch is open to attain a boost voltage higher than supply voltage. A clock for controlling the switch operation is an astable circuit having an operational amplifier with an RC timing feedback to one input and a hysteresis feedback to the other input. The hysteresis circuit includes a resistor coupled at one end to a reference voltage and through a diode to the amplifier output. This circuit has an increasing frequency with increasing supply voltage to reduce switch closed time and limit the increase of inductor current to safe levels.

Abstract: A motor driver interface (MDI) circuit for an H-bridge electric motor drive apparatus is responsive to an enable signal to turn off all switching transistors in a not enabled mode and turn on the upper bridge transistors in an enabled mode and includes large resistors, sufficiently large to prevent motor activation therethrough, from the motor terminals to the power supply terminals to establish a bias voltage in the not enabled mode. Fault detection apparatus compares the voltages at the motor terminals with a first reference voltage apparatus in the not enabled mode and a second reference voltage apparatus in the enabled mode in response to the enable signal.

Abstract: A control for an inductive load switches current on and off to regulate about a command value, a decaying recirculation current flowing through the load during the switch off periods. The current is sensed during the switch on periods and charges a capacitor to provide a simulation signal representing the motor current. The capacitor is allowed to discharge through a resistor during the switch off periods at the rate of the decaying recirculation current. The simulation signal is compared to the command value to control the switching. The simulation signal is sensed during a command value of zero current to determine offset errors for calibration purposes.

Abstract: In a television receiver, a non-saturating kinescope driver amplifier arrangement includes an input current limiter circuit coupled between a source of video signal and a current responsive signal input of a feedback kinescope driver amplifier. The limiter circuit, e.g., including a diode limiter, limits the magnitude of input signal currents applied to the current input of the amplifier to prevent the amplifier from exhibiting a saturated conductive state.

Abstract: A television receiver with a planar faceplate kinescope includes an automatic kinescope bias (AKB) control system wherein the kinescope electron gun is energized to induce a cathode output current, representative of the kinescope black image current level, in response to an auxiliary drive signal applied to the electron gun during AKB operating intervals. The auxiliary signal exhibits an amplitude for inducing the cathode current only during horizontal trace intervals encompassed by the interval when the auxiliary signal occurrs.

Abstract: In a television receiver, the bias of the G2 screen grid of an image displaying kinescope is adjusted to produce a black level condition for the kinescope. Prior to adjusting the screen grid bias, the normal bias voltage of both the cathode and G1 grid electrodes of the kinescope are modified to produce a predetermined cathode-to-G1 grid voltage.

Abstract: In an automatic kinescope bias (AKB) control system for a television receiver, a voltage representative of kinescope bias is derived from a sensing point coupled to the television signal processing channel and to AKB signal processing circuits. A switching network attenuates large white-going television signal amplitude components at the sensing point during picture information intervals, to preclude sense point voltage levels which could otherwise ultimately disrupt the operation of the AKB signal processing circuits during AKB operating intervals.

Abstract: A kinescope driver amplifier comprises a resistive feedback network coupled from the output to the input of the amplifier. The feedback network includes first and second series resistor of mutually different values. The larger value resistor is connected to amplifier output, and the smaller value resistor is connected to the amplifier input.

Abstract: In an automatic kinescope bias (AKB) control system, a signal with a magnitude representative of the black current level conducted by the kinescope of a television receiver is derived from a sense point. The derived signal is coupled via a signal path to a processing network including input clamping and sampling networks for developing a bias correction voltage. A source of auxiliary control signal, coupled to the signal path prior to the clamping network, is subject to being undesirably influenced by impedance variations manifested by the sense point. An impedance included in the signal path between the sense point and the auxiliary signal source compensates for the sense point impedance variations, and also increases the immunity of the clamping network to spurious signals including noise and locally generated interference.

Abstract: An automatic kinescope bias (AKB) control system for a television receiver operates in response to an enabling timing signal for maintaining a desired level of kinescope blanking current. The timing signal is applied to a control input of the AKB system via a timing signal coupling path. The timing signal input to the AKB system is inhibited for a given time interval after the receiver is initially energized, to delay AKB action until the kinescope has reached a desired operating temperature. The timing signal is inhibited by means of a control network coupled to the timing signal path. The given time interval is determined by a time constant circuit which is associated with the control network and which is substantially insensitive to the amplitude, and duty cycle of the timing signal.

Abstract: A television receiver includes a DC coupled video output amplifier for supplying video signals to the cathode of an image reproducing kinescope, and an automatic kinescope bias (AKB) control system for maintaining a desired cathode black image current level. A video processor supplies video signals to the output amplifier via an input network including a manually adjustable resistor for pre-setting the amplifier gain. During AKB operating intervals, a substantially zero voltage drop is maintained across the adjustable gain control resistor so that the setting of the adjustable gain control resistor desirably has no influence on the kinescope cathode bias voltage monitored by the AKB system.