Chik Yam Lee

Bio: Chik Yam Lee is an academic researcher from International Rectifier. The author has contributed to research in topics: Voltage & Electronic circuit. The author has an hindex of 4, co-authored 7 publications receiving 420 citations.

H-bridge drive utilizing a pair of high and low side MOSFET's in a common insulation housing

Abstract: A fully protected H-bridge for a d-c motor consists of two high side MOSFETs and a control and logic IC on a first conductive heat sink all within a first package and two discrete low side MOSFETs. The entire bridge is controlled by the IC. Shoot thru protection is provided for each leg, and a PMW soft start sequence is provided through the control of the low side MOSFETs, programed by an external, chargeable RC circuit. Input signals to the high side MOSFETs select the operation modes. Protective circuits are provided for short circuit current and over current conditions. Sleep mode and braking/non braking control is also provided.

High side power switch with charge pump and bootstrap capacitor

Abstract: A power switching circuit (10) comprising a power semiconductor switching device (Q1), a charge pump circuit (CHP) having a control input to control whether it is on or off and a charge pump output, the charge pump output being coupled to a control terminal of the power semiconductor switching device, a bootstrap power supply for supplying power to driver circuitry for the power semiconductor switching device, the bootstrap power supply comprising a bootstrap capacitor (CBS) coupled to a charging current source, the bootstrap power supply providing power to the driver circuitry when the power semiconductor switching device is being switched by the driver circuitry in a pulsed mode, and the charge pump (CHP) supplying a control voltage to turn on the power semiconductor switching device (Q1).

Temperature compensated bandgap voltage reference

Abstract: A bandgap voltage reference circuit comprising a first circuit providing a first voltage substantially proportional to Vbc of a first bipolar transistor, a second circuit providing a second voltage ΔVbc substantially proportional to the difference of two Vbc voltages of two bipolar transistors, and a comparator having respective inputs coupled to Vbe and ΔVbe and an output coupled to the base of the first bipolar transistor whereby a voltage substantially proportional to the sum of respective constants multiplying Vbe and ΔVbe is provided at the output of the comparator.

Mosfet gate driver with a negative gate bias voltage

Abstract: A circuit for preventing shoot-through in a high side switching transistor coupled in series with a low side switching transistor across a supply voltage, the circuit comprising a voltage reference circuit having an output providing a reference voltage which is negative with respect to the supply voltage provided to the high side switching transistor, the reference voltage being applied to the control electrode of the high side switching transistor when the high side switching transistor is off and the source of the high side switching transistor exceeds the reference voltage and the low side switching transistor is on.

MOSFET gate driver circuit

Abstract: Gate drive circuit for preventing strike-through in a high side switching transistor (M1) connected in series with a low side switching transistor (M2) is connected across a supply voltage (Vdd), characterized by a reference voltage circuit (10) having an output, a reference voltage (Vn) delivers, which is always less than the supply voltage (Vdd) corresponding to the high side switching transistor (M1) is supplied with the reference voltage (Vn) is supplied to the control electrode of the high side switch transistor (M1) when the high side switch transistor (M1) the source terminal of the high side switch transistor (M1) is turned off, has a voltage that is greater than the reference voltage and the low side switching transistor (M2) is turned on.

Display screen or portion thereof with graphical user interface

Abstract: Newness and distinctiveness is claimed in the features of ornamentation as shown inside the broken line circle in the accompanying representation.

Surgical stapling instrument with an articulatable end effector

Abstract: A surgical instrument can comprise a channel configured to support a staple cartridge and, in addition, an anvil pivotable between open and closed positions relative to the channel. The surgical instrument can further comprise a cutting member configured to incise tissue positioned captured between the staple cartridge and the anvil and, in addition, means for stopping the cutting member prior to a distal end datum, wherein the distal end datum can be defined by the distal-most staple cavity in the staple cartridge. In such embodiments, the incision within the tissue may not extend beyond the portion of the tissue that has been stapled.

Articulating surgical stapling instrument incorporating a two-piece e-beam firing mechanism

Abstract: A surgical severing and stapling instrument, suitable for laparoscopic and endoscopic clinical procedures, clamps tissue within an end effector of an elongate channel pivotally opposed by an anvil. An E-beam firing bar moves distally through the clamped end effector to sever tissue and to drive staples on each side of the cut. The E-beam firing bar affirmatively spaces the anvil from the elongate channel to assure properly formed closed staples, especially when an amount of tissue is clamped that is inadequate to space the end effector. In particular, an upper pin of the firing bar longitudinally moves through an anvil slot and a channel slot is captured between a lower cap and a middle pin of the firing bar to assure a minimum spacing. Forming the E-beam from a thickened distal portion and a thinned proximal strip enhances manufacturability and facilitates use in such articulating surgical instruments.

Powered surgical instrument

Abstract: A surgical instrument including a handle assembly, a first endoscopic portion, a motor, and a first end effector is disclosed. The first endoscopic portion is selectively connectable to a distal portion of the handle assembly and defines a longitudinal axis. The first endoscopic portion includes a housing adjacent its proximal portion and includes an actuation member. The motor is disposed in mechanical cooperation with the housing of the first endoscopic portion and is operatively connected to the actuation member for moving the actuation member substantially along the longitudinal axis. The first end effector is selectively connectable to a distal portion of the first endoscopic portion and is configured to perform a first stapling function.

Motor-driven surgical cutting and fastening instrument with tactile position feedback

Abstract: A surgical cutting and fastening instrument is disclosed. According to various embodiments, the instrument includes an end effector comprising an elongate channel, a clamping member pivotably connected to the channel, and a moveable cutting instrument for traversing the channel to cut an object clamped in the end effector by the clamping member when the clamping member is in a clamped position. The instrument may also comprise a main drive shaft assembly for actuating the cutting instrument in the end effector, a gear drive train connected to the main drive shaft assembly, and a motor for actuating the gear drive train. The instrument may also includes a closure trigger and a firing trigger, separate from the closure trigger, for actuating the motor when the firing trigger is retracted. Also, the instrument may comprise a mechanical closure system connected to the closure trigger and to the clamping member for causing the clamping member to pivot to the clamped position when the closure trigger is retracted.