Miscellaneous active electrical nonlinear devices – circuits – and – Signal converting – shaping – or generating – Current driver
Patent
1993-12-20
1996-02-06
Callahan, Timothy P.
Miscellaneous active electrical nonlinear devices, circuits, and
Signal converting, shaping, or generating
Current driver
327379, 327483, 327575, 326 85, 326 87, 326 91, H03K 1704, H03K 1908
Patent
active
054898617
ABSTRACT:
An output buffer circuit with edge-rate control capable of maintaining both rising and falling edge-rates within narrow specifications in the face of wide variations in load impedance. In particular, the output buffer of the present invention is intended for coupling to a common bus whereby it may be presented with very low resistive impedance loads and varying capacitive loads. The control schemes for both the pull-up and the pull-down parts of the circuit of the present invention utilize in part fixed currents charging a selected capacitance in order to achieve a metering of the charging or discharging current at the buffer's output. For the pull-down part of the circuit a dual MOS/Bipolar pull-down scheme is used, with the MOS transistors sequentially turning on in a gradual fashion so as to smooth the onset of current sinking. Subsequently, after a measured delay, a bipolar pull-down transistor is turned on. There is also a contingent bipolar pull-down transistor to aid in switching the buffer output from logic-high to logic-low if the MOS transistors and first bipolar transistor acting together are not sufficient. Later, as current-sinking is being turned off, there is again a sequential deactivation of the pull-down transistors so as to round the turn-off curve. The dual MOS/bipolar pull-down scheme provides a degree of temperature compensation of the pulldown current and a lower output capacitance than when one type of transister is used.
REFERENCES:
patent: 3912946 (1975-10-01), Graziadei
patent: 3961206 (1976-06-01), Lau
patent: 4627081 (1986-12-01), Gay
patent: 4779014 (1988-10-01), Masuoka et al.
patent: 4845386 (1989-07-01), Ueno
patent: 5124582 (1992-06-01), Nakamura et al.
patent: 5138195 (1992-08-01), Satou et al.
patent: 5223745 (1993-06-01), Ohannes et al.
patent: 5233237 (1993-08-01), Ohannes et al.
patent: 5287021 (1994-02-01), Obregon et al.
patent: 5311077 (1994-05-01), Brown
Bohan Thomas L.
Callahan Timothy P.
Caseiro Chris A.
Englund Terry L.
National Semiconductor Corporation
LandOfFree
High power, edge controlled output buffer does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with High power, edge controlled output buffer, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and High power, edge controlled output buffer will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2177270