Motorola Corporation

Rene M Delgado

Seshagiri Prasad Kalluri

William J Ooms

Clifford D Leitch

James B Eifert

Jules D Campbell, Jr

Carl Lynn Shurboff

Gianfranco Gerosa

Steve Lim

Method and apparatus for reducing the time required to test an integrated circuit (10) using slew rate control. Using a very slow slew rate during normal operation may reduce electromagnetic interference, while using a faster slew rate during testing may reduce the test costs. In one embodiment, terminal control circuitry (40) includes a fast test control bit (50) to select a slow slew rate during normal operation, to select a faster slew rate during functional testing, and to optionally select a variety of slew rates during a special test to more fully characterize the behavior of integrated circuit (10). In one embodiment, each pre-driver circuit (80, 81) includes a low resistance device (61, 63) which may be selectively enabled or disabled to join with capacitors (66, 67) in output driver (82) to affect the slew rate of the signal driven as an output by integrated circuit terminal (83).

Method and apparatus for reducing the time required to test an

Method and apparatus for selectively enabling a pull device coupled to a multiplexed terminal connector based on the function of the terminal connector. When the terminal functions as a general purpose input/output (GPIO), the pull device is enabled on reset or on setting a control bit. For operation as a data port, the pull device is disabled, and on reset the pull device is enabled only after any pending data transaction has completed. Upon completion of the reset period the pull device is again disabled for data port operation. In one embodiment, a terminal has a first interruptible function and a second uninterruptible function. The terminal is coupled to a pull device and control logic. If the second function is active, the control logic enables the pull device with a time delay sufficient that the second function is completed prior to the enabling of the pull device.

Integrated circuit having programmable pull device configured to

An output buffer (30) is connected to an output signal line and receives an internal power supply voltage, for example 3.3 volts, which is lower than a voltage, for example 5 volts, that other devices which may be connected to the output signal line are able to drive. To protect an output transistor (71) from the harmful effects of the higher voltages on the output signal line, the output buffer (30) includes a special bulk biasing circuit (80). The bulk biasing circuit (80) biases the bulk of the output transistor (71) at an internal power supply voltage when the output buffer is driving and when not driving to a voltage determined by the output signal. To prevent overlap currents, the output buffer (30) includes a special gate biasing circuit (100), which momentarily drives the gate of the output transistor (71) to a voltage equal to the internal power supply voltage when the output buffer (30) stops driving.

High reliability output buffer for multiple voltage system

A divider circuit for producing a quotient result within one cycle time is provided. The invention utilizes combinational circuitry for performing a division operation by computing a scaled reciprocal of the denominator, and multiplying the scaled output by a similarly scaled numerator. The denominator is scaled such that it falls within a predetermined range, and the reciprocal value may be looked up from a memory device such as a ROM. The output of the multiplier may also be scaled in order to produce the desired result. The resulting quotient has a controlled error over a wide range of numerator and denominator input values.

Method and apparatus for obtaining the quotient of two numbers within

An output buffer integrated circuit, including an output signal, is provided having an improved Vdd and Vss noise characteristics. The output buffer comprise a plurality of pull-up stages and pull-down stages functioning as complementary pairs. The pull-up stage pulls the output signal to the Vdd potential, and the pull-down stages pulls the output to the Vss potential. Each stage provides a pulling signal to turn on a pulling transistor in response to the pulling signal of the previous stage. The first pulling stage provides the pulling signal in response to the input signal. Each stage sequentially pulls the output signal within a substantially constant time. The constant time delay within each stage is provided by sizing the width of the active elements on the integrated circuit. The pulling stages turn off the pulling transistors instantaneously in response to the invert of the input signal.

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Austin, TX, United States of America

Rene M Delgado