Abstract: An output CMOS buffer includes MOS enhancement transistors and has a second complementary pair of natural or low threshold transistors, connected respectively in parallel to transistors of opposite type of conductivity of the complementary pair of enhancement MOS transistors of the final buffer stage. The gate terminals of the pair of natural or low threshold transistors are controlled by respective inverters, each supplied through a slew rate limiter of the slope of the driving current and are respectively connected between the positive supply node of the output buffer and a negative (below ground potential) node and between the common ground node of the output buffer and a positive supply node. The negative voltage and the positive voltage on the nodes are at least equal to the absolute value of the threshold voltage of the natural or low threshold transistors.

Abstract: Various apparatuses, methods and systems for switched mode electronic circuits with reduced EMI are disclosed herein. For example, some embodiments of the present invention provide apparatuses including a power supply, an output, and a composite switch connected between the power supply and the output. The composite switch includes a plurality of transistors connected in parallel, a switch closing delay line having a plurality of switch closing outputs each connected to a control input of one of the plurality of transistors, and a switch opening delay line having a plurality of switch opening outputs each connected to one of the plurality of switch closing outputs. The switch closing delay line and switch opening delay line are connected in an order that opens the plurality of transistors in a staggered order in time and closes the plurality of transistors in a reverse staggered order in time.

Abstract: An impedance buffer has a single comparator with a first input and a second input. A first leg has a first pull-up array in series with a reference resistor. The first input of the single comparator is electrically coupled to a node between the first pull up array and the reference resistor. A second leg has a second pull-up array in series with a pull-down array. The second leg is coupled through a switch to the second input of the single comparator.

Abstract: An integrated circuit device includes a high-speed serial interface circuit that includes a receiver circuit that receives differential signals through a serial bus, first and second guard terminals that prevent radiation, first and second terminals that are disposed between the first and second guard terminals and receive the differential signals, a first power supply terminal to which a high-voltage-side power supply voltage for the receiver circuit is supplied, and a second power supply terminal to which a low-voltage-side power supply voltage is supplied. A first switch element is provided between a line from the first guard terminal and a line from the second power supply terminal, and a second switch element is provided between a line from the second guard terminal and a line from the second power supply terminal. The first and second switch elements are turned ON in a high-speed serial interface mode.

Abstract: An off-chip driver (OCD) includes: a logic circuit, for providing a logic signal input; a pre-driver stage, coupled to the logic circuit, for providing a ramped up voltage in response to the logic signal input; a final driver stage, coupled to the pre-driver stage, for providing an output voltage in response to the ramped up voltage; and a bias circuit, coupled to the pre-driver stage, for providing a constant bias voltage to the pre-driver stage, wherein the constant bias voltage keeps the pre-driver stage within an operational range to compensate for variations in process, temperature and supply voltage.

Abstract: Disclosed is an impedance adjustment circuit including a comparator and a resistor control circuit. The comparator compares the resistance value of an external resistor and that of a replica resistor that forms a replica of a terminal resistor. The resistor control circuit includes a replica resistor control counter, a resistor-under-adjustment control signal holding circuit and a monitor circuit. The replica resistor control counter counts up and down based on the comparison result by the comparator to output a control signal to the replica resistor. The resistor-under-adjustment control signal holding circuit holds a control signal that is delivered to the terminal resistor.

Abstract: A system including a preemphasis driver circuit and a method. One embodiment includes an output terminal, a main driver coupled between the input terminal and the output terminal and an auxiliary driver coupled to the output terminal, wherein at least one unclocked delay element is coupled between the input terminal and the auxiliary driver.

Abstract: A floating driving circuit according to the present invention comprises an input circuit to receive an input signal. A latch circuit receives a trigger signal for generating a latch signal. The latch signal is used to turn on/off a switch. A coupling capacitor is connected between the input circuit and the latch circuit to generate the trigger signal in response to the input signal. A diode is connected from a voltage source to a floating supply terminal of the latch circuit for charging a capacitor. The capacitor is coupled between the floating supply terminal and a floating ground terminal of the latch circuit to provide a supply voltage to the latch circuit. The latch circuit is controlled by the input signal via the coupling capacitor.

Abstract: An active-load dominant circuit for common-mode glitch interference cancellation, biased between a first voltage potential and a second voltage potential with an accompanying common-mode glitch interferer. The active-load dominant circuit includes a pair of pull-up networks and a pair of active-load networks. The common-mode glitch interferer is cancelled out due to a symmetric structure of the pair of pull-up networks. At least one set signal and at least one reset signal are provided to a latch in response to a clock signal or a complemented clock signal. At least one of the set signal and the reset signal can be pulled up to the first voltage potential or pulled down to the second voltage potential. The voltage difference of the set signal and the reset signal is large enough for a latch.

Abstract: A data output driving circuit for a semiconductor apparatus can include a code multiplier configured to multiply a received first code by a multiplication factor determined in response to a control signal and generating a second code; a signal line configured to transmit the second code; and a plurality of data output drivers commonly connected to the signal line and changed in an impedance thereof in response to the second code.

Abstract: An interface driver circuit includes a plurality of delay cells. Each delay cell includes a data input, a delayed data output configured to communicate with the data input of an adjacent one of the plurality of delay cells. A delay time input is configured to set a delay value between receiving data at the data input and generating the delayed data output. A plurality of predrivers is configured to receive an output enable signal. A plurality of predrivers is configured to receive a corresponding one of the plurality of delayed data outputs. A plurality of predrivers is configured to generate a predriver output signal based on the output enable signal and the corresponding one of the plurality of delayed data outputs. The output enable signal enables and disables the plurality of predrivers and is independent of data of each delayed data output.

Abstract: Differential signal output nodes of a novel CML buffer are DC-coupled by contiguous conductors to the differential signal input nodes of a load (for example, a CML logic element). The CML buffer includes a pulldown load latch that increases buffer transconductance and that provides a DC bias voltage across the conductors and onto the input nodes of the load, thereby obviating the need for the load to have DC biasing circuitry. Capacitors of a conventional AC coupling between buffer and load are not needed, thereby reducing the amount of die area needed to realize the circuit and thereby reducing the capacitance of the buffer-to-load connections. Switching power consumption is low due to the low capacitance buffer-to-load connections. Differential signals can be communicated from buffer to load over a wide frequency range of from less than five kilohertz to more than one gigahertz with less than fifty percent signal attenuation.

Abstract: An output driver of a semiconductor memory apparatus comprises a voltage dividing block configured to generate divide voltages by dividing an internal voltage, a threshold voltage detecting block configured to generate a detecting voltage corresponding to a change in a threshold voltage of a transistor, a drive capability control signal generating block 300 configured to generate a compare signal by comparing the levels of the detecting voltage with the divide voltage and generate a control signal in response to an input signal when the compare signal is enabled, and a drive capability controlling block comprising a driver configured to perform a driving operation in response to the input signal, and a control driver configured to perform a driving operation in response to the control signal.

Abstract: The configurations of an output preset circuit for an output driver circuit and the controlling methods thereof are provided. The proposed output preset circuit includes a latch generating an latch output signal and a pull-up circuit receiving an preset enable signal and the latch output signal, in which the pull-up circuit increases an output voltage of the output driver circuit from a ground level to a first level when the preset enable signal is at a low level and the latch output signal is at the high level.

Abstract: Stacked inverter delay chains. In accordance with a first embodiment of the present invention, a series stack of two p-type devices is coupled to a series stack of three n-type devices, forming a stacked inverter comprising desirable delay, die area and power characteristics. Two stacked inverters are coupled together to form a stacked inverter delay chain that is more efficient in terms of die area, active and passive power consumption than conventional delay chains comprising conventional inverters.

Abstract: An interface detecting circuit and interface detecting method are provided, whereby operations can be carried out depending on peripheral devices connected to USB terminals, and whereby the system can be simplified and software load can be reduced. A pull-down resistor is connected to an ID terminal of a Mini-A receptacle of a peripheral device, the voltage generated by the pull-down resistor, which is pulled down by the ID terminal of the Mini-A receptacle of the peripheral device, and a pull-up resistor, which is pulled up by the ID terminal of a Mini-B receptacle of a device, is detected in an analog fashion, using a detecting section comprised of comparators, and, via a logic section, a logic output is subjected to noise cancellation in a filter section and is memorized in a register section. The operations of other devices are determined according to the states memorized in the register section.

Abstract: Source transistor configurations are described for reducing leakage and delay within integrated circuits. Virtual power and ground nodes are supported with the use of stacked transistor configurations, such as a two transistor stack between a first virtual supply connection and VSS, and a second virtual supply connection and VDD. Gate drives of these stacked transistors are modulated with different voltage levels in response to the operating power mode of the circuit, for example active mode, active-standby mode, and deep power-down mode. Means for driving these source stacks are described. In one embodiment separate virtual nodes are adapted for different types of circuits, such as buffers, row address strobe, and column address strobe. Other techniques, such as directional placement of the transistors is also described.

Abstract: An advanced repeater with duty cycle adjustment. In accordance with a first embodiment of the present invention, an advanced repeater includes an output stage for driving an output signal line responsive to an input signal and a plurality of active devices for selectably adjusting a duty cycle of the signal. The advanced repeater may further include circuitry for producing a delayed version of the signal.

Abstract: A booster circuit for reducing the nominal latency of a logic gate. The booster circuit includes a charge sharing mechanism to transfer a stored charge to the output of the logic gate in response to a logic state transition on the input of the logic gate. The transfer of stored charge also reduces the charge drawn from the supply during the output transition.

Abstract: In an output buffer circuit including Inverter 1 to Inverter 3, Delay Circuit 1 to Delay Circuit 3 for delaying an input signal for a specific time, Buffer 1 to Buffer 3, and a function for transmitting a logic signal to a transmission path and in accordance with an amount of signal attenuation in the transmission path, creating at a transmission side a waveform including four or more kinds of signal voltages, the preemphasis amount is made variable and the ON resistance Rs of the buffer is made constant. Selector circuit 1 to Selector circuit 3 are situated before the buffers, the inverter, capable of selecting through selector logic a signal to be inputted to the buffer, inverts a data signal, and the preemphasis amount and the number of preemphasis taps are adjusted through a selection signal for the selector logic.

Abstract: A bi-directional buffer is connected between a first node and a second node, wherein the first node is connected by a first pull-up resistor to a first voltage supply rail, and the second node is connected by a second pull-up resistor to a second voltage supply rail. In an embodiment, the bi-directional buffer is enabled when a voltage of the first node does not exceed a first threshold voltage, and/or a voltage of the second node does not exceed a second threshold voltage. However, when the voltage of the first node exceeds the first threshold voltage, and the voltage of the second node exceeds the second threshold voltage, the bi-directional buffer is disabled, which disconnects the first and second nodes. This allows the first node to be pulled up to the first voltage supply rail, and the second node to be pulled up to the second voltage supply rail.

Abstract: A calibration circuit of an on-die termination device includes a code generating unit configured to receive a voltage of a calibration node and a reference voltage, to generate calibration codes. The calibration unit also includes a calibration resistor unit having parallel resistors which are turned on/off in response to each of the calibration codes and connected to the calibration node, a turn-on strength of at least one of the parallel resistors being controlled by a control signal.

Abstract: Aspects of the disclosure provide a fine tunable digital delay circuit that can be applied in a high frequency digital circuit. Further, the digital delay circuit can utilize a level restoring technique to enable a wide tunable delay range. The delay circuit can include a delay element configured to receive an input signal at an input node and output a controlled signal having a controlled rise time and a controlled fall time at a controlled node, a first plurality of transistors configured to bias a supply node of the delay element to govern the controlled rise time of the controlled signal, and a second plurality of transistors configured to bias a ground node of the delay element to govern the controlled fall time of the controlled signal. The delay circuit can further include a restoring circuit configured to charge or discharge the controlled node.

Abstract: Techniques are provided for controlling an on-chip termination (OCT) in an output driver. The OCT control circuit calibrates the effective resistance of transistors in the output driver to match an external resistor using a feedback loop. The feedback loop monitors the output voltage and generates an analog calibration signal that varies the output impedance of a selected group of the output transistors that are enabled to drive the output terminal. Digital signals under the control of the user select the number of output transistors to be enabled based on the output driver requirements of the circuit. The analog calibration signal varies the signal level driving the selected output transistors to modify the effective output impedance of the circuit for better termination matching.

Abstract: A semiconductor memory device is provided. The device includes an on die termination circuit controlling a termination resistance value by detecting a phase change of a signal inputted through a pad. Additionally, the on die termination circuit changes the termination resistance value when an identical phase signal is inputted during n (n is positive integer) periods of a clock signal.

Abstract: At least one of the disclosed systems includes driver logic that is capable of driving a device and pre-driver logic coupled to the driver logic and that drives the driver logic. If the pre-driver logic receives an input signal of a first type, the pre-driver logic activates a first transistor such that the pre-driver logic provides an output signal. If the pre-driver logic receives an input signal of a second type, the pre-driver logic activates a second transistor and a third transistor that together cause the pre-driver logic to provide a different output signal. If the third transistor is not activated, the pre-driver logic provides the output signal.

Abstract: A low-impedance output stage which operates from a low voltage power supply. In an embodiment, the output stage contains an operational amplifier and two PMOS transistors used in a feedback configuration resulting in low output impedance. The output stage may also include a capacitor connected between the output terminal of the output stage and the input of the PMOS transistor providing the output, resulting in an overall output impedance which remains low even at higher frequencies, thus enabling use of the output stage to drive capacitive loads without causing resonance.

Abstract: A semiconductor memory device has a data output device. The data output device is provided with a slew rate control unit for detecting the number of transitions of a plurality of output data to output slew rate control information; and an output driving unit for driving the plurality of output data with a pull-up drivability and a pull-down drivability adjusted based on the slew rate control information.

Abstract: Methods and corresponding systems for buffering an input signal include outputting a first logic value in response to the input signal being below a lower threshold. A second logic value is output in response to the input signal rising above the lower threshold. Thereafter, the second logic value is maintained until the input exceeds a higher threshold and thereafter falls below the higher threshold. In response to the input signal falling below the higher threshold, the first logic value is output, and maintained at the first logic value, until the input falls below the lower threshold and thereafter rises above the lower threshold.

Abstract: A delay circuit includes: a current control circuit which has n (n is 1 or larger natural number) control pins and a first output line, and is capable of controlling current outputted from the first output line in response to n control signals inputted to the corresponding n control pins; a current mirror circuit connected with the first output line to produce current mirror current from the current and output the current mirror current from a second output line; a first active element having a gate pin and an input pin, the gate pin is connected with the second output line, and the input pin is connected with the first voltage line; a second active element having a gate pin and an input pin, the gate pin is connected with the first output line, and the input pin is connected with the second voltage line; and an inverter circuit having third and fourth active elements connected in series between an output pin of the first active element and an output pin of the second active element.

Abstract: Data transmitter includes a first and second output nodes terminated to a first level, a controller configured to generate an off signal that is activated by logically combining first and second data during a low-power mode, a first driver configured to drive the first or second output node to a second level in response to the first data and a second driver configured to drive the first or second output node to the second level with a driving force different from that of the first driver in response to the second data, the second driver being turned off when the off signal is activated.

Abstract: A line driver circuit for stabilizing a signal that is output through a transmission line, wherein the line driver circuit receives a first signal having a first swing width corresponding to a difference between a first voltage and a second voltage, creates a second signal having a second swing width less than the first swing width, and outputs the second signal through a transmission line. The line driver circuit includes: a pull-up circuit that pulls up the second signal to a high level; a pull-down circuit that is connected to the pull-up circuit and pulls down the second signal to a low level; and an initializing circuit that is connected to a node of the transmission line, outputs a signal having a voltage of the low level or the high level to the node of the transmission line, and initializes the voltage at the node of the transmission line to the low level or the high level.

Abstract: A power switching circuit in CMOS technology has a power MOS transistor and a driver stage. The power MOS transistor is operated at a higher supply voltage in excess of its maximum allowable gate-source voltage; and the driver stage of the level shifter is operated at a lower supply voltage substantially lower than the supply voltage for the power MOS transistor. The driver stage includes a pair of driver MOS transistors coupled in series between a higher supply voltage rail and a reference potential rail, and at an interconnection node coupled to the gate of the power MOS transistor. The gates of the driver MOS transistors are AC-coupled to drive signals of mutually opposite phase; and the gates of the driver MOS transistors are each connected to the higher voltage supply rail through a respective parallel connection of a first resistor and a second resistor connected in series with a non-linear component.

Abstract: Methods, devices, and systems are disclosed, including those for a buffer having pre-driver circuitry configured to provide voltages to thin-gate dielectric transistors. One such buffer may comprise a plurality of pre-drivers wherein each pre-driver of the plurality of pre-drivers is operably coupled to a transistor of a plurality of transistors. The buffer may further comprise one or more clamping devices, wherein at least one transistor of the plurality of transistors has a gate coupled to at least one clamping device of the one or more clamping devices.

Abstract: This document discusses, among other things, output slew rate control. Methods and structures are described to provide slew rate control of an output driver circuit such as a DRAM output driver on a die. A selectable combination of series coupled transistors are configured as a parallel array of complementary inverter pairs to provide a divided voltage to a calibrator. The calibrator is configured to respond to a differential voltage to adjust the divided voltage such that the differential voltage is forced to zero. The calibrator outputs a plurality of discrete signals from an up/down counter to switch on and off the individual transistors of the parallel array to increase and decrease a collective current. In some embodiments, transistor channel currents are modulated to step-adjust a voltage based on a ratio associated with a static resistance. In various embodiments, the divided voltage is an analog voltage based on a resistance associated with trim circuitry.

Abstract: A calibration circuit includes: replica buffers; an up-down counter that changes impedance codes of the replica buffers; latch circuits each holding the impedance codes; an end-determining circuit that activates the latch circuits in response to a completion of impedance adjustments of the replica buffers; and a 32 tCK cycle counter that forcibly activates the latch circuits in response to a lapse of a predetermined period since issuance of the calibration command. Thereby, even when the adjustment is not completed during one calibration period, a subsequent calibration operation can be executed from a previous point.

Abstract: A rail-to-rail high speed subLVDS receiver demonstrates good jitter and duty cycle performance for high-speed signals at low power supply levels. A sample receiver includes a voltage shifter for shifting the voltage levels of a differential input signal so that a shifted differential input signal is produced. The shifted differential input signal can be applied to a first differential pair, and the differential input signal can be applied to a second differential pair. The outputs of the first and second differential pairs can be summed together to produce a differential output signal. The differential output signal can be output using an output block. A clamp circuit can be used to adjust the gain of the first differential pair responsive to a common mode voltage of the first and second differential input signals.

Abstract: A combined input and termination circuit comprises a fixed portion of impedance and a programmable portion of impedance. The fixed portion is able to be fixed in a driver mode and a termination mode. The programmable portion is able to be configured to have a desired impedance in a driver mode or a termination mode while maintaining minimum associated capacitance.

Abstract: This document discusses, among other things, output slew rate control. Methods and structures are described to provide slew rate control of an output driver circuit such as a DRAM output driver on a die. A selectable combination of series coupled transistors are configured as a parallel array of complementary inverter pairs to provide a divided voltage to a calibrator. The calibrator is configured to respond to a differential voltage to adjust the divided voltage such that the differential voltage is forced to zero. The calibrator outputs a plurality of discrete signals from an up/down counter to switch on and off the individual transistors of the parallel array to increase and decrease a collective current. In some embodiments, transistor channel currents are modulated to step-adjust a voltage based on a ratio associated with a static resistance. In various embodiments, the divided voltage is an analog voltage based on a resistance associated with trim circuitry.

Abstract: An output driver for use in a semiconductor is capable of maintaining its slew rate constantly regardless of PVT (Process/Voltage/Temperature) variation. The output driver includes a pre-driving unit for pre-driving a data signal; a main driving unit for driving an output pad in response to the output signal of the pre-driving unit; and a slew rate modeling unit for generating a pre-driver bias signal to constantly maintain effective resistances of a pull-up path and a pull-down path of the pre-driving unit by modeling the pre-driving unit.

Abstract: An input circuit for a semiconductor integrated circuit in which an operational state is constant even when a process condition, a temperature, a voltage, and the like are varied at the time of operation is provided. The input circuit includes a first input unit that performs a first amplifying operation on a potential difference between a reference voltage and an input signal and outputs a result of the amplification, and a second input unit that performs a second amplifying operation on a signal amplified by the first input unit and outputs a result of the amplification.

Abstract: In an electronic device according to the present invention, a source of the first signal-wire drive transistor is connected to a first power supply, a drain of the first signal-wire drive transistor is connected to a signal wire, and a control circuit controls a gate voltage so that a current flowing in the signal wire is amplified toward a voltage to which a potential of the signal wire transits during the potential transition in the signal wire and further controls the gate voltage so that a voltage value obtained after the potential transition in the signal wire is retained after the potential transition in the signal wire.

Abstract: A semiconductor integrated circuit, a semiconductor integrated circuit control method, and a signal transmission circuit realizing optimization of the performance of a semiconductor integrated circuit and reduction of the power consumption. In the semiconductor integrated circuit, the semiconductor integrated circuit control method, and the signal transmission circuit, functional circuit blocks are composed of MIS transistors fabricated on an SOI structure silicon substrate and have at least one potential set including a high-potential side potential, a low-potential side potential, a substrate potential of a P-channel MIS transistor, and a substrate potential of an N-channel MIS transistor.

Abstract: Apparatus and methods for adjusting the buffer strength of an output buffer to match its capacitive load use selectively enabled stages of a multiple stage output buffer. A user can opt for a default capacitive load, or adjust the strength by enabling one or more stages of the multiple stage output buffer.

Abstract: In data transmission apparatus, a transmission line is connected with a transmitting unit and includes a first transmission line and a second transmission line. A receiving unit is connected with the transmission line. A terminating resistance is connected between a first reception node connected with the first transmission line on a receiving unit side and a second reception node connected with the second transmission line on a receiving unit side. The transmitting unit transmits a transmission data to the receiving unit through the transmission line. The receiving unit detects a reception data corresponding to the transmission data based on an amplitude voltage as a voltage difference between the first reception node and the second reception node.

Abstract: Apparatus including a reference circuit configured to provide a particular impedance and having a first plurality of switching devices and a resistive device coupled to each other in parallel; a second plurality of switching devices coupled to each other in parallel and coupled in series with the reference circuit between a supply node and a supply return node; and processing logic coupled to the second plurality of switching devices and configured to selectively enable and disable a combination of switching devices of the second plurality of switching devices that results in an impedance of the enabled switching devices more closely matching the particular impedance of the reference circuit than at least one other combination of enabled and disabled switching devices of the second plurality of switching devices.

Abstract: An output driver and method thereof. In the method, a current may be adjusted to adjust a power consumption in response to a change in a data rate. A first example output driver may include at least one transistor receiving at least one input signal, at least one resistor connected between the at least one transistor and a first voltage and a tail current source connected between the at least one transistor and a second voltage, the tail current source controlling a given current level of at least one signal based at least in part on the given data rate. A second example output driver may include a first differential amplification unit, including a first tail current source, receiving first and second input signals and a second differential amplification unit, including a second tail current source, receiving third and fourth input signals, at least one of the first and second tail current sources controlling a given current level of at least one signal based at least in part on the given data rate.

Abstract: A ratio asymmetric inverter has a signal input, signal output, first and second power inputs, pullup and pulldown transistors, and at least one delay element. The pullup transistor has a gate terminal, a source terminal coupled to the first power input, and a drain terminal coupled to the signal output. The pulldown transistor has a gate terminal, a drain terminal coupled to the signal output, and a source terminal coupled to the second power input. The signal input is respectively coupled to the gate terminals of the pullup transistor and the pulldown transistor via first and second signal paths. The at least one delay element is included in only one of the first and second signal paths, to impart a longer propagation delay to the one of the first and second signal paths.

Abstract: When a plurality of output buffer circuits are provided, chip layout size, power consumption, and number of pins of an LSI circuit are reduced. A voltage generation circuit generates reference voltages corresponding respectively to the output buffer circuits. A comparison circuit compares the reference voltages with an output voltage of a dummy buffer circuit. A counter counts a clock signal until a comparison result of the comparison circuit matches. The dummy buffer circuit adjusts output impedance corresponding respectively to the output buffer circuits based on a count value of the counter. Adjustment value holders hold respective count values when a comparison result of the comparison circuit, obtained based on respective corresponding reference voltages, matches. The output buffer circuits respectively adjust output impedances based on respectively held count values.

Abstract: An input buffer has a high voltage leg in parallel with a low voltage leg. The low voltage leg pulls up the pad when the pad voltage is below the power supply voltage. The high voltage leg remains off when the pad voltage is below the power supply. The low voltage leg is turned off when the pad voltage is above the power supply voltage. The high voltage leg is on when the pad voltage is above power supply voltage. A low voltage bias circuit and a high voltage bias circuit protect the transistors in the low and voltage legs when the pad voltage is above the power supply voltage. As a result, the pull-up circuit is high voltage tolerant and does not sink the current from pad.