NTS0102

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Product data sheet

Rev. 3 — 17 November 2011

16 of 27

NXP Semiconductors

NTS0102

Dual supply translating transceiver; open drain; auto direction sensing

The gate bias voltage of the pass gate transistor (T3) is set at approximately one

transition the output one-shot accelerates the output transition by switching on the PMOS

transistors (T1, T2) bypassing the 10 k

 pull-up resistors and increasing current drive

capability. The one-shot is activated once the input transition reaches approximately

acceleration time the driver output resistance is between approximately 50

 and 70 . To

circuit to turn-off before applying a signal in the opposite direction. Pull-up resistors are

included in the device for DC current sourcing capability.

14.3 Input driver requirements

As the NTS0102 is a switch type translator, properties of the input driver directly effect the

output signal. The external open-drain or push-pull driver applied to an I/O determines the

static current sinking capability of the system; the max data rate, HIGH-to-LOW output

impedance and edge-rate of the external driver. The limits provided for these parameters

in the datasheet assume a driver with output impedance below 50

 is used.

14.4 Output load considerations

The maximum lumped capacitive load that can be driven is dependant upon the one-shot

pulse duration. In cases with very heavy capacitive loading there is a risk that the output

will not reach the positive rail within the one-shot pulse duration.

To avoid excessive capacitive loading and to ensure correct triggering of the one-shot it's

recommended to use short trace lengths and low capacitance connectors on NTS0102

PCB layouts. To ensure low impedance termination and avoid output signal oscillations

and one-shot re-triggering, the length of the PCB trace should be such that the round trip

delay of any reflection is within the one-shot pulse duration (approximately 50 ns).

14.5 Power up

first. There is no special power-up sequencing required. The NTS0102 includes circuitry

14.6 Enable and disable

An output enable input (OE) is used to disable the device. Setting OE = LOW

external load) indicates the delay between when OE goes LOW and when outputs

must allow for one one-shot circuitry to become operational after OE is taken HIGH. To

ensure the high-impedance OFF-state during power-up or power-down, pin OE should be

tied to GND through a pull-down resistor, the minimum value of the resistor is determined

by the current-sourcing capability of the driver.