74LVTH16501 Series

The ’LVTH16501 devices are 18-bit universal bus transceivers designed for low-voltage (3.3-V) VCCoperation, but with the capability to provide a TTL interface to a 5-V system environment. Data flow in each direction is controlled by output-enable (OEAB andOEBA), latch-enable (LEAB and LEBA), and clock (CLKAB and CLKBA) inputs. For A-to-B data flow, the devices operate in the transparent mode when LEAB is high. When LEAB is low, the A data is latched if CLKAB is held at a high or low logic level. If LEAB is low, the A data is stored in the latch/flip-flop on the low-to-high transition of CLKAB. When OEAB is high, the outputs are active. When OEAB is low, the outputs are in the high-impedance state. Data flow for B to A is similar to that of A to B but usesOEBA, LEBA, and CLKBA. The output enables are complementary (OEAB is active high andOEBAis active low). Active bus-hold circuitry holds unused or undriven inputs at a valid logic state. Use of pullup or pulldown resistors with the bus-hold circuitry is not recommended. When VCCis between 0 and 1.5 V, the devices are in the high-impedance state during power up or power down. However, to ensure the high-impedance state above 1.5 V,OEshould be tied to VCCthrough a pullup resistor and OE should be tied to GND through a pulldown resistor; the minimum value of the resistor is determined by the current-sinking/current-sourcing capability of the driver. These devices are fully specified for hot-insertion applications using Ioffand power-up 3-state. The Ioffcircuitry disables the outputs, preventing damaging current backflow through the devices when they are powered down. The power-up 3-state circuitry places the outputs in the high-impedance state during power up and power down, which prevents driver conflict. The ’LVTH16501 devices are 18-bit universal bus transceivers designed for low-voltage (3.3-V) VCCoperation, but with the capability to provide a TTL interface to a 5-V system environment. Data flow in each direction is controlled by output-enable (OEAB andOEBA), latch-enable (LEAB and LEBA), and clock (CLKAB and CLKBA) inputs. For A-to-B data flow, the devices operate in the transparent mode when LEAB is high. When LEAB is low, the A data is latched if CLKAB is held at a high or low logic level. If LEAB is low, the A data is stored in the latch/flip-flop on the low-to-high transition of CLKAB. When OEAB is high, the outputs are active. When OEAB is low, the outputs are in the high-impedance state. Data flow for B to A is similar to that of A to B but usesOEBA, LEBA, and CLKBA. The output enables are complementary (OEAB is active high andOEBAis active low). Active bus-hold circuitry holds unused or undriven inputs at a valid logic state. Use of pullup or pulldown resistors with the bus-hold circuitry is not recommended. When VCCis between 0 and 1.5 V, the devices are in the high-impedance state during power up or power down. However, to ensure the high-impedance state above 1.5 V,OEshould be tied to VCCthrough a pullup resistor and OE should be tied to GND through a pulldown resistor; the minimum value of the resistor is determined by the current-sinking/current-sourcing capability of the driver. These devices are fully specified for hot-insertion applications using Ioffand power-up 3-state. The Ioffcircuitry disables the outputs, preventing damaging current backflow through the devices when they are powered down. The power-up 3-state circuitry places the outputs in the high-impedance state during power up and power down, which prevents driver conflict.