SN54GTL16923, SN74GTL16923
18-BIT LVTTL-TO-GTL/GTL+ BUS TRANSCEIVERS

SCBS674C - AUGUST 1996 - REVISED MARCH 1997

Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of TexasInstruments semiconductor products and disclaimers thereto appears at the end of this data sheet.

features

• Members of the Texas Instruments Widebus^TM Family
• Translate Between GTL/GTL+ Signal Levels and LVTTL or 5-V TTL Signal Levels
• Support Mixed-Mode (3.3 V and 5 V) Signal Operation on A Port and Control Inputs
• Support GTL/GTL+ Signal Operation on B Port
• D-Type Flip-Flops With Qualified Storage Enable
• Bus-Hold Data Inputs Eliminate the Need for External Pullup Resistors on A Port
• Flow-Through Architecture Facilitates Printed Circuit Board Layout
• Package Options Include Plastic Thin Shrink Small-Outline (DGG) and Ceramic Quad Flat (HV) Packages

Widebus is a trademark of Texas Instruments Incorporated.

description

These 18-bit registered bus transceivers contain two sets of D-type flip-flops for temporary storage of data flowing in either direction.

The B port operates at GTL (V_TT = 1.2 V and V_REF = 0.8 V) and GTL+ (V_TT = 1.5 V and V_REF = 1 V) levels, while the A port and control pins are compatible with LVTTL and 5-V TTL logic levels.

Data flow in each direction is controlled by the output-enable ( and ) and the clock (CLKAB and CLKBA) inputs. The clock-enable ( and ) inputs are used to enable or disable the clock for all 18 bits at a time. However, and are designed to control each 9-bit transceiver independently, which makes the device more versatile.

For A-to-B data flow, the device operates on the low-to-high transition of CLKAB if is low. When is low, the outputs are active. When is high, the outputs are in the high-impedance state. Data flow for B to A is similar to that of A to B but uses , CLKBA, and .

Active bus-hold circuitry is provided to hold unused or floating TTL inputs at a valid logic state.

V_REF is the reference voltage input for the GTL B port.

To ensure the high-impedance state during power up or power down, should be tied to V_CC through a pullup resistor; the minimum value of the resistor is determined by the current-sinking capability of the driver.

The SN54GTL16923 is characterized for operation over the full military temperature range of -55°C to 125°C. The SN74GTL16923 is characterized for operation from -40°C to 85°C.