FEATURES

· Member of Texas Instruments Widebus™

Family

· OEC™ Circuitry Improves Signal Integrity and

Reduces Electromagnetic Interference

· D-Type Flip-Flops With Qualified Storage

Enable

· Translates Between GTL/GTL+ Signal Levels

and LVTTL Logic Levels

· Supports Mixed-Mode (3.3 V and 5 V) Signal

Operation on A-Port and Control Inputs

· Ioff Supports Partial-Power-Down Mode

Operation

· Bus Hold on Data Inputs Eliminates the Need

for External Pullup/Pulldown Resistors on

A Port

· Distributed VCC and GND Pins Minimize

High-Speed Noise

· Latch-Up Performance Exceeds 250 mA Per

JESD 17

· ESD Protection Exceeds JESD 22

– 2000-V Human-Body Model (A114-A)

– 200-V Machine Model (A115-A)

– 1000-V Charged-Device Model (C101)

DESCRIPTION/ORDERING INFORMATION

The SN74GTL16622A is an 18-bit registered bus

transceiver that provides LVTTL-to-GTL/GTL+ and

GTL/GTL+-to-LVTTL signal-level translation. This

device is partitioned as two separate 9-bit

transceivers with individual clock-enable controls and

contains D-type flip-flops for temporary storage of

data flowing in either direction. This device provides

an interface between cards operating at LVTTL logic

levels and a backplane operating at GTL/GTL+ signal

levels. Higher-speed operation is a direct result of the

reduced output swing (<1 V), reduced input threshold

levels, and OEC™ circuitry.

The user has the flexibility of using this device at either GTL (VTT = 1.2 V and VREF = 0.8 V) or the preferred

higher noise margin GTL+ (VTT = 1.5 V and VREF = 1 V) signal levels. GTL+ is the Texas Instruments derivative

of the Gunning Transceiver Logic (GTL) JEDEC standard JESD 8-3. The B port normally operates at GTL or

GTL+ signal levels, while the A-port and control inputs are compatible with LVTTL logic levels and are 5-V

tolerant. VREF is the reference input voltage for the B port.

Data flow in each direction is controlled by the output-enable (OEAB and OEBA) and clock (CLKAB and CLKBA)

inputs. The clock-enable (CEAB and CEBA) inputs 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 CEAB is low. When OEAB is

low, the outputs are active. When OEAB 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 OEBA, CLKBA, and CEBA.

This device is fully specified for partial-power-down applications using Ioff. The Ioff circuitry disables the outputs,

preventing damaging current backflow through the device when it is powered down.

Active bus-hold circuitry holds unused or undriven LVTTL inputs at a valid logic state. Use of pullup or pulldown

resistors with the bus-hold circuitry is not recommended.

To ensure the high-impedance state during power up or power down, OE should be tied to VCC through a pullup

resistor; the minimum value of the resistor is determined by the current-sinking capability of the driver.