FEATURES

· TI-OPC? Circuitry Limits Ringing on

Unevenly Loaded Backplanes

· OEC? Circuitry Improves Signal Integrity and

Reduces Electromagnetic Interference

· Bidirectional Interface Between GTLP Signal

Levels and LVTTL Logic Levels

· LVTTL Interfaces Are 5-V Tolerant

· Medium-Drive GTLP Outputs (50 mA)

· LVTTL Outputs (–24 mA/24 mA)

· GTLP Rise and Fall Times Designed for

Optimal Data-Transfer Rate and Signal

Integrity in Distributed Loads

· Ioff and Power-Up 3-State Support Hot

Insertion

· Bus Hold on A-Port Data Inputs

· Latch-Up Performance Exceeds 100 mA Per

JESD 78, Class II

· 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 SN74GTLPH306 is a medium-drive, 8-bit bus transceiver that provides LVTTL-to-GTLP and GTLP-to-LVTTL

signal-level translation. The device provides a high-speed interface between cards operating at LVTTL logic

levels and a backplane operating at GTLP signal levels. High-speed (about three times faster than standard

LVTTL or TTL) backplane operation is a direct result of GTLP's reduced output swing (<1 V), reduced input

threshold levels, improved differential input, OEC? circuitry, and TI-OPC? circuitry. Improved GTLP OEC and

TI-OPC circuits minimize bus-settling time and have been designed and tested using several backplane models.

The medium drive allows incident-wave switching in heavily loaded backplanes with equivalent load impedance

down to 19 W.

GTLP is the Texas Instruments (TI?) derivative of the Gunning Transceiver Logic (GTL) JEDEC standard JESD

8-3. The ac specification of the SN74GTLPH306 is given only at the preferred higher-noise-margin GTLP, but the

user has the flexibility of using this device at either GTL (VTT = 1.2 V and VREF = 0.8 V) or GTLP (VTT = 1.5 V and

VREF = 1 V) signal levels.

Normally, the B port operates at GTLP signal levels. The A-port and control inputs operate at LVTTL logic levels,

but are 5-V tolerant and are compatible with TTL and 5-V CMOS inputs. VREF is the B-port differential input

reference voltage.

This device is fully specified for hot-insertion applications using Ioff and power-up 3-state. The Ioff circuitry

disables the outputs, preventing damaging current backflow through the device when it is 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.

This GTLP device features TI-OPC circuitry, which actively limits overshoot caused by improperly terminated

backplanes, unevenly distributed cards, or empty slots during low-to-high signal transitions. This improves signal

integrity, which allows adequate noise margin to be maintained at higher frequencies.

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

pulldown resistors with the bus-hold circuitry is not recommended.

When VCC is between 0 and 1.5 V, the device is in the high-impedance state during power up or power down.

However, to ensure the high-impedance state above 1.5 V, the output-enable (OE) input 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.