SN54GTL16923 Datasheet, PDF (1/9 Pages) Texas Instruments – 18-BIT LVTTL-TO-GTL/GTL BUS TRANSCEIVERS

SN54GTL16923, SN74GTL16923
18-BIT LVTTL-TO-GTL/GTL+ BUS TRANSCEIVERS
D Members of the Texas Instruments
Widebus ™ Family
D D-Type Flip-Flops With Qualified Storage
Enable
D Translate Between GTL/GTL+ Signal Levels
and LVTTL Logic Levels
D Support Mixed-Mode Signal Operation on
All Ports (5-V Input/Output Voltages With
3.3-V V_CC)
D I_off Supports Partial-Power-Down-Mode
Operation
D Bus Hold on Data Inputs Eliminates the
Need for External Pullup/Pulldown
Resistors on A Port
SCBS674E – AUGUST 1996 – REVISED NOVEMBER 1999
D Distributed V_CC and GND-Pin Configuration
Minimizes High-Speed Switching Noise
D ESD Protection Exceeds JESD 22
– 2000-V Human-Body Model (A114-A)
– 200-V Machine Model (A115-A)
– 1000-V Charged-Device Model (C101)
D Latch-Up Performance Exceeds 250 mA Per
JESD 17
D Package Options Include Plastic Thin
Shrink Small-Outline (DGG) and Ceramic
Quad Flat (HV) Packages
description
The ’GTL16923 devices are 18-bit registered bus transceivers that provide LVTTL-to-GTL/GTL+ and
GTL/GTL+-to-LVTTL signal-level translation. They are partitioned as two 9-bit transceivers with individual
output-enable controls and contain D-type flip-flops for temporary storage of data flowing in either direction. The
devices provide 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 output edge control (OEC™).
The user has the flexibility of using these devices at either GTL (V_TT = 1.2 V and V_REF = 0.8 V) or the preferred
higher noise margin GTL+ (V_TT = 1.5 V and V_REF = 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. All inputs can
be driven from either 3.3-V or 5-V devices which allows use in a mixed 3.3-V/5-V system environment. V_REF
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 are used to enable or disable the clock for all 18 bits at a
time. However, OEAB and OEBA 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 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.
These devices are fully specified for partial-power-down applications using I_off. The I_off circuitry disables the
outputs, preventing damaging current backflow through the devices when they are 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 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.
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
Widebus and OEC are trademarks of Texas Instruments Incorporated.
UNLESS OTHERWISE NOTED this document contains PRODUCTION
DATA information current as of publication date. Products conform to
specifications per the terms of Texas Instruments standard warranty.
Production processing does not necessarily include testing of all
parameters.
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Copyright © 1999, Texas Instruments Incorporated
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