SN74ALVCH16271
12-BIT TO 24-BIT MULTIPLEXED BUS EXCHANGER
WITH 3-STATE OUTPUTS

SCES017C - JULY 1995 - REVISED APRIL 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

• Member of the Texas Instruments Widebus^TM Family
• EPIC^TM (Enhanced-Performance Implanted CMOS) Submicron Process
• ESD Protection Exceeds 2000 V Per MIL-STD-883, Method 3015; Exceeds 200 V Using Machine Model (C = 200 pF, R = 0)
• Latch-Up Performance Exceeds 250 mA Per JEDEC Standard JESD-17
• Bus Hold on Data Inputs Eliminates the Need for External Pullup/Pulldown Resistors
• Package Options Include Plastic Shrink Small-Outline (DL) and Thin Shrink Small-Outline (DGG) Packages

EPIC and Widebus are trademarks of Texas Instruments Incorporated.

description

This 12-bit to 24-bit bus exchanger is designed for 2.3-V to 3.6-V V_CC operation.

The SN74ALVCH16271 is intended for applications where two separate data paths must be multiplexed onto, or demultiplexed from, a single data path. This device is particularly suitable as an interface between conventional DRAMs and high-speed microprocessors.

A data is stored in the internal A-to-B registers on the low-to-high transition of the clock (CLK) input, provided that the clock-enable () inputs are low. Proper control of these inputs allows two sequential 12-bit words to be presented as a 24-bit word on the B port.

Transparent latches in the B-to-A path allow asynchronous operation to maximize memory access throughput. These latches transfer data when the latch-enable () inputs are low. The select () line selects 1B or 2B data for the A outputs. Data flow is controlled by the active-low output enables (, ).

To ensure the high-impedance state during power up or power down, the output enables 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.

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

The SN74ALVCH16271 is characterized for operation from -40°C to 85°C.