Features: · Fast Access Times: 20/25/35/50 ns
· Fast-Fall-Through Time Architecture Based on CMOS Dual-Port SRAM Technology
· Input Port and Output Port Have Entirely Independent Timing
· Expandable in Width and Depth
· Full, Half-Full, and Empty Status Flags
· Data Retransmission Capability
· TTL-Compatible I/O
· Pin and Functionally Compatible with Sharp LH5499 and with Am/IDT/MS7204
· Control Signals Assertive-LOW for Noise Immunity
· Packages:
28-Pin, 300-mil PDIP
28-Pin, 300-mil SOJ *
32-Pin PLCC
Pinout
Specifications
|
PARAMETER |
RATING |
| Supply Voltage to VSS Potential |
0.5 V to 7 V |
| Signal Pin Voltage to VSS Potential 2 |
0.5 V to VCC + 0.5 V (not to exceed 7 V) |
| DC Output Current 3 |
±50 mA |
| Storage Temperature Range |
65° to 150 |
| Power Dissipation (Package Limit) |
1.0 W |
| DC Voltage Applied to Outputs In High-Z State |
0.5 V to VCC + 0.5 V (not to exceed 7 V) |
NOTES:
1. Stresses greater than those listed under 'Absolute Maximum Ratings' may cause permanent damage to the device. This is a stress rating for transient conditions only. Functional operation of the device at these or any other conditions outside of those indicated in the 'Operating Range' of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect reliability.
2. Negative undershoots of 1.5 V in amplitude are permitted for up to 10 ns once per cycle.
3. Outputs should not be shorted for more than 30 seconds. No more than one output should be shorted at any time. DescriptionThe LH540204 is a FIFO (First-In, First-Out) memory device, based on fully-static CMOS dual-port SRAM technology, capable of storing up to 4096 nine-bit words. It follows the industry-standard architecture and package pinouts for nine-bit asynchronous FIFOs. Each nine-bit LH540204 word may consist of a standard eight-bit byte, together with a parity bit or a block-marking/framing bit.
The input and output ports operate entirely independently of each other, unless the LH540204 becomes either totally full or else totally empty. Data flow at a port is initiated by asserting either of two asynchronous, assertive- LOW control inputs: Write (W) for data entry at the input port, or Read (R) for data retrieval at the output port.
Full, Half-Full, and Empty status flags monitor the extent to which the internal memory has been filled. The system may make use of these status outputs to avoid the risk of data loss, which otherwise might occur either by attempting to write additional words into an already-full LH540204, or by attempting to read additional words from an already-empty LH540204. When an LH540204 is operating in a depth-cascaded configuration, the Half-Full Flag is not available.
LH540204 Data Sheet
