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Texas Instruments SN74ALS233BFN
- Part No.:
- SN74ALS233BFN
- Manufacturer:
- Texas Instruments
- Category:
- FIFOs Memory
- Package:
- -
- Datasheet:
-
SN74ALS233BFN.pdf
- Description:
- IC FIFO SYNC 16X5 30NS
- Quantity:
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Product details
Overview
SN74ALS233BFN from Texas Instruments is a 16 × 5 asynchronous first-in, first-out (FIFO) memory IC with independent write/read clocks, 3-state outputs, and 40 MHz maximum clock frequency. It features 80-bit storage (16 words × 5 bits), fall-through time of 14 ns (typ), and operates across 0°C to 70°C. Used in data buffering between mismatched-speed digital subsystems such as UART-to-processor interfaces.
For engineers reviewing the SN74ALS233BFN datasheet, SN74ALS233BFN pinout, SN74ALS233BFN application, or SN74ALS233BFN equivalent, key selection considerations include asynchronous dual-clock operation, status flag behavior (FULL/EMPTY/FULL–1/EMPTY+1), 3-state output enable timing, and PLCC-20 package compatibility with legacy board layouts.
Technical Context
This FIFO implements a ring-counter-based pointer architecture with separate write (LDCK) and read (UNCK) address counters, enabling true asynchronous data transfer without shared clock domains. Internal stack control logic monitors word count in real time to drive four dedicated status flags.
It uses advanced low-power Schottky (ALS) bipolar technology, delivering TTL-compatible input thresholds (VIL = 0.8 V, VIH = 2 V) and robust output drive (IOL = 24 mA for Q outputs). Reset (RST) initializes pointers and forces EMPTY low while setting FULL, FULL–1, and EMPTY+1 high - but leaves Q outputs floating.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Depth × Width | 16 words × 5 bits = 80-bit buffer; supports word-parallel data flow with fixed 5-bit bus width. |
| Max Clock Frequency | 40 MHz for both LDCK and UNCK; enables ≤25 ns clock period timing in high-speed interface bridging. |
| Fall-Through Time | 14 ns typical; defines minimum latency from LDCK↑ to valid Q output when FIFO transitions from empty. |
| Status Flags | FULL, EMPTY, FULL–1, EMPTY+1 - all active-low; provide precise word-count state for handshaking without external logic. |
| Output Drive | 3-state Q outputs with IOL = 24 mA / IOH = –1.6 mA; compatible with standard TTL loads and bus-sharing topologies. |
| Supply Voltage | VCC = 4.5 V to 5.5 V; requires stable +5 V rail; not 3.3 V compatible. |
| Operating Temperature | 0°C to 70°C ambient; rated for commercial-grade industrial equipment, not extended or automotive temp ranges. |
Pinout & Package
SN74ALS233BFN is housed in a 20-pin plastic J-leaded chip carrier (PLCC-FN), 0.900″ × 0.900″ body, J-bend leads, JEDEC MS-018 compliant. Pin 1 identifier located at corner with chamfered edge.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (RST) | Asynchronous reset input | Active-low; resets internal read/write pointers and status flags (EMPTY → low, others → high); does not clear Q outputs. |
| 2–6 (D0–D4) | Data inputs | 5-bit parallel input bus; sampled on rising edge of LDCK; noninverting relationship to Q outputs. |
| 7 (GND) | Ground reference | Primary signal return; must be low-impedance connection to minimize noise coupling into sensitive timing paths. |
| 8 (VCC) | Power supply | +5 V supply (4.5–5.5 V); requires local 0.1 µF ceramic decoupling adjacent to pin. |
| 9–12 (Q0–Q4) | Data outputs | 5-bit 3-state parallel outputs; enabled by OE high; output impedance < 10 Ω when active. |
| 13 (OE) | Output enable | Active-high; controls Q0–Q4 only; no effect on status flag outputs (FULL/EMPTY/etc.). |
| 14 (EMPTY) | Status flag output | Active-low; indicates zero words stored; used to inhibit UNCK until first write occurs. |
| 15 (UNCK) | Read clock input | Rising-edge triggered; advances read pointer and updates Q outputs; ignored when EMPTY = low. |
| 16 (FULL) | Status flag output | Active-low; indicates 16 words stored; blocks further LDCK pulses until at least one word is read. |
| 17 (LDCK) | Write clock input | Rising-edge triggered; advances write pointer and latches D0–D4; ignored when FULL = low. |
| 18 (FULL–1) | Status flag output | Active-low; asserts when exactly 15 words stored; enables early flow-control signaling before full condition. |
| 19 (EMPTY+1) | Status flag output | Active-low; asserts when exactly one word remains; supports predictive read scheduling. |
| 20 (D4) | Data input | Duplicate listing in FN package top view - confirmed as D4 (same as pin 6); no functional duplication. |
Key Features
| Feature | Design Value |
|---|---|
| Independent asynchronous clocks | Separate LDCK and UNCK inputs allow mismatched write/read rates up to 40 MHz each - essential for bridging UART, DMA, or microcontroller peripherals. |
| Four dedicated status flags | FULL, EMPTY, FULL–1, EMPTY+1 provide deterministic, glitch-free handshaking without external counters or comparators. |
| Fast fall-through time | 14 ns typical delay from LDCK↑ to valid Q output after reset or empty condition - minimizes startup latency in burst-mode transfers. |
| 3-state output control | OE pin enables/disables Q0–Q4 independently of status flags, supporting shared-bus architectures without contention. |
| ALS Schottky logic family | Combines TTL-compatible voltage levels with lower power than standard LS, while retaining speed advantages over standard TTL. |
Applications
| UART Data Buffering | Microcontroller Peripheral Interface |
|---|---|
|
Use Scenario: Isolating variable-rate UART transmission from fixed-rate CPU polling or interrupt servicing. IC Role / Device Role / Timing Role: Asynchronous FIFO buffer absorbing transmit/receive bursts while decoupling clock domains. Use Value: Eliminates CPU wait states and UART overrun/underrun errors by providing 16-word depth with precise EMPTY/FULL signaling. |
Use Scenario: Interfacing a slow ADC or sensor array to a fast microcontroller data acquisition loop. IC Role / Device Role / Timing Role: Temporary storage element synchronizing sampling clock (e.g., 1 MHz) with processing clock (e.g., 20 MHz). Use Value: Enables continuous sampling without CPU intervention; FULL–1 flag triggers preemptive read to avoid overflow. |
| Digital Signal Chain Bridging | Legacy System Bus Expansion |
|
Use Scenario: Connecting a high-speed DSP serial port to a lower-speed FPGA-based protocol engine. IC Role / Device Role / Timing Role: Clock-domain crossing buffer with status-driven handshaking for reliable packetized data transfer. Use Value: Prevents metastability and data loss using hardware-managed pointers and deterministic flag timing (tPLH/tPHL ≤ 32 ns). |
Use Scenario: Adding FIFO capability to an older 8-bit ISA or VMEbus system lacking native buffering. IC Role / Device Role / Timing Role: Standalone 5-bit-wide data staging register with TTL-compatible control signals. Use Value: Enables plug-in upgrade of legacy backplanes using existing PLCC socket footprints and 5 V logic rails. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar FIFO memory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74ACT233FN | Advanced CMOS (ACT) family; 5 V tolerant, lower ICC (25 mA typ), but slower max clock (25 MHz) and no FULL–1/EMPTY+1 flags. | Lacks fine-grained status signaling; requires external logic for early-full detection; better for low-power, moderate-speed designs. | Choose SN74ACT233FN only if power budget is critical and 25 MHz suffices; verify absence of FULL–1/EMPTY+1 doesn't impact handshaking. |
| 7203L15P | CMOS FIFO (IDT); 16 × 8 configuration, 33 MHz max, 5 V operation, includes programmable almost-full/empty thresholds. | Wider 8-bit bus and configurable thresholds support more flexible data packing, but pinout and flag logic differ significantly. | Choose 7203L15P when 8-bit data path or threshold customization is required; expect PCB redesign due to different pin assignment and control protocol. |
Compared with SN74ALS233BFN, SN74ACT233FN trades speed and status granularity for lower power, while 7203L15P offers greater flexibility at the cost of compatibility - neither is pin- or functionally identical, requiring layout and firmware adaptation.
Availability
SN74ALS233BFN is available at Aetrix Electronics and suitable for UART buffering, microcontroller peripheral interfacing, digital signal chain bridging, and legacy bus expansion requiring stable component supply and long-term obsolescence management.
Supply support for SN74ALS233BFN includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Texas Instruments is a global semiconductor leader founded in 1930, specializing in analog, embedded processing, and logic solutions with broad industrial and communications portfolio coverage.
The SN74ALS233BFN belongs to TI's legacy ALS logic family, designed specifically for high-speed, low-power asynchronous data buffering in commercial-grade digital systems where TTL compatibility and deterministic timing are essential.
FAQ
What is the operating temperature range for SN74ALS233BFN?
The SN74ALS233BFN is characterized for operation from 0°C to 70°C ambient temperature. It is specified only for commercial-grade environments and is not rated for extended industrial (–40°C to 85°C) or automotive temperature ranges. Thermal derating or additional heatsinking is not supported per datasheet.
Does SN74ALS233BFN support 3.3 V logic interfaces?
No, SN74ALS233BFN is a 5 V-only device requiring VCC between 4.5 V and 5.5 V. Its input thresholds (VIH = 2.0 V min, VIL = 0.8 V max) and output voltage levels (VOH ≥ 2.4 V at –2.6 mA) are TTL-compatible but not 3.3 V tolerant. Direct connection to 3.3 V logic requires level-shifting circuitry.
How does the RST pin affect Q outputs on SN74ALS233BFN?
The RST pin on SN74ALS233BFN resets internal read/write pointers and forces EMPTY low and FULL/FULL–1/EMPTY+1 high, but it does not drive Q0–Q4 to defined logic states. Those outputs remain in their last driven or high-impedance condition until the first valid LDCK↑ after reset or until OE is asserted and data is loaded.
Can SN74ALS233BFN be cascaded for wider data paths?
Yes, SN74ALS233BFN supports cascading in the word-width direction (i.e., stacking multiple devices to create 10-bit, 15-bit, or wider buses) using common LDCK, UNCK, RST, and OE signals. Cascading in word-depth (e.g., 32 × 5) is not supported - the architecture lacks depth-expansion control signals.
What is the meaning of the FULL–1 and EMPTY+1 flags on SN74ALS233BFN?
FULL–1 goes low when exactly 15 words are stored, signaling imminent full condition to allow preemptive read initiation. EMPTY+1 goes low when exactly one word remains, enabling predictive unload scheduling. Both flags provide finer-grained flow control than FULL/EMPTY alone, reducing risk of overflow or underflow in real-time systems.
SN74ALS233BFN Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- *
- Package/Case:
- -
- Packaging:
- Bulk
- Product Status:
- Active
- Programmable:
- Not Verified
- Memory Size:
- -
- Function:
- -
- Data Rate:
- -
- Access Time:
- -
- Voltage - Supply:
- -
- Current - Supply (Max):
- -
- Bus Directional:
- -
- Expansion Type:
- -
- Programmable Flags Support:
- -
- Retransmit Capability:
- -
- FWFT Support:
- -
- Operating Temperature:
- -
- Mounting Type:
- -
- Supplier Device Package:
- -
SN74ALS233BFN FAQ
1.How can I place an order for SN74ALS233BFN through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74ALS233BFN on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for SN74ALS233BFN reliable?
The price and inventory of SN74ALS233BFN are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74ALS233BFN is usually 5 days.
3.What payment methods are accepted for SN74ALS233BFN?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74ALS233BFN transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74ALS233BFN?
SN74ALS233BFN orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74ALS233BFN order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for SN74ALS233BFN?
For technical support, including SN74ALS233BFN datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74ALS233BFN requirements.
6.How does Aetrix verify that SN74ALS233BFN is sourced from the original manufacturer or authorized distributors?
All SN74ALS233BFN products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that SN74ALS233BFN meets industry standards.
7.What is the process for return or replacement of SN74ALS233BFN?
All SN74ALS233BFN units undergo pre-shipment inspection (PSI). If there is an issue with SN74ALS233BFN, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The SN74ALS233BFN part is unused and in its original packaging.
Return procedure for SN74ALS233BFN:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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