My Inquiry
My Account
Texas Instruments SN74CBT3245APWE4
- Part No.:
- SN74CBT3245APWE4
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 20-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
SN74CBT3245APWE4.pdf
- Description:
- IC BUS SWITCH 8 X 1:1 20TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,678
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
SN74CBT3245APWE4 from Texas Instruments is an octal FET bus switch IC designed for high-speed TTL-compatible bidirectional data routing between two 8-bit ports (A and B). It features 5-Ω on-state resistance, 0.25 ns typical propagation delay at 5 V, and operates from −40°C to 85°C with supply voltage 4–5.5 V. It is used in address/data bus isolation and hot-swap interface circuits.
For engineers reviewing the SN74CBT3245APWE4 datasheet, SN74CBT3245APWE4 pinout, SN74CBT3245APWE4 application, or SN74CBT3245APWE4 equivalent, key selection criteria include on-resistance matching, OE-controlled bidirectional switching, TTL-level compatibility, thermal performance in TSSOP-20, and absence of level-shifting functionality.
Technical Context
The SN74CBT3245APWE4 implements eight independent FET transmission gates controlled by a single active-low output-enable (OE) signal. When OE is low, A1–A8 are electrically connected to B1–B8 with minimal RC delay; when OE is high, both ports enter high-impedance states. No internal logic or latching is present - it functions purely as a passive analog switch array.
Its design targets low-capacitance, low-resistance signal path integrity: Cio(OFF) = 4 pF ensures minimal crosstalk during disable, while Ci = 4 pF per control input reduces loading on upstream drivers. The device requires no power sequencing coordination but recommends OE tied to VCC via pull-up resistor during power-up/down to guarantee defined high-Z state.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| On-state resistance (ron) | 5 Ω typical at VCC = 4.5 V - enables <10 mV drop at 20 mA, preserving TTL logic margins across bus segments. |
| Propagation delay (tpd) | 0.25 ns typical at VCC = 5 V - supports >1 GHz data rates in short-run PCB traces with CL = 50 pF. |
| Supply voltage range | 4 V to 5.5 V - compatible with standard 5-V TTL and mixed-voltage systems where VCC is regulated to 5 V ±10%. |
| Input voltage levels | VIH = 2 V, VIL = 0.8 V - fully compatible with legacy TTL outputs without level translation. |
| Off-state capacitance (Cio) | 4 pF - limits capacitive loading and signal coupling between isolated bus sections during disable. |
| Operating temperature | −40°C to +85°C - qualified for industrial-grade embedded control and instrumentation applications. |
| Control input leakage | ±5 μA max - allows direct connection to microcontroller GPIO without external current-limiting resistors. |
Pinout & Package
TSSOP-20 package (PW), 6.5 mm × 4.4 mm, 1.2 mm max height, 0.65 mm lead pitch, exposed pad not present. Pin 1 index located at top-left corner with beveled edge marking.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 3, 4, 5, 6, 7, 8 | A1–A8 inputs/outputs | Port A side of bidirectional switch; electrically identical to B pins when OE active; no internal directionality. |
| 9 | GND | Ground reference for all switch channels and control circuitry; must be low-impedance for noise immunity. |
| 10 | VCC | Positive supply for FET gate drive and control logic; bypass capacitor required near pin for transient stability. |
| 11 | OE | Active-low output enable; drives all eight switches simultaneously; must be pulled up to VCC during power transitions. |
| 12, 13, 14, 15, 16, 17, 18, 19 | B1–B8 inputs/outputs | Port B side of bidirectional switch; functionally symmetric with A pins; no internal bias or termination. |
| 20 | NC | No internal connection - left unconnected; not usable as thermal pad or ground tie. |
Key Features
| Feature | Design Value |
|---|---|
| Standard '245-type pinout | Enables drop-in replacement for legacy 74LS245/74ACT245 in existing layouts without PCB redesign. |
| 5-Ω low on-resistance | Maintains signal integrity for 5-V TTL buses carrying up to 128 mA total channel current without voltage droop. |
| TTL-compatible control inputs | Accepts standard 5-V TTL logic thresholds (VIH = 2 V, VIL = 0.8 V), eliminating need for level shifters. |
| High-impedance off-state | Isolates A and B ports with <1 μA leakage and 4 pF capacitance, preventing bus contention during power sequencing. |
| Minimal propagation delay | 0.25 ns typical ensures timing-critical applications (e.g., memory bus arbitration) retain setup/hold margin. |
Applications
| Memory Bus Isolation | Hot-Swap Backplane Interface |
|---|---|
Use Scenario: Isolating DRAM address/data lines from CPU during memory module insertion/removal. IC Role / Device Role / Timing Role: Bidirectional analog switch enabling/disabling physical bus continuity under system controller command. Use Value: Prevents bus contention and data corruption during live module replacement while maintaining full 5-V TTL signal fidelity. | Use Scenario: Enabling/disabling communication paths between hot-pluggable I/O cards and host backplane. IC Role / Device Role / Timing Role: OE-controlled bus gate that decouples card-side signals from backplane until firmware confirms safe insertion. Use Value: Eliminates need for complex power sequencing ICs; provides sub-ns isolation timing compatible with PCIe Gen1 signaling. |
| Legacy System Bus Expansion | Test Equipment Signal Routing |
Use Scenario: Adding peripheral devices to ISA or LPC bus without altering master timing or loading. IC Role / Device Role / Timing Role: Transparent 8-bit data path switch activated only when peripheral is selected. Use Value: Adds zero additional clock cycles to bus transactions; preserves original timing budgets due to <0.3 ns delay. | Use Scenario: Reconfiguring signal paths in automated test equipment (ATE) for multi-DUT parallel testing. IC Role / Device Role / Timing Role: Low-capacitance, low-resistance analog multiplexer for routing 5-V digital stimulus/capture signals. Use Value: Enables <10 ps jitter contribution and <1 mV crosstalk between adjacent channels at 100 MHz. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal bus switch applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74CBTD3384ADW | Includes 5-V tolerant inputs (VI = −0.5 to 7 V), higher ICC (100 μA), same ron and tpd. | Supports mixed-voltage domains (e.g., 3.3-V controller driving 5-V bus); not needed for pure 5-V systems. | Select SN74CBTD3384ADW only if interfacing with non-5-V logic families; otherwise SN74CBT3245APWE4 offers lower quiescent current. |
| 74LVC245APW | CMOS-based, 3.3-V only (VCC = 1.65–3.6 V), higher ron (~15 Ω), different pinout (non-'245). | Requires level translation for 5-V buses; unsuitable as direct replacement without layout change. | Choose 74LVC245APW only for new 3.3-V designs; SN74CBT3245APWE4 remains optimal for legacy 5-V bus isolation. |
Compared with SN74CBTD3384ADW and 74LVC245APW, the SN74CBT3245APWE4 delivers lowest on-resistance and strictest '245 pin compatibility for 5-V systems, while avoiding unnecessary voltage tolerance overhead or incompatible voltage domain constraints.
Availability
SN74CBT3245APWE4 is available at Aetrix Electronics and suitable for memory bus isolation, hot-swap backplane interfaces, and legacy system bus expansion requiring stable component supply and long-term industrial lifecycle support.
Supply support for SN74CBT3245APWE4 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 company headquartered in Dallas, Texas, specializing in analog, embedded processing, and logic solutions for industrial, automotive, and communications markets.
The SN74CBT3245APWE4 belongs to TI's CBT (Crossbar Bus Transceiver) family, engineered specifically for ultra-low-delay, low-resistance bidirectional bus switching in 5-V TTL environments without level translation.
FAQ
What is the maximum continuous current per channel for the SN74CBT3245APWE4?
The SN74CBT3245APWE4 supports up to 128 mA continuous channel current per switch path. This rating applies under recommended operating conditions (VCC = 4–5.5 V, TA = −40°C to 85°C) and assumes proper PCB thermal management. Exceeding this current may increase on-resistance or cause thermal shutdown in sustained operation.
Does the SN74CBT3245APWE4 support level shifting between different voltage domains?
No, the SN74CBT3245APWE4 does not provide level shifting. It operates strictly as a bidirectional analog switch within a single 4–5.5 V supply domain. Both A and B ports must be referenced to the same VCC and GND. For mixed-voltage interfacing, external level translators are required alongside the SN74CBT3245APWE4.
Can the OE pin of the SN74CBT3245APWE4 be driven directly by a microcontroller GPIO?
Yes, the OE pin of the SN74CBT3245APWE4 accepts standard TTL logic levels (VIH ≥ 2 V, VIL ≤ 0.8 V) and draws only ±5 μA leakage current. A 3.3-V or 5-V microcontroller GPIO can drive OE directly without series resistors, provided the GPIO supports open-drain or push-pull output with sufficient sink/source capability.
What is the thermal resistance (θJA) of the SN74CBT3245APWE4 in its TSSOP-20 package?
The SN74CBT3245APWE4 in the PW (TSSOP-20) package has a junction-to-ambient thermal resistance (θJA) of 83°C/W, measured per JESD 51-7. This value assumes standard JEDEC 2S2P test board conditions. Actual thermal performance improves with copper pour, thermal vias, and airflow - critical for sustained 128 mA channel loads.
Is the NC pin on the SN74CBT3245APWE4 internally connected or usable as a thermal pad?
The NC (pin 20) on the SN74CBT3245APWE4 is explicitly designated "no internal connection" in the datasheet and has no electrical or thermal function. It must remain unconnected - neither grounded nor tied to VCC. Unlike some QFN packages, the TSSOP-20 variant contains no exposed thermal pad, so pin 20 provides no thermal relief.
SN74CBT3245APWE4 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74CBT
- Package/Case:
- 20-TSSOP (0.173", 4.40mm Width)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Type:
- Bus Switch
- Circuit:
- 8 x 1:1
- Independent Circuits:
- 1
- Current - Output High, Low:
- -
- Voltage Supply Source:
- Single Supply
- Voltage - Supply:
- 4V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-TSSOP
SN74CBT3245APWE4 FAQ
1.How can I place an order for SN74CBT3245APWE4 through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74CBT3245APWE4 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 SN74CBT3245APWE4 reliable?
The price and inventory of SN74CBT3245APWE4 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74CBT3245APWE4 is usually 5 days.
3.What payment methods are accepted for SN74CBT3245APWE4?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74CBT3245APWE4 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74CBT3245APWE4?
SN74CBT3245APWE4 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74CBT3245APWE4 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 SN74CBT3245APWE4?
For technical support, including SN74CBT3245APWE4 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74CBT3245APWE4 requirements.
6.How does Aetrix verify that SN74CBT3245APWE4 is sourced from the original manufacturer or authorized distributors?
All SN74CBT3245APWE4 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 SN74CBT3245APWE4 meets industry standards.
7.What is the process for return or replacement of SN74CBT3245APWE4?
All SN74CBT3245APWE4 units undergo pre-shipment inspection (PSI). If there is an issue with SN74CBT3245APWE4, 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 SN74CBT3245APWE4 part is unused and in its original packaging.
Return procedure for SN74CBT3245APWE4:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SN74CBT3245APWE4 Tags
-
SN74HC138DR
Texas Instruments
-
TC7SB3157CFU,LF(CT
Toshiba Semiconductor and Storage
-
74CBTLV3257PW,118
Nexperia USA Inc.
-
SN74CBTLV3257PWR
Texas Instruments
-
74CBTLV3257GUX
Nexperia USA Inc.
-
74HC154BQ,118
Nexperia USA Inc.
-
P3S0200GMX
NXP USA Inc.
-
SN74CB3Q3245PWR
Texas Instruments
-
SN74CB3Q3257RGYR
Texas Instruments
-
TCA9543APWR
Texas Instruments
-
TCA9546APWR
Texas Instruments
-
SN74HC138N
Texas Instruments
Tech Hub
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…
