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Texas Instruments SN74CB3Q3257PW
- Part No.:
- SN74CB3Q3257PW
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 16-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
SN74CB3Q3257PW.pdf
- Description:
- IC MUX/DEMUX 4 X 2:1 16TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:503
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Product details
Overview
SN74CB3Q3257PW from Texas Instruments is a 4-bit 1-of-2 FET multiplexer/demultiplexer bus switch optimized for high-bandwidth signal routing in 2.5V/3.3V systems. It delivers rail-to-rail 0–5V switching, 4Ω typical on-state resistance (ron), <0.32ns propagation delay at 3.3V, and 5V-tolerant I/Os with device powered up or down - enabling robust USB interface and differential signal gating in optical networking equipment.
For engineers reviewing the SN74CB3Q3257PW datasheet, SN74CB3Q3257PW pinout, SN74CB3Q3257PW application, or SN74CB3Q3257PW equivalent, key selection criteria include its 20MHz max switching frequency (fOE), 3.5pF typical off-state I/O capacitance (Cio(OFF)), Ioff-enabled partial-power-down operation, and compatibility with TTL/3.3V/5V CMOS control inputs across –40°C to 105°C.
Technical Context
The SN74CB3Q3257PW integrates four independent 1-of-2 analog/digital switches, each controlled by a dedicated select (S) input and shared active-low output-enable (OE) per pair. Its charge-pump architecture elevates the gate voltage of pass transistors to maintain flat ron over 2.3V–3.6V VCC, enabling bidirectional, near-zero-delay data flow between A and B ports without directionality constraints.
Each channel supports 0–5V signaling regardless of VCC (2.5V or 3.3V), with undershoot clamp diodes on all I/O and control pins, 5.5V absolute max VI/O rating, and JESD78 Class II latch-up immunity (>100mA). The device enters high-impedance isolation during power-off via Ioff protection, preventing backflow current when VCC = 0V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 2.3V to 3.6V - supports dual-rail 2.5V/3.3V system interfacing without level shifters |
| ron (Typical) | 4Ω at 2.5V/3.3V - ensures minimal insertion loss and signal integrity up to 500MHz bandwidth |
| tpd (Max @ 3.3V) | 0.32ns - enables sub-nanosecond timing-critical routing in high-speed serial links |
| Cio(OFF) (Typical) | 3.5pF on B port - reduces capacitive loading and crosstalk in dense PCB layouts |
| fOE (Max) | 20MHz - defines maximum toggle rate for OE-controlled channel enable/disable sequencing |
| Ioff (Max) | 1µA at VCC = 0V - guarantees safe hot-insertion and partial-power-down mode operation |
| VI/O Tolerance | 0–5.5V - allows direct connection to 5V logic, USB D+/D−, or analog signals without external clamping |
Pinout & Package
TSSOP-16 (PW) package: 5mm × 6.4mm body, 0.65mm pitch, exposed thermal pad (not electrically connected), RoHS-compliant NiPdAu/Sn lead finish, MSL Level-1 (260°C peak reflow).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| S | Select input (shared per 2-channel group) | Controls path between 1A↔1B1/1B2, 2A↔2B1/2B2, etc.; logic-high selects B2, logic-low selects B1 |
| OE | Active-low output enable | Drives all four channels into high-Z when high; must be pulled up to VCC for power-up safety |
| 1A–4A | Common I/O terminals | Bidirectional data ports - connect to system bus or controller; support 0–5V swing |
| 1B1/1B2–4B1/4B2 | Channel I/O terminals | Paired endpoints per multiplexer; no internal directionality - signal flows either way when enabled |
| VCC | Supply pin | Single 2.3–3.6V supply powers charge pump and logic; requires 0.1µF local bypass |
| GND | Ground reference | Return path for all I/O and internal circuitry; tie to system ground plane with low-inductance connection |
Key Features
| Feature | Design Value |
|---|---|
| Rail-to-rail 0–5V switching | Operates with 2.5V VCC (0–3.3V I/O) or 3.3V VCC (0–5V I/O), eliminating external level translators in mixed-voltage systems |
| 5V-tolerant I/Os | Withstands 5.5V on any I/O pin regardless of VCC state - critical for USB 2.0, PCIe Gen1, and legacy 5V peripheral interfacing |
| Charge-pump ron stabilization | Maintains 4Ω typical ron across full VCC (2.3–3.6V) and temperature (–40°C to 105°C), ensuring consistent signal attenuation |
| Low Cio(OFF) = 3.5pF | Minimizes stub capacitance and reflection-induced distortion in high-frequency traces (e.g., 100Ω differential pairs) |
| Ioff partial-power-down | Blocks >99.9% back-current when VCC = 0V - enables live insertion into powered-backplane systems without damage |
Applications
| USB 2.0 Interface Switching | Differential Signal Routing |
|---|---|
Use Scenario: Selecting between two USB 2.0 upstream ports on an IP phone or optical module while maintaining full 480Mbps signaling integrity. IC Role / Device Role / Timing Role: Bidirectional analog switch providing low-capacitance, low-ron path for D+ and D− lines with no added jitter or skew. Use Value: Enables single-connector USB device sharing across dual hosts without signal degradation - validated at 500MHz bandwidth. |
Use Scenario: Gating LVDS or RSDS video streams in EPON optical line terminals where EMI-sensitive differential pairs require minimal loading. IC Role / Device Role / Timing Role: Low-distortion signal gate isolating active video paths from idle receivers to reduce common-mode noise coupling. Use Value: 3.5pF Cio(OFF) prevents impedance discontinuity; flat ron avoids amplitude imbalance between +/− legs. |
| Bus Isolation in PBX Systems | WiMAX Baseband Signal Multiplexing |
Use Scenario: Isolating CPU address/data buses from peripheral modules during firmware updates in private branch exchange (PBX) controllers. IC Role / Device Role / Timing Role: High-speed digital bus switch enabling clean break-before-make transitions with <0.32ns tpd to prevent bus contention. Use Value: 20MHz fOE supports rapid channel reconfiguration; Ioff blocks leakage during hot-swap maintenance cycles. |
Use Scenario: Multiplexing baseband I/Q signals between multiple RF transceivers and a shared ADC/DAC in WiMAX infrastructure equipment. IC Role / Device Role / Timing Role: Four independent 1:2 analog muxes routing 0–3.3V baseband waveforms with rail-to-rail fidelity and no DC offset. Use Value: 4Ω ron preserves SNR across 20MHz LTE/WiMAX channels; 5V-tolerant I/O accommodates DAC output headroom. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar FET bus switch applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74CBT3257PW | No charge pump; ron = 6Ω typical at 5V, not 5V-tolerant at VCC < 4.5V | Limited to 3.3V-only systems; unsuitable for 0–5V mixed-signal routing | Choose only if operating strictly at 5V VCC and 5V I/O levels |
| TS3A226AEYFFR | Lower ron (0.7Ω), but max VI/O = 3.6V and no Ioff; 10-pin UQFN vs 16-pin TSSOP | Not suitable for 5V-tolerant or partial-power-down designs; requires layout redesign | Select only for ultra-low-loss 3.3V-only signal paths where board space is constrained |
Compared with SN74CB3Q3257PW, SN74CBT3257PW lacks 5V tolerance below 4.5V VCC and charge-pump ron stability, while TS3A226AEYFFR sacrifices Ioff and VI/O range for lower ron - making SN74CB3Q3257PW the sole choice for robust 0–5V, hot-pluggable, wide-VCC bus switching.
Availability
SN74CB3Q3257PW is available at Aetrix Electronics and suitable for optical networking, IP telephony, and wireless infrastructure applications requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.
Supply support for SN74CB3Q3257PW 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 specializing in analog, embedded processing, and connectivity technologies, with decades of expertise in high-speed interface solutions.
The SN74CB3Q3257PW belongs to TI's CB3Q family of charge-pump bus switches, engineered specifically for broadband communications, optical transport, and mixed-signal routing where 5V tolerance, rail-to-rail operation, and sub-nanosecond timing are mandatory.
FAQ
What is the maximum signal frequency supported by the SN74CB3Q3257PW?
The SN74CB3Q3257PW supports signal routing up to 500MHz, verified by its high-bandwidth data path design and 4Ω typical on-state resistance. This capability is enabled by low 3.5pF off-state I/O capacitance and flat ron across voltage/temperature - making SN74CB3Q3257PW suitable for USB 2.0, LVDS, and baseband RF applications without signal degradation.
Does the SN74CB3Q3257PW support 5V-tolerant I/O when powered at 2.5V?
Yes, the SN74CB3Q3257PW supports 0–5.5V I/O voltage regardless of VCC state - including when powered at 2.5V or even unpowered (VCC = 0V). This 5V tolerance is intrinsic to its FET architecture and clamp diode protection, allowing SN74CB3Q3257PW to interface directly with 5V peripherals in mixed-voltage systems without external components.
How does the Ioff feature function in the SN74CB3Q3257PW during partial-power-down?
The Ioff feature in SN74CB3Q3257PW disables current flow between I/O pins when VCC = 0V, limiting leakage to ≤1µA. This prevents damaging back-current from live buses into a powered-down device - a critical requirement for hot-plug systems like optical line terminals. SN74CB3Q3257PW maintains full Ioff protection across –40°C to 105°C.
What is the recommended bypass capacitor for the SN74CB3Q3257PW VCC pin?
A 0.1µF ceramic capacitor placed as close as possible to the VCC pin (Pin 16) is the recommended bypass solution for SN74CB3Q3257PW. This value suppresses high-frequency noise generated by fast-switching FETs and ensures stable charge-pump operation. TI further recommends pairing it with a 1µF capacitor in parallel for broader noise rejection across the 10kHz–100MHz range.
Can the SN74CB3Q3257PW be used for analog signal switching, such as audio or sensor signals?
Yes, SN74CB3Q3257PW is qualified for both digital and analog applications including audio routing and sensor signal gating. Its rail-to-rail 0–5V switching, 4Ω ron, and low 3.5pF off-capacitance preserve analog waveform fidelity - confirmed in TI's application report SCDS135E for differential signal interfaces and low-distortion signal gating use cases.
SN74CB3Q3257PW Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74CB
- Package/Case:
- 16-TSSOP (0.173", 4.40mm Width)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Type:
- Multiplexer/Demultiplexer
- Circuit:
- 4 x 2:1
- Independent Circuits:
- 1
- Current - Output High, Low:
- -
- Voltage Supply Source:
- Single Supply
- Voltage - Supply:
- 2.3V ~ 3.6V
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-TSSOP
SN74CB3Q3257PW FAQ
1.How can I place an order for SN74CB3Q3257PW through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74CB3Q3257PW 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 SN74CB3Q3257PW reliable?
The price and inventory of SN74CB3Q3257PW are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74CB3Q3257PW is usually 5 days.
3.What payment methods are accepted for SN74CB3Q3257PW?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74CB3Q3257PW transactions.
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4.How is shipping managed for SN74CB3Q3257PW?
SN74CB3Q3257PW orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74CB3Q3257PW 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 SN74CB3Q3257PW?
For technical support, including SN74CB3Q3257PW datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74CB3Q3257PW requirements.
6.How does Aetrix verify that SN74CB3Q3257PW is sourced from the original manufacturer or authorized distributors?
All SN74CB3Q3257PW 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 SN74CB3Q3257PW meets industry standards.
7.What is the process for return or replacement of SN74CB3Q3257PW?
All SN74CB3Q3257PW units undergo pre-shipment inspection (PSI). If there is an issue with SN74CB3Q3257PW, 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 SN74CB3Q3257PW part is unused and in its original packaging.
Return procedure for SN74CB3Q3257PW:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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