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NXP Semiconductors CBT3857PW,118
- Part No.:
- CBT3857PW,118
- Manufacturer:
- NXP Semiconductors
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 24-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
CBT3857PW,118.pdf
- Description:
- IC BUS SWITCH 10 X 1:1 24TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,972
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Product details
Overview
CBT3857PW,118 from NXP Semiconductors (formerly Philips) is a 10-bit CMOS bus switch optimized for DDR SDRAM interfaces, featuring 10 kΩ internal pull-down resistors on the B port, SSTL_2-compatible enable input, and 24-pin TSSOP package. It operates from 3.0 V to 3.6 V, delivers 720 ps typical propagation delay, and supports 200 Mbps data rates in high-speed memory subsystems.
For engineers reviewing the CBT3857PW,118 datasheet, CBT3857PW,118 pinout, CBT3857PW,118 application, or CBT3857PW,118 equivalent, key selection criteria include its flow-through architecture for PCB layout optimization, on-resistance of 20–30 Ω eliminating external series termination, and integrated termination enabling full DDR solutions with SSTL16857 and PCK857.
Technical Context
The CBT3857PW,118 implements a low-voltage, bidirectional analog switch topology using NMOS pass transistors with no level-shifting circuitry-enabling direct connection between A and B ports when OE is low. Its SSTL_2-compatible OE input accepts reference-based thresholds (VREF ±350 mV AC), and internal 50 kΩ pull-up on OE ensures defined logic state during power-up.
Designed specifically for DDR SDRAM DIMM applications, the device provides controlled impedance switching with 24 Ω typical on-resistance matched to transmission line requirements, while internal 10 kΩ pull-downs on all ten B-port outputs suppress floating states during disable. It is characterized across 0°C to +85°C and meets JESD78 latch-up (>500 mA) and JESD22 ESD specifications (2000 V HBM).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 3.0 V to 3.6 V - Ensures compatibility with DDR SDRAM core and I/O supply rails |
| tPLH / tPHL | 720 ps typical - Enables timing-critical 200 Mbps DDR signaling without added delay penalty |
| ron | 20–30 Ω - Matches trace impedance to eliminate need for external series termination resistors |
| CIN / COUT | 2.8 pF / 6.4 pF - Minimizes capacitive loading on DDR address/control buses |
| Internal Termination | 10 kΩ pull-down on B1–B10 - Prevents floating outputs during high-impedance state in memory modules |
| OE Input Logic | SSTL_2 compatible with VREF = 0.38 × VCC - Interfaces directly with DDR controller OE signals |
| Operating Temperature | 0°C to +85°C - Validated for commercial-grade DIMM and motherboard environments |
Pinout & Package
Package: 24-pin plastic TSSOP (SOT355-1), 4.4 mm body width, lead pitch 0.65 mm.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VREF (Pin 1) | Reference voltage output | Provides 0.38 × VCC for SSTL_2 threshold generation; must be connected to OE input reference |
| A1–A10 (Pins 2–11) | Data inputs | Unidirectional or bidirectional signal entry points; connect to DDR controller side |
| GND (Pin 12) | Ground reference | Primary return path for switch current and termination networks |
| VCC (Pin 24) | Positive supply | 3.0–3.6 V power source; decoupling required near pin for DDR noise immunity |
| B1–B10 (Pins 13–22) | Data outputs | Terminated outputs with internal 10 kΩ pull-downs; connect to SDRAM side |
| OE (Pin 23) | Output enable control | Active-low SSTL_2 input; 50 kΩ internal pull-up ensures default HIGH (open) state at power-on |
Key Features
| Feature | Design Value |
|---|---|
| Flow-through pinout | Input A1–A10 and output B1–B10 arranged linearly across opposite sides-reduces layer count and crosstalk in DDR routing |
| Integrated 10 kΩ pull-downs | Eliminates 20 discrete 10 kΩ resistors on B-port lines-saves board area and improves signal integrity in DIMM designs |
| 24 Ω typical on-resistance | Matches standard PCB trace impedance-prevents reflections without external series resistors on DDR address/control nets |
| SSTL_2-compatible OE | Accepts VREF-referenced thresholds-enables direct interface with DDR memory controllers without level translators |
| Latch-up immunity | Exceeds 500 mA per JESD78-ensures robustness against transient ground bounce in high-speed memory systems |
Applications
| DDR SDRAM DIMM Address Bus | DDR SDRAM DIMM Control Bus |
|---|---|
Use Scenario: Routing address signals from memory controller to multiple SDRAM chips on a 184-pin DIMM module. IC Role / Device Role / Timing Role: Bidirectional bus switch isolating controller-side A-port from terminated B-port, enabling fanout without signal degradation. Use Value: Flow-through pinout simplifies layer stacking; 24 Ω ron and 10 kΩ pull-downs maintain signal integrity across 10-bit address lines at 200 Mbps. | Use Scenario: Distributing command signals (RAS#, CAS#, WE#) across DDR SDRAM devices on a dual-sided DIMM. IC Role / Device Role / Timing Role: Low-delay switch enabling shared control bus with per-chip isolation and termination. Use Value: 720 ps propagation delay preserves setup/hold margins; SSTL_2 OE synchronizes cleanly with DDR controller timing. |
| DDR Memory Buffer Interface | DDR Register-to-SDRAM Interface |
Use Scenario: Interfacing a DDR register (e.g., SSTL16857) to downstream SDRAM banks in registered DIMMs. IC Role / Device Role / Timing Role: Signal conditioning and isolation stage between register outputs and SDRAM inputs. Use Value: Internal 10 kΩ pull-downs prevent floating states during register update cycles; 3.3 V operation matches SSTL logic levels. | Use Scenario: Connecting PCK857 clock driver outputs to SDRAM clock-enable inputs in high-density memory modules. IC Role / Device Role / Timing Role: Controlled-impedance switch enabling clock-enable distribution with defined DC bias. Use Value: 24 Ω ron minimizes skew between parallel CE# lines; GND/VCC pins placed adjacent to reduce supply inductance. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bus switch applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74CBTD3384DBR | 8-bit, 5 V tolerant, no internal termination resistors, higher ICCZ (2.5 mA) | Requires external pull-downs; suited for general-purpose 5 V logic, not DDR-optimized | Select only if operating at 5 V or needing higher voltage tolerance; lacks DDR-specific features |
| PI3CH400QE | 10-bit, 3.3 V, no internal termination, 12 ns enable/disable time vs. 1–3 ns for CBT3857PW,118 | Slower switching limits use in >133 MHz DDR; requires external termination network | Use where cost is prioritized over DDR timing compliance; verify tdis/tens meet system margin |
Compared with SN74CBTD3384DBR and PI3CH400QE, the CBT3857PW,118 uniquely integrates DDR-optimized features-including SSTL_2 OE, 10 kΩ B-port pull-downs, and sub-nanosecond enable timing-making it the only solution requiring zero external termination components in 184-pin DDR DIMM designs.
Availability
CBT3857PW,118 is available at Aetrix Electronics and suitable for DDR SDRAM DIMM manufacturing, memory module repair, and industrial embedded memory subsystems requiring stable component supply and long-term obsolescence management.
Supply support for CBT3857PW,118 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
NXP Semiconductors is a global semiconductor company delivering high-performance mixed-signal and RF solutions for automotive, industrial, and communication markets, with roots in Philips' semiconductor division.
The CBT3857PW,118 belongs to NXP's legacy CBT (CrossBar Technology) bus switch family, designed specifically for high-speed memory interface applications including DDR SDRAM, RDRAM, and early high-bandwidth digital interconnects.
FAQ
What is the function of the VREF pin on the CBT3857PW,118?
The VREF pin on the CBT3857PW,118 outputs a reference voltage equal to 0.38 × VCC (1.15–1.35 V at 3.0–3.6 V supply), which sets the switching thresholds for the SSTL_2-compatible OE input. This pin must be connected directly to the OE input's reference node to ensure correct AC and DC high/low-level detection per JEDEC SSTL-2 specifications. The CBT3857PW,118 relies on this internally generated VREF to interface reliably with DDR memory controllers without external voltage dividers.
Does the CBT3857PW,118 require external pull-down resistors on the B port?
No, the CBT3857PW,118 includes internal 10 kΩ pull-down resistors on all ten B-port outputs (B1–B10), eliminating the need for external termination components. This integration reduces bill-of-materials count and PCB footprint in DDR SDRAM DIMM designs. The CBT3857PW,118 datasheet explicitly confirms these resistors are fabricated monolithically and characterized across temperature and voltage-no external pull-downs are recommended or required for standard operation.
What is the maximum data rate supported by the CBT3857PW,118?
The CBT3857PW,118 is designed for use in Double Data Rate (DDR) SDRAM applications up to 200 Mbps, as stated in its official product specification. This rating is validated by its 720 ps typical propagation delay, 24 Ω on-resistance, and 6.4 pF output capacitance-parameters that collectively support clean signal edges and minimal jitter at DDR timing margins. The CBT3857PW,118 does not specify support beyond 200 Mbps, and operation at higher rates is not guaranteed by NXP's characterization.
Can the CBT3857PW,118 be used in 5 V systems?
No, the CBT3857PW,118 is rated for 3.0 V to 3.6 V VCC operation only, with absolute maximum VCC of +4.6 V. Its internal circuitry-including SSTL_2 input thresholds referenced to VREF and NMOS switch design-is optimized for 3.3 V DDR logic. Applying 5 V exceeds recommended conditions and risks parametric failure or reliability degradation. For 5 V bus switching, alternative parts such as SN74CBTD3384DBR should be considered-not the CBT3857PW,118.
Is the CBT3857PW,118 pin-compatible with other CBT-series switches like CBT3383 or CBT3384?
No, the CBT3857PW,118 is not pin-compatible with CBT3383 or CBT3384. It uses a unique 24-pin TSSOP (SOT355-1) pinout with VREF on Pin 1, GND on Pin 12, and OE on Pin 23-distinct from the 20-pin SO and TSSOP packages of CBT3383/CBT3384. The CBT3857PW,118 also differs electrically: it includes B-port pull-downs and SSTL_2 OE, whereas CBT3383/CBT3384 lack both features. Direct substitution would require PCB redesign and firmware revalidation.
CBT3857PW,118 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- NXP Semiconductors
- Series:
- 74CBT
- Package/Case:
- 24-TSSOP (0.173", 4.40mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Type:
- Bus Switch
- Circuit:
- 10 x 1:1
- Independent Circuits:
- 1
- Current - Output High, Low:
- -
- Voltage Supply Source:
- Single Supply
- Voltage - Supply:
- 3V ~ 3.6V
- Operating Temperature:
- 0°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 24-TSSOP
CBT3857PW,118 FAQ
1.How can I place an order for CBT3857PW,118 through Aetrix?
Please submit a Request for Quotation (RFQ) for CBT3857PW,118 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 CBT3857PW,118 reliable?
The price and inventory of CBT3857PW,118 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for CBT3857PW,118 is usually 5 days.
3.What payment methods are accepted for CBT3857PW,118?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for CBT3857PW,118 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for CBT3857PW,118?
CBT3857PW,118 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your CBT3857PW,118 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 CBT3857PW,118?
For technical support, including CBT3857PW,118 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your CBT3857PW,118 requirements.
6.How does Aetrix verify that CBT3857PW,118 is sourced from the original manufacturer or authorized distributors?
All CBT3857PW,118 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 CBT3857PW,118 meets industry standards.
7.What is the process for return or replacement of CBT3857PW,118?
All CBT3857PW,118 units undergo pre-shipment inspection (PSI). If there is an issue with CBT3857PW,118, 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 CBT3857PW,118 part is unused and in its original packaging.
Return procedure for CBT3857PW,118:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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