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Analog Devices Inc. LTC4305CDHD#PBF
- Part No.:
- LTC4305CDHD#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Specialized
- Package:
- 16-WFDFN Exposed Pad
- Datasheet:
-
LTC4305CDHD#PBF.pdf
- Description:
- IC INTERFACE SPECIALIZED 16DFN
- Quantity:
- Payment:
- Shipping:
Inventory:4,401
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Product details
Overview
LTC4305CDHD#PBF from Analog Devices (formerly Linear Technology) is a 2-channel, bidirectional I²C/SMBus bus multiplexer with capacitive isolation buffers, programmable stuck-bus timeout, and rise time accelerator circuitry. It operates from 2.7V to 5.5V supply, supports independent downstream pull-up voltages (2.2V–5.5V), and delivers ±10kV HBM ESD protection. Used in multi-module I²C systems like SFP hot-swap backplanes and server management buses.
For engineers reviewing the LTC4305CDHD#PBF datasheet, LTC4305CDHD#PBF pinout, LTC4305CDHD#PBF application, or LTC4305CDHD#PBF equivalent, key selection criteria include its 1:2 channel switching capability, supply-independent bidirectional buffering, nested addressing (27 addresses), SMBus-compatible ALERT protocol, and programmable 7.5/15/30ms timeout modes - all critical for fault-tolerant, high-density I²C expansion.
Technical Context
The LTC4305CDHD#PBF implements dual upstream-downstream buffer pairs with offset-voltage-controlled FET switches (VOS,UP-BUF ≤ 150mV at 5.5V), enabling transparent clock stretching and arbitration across isolated segments. Its stuck-low detection uses dual 0.52V threshold comparators with hysteresis (80mV) and three selectable timeout windows controlled via TIMSET1/TIMSET0 bits in Register 2.
Rise time acceleration activates only when connected downstream buses meet dual conditions: pin voltage >0.8V and slew rate ≥0.8V/µs; boost current (IBOOST = 4–5.5mA) is regulated to prevent overshoot on light loads. The device features dedicated ALERT1/ALERT2 fault inputs with 1.0V logic thresholds and 80mV hysteresis, feeding an open-drain ALERT output compliant with SMBus Alert Response Address (ARA) protocol.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage Range | 2.7V to 5.5V - enables operation across 3.3V and 5V system domains without level shifters |
| Max I²C Clock Frequency | 400kHz - full-speed I²C compatibility, supporting standard and fast-mode peripherals |
| Stuck-Low Timeout Options | 7.5ms / 15ms / 30ms - configurable via TIMSET1/TIMSET0 bits to match bus capacitance and noise profile |
| Input Capacitance (SDA/SCL) | 6–10pF - low pin capacitance minimizes loading on upstream bus, preserving signal integrity |
| Buffer Offset Voltage (Downstream) | 60–200mV - ensures reliable logic-level translation across VCC and downstream pull-up voltage mismatches |
| Rise Time Accelerator Current | 4–5.5mA - actively sources current during rising edges to reduce rise time on high-capacitance buses |
| ESD Robustness | ±10kV HBM - protects against electrostatic discharge during live insertion/removal in backplane applications |
| Operating Temperature | 0°C to 70°C - commercial-grade rating suitable for industrial control and telecom equipment enclosures |
Pinout & Package
Package: 16-lead (4mm × 5mm) plastic DFN with exposed pad (Pin 17), θJA = 43°C/W when pad is connected to PCB ground.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (ALERT2) | Fault alert input - Channel 2 | Open-drain input; pulled low by downstream devices to signal faults; monitored independently of connection state |
| 2 (ALERT) | Fault alert output | Open-drain SMBus-compliant output; asserted low on ALERT1/ALERT2 activity, stuck-bus timeout, or failed connection attempt |
| 3 (SDAIN) | Upstream SDA bidirectional I/O | Connects to master-side SDA; buffered to downstream channels; requires external pull-up |
| 4 (GND) | Device ground reference | Primary return path for all internal circuits; exposed pad (Pin 17) must be connected to GND for thermal performance |
| 5 (SCLIN) | Upstream SCL bidirectional I/O | Connects to master-side SCL; buffered to downstream channels; requires external pull-up |
| 6 (ENABLE) | Digital interface enable/reset | Active-high control: low resets registers and disables I²C access but preserves ALERT monitoring |
| 7 (VCC) | Power supply input | 2.7–5.5V supply; bypass capacitor ≥0.01µF required between VCC and GND for stable operation |
| 8–10 (ADR0–ADR2) | I²C address configuration inputs | Three-state pins (float/VCC/GND) yield 27 unique slave addresses; tolerate ±5µA leakage while decoding correctly |
| 11 (READY) | Connection status indicator | N-channel open-drain output; pulled low when no downstream channel is connected; requires external 10kΩ pull-up |
| 12 (SCL1) | Downstream Channel 1 SCL output | Connects to SCL line of downstream bus 1; buffered and isolated; requires external pull-up if used |
| 13 (SDA1) | Downstream Channel 1 SDA output | Connects to SDA line of downstream bus 1; buffered and isolated; requires external pull-up if used |
| 14 (ALERT1) | Fault alert input - Channel 1 | Open-drain input; identical function to ALERT2; enables per-channel fault reporting |
| 15 (SDA2) | Downstream Channel 2 SDA output | Connects to SDA line of downstream bus 2; buffered and isolated; requires external pull-up if used |
| 16 (SCL2) | Downstream Channel 2 SCL output | Connects to SCL line of downstream bus 2; buffered and isolated; requires external pull-up if used |
Key Features
| Feature | Design Value |
|---|---|
| Capacitance buffering | Isolates upstream bus capacitance from downstream segments - enables fan-out beyond I²C spec limits without signal degradation |
| Programmable stuck-bus disconnect | Automatically isolates downstream channels after 7.5/15/30ms low condition - prevents system lockup in noisy or faulty peripheral environments |
| Supply-independent bidirectional buffering | Supports mixed-voltage downstream buses (2.2–5.5V) independent of VCC - eliminates need for external level translators |
| Nested addressing | 27 unique I²C addresses via ADR0–ADR2 - allows multiple LTC4305CDHD#PBF devices on same bus without address conflict |
| SMBus ALERT Response Protocol | Responds to Alert Response Address (0001100b) - enables standardized fault identification and resolution in SMBus-managed systems |
| Rise time accelerator circuitry | 4–5.5mA regulated boost current - reduces SDA/SCL rise time on high-CBUS traces without excessive edge rates or ringing |
Applications
| Server Baseboard Management Controller (BMC) | Hot-Swappable SFP+ Module Backplane |
|---|---|
Use Scenario: BMC monitors temperature, voltage, and fan sensors across multiple daughterboards via shared I²C bus. IC Role / Device Role / Timing Role: LTC4305CDHD#PBF acts as a fault-isolated 1:2 I²C multiplexer, preventing sensor failures on one board from blocking communication with others. Use Value: Enables reliable hot-swap capability and modular diagnostics - each downstream segment remains electrically isolated until explicitly enabled. |
Use Scenario: Host controller enumerates and configures multiple SFP+ transceivers plugged into a backplane, each with its own I²C EEPROM. IC Role / Device Role / Timing Role: LTC4305CDHD#PBF provides capacitive buffering and live-insertion protection, allowing safe module insertion/removal without disrupting active I²C traffic. Use Value: Prevents SDA/SCL corruption during hot-swap events - rise time accelerators maintain signal integrity despite added trace capacitance from connectors. |
| Industrial PLC I/O Expansion Rack | Multi-Sensor IoT Gateway |
Use Scenario: Central PLC CPU communicates with distributed I/O modules over long, daisy-chained I²C lines subject to EMI and ground shifts. IC Role / Device Role / Timing Role: LTC4305CDHD#PBF serves as a buffered repeater with programmable timeout, isolating noise-induced bus hangs to individual modules. Use Value: Guarantees deterministic recovery from stuck-bus faults - timeout disconnect restores upstream bus availability within ≤30ms. |
Use Scenario: Edge gateway aggregates data from diverse environmental sensors (temperature, humidity, CO₂) using separate I²C sub-buses. IC Role / Device Role / Timing Role: LTC4305CDHD#PBF functions as a software-configurable 2-channel switch, enabling dynamic sensor polling without hardware reconfiguration. Use Value: Supports mixed-voltage sensors (3.3V and 5V) on same host - downstream pull-ups operate independently of VCC, eliminating level-shifter components. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar I²C bus multiplexing applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TCA9548AIPWR | 8-channel I²C switch with no rise time acceleration, no stuck-bus timeout, and no ALERT input support; lower ESD rating (±2kV) | Lacks per-channel fault reporting and automatic bus recovery - requires host firmware to detect and clear stuck conditions | Choose TCA9548AIPWR only for cost-sensitive, low-noise, low-channel-count applications where fault autonomy is not required |
| PCA9546ADW | 4-channel I²C switch with no buffering, no level translation, and no programmable timeout; supports only 3.3V operation | No capacitive isolation - adds load to upstream bus; incompatible with mixed-voltage downstream buses | Select PCA9546ADW only when expanding to ≥4 channels on a single 3.3V domain with minimal bus capacitance |
Compared with TCA9548AIPWR and PCA9546ADW, the LTC4305CDHD#PBF uniquely combines capacitive buffering, programmable stuck-bus recovery, SMBus ALERT protocol, and supply-independent downstream pull-ups - making it the only option for robust, mixed-voltage, hot-swap-capable I²C expansion in mission-critical systems.
Availability
LTC4305CDHD#PBF is available at Aetrix Electronics and suitable for server BMC interfaces, SFP+ backplane management, industrial PLC I/O expansion, and multi-sensor IoT gateways requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.
Supply support for LTC4305CDHD#PBF 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
Analog Devices, Inc. (including legacy Linear Technology products) designs high-performance analog, mixed-signal, and power management ICs for precision instrumentation, industrial automation, and communications infrastructure.
The LTC4305 product line delivers intelligent I²C/SMBus signal conditioning - specifically engineered for fault-resilient, high-density bus expansion in telecom, computing, and industrial control systems where live insertion, voltage mismatch, and bus reliability are critical.
FAQ
What is the operating temperature range for the LTC4305CDHD#PBF?
The LTC4305CDHD#PBF is rated for 0°C to 70°C ambient operation, matching the "C" grade designation in its part number. This commercial temperature range is validated across all electrical specifications including buffer offset voltage, rise time acceleration current, and stuck-low timeout accuracy. It is suitable for enclosed industrial and telecom equipment where internal board temperatures remain within this envelope.
Does the LTC4305CDHD#PBF support level shifting between different supply voltages?
Yes, the LTC4305CDHD#PBF supports true bidirectional level shifting: its upstream side operates from VCC (2.7–5.5V), while each downstream channel can be pulled up to an independent voltage from 2.2V to 5.5V. This is achieved through supply-independent buffer architecture - no external level shifters are needed, and logic thresholds adapt automatically to downstream pull-up voltage.
How does the stuck-bus timeout feature work in the LTC4305CDHD#PBF?
The LTC4305CDHD#PBF continuously monitors internal SDA/SCL node voltages. If either falls below 0.52V for longer than the selected timeout (7.5ms, 15ms, or 30ms), it asserts ALERT low and disconnects downstream channels by de-biasing the upstream-downstream buffers. The timeout mode is set via TIMSET1/TIMSET0 bits in Register 2, and the real-time status is reported in Register 0's Timeout Real Time bit.
Can the LTC4305CDHD#PBF be used without connecting the exposed thermal pad?
Yes, the exposed pad (Pin 17) may be left unconnected, but thermal performance degrades significantly: θJA increases from 43°C/W (with pad connected to PCB ground) to 140°C/W (unconnected). For continuous operation at full load or elevated ambient temperatures, Analog Devices specifies that the pad must be soldered to a thermal plane to maintain TJ ≤ 125°C and ensure reliability.
What happens to the READY pin when both downstream channels are connected?
When one or more downstream channels are connected to the upstream bus, the LTC4305CDHD#PBF turns off the N-channel MOSFET driving the READY pin, allowing the external 10kΩ pull-up resistor to raise READY to the local supply voltage. READY remains high as long as at least one channel is active - it goes low only when all downstream FETs are open (disconnected), providing unambiguous connection status feedback to the host controller.
LTC4305CDHD#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-WFDFN Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Applications:
- Multiplexer with Amplifier
- Interface:
- SMBus (2-Wire/I2C)
- Voltage - Supply:
- 2.2V ~ 5.5V
- Supplier Device Package:
- 16-DFN (5x4)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
LTC4305CDHD#PBF FAQ
1.How can I place an order for LTC4305CDHD#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC4305CDHD#PBF 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 LTC4305CDHD#PBF reliable?
The price and inventory of LTC4305CDHD#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC4305CDHD#PBF is usually 5 days.
3.What payment methods are accepted for LTC4305CDHD#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC4305CDHD#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC4305CDHD#PBF?
LTC4305CDHD#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC4305CDHD#PBF 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 LTC4305CDHD#PBF?
For technical support, including LTC4305CDHD#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC4305CDHD#PBF requirements.
6.How does Aetrix verify that LTC4305CDHD#PBF is sourced from the original manufacturer or authorized distributors?
All LTC4305CDHD#PBF 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 LTC4305CDHD#PBF meets industry standards.
7.What is the process for return or replacement of LTC4305CDHD#PBF?
All LTC4305CDHD#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC4305CDHD#PBF, 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 LTC4305CDHD#PBF part is unused and in its original packaging.
Return procedure for LTC4305CDHD#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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