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Analog Devices Inc. LTC4255CG#PBF
- Part No.:
- LTC4255CG#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Power Supply Controllers, Monitors
- Package:
- 28-SSOP (0.209", 5.30mm Width)
- Datasheet:
-
LTC4255CG#PBF.pdf
- Description:
- IC NETWORK POWER CTRLR 28SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:141
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Product details
Overview
LTC4255CG#PBF from Analog Devices (formerly Linear Technology) is a quad –48V network power controller with independent relay drivers and I²C-compatible interface. It controls four isolated –48V power channels, each featuring programmable current limit (125–170 mV short-circuit sense), open-circuit detection (1–4.5 mV threshold), power good indication (1–3 V), and latchoff/autoretry fault recovery. Used in IP phone systems and DTE power distribution for IEEE 802.3af-compliant PoE midspan or endpoint applications.
For engineers reviewing the LTC4255CG#PBF datasheet, LTC4255CG#PBF pinout, LTC4255CG#PBF application, or LTC4255CG#PBF equivalent, key selection criteria include –48V channel isolation, I²C addressability (5-bit, up to 32 devices), 28-pin SSOP package compatibility, and integrated relay driver outputs with 18V clamp protection.
Technical Context
The LTC4255CG#PBF implements a digitally controlled hot-swap architecture for negative-rail telecom power. Each channel integrates an external N-channel MOSFET gate driver (GATE1–4), current-sense amplifier (SENSE1–4), relay driver (RELAY1–4), and status monitoring logic with dedicated FAULT interrupt output.
Its I²C interface supports standard-mode (400 kHz) operation with programmable address (AD0–AD4), enabling centralized control of up to 128 channels across 32 devices. Fault handling includes configurable current-limit timer (4.8–115.2 ms), open-circuit enable delay (50–649 ms), and autoretry duty cycle (0.83% or 6%).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VEE Range | –48V to –72V referenced to AGND; supports standard telecom –48V supply with margin for transients |
| Short-Circuit Sense Voltage | 125–170 mV (typ. 150 mV); sets precise current limit threshold at sense resistor |
| Open-Circuit Sense Threshold | 1–4.5 mV (typ. 3 mV); enables reliable no-load detection without false triggers |
| Power_OK Threshold | 1–3 V (typ. 2 V) relative to VEE; confirms stable output voltage before enabling downstream loads |
| I²C Clock Frequency | Up to 400 kHz; enables fast configuration and status polling without bus contention |
| Operating Temperature | 0°C to 70°C (Commercial grade); validated for indoor telecom equipment environments |
| Package | 28-lead plastic SSOP (5.3 mm wide); surface-mount compatible with standard reflow profiles |
Pinout & Package
The LTC4255CG#PBF is housed in a 28-lead plastic SSOP (G package), 5.3 mm body width, with 0.65 mm lead pitch. Pin 1 is FAULT (open-drain fault indicator), pin 14 is VCC (12V digital supply), pin 22 is VEE (–48V analog supply), and pins 16/19/23/26 are SENSE1–4 (current sense inputs).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| FAULT (1) | Open-drain fault interrupt output | Pulls low on short-circuit or open-circuit fault; eliminates need for software polling |
| SCL (2), SDA (3) | I²C serial clock/data bidirectional lines | Support 400 kHz standard-mode interface; require external pull-up to ≤6V |
| AD0–AD4 (4–8) | I²C address input bits | Set 5-bit device address; internal 30–90 kΩ pull-ups allow floating = high |
| RELAY1–4 (9–12) | Open-collector relay driver outputs | Sink 50 mA to DGND; 18V Zener clamp protects against coil flyback |
| DGND (13), AGND (15) | Digital/analog ground references | Must be within ±5 V of each other; separate planes recommended for noise isolation |
| SENSE1–4 (16,19,23,26) | Current sense inputs | Monitor voltage drop across external sense resistors (e.g., 0.33 Ω) to detect faults |
| GATE1–4 (17,20,24,27) | MOSFET gate drive outputs | 50 µA pull-up to ~13 V above VEE; actively modulated during current foldback |
| OUT1–4 (18,21,25,28) | Output voltage monitor inputs | Enable Power_OK bit when VOUT–VEE < 2 V; trigger foldback if near AGND |
Key Features
| Feature | Design Value |
|---|---|
| Independent per-channel control | Each of four –48V channels has dedicated ON/OFF, current limit, and fault reporting via I²C registers |
| Programmable current foldback | Reduces FET power dissipation during shorts by lowering gate voltage when OUT is near AGND |
| Configurable fault response | Software-selectable latchoff or autoretry with programmable duty cycle (0.83% or 6%) |
| Integrated relay drivers | Four open-collector outputs with 18V clamping protect external relays from inductive kickback |
| Hardware fault interrupt | Active-low FAULT pin signals any channel fault event, enabling immediate host controller response |
Applications
| IP Phone Power Management | DTE Power Distribution |
|---|---|
Use Scenario: Powering IEEE 802.3af-compliant VoIP phones from a centralized –48V source with per-port fault isolation. IC Role / Device Role / Timing Role: Quad-channel hot-swap controller managing power sequencing, short-circuit protection, and Power_OK signaling for each phone port. Use Value: Enables safe hot insertion/removal of phones while preventing system-wide shutdown during single-port faults. |
Use Scenario: Distributing –48V power to multiple data terminal equipment (DTE) units in telecom central offices or enterprise wiring closets. IC Role / Device Role / Timing Role: Centralized power supervisor providing independent channel enable/disable, current monitoring, and relay-controlled load switching. Use Value: Eliminates manual breaker resets; allows remote diagnostics and automated recovery via I²C interface. |
| Midspan PoE Injector | Network Equipment Shelf Power |
Use Scenario: Adding PoE capability to legacy Ethernet switches using midspan injectors supporting up to 16 ports via cascaded LTC4255CG#PBF devices. IC Role / Device Role / Timing Role: Primary power controller implementing IEEE 802.3af Class 0–3 detection, classification, and current-limited delivery per port. Use Value: Achieves 32-channel scalability with only two I²C lines and five address pins-reducing interconnect complexity vs. discrete solutions. |
Use Scenario: Managing redundant –48V feeds to line cards in carrier-grade routers or optical transport platforms. IC Role / Device Role / Timing Role: Dual-redundant power supervisor ensuring failover between primary/backup supplies with synchronized fault reporting. Use Value: Maintains uptime during supply faults via autonomous channel disable and FAULT-driven host alerting. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar negative-voltage hot-swap controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC4251CS6#TRMPBF | SOT-23-6, single-channel, –15V to –80V range, no relay drivers, lower integration | Targeted at space-constrained, single-port applications without relay control needs | Select when board area is critical and relay functionality is handled externally |
| LT4250CG#PBF | SO-8, single-channel, –20V to –80V, active current limiting, no I²C interface, no open-circuit detection | Used in simpler hot-swap circuits requiring analog-only control and minimal feature set | Select for cost-sensitive designs where digital configurability and multi-channel coordination are unnecessary |
Compared with LTC4251CS6#TRMPBF and LT4250CG#PBF, the LTC4255CG#PBF uniquely delivers quad-channel coordination, integrated relay drivers, I²C programmability, and open-circuit detection-making it the only choice for scalable, intelligent –48V power distribution with full fault autonomy.
Availability
LTC4255CG#PBF is available at Aetrix Electronics and suitable for IP phone systems, DTE power distribution, midspan PoE injectors, and network equipment shelf power requiring stable component supply and long-term industrial availability.
Supply support for LTC4255CG#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 acquired Linear Technology in 2017 and maintains its high-reliability analog/power IC portfolio. The company specializes in precision signal conditioning, power management, and interface solutions for demanding industrial and telecom applications.
The LTC4255CG#PBF belongs to Linear's legacy hot-swap controller product line, designed specifically for robust –48V telecom power distribution with digital supervision, fault resilience, and multi-unit scalability in carrier-class infrastructure.
FAQ
What is the absolute maximum VEE rating for the LTC4255CG#PBF?
The LTC4255CG#PBF has an absolute maximum VEE rating of –80V referenced to AGND. This provides 32V headroom above the nominal –48V telecom supply, accommodating transient surges and ensuring safe operation during line faults or lightning-induced spikes without latchup or damage.
Does the LTC4255CG#PBF support automatic retry after a short-circuit fault?
Yes, the LTC4255CG#PBF supports programmable autoretry after short-circuit faults. Setting the Autoretry Enable Bit (B1) in Register 2 activates automatic restart after the retry timer expires. Duty cycle is selectable (0.83% or 6%) via Bit B3, enforcing safe thermal limits during sustained faults.
How many LTC4255CG#PBF devices can be addressed on a single I²C bus?
Up to 32 LTC4255CG#PBF devices can be addressed on one I²C bus using the five hardware address pins AD0–AD4. Each device provides four independent –48V channels, enabling centralized control of up to 128 total power channels with only two digital lines (SCL/SDA).
What is the purpose of the RELAY1–4 pins on the LTC4255CG#PBF?
The RELAY1–4 pins on the LTC4255CG#PBF are open-collector NPN outputs that drive external relays to connect/disconnect the –48V supply path. Each sinks 50 mA and includes an internal 18V Zener clamp to suppress inductive kickback from relay coils, eliminating need for external flyback diodes.
Can the LTC4255CG#PBF detect open-circuit conditions on powered loads?
Yes, the LTC4255CG#PBF detects open-circuit conditions using the SENSE1–4 inputs. When voltage across the sense resistor falls below 1–4.5 mV for longer than the programmable open-circuit filter time (9.6–28.8 ms), the FET is turned off and the FAULT pin asserts, indicating loss of load integrity.
LTC4255CG#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 28-SSOP (0.209", 5.30mm Width)
- Packaging:
- Tube
- Product Status:
- Last Time Buy
- Programmable:
- Not Verified
- Applications:
- Network Power Controller
- Voltage - Input:
- -
- Voltage - Supply:
- 10.8V ~ 13.2V
- Current - Supply:
- 10 mA
- Operating Temperature:
- 0°C ~ 70°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-SSOP
LTC4255CG#PBF FAQ
1.How can I place an order for LTC4255CG#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC4255CG#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 LTC4255CG#PBF reliable?
The price and inventory of LTC4255CG#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC4255CG#PBF is usually 5 days.
3.What payment methods are accepted for LTC4255CG#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC4255CG#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC4255CG#PBF?
LTC4255CG#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC4255CG#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 LTC4255CG#PBF?
For technical support, including LTC4255CG#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC4255CG#PBF requirements.
6.How does Aetrix verify that LTC4255CG#PBF is sourced from the original manufacturer or authorized distributors?
All LTC4255CG#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 LTC4255CG#PBF meets industry standards.
7.What is the process for return or replacement of LTC4255CG#PBF?
All LTC4255CG#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC4255CG#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 LTC4255CG#PBF part is unused and in its original packaging.
Return procedure for LTC4255CG#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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