My Inquiry
My Account
Analog Devices Inc. LTC4268CDKD-1#PBF
- Part No.:
- LTC4268CDKD-1#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Power Over Ethernet (PoE) Controllers
- Package:
- 32-WFDFN Exposed Pad
- Datasheet:
-
LTC4268CDKD-1#PBF.pdf
- Description:
- IC POE CNTRL 1 CHANNEL 32DFN
- Quantity:
- Payment:
- Shipping:
Inventory:3,879
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
LTC4268CDKD-1#PBF from Analog Devices (formerly Linear Technology) is a high-power IEEE 802.3af Powered Device (PD) controller with integrated synchronous flyback regulator, designed for PoE applications up to 35W. It features dual-level current limiting (750mA operational / 300mA inrush), No-Opto™ isolated feedback, and a rugged 0.6Ω internal MOSFET. It enables robust power delivery in PTZ security cameras, dual-radio WAPs, and RFID readers.
For engineers reviewing the LTC4268CDKD-1#PBF datasheet, LTC4268CDKD-1#PBF pinout, LTC4268CDKD-1#PBF application, or LTC4268CDKD-1#PBF equivalent, key selection criteria include its -57V input rating, 7mm × 4mm DFN package with exposed thermal pad, dual PWRGD outputs (active-high referenced to VNEG and active-low referenced to VPORTN), and programmable classification current up to 75mA.
Technical Context
The LTC4268CDKD-1#PBF implements a current-mode synchronous flyback controller with patented No-Opto feedback, eliminating optocouplers while maintaining full IEEE 802.3af isolation. Its control loop uses VCMP as the error amplifier output and current comparator input, with load compensation via RCMP/CCMP pins to maintain tight multi-output regulation under varying loads.
It integrates a precision dual-current-limit PD front end: ILIM_EN selects between 750mA (floating), 300mA (low), or 1.45A safeguard mode; UVLO thresholds (15.3V turn-on / 9.7V turn-off) are independent of VPORTN; and signature resistance is factory trimmed to 26kΩ ±1.25kΩ (including diode drop) for guaranteed IEEE compliance.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | –1.5V to –57V (negative supply referenced to VPORTP); supports full IEEE 802.3af range including worst-case –57V surge. |
| Operational Current Limit | 750mA (typical) with ±5% tolerance; enables 35W PoE delivery at –48V while staying within IEEE inrush limits. |
| Oscillator Frequency | 84–110kHz (typ. 100kHz) set by external 33–200pF capacitor; adjustable from 50kHz to 250kHz via RtON and COSC. |
| Feedback Regulation Voltage | 1.237V ±1.3mV over temperature; used with third-winding sensing to achieve ±1% output voltage accuracy across loads. |
| On-Resistance (RON) | 0.6Ω (max) at –48V and 700mA; minimizes conduction loss in high-current PD power path. |
| Signature Resistance | 26kΩ ±1.25kΩ (measured two-point per IEEE 802.3af); includes internal 25kΩ resistor plus diode drop compensation. |
| Operating Temperature | 0°C to 70°C (C-grade); junction limit 150°C with θJA = 49°C/W; requires exposed pad soldered to GND plane for thermal management. |
Pinout & Package
The LTC4268CDKD-1#PBF is housed in a 32-pin, 7mm × 4mm plastic DFN package (DKD32) with an exposed thermal pad (Pin 33) that must be soldered to a GND-connected heatsinking plane. Pin pitch is 0.5mm; lead-free finish; RoHS compliant.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VPORTP (32) | Positive Power Input Reference | Return node for input diode bridge; all VPORTN voltages referenced to this pin; must connect to system ground via bridge. |
| VPORTN (5,6,7) | Negative Power Input | Main PoE input rail (–1.5V to –57V); three parallel pins reduce IR drop and improve thermal handling for 750mA current. |
| VNEG (26,27,28) | System Negative Rail | Internal switch connects VPORTN to VNEG above UVLO threshold; powers flyback controller; three pins support high-current return path. |
| PWRGD (29,30) | Dual Power-Good Outputs | Pin 29: Active-high open-collector (to VNEG), clamped at 14V; Pin 30: Active-low open-drain (to VPORTN); enable sequencing of downstream converters. |
| PG (24) | Primary Gate Driver | Drives external N-channel MOSFET gate; high-current capability supports fast switching with minimal dead-time loss. |
| SG (9) | Secondary Gate Driver | Drives synchronous rectifier on secondary side; timing coordinated with PG to minimize shoot-through risk. |
| FB (16) | Feedback Amplifier Input | Accepts third-winding voltage during flyback period; internal 1.237V reference enables precise output regulation without optocoupler. |
| VCMP (17) | Current Comparator Input | Output of error amplifier; directly proportional to peak primary current; sets duty cycle and enables slope compensation. |
| RCLASS (3) | Classification Current Set | Resistor to VPORTN programs classification current from 10mA to 75mA per IEEE 802.3af Class 0–5. |
| ILIM_EN (4) | Current Limit Mode Select | Floating = 750mA high mode; tied to VPORTN = 300mA low mode; enables safe inrush control and fault recovery. |
Key Features
| Feature | Design Value |
|---|---|
| No-Opto™ Flyback Control | Eliminates optocoupler and TL431, reducing BOM cost and board space while maintaining ±1% output regulation across line/load/temperature. |
| Dual PWRGD Outputs | Active-high (to VNEG) and active-low (to VPORTN) signals provide flexible power sequencing for isolated DC/DC stages and microcontrollers. |
| Programmable Classification | Supports IEEE 802.3af Classes 0–5 via single RCLASS resistor; accuracy ±3.5% over temperature ensures reliable PSE negotiation. |
| Thermal & Overcurrent Protection | Integrated thermal shutdown disables MOSFET and asserts invalid PWRGD; dual current limit prevents damage during startup and overload. |
| Robust Input Stage | Withstands –57V transients; absolute max VPORTN = –90V; internal 20V VCC clamp protects bias circuitry during surges. |
Applications
| PTZ Security Cameras | Dual-Radio Wireless Access Points |
|---|---|
|
Use Scenario: Outdoor pan-tilt-zoom camera requiring 24V/1A for motor control, 5V/2A for imaging sensor, and 3.3V/500mA for SoC-all powered over single Ethernet cable. IC Role / Device Role: Primary PD controller and synchronous flyback regulator delivering three tightly regulated rails with no optocoupler. Use Value: Enables compact, fanless enclosure design by achieving >88% efficiency at full 35W load and eliminating optocoupler aging concerns. |
Use Scenario: Enterprise-grade 802.11ac access point with dual 5GHz/2.4GHz radios, PoE-powered via spare pair, needing 12V/1.5A and 5V/3A outputs. IC Role / Device Role: High-efficiency PD interface with synchronous rectification and load-compensated feedback for stable RF supply rails. Use Value: Maintains <±1% output regulation across radio transmit bursts, preventing RF desense and ensuring consistent throughput. |
| RFID Readers | Industrial PoE Controllers |
|
Use Scenario: UHF RFID reader powering antenna module (15V/800mA), baseband processor (3.3V/600mA), and I/O interface (5V/200mA) from single PoE port. IC Role / Device Role: Integrated PD + flyback controller with dual PWRGD outputs enabling safe power-up sequencing of sensitive analog front-end. Use Value: Eliminates need for external supervisor ICs; PWRGD signals coordinate FPGA configuration before RF power-up, preventing latch-up. |
Use Scenario: DIN-rail mounted industrial controller drawing 30W PoE power for PLC logic, CAN bus transceivers, and isolated I/O drivers. IC Role / Device Role: Rugged PD front end with 0.6Ω RON, thermal protection, and wide –40°C to +70°C operating range (C-grade variant). Use Value: Sustains full 35W operation in unventilated enclosures via exposed-pad thermal design; withstands 20Ω source impedance per IEEE 802.3af. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Powered Device controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC4275CDKD-2#PBF | Supports IEEE 802.3at (PoE+) up to 60W; higher 1.2A current limit; different classification resistor mapping; no No-Opto topology. | Required for >35W systems; needs external optocoupler; larger solution size due to added isolation components. | Select when upgrading to PoE+ or needing >35W; not drop-in-requires layout and feedback redesign. |
| MAX5984DETE+T | IEEE 802.3af-compliant PD controller only (no integrated flyback); requires external PWM controller and MOSFETs; 600mA current limit. | Suitable for discrete flyback designs where flexibility in transformer selection or custom regulation is needed. | Choose when modular architecture is preferred or when existing flyback design must be reused; adds 3–4 ICs and increases footprint. |
Compared with LTC4268CDKD-1#PBF, LTC4275CDKD-2#PBF delivers higher power but sacrifices No-Opto simplicity and board area, while MAX5984DETE+T offers design flexibility at the cost of increased component count, BOM complexity, and thermal management effort.
Availability
LTC4268CDKD-1#PBF is available at Aetrix Electronics and suitable for PTZ security cameras, dual-radio wireless access points, and industrial PoE controllers requiring stable component supply, long-term lifecycle support, and guaranteed RoHS-compliant sourcing.
Supply support for LTC4268CDKD-1#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 legacy of high-performance analog and power management ICs for demanding industrial, communications, and automotive applications.
The LTC4268-1 product line was developed specifically for high-efficiency, isolated PoE-powered devices needing integrated PD control and synchronous flyback regulation-targeting applications where space, reliability, and IEEE compliance are critical.
FAQ
What is the maximum input voltage rating for the LTC4268CDKD-1#PBF?
The LTC4268CDKD-1#PBF supports a VPORTN voltage range of –1.5V to –57V, with absolute maximum ratings extending to –90V. Its UVLO turn-on occurs at 15.3V (referenced to GND), and it complies fully with IEEE 802.3af's –57V maximum specification. The device includes internal clamps to protect against transients beyond nominal operating conditions.
Does the LTC4268CDKD-1#PBF require an optocoupler for isolation?
No, the LTC4268CDKD-1#PBF uses Linear Technology's patented No-Opto™ feedback topology, which achieves full IEEE 802.3af isolation without an optocoupler. It relies on third-winding sensing and internal error amplification via the FB and VCMP pins to regulate output voltage with ±1% accuracy across temperature and load.
How is the classification current programmed on the LTC4268CDKD-1#PBF?
The classification current for the LTC4268CDKD-1#PBF is set using an external resistor (RCLASS) connected between Pin 3 (RCLASS) and VPORTN. Values from 16.2kΩ (Class 0, 10mA) to 16.5Ω (Class 5, 75mA) configure IEEE 802.3af classes. Accuracy is ±3.5% over temperature, and total classification current includes both RCLASS-set current and 0.62mA IC quiescent draw.
What thermal management is required for the LTC4268CDKD-1#PBF?
The LTC4268CDKD-1#PBF requires its exposed thermal pad (Pin 33) to be soldered to a GND-connected copper plane for effective heat dissipation. With θJA = 49°C/W, continuous 35W operation demands ≥4 cm² of 2-oz copper. Thermal shutdown activates at 150°C junction temperature and forces PWRGD invalid until cooldown below the hysteresis threshold.
Can the LTC4268CDKD-1#PBF drive multiple output rails simultaneously?
Yes, the LTC4268CDKD-1#PBF's synchronous flyback controller supports multiple isolated output rails using a single transformer with multiple secondary windings. Load compensation via RCMP and CCMP pins ensures tight cross-regulation (<±2%) across all outputs-even under asymmetric loading-without additional post-regulators.
LTC4268CDKD-1#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 32-WFDFN Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Type:
- Controller (PD), DC/DC
- Number of Channels:
- 1
- Power - Max:
- 35 W
- Internal Switch(s):
- No
- Auxiliary Sense:
- No
- Standards:
- 802.3af (PoE)
- Voltage - Supply:
- 57V (Max)
- Current - Supply:
- 3mA (Max)
- Operating Temperature:
- 0°C ~ 70°C
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 32-DFN (7x4)
LTC4268CDKD-1#PBF FAQ
1.How can I place an order for LTC4268CDKD-1#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC4268CDKD-1#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 LTC4268CDKD-1#PBF reliable?
The price and inventory of LTC4268CDKD-1#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC4268CDKD-1#PBF is usually 5 days.
3.What payment methods are accepted for LTC4268CDKD-1#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC4268CDKD-1#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC4268CDKD-1#PBF?
LTC4268CDKD-1#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC4268CDKD-1#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 LTC4268CDKD-1#PBF?
For technical support, including LTC4268CDKD-1#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC4268CDKD-1#PBF requirements.
6.How does Aetrix verify that LTC4268CDKD-1#PBF is sourced from the original manufacturer or authorized distributors?
All LTC4268CDKD-1#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 LTC4268CDKD-1#PBF meets industry standards.
7.What is the process for return or replacement of LTC4268CDKD-1#PBF?
All LTC4268CDKD-1#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC4268CDKD-1#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 LTC4268CDKD-1#PBF part is unused and in its original packaging.
Return procedure for LTC4268CDKD-1#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LTC4268CDKD-1#PBF Tags
-
TPS2378DDAR
Texas Instruments
-
TPS23753APWR
Texas Instruments
-
TPS23756PWPR
Texas Instruments
-
TPS23750PWPR
Texas Instruments
-
MP8007GV-Z
Monolithic Power Systems Inc.
-
TPS23861PWR
Texas Instruments
-
TPS23753PWR
Texas Instruments
-
PD69201ILD-TR
Microchip Technology
-
SI3402-B-GM
Skyworks Solutions Inc.
-
SI3402-B-GMR
Skyworks Solutions Inc.
-
SI34071-A01-GMR
Skyworks Solutions Inc.
-
SI3404-A-GMR
Skyworks Solutions Inc.
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…
