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Analog Devices Inc. LT3504EUFD#PBF
- Part No.:
- LT3504EUFD#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 28-WFQFN Exposed Pad
- Datasheet:
-
LT3504EUFD#PBF.pdf
- Description:
- IC REG BUCK ADJ 1A QUAD 28QFN
- Quantity:
- Payment:
- Shipping:
Inventory:4,360
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Product details
Overview
LT3504EUFD#PBF from Analog Devices (formerly Linear Technology) is a quad 40V/1A synchronous step-down switching regulator IC with integrated boost regulator for 100% duty cycle operation. It delivers four independent 1A outputs, supports 3.2V–40V input, features resistor-programmed switching frequency (350kHz–2.2MHz), and operates in automotive battery regulation, industrial control supplies, and distributed power systems.
For engineers reviewing the LT3504EUFD#PBF datasheet, LT3504EUFD#PBF pinout, LT3504EUFD#PBF application, or LT3504EUFD#PBF equivalent, key selection criteria include its 28-lead 4mm × 5mm QFN package, 800mV feedback reference, independent RUN/SS pins for sequencing, and SKY pin architecture enabling high-duty-cycle buck conversion without external charge pumps.
Technical Context
The LT3504EUFD#PBF integrates four independent current-mode buck regulators plus a dedicated boost regulator (SW5/SKY) that generates +4.85V above VIN to drive internal bipolar switches. Each channel uses cycle-by-cycle peak current limiting and catch diode current limiting for overload protection.
It employs antiphase clocking (CH1/CH3/CH5 vs CH2/CH4) to reduce input ripple, supports output voltage tracking via RUN/SS pin resistor dividers, and includes thermal shutdown, soft-start, and a power-good (PG) open-collector output indicating regulation status across all four FB pins.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.2V to 40V - enables direct connection to automotive batteries (12V/24V) and industrial rails without pre-regulation. |
| Output Current per Channel | 1A continuous - supports powering multiple SoC cores, FPGAs, or mixed-signal subsystems from a single IC. |
| Feedback Reference Voltage | 790–816mV (typ. 800mV) - sets precise output voltage via external resistor divider; low tolerance minimizes output error. |
| Switching Frequency Range | 350kHz to 2.2MHz - adjustable via RT resistor or external SYNC signal; higher frequencies allow smaller magnetics. |
| Operating Junction Temp | –40°C to +125°C - qualified for under-hood automotive and industrial environments with full parameter guarantee. |
| Package | 28-lead 4mm × 5mm QFN with exposed thermal pad - provides low θJA (43°C/W) for high-power density layouts. |
| Power Good Output | Open-drain PG pin asserts high when all four FB voltages exceed 710mV - enables system-level power sequencing and fault detection. |
Pinout & Package
Tiny 28-lead (4mm × 5mm) thermally enhanced plastic QFN package with exposed GND pad (Pin 29) requiring PCB soldering for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| DA1–DA4 (Pins 1,3,6,8) | Catch diode anode sense inputs | Monitor Schottky diode current to prevent inductor current runaway during transients. |
| SW1–SW4 (Pins 2,4,5,7) | Buck switch node outputs | Drive external inductors and diodes; each supports 1.45–2.1A peak switch current. |
| VIN (Pins 9,11,26,28) | Main input power supply | Supplies internal regulators and power switches; must be locally bypassed at Pins 10/27. |
| GND (Pins 10,18,27,29) | Ground reference and thermal path | Exposed pad (Pin 29) is mandatory GND connection for thermal performance and EMI reduction. |
| RUN/SS1–RUN/SS4 (Pins 12–15) | Channel enable & soft-start control | Individual 1.3µA current source ramps voltage to control startup timing and enable output tracking. |
| EN/UVLO (Pin 16) | Global enable & programmable UVLO | 1.44V rising threshold enables startup; hysteresis prevents chatter near dropout. |
| RT/SYNC (Pin 17) | Oscillator programming & sync input | Resistor-to-GND sets frequency; external logic-level clock synchronizes all four channels. |
| FB1–FB4 (Pins 19–22) | Output voltage feedback inputs | Each regulated to 800mV; determines VOUT via R1/R2 divider per channel. |
| PG (Pin 23) | Power-good status indicator | Open-collector output pulled low until all four outputs reach regulation (FB > 710mV). |
| SW5 (Pin 24) | Boost regulator switch output | Drives external inductor to generate SKY voltage; 220–320mA switch current limit. |
| SKY (Pin 25) | Boost regulator output rail | Provides +4.85V above VIN to fully saturate internal bipolar switches; requires 1µF capacitor to VIN. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated boost regulator (SW5/SKY) | Eliminates need for four external charge pumps, enabling true 100% duty cycle operation across all channels. |
| Independent RUN/SS pins | Enable per-channel soft-start ramping and precise output voltage sequencing/tracking without external circuitry. |
| Antiphase switching (CH1/3/5 vs CH2/4) | Reduces input capacitor RMS current and total input ripple by interleaving switching edges. |
| Internal compensation | Reduces external component count; simplifies design while maintaining stability across wide load/input ranges. |
| Cycle-by-cycle current limiting | Protects against short-circuit and overload faults on each SW pin with fast response and no external sensing. |
Applications
| Automotive Battery Regulation | Industrial Control Supplies |
|---|---|
Use Scenario: Powering infotainment head units, ADAS camera modules, and body control modules from 12V/24V vehicle batteries with transient ride-through up to 40V. IC Role / Device Role / Timing Role: Quad buck regulator providing isolated 5V, 3.3V, 2.5V, and 1.8V rails with independent sequencing and fault monitoring. Use Value: Eliminates need for discrete DC/DC stages; 100% duty cycle maintains regulation during cold-crank (≤6V) and load-dump (≤40V) events. | Use Scenario: Generating multiple isolated supply rails for PLC I/O modules, motor drives, and sensor interface boards in factory automation systems. IC Role / Device Role / Timing Role: Centralized power management IC delivering four regulated outputs with synchronized switching and thermal protection. Use Value: Reduces board area and BOM count versus four discrete converters; antiphase operation lowers EMI filtering requirements. |
| Wall Transformer Regulation | Distributed Supply Regulation |
Use Scenario: Converting unregulated 9–36V AC/DC adapter outputs into clean, sequenced 5V/3.3V/2.5V/1.8V rails for networking equipment and embedded gateways. IC Role / Device Role / Timing Role: High-efficiency quad buck controller supporting wide-input universal adapters with programmable UVLO. Use Value: Resistor-programmed EN/UVLO ensures reliable startup only after adapter stabilizes; soft-start prevents inrush into downstream capacitors. | Use Scenario: Local point-of-load regulation in telecom base stations and server backplanes where multiple voltage domains coexist. IC Role / Device Role / Timing Role: Distributed power IC supplying independent rails to FPGA banks, memory interfaces, and analog front-ends with PG monitoring. Use Value: Power-good pin enables centralized health monitoring; independent RUN/SS allows staggered startup to limit peak input current. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar quad buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3375EFE#PBF | Eight 300mA channels (configurable as 1×8, 2×4, 4×2); lower per-channel current but higher integration of LDOs and sequencing logic. | Better suited for low-current, highly configurable multi-rail systems; lacks 100% duty cycle and SKY boost architecture. | Select LTC3375EFE#PBF when system requires fine-grained current allocation and built-in LDO post-regulation instead of high-current buck-only outputs. |
| TPS544B20RJER | Single 12A buck converter with PMBus interface; no multi-channel integration or 100% duty cycle capability. | Designed for high-current CPU/GPU core rails with digital telemetry; not a functional substitute for quad-output regulation. | Choose TPS544B20RJER only for single-rail, digitally controlled high-current applications-requires four separate units to match LT3504EUFD#PBF's channel count. |
Compared with LTC3375EFE#PBF and TPS544B20RJER, the LT3504EUFD#PBF uniquely combines four 1A buck channels, integrated SKY boost for 100% duty cycle, and antiphase ripple reduction-making it optimal for space-constrained, wide-input industrial and automotive multi-rail designs where discrete solutions would increase cost and complexity.
Availability
LT3504EUFD#PBF is available at Aetrix Electronics and suitable for automotive battery regulation, industrial control supplies, and distributed supply regulation requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LT3504EUFD#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. (ADI) acquired Linear Technology in 2017 and maintains its high-performance power management portfolio with rigorous automotive and industrial qualification standards.
The LT3504EUFD#PBF belongs to Linear's high-voltage monolithic buck regulator product line, designed specifically for robust, wide-input multi-rail power conversion in harsh environments where reliability, thermal efficiency, and minimal external components are critical.
FAQ
What is the maximum input voltage rating for the LT3504EUFD#PBF?
The LT3504EUFD#PBF has an absolute maximum VIN rating of 40V. It operates continuously across 3.2V–40V input range, with guaranteed regulation up to 40V. However, constant-frequency operation without pulse-skipping is limited by minimum on-time and programmed switching frequency; exceeding this limit causes pulse-skipping but remains safe if inductor saturation and switch current limits are respected. The LT3504EUFD#PBF must not be started at input voltages above 36V due to instantaneous power dissipation risks.
How does the SKY pin function in the LT3504EUFD#PBF?
The SKY pin in the LT3504EUFD#PBF is the output of the integrated boost regulator (SW5), delivering a voltage precisely 4.85V above VIN. This rail powers the internal bipolar switch drivers, enabling full saturation and efficient 100% duty cycle operation. A 1µF capacitor must connect SKY to VIN; driving SKY externally or drawing current from it violates the LT3504EUFD#PBF's operating conditions and may cause failure. The SKY voltage is monitored internally to prevent buck regulator switching until it reaches 4.5V above VIN.
Can the LT3504EUFD#PBF support output voltage sequencing between channels?
Yes, the LT3504EUFD#PBF supports precise output voltage sequencing using its independent RUN/SS pins. By connecting resistor dividers from earlier-regulated outputs to subsequent RUN/SS pins, one channel's output can track and delay another's startup. An internal 1.3µA current source ramps each RUN/SS pin voltage, and the corresponding buck regulator begins switching only when that pin exceeds 0.1V. This enables controlled power-up order without external controllers-critical for FPGAs, processors, and mixed-signal ASICs requiring strict rail sequencing.
What is the purpose of the DA pins on the LT3504EUFD#PBF?
The DA1–DA4 pins on the LT3504EUFD#PBF serve as catch diode anode current sense inputs. Each DA pin connects to the anode of its respective external Schottky diode and feeds an internal comparator that monitors diode conduction. When diode current exceeds the programmed limit (0.75–1.67A depending on FB voltage), the comparator disables switching to prevent inductor current runaway during transient overloads or short circuits. This feature enhances fault robustness beyond standard cycle-by-cycle switch current limiting and is integral to the LT3504EUFD#PBF's short-circuit protection architecture.
Does the LT3504EUFD#PBF require external compensation components?
No, the LT3504EUFD#PBF features internal compensation, eliminating the need for external Type II or Type III compensation networks. Its control loop is optimized for stability across the full 3.2V–40V input range and 0–1A load range with standard output capacitor ESR values. This reduces design complexity and PCB area versus controllers requiring external compensation. However, output capacitor selection remains critical: ceramic types with adequate capacitance and low ESR are recommended to ensure transient response and loop stability, especially at high switching frequencies.
LT3504EUFD#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 28-WFQFN Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 4
- Voltage - Input (Min):
- 3.2V
- Voltage - Input (Max):
- 40V
- Voltage - Output (Min/Fixed):
- 0.8V
- Voltage - Output (Max):
- 40V
- Current - Output:
- 1A
- Frequency - Switching:
- 250kHz ~ 2.1MHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-QFN (4x5)
LT3504EUFD#PBF FAQ
1.How can I place an order for LT3504EUFD#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3504EUFD#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 LT3504EUFD#PBF reliable?
The price and inventory of LT3504EUFD#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3504EUFD#PBF is usually 5 days.
3.What payment methods are accepted for LT3504EUFD#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3504EUFD#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3504EUFD#PBF?
LT3504EUFD#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3504EUFD#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 LT3504EUFD#PBF?
For technical support, including LT3504EUFD#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3504EUFD#PBF requirements.
6.How does Aetrix verify that LT3504EUFD#PBF is sourced from the original manufacturer or authorized distributors?
All LT3504EUFD#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 LT3504EUFD#PBF meets industry standards.
7.What is the process for return or replacement of LT3504EUFD#PBF?
All LT3504EUFD#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3504EUFD#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 LT3504EUFD#PBF part is unused and in its original packaging.
Return procedure for LT3504EUFD#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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