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Analog Devices Inc. LTC3728LEUH#TRPBF
- Part No.:
- LTC3728LEUH#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 32-WFQFN Exposed Pad
- Datasheet:
-
LTC3728LEUH#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 32QFN
- Quantity:
- Payment:
- Shipping:
Inventory:4,914
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Product details
Overview
LTC3728LEUH#TRPBF from Analog Devices (formerly Linear Technology) is a dual-phase, synchronous step-down controller IC driving two independent N-channel MOSFET stages in 180° out-of-phase operation. It delivers up to 5A per channel at 5V and 3.3V outputs, supports 4.5V–28V input, features 0.8V ±1% reference accuracy, and operates at phase-lockable frequencies from 250kHz to 550kHz - ideal for high-efficiency notebook CPU core and I/O power rails.
For engineers reviewing the LTC3728LEUH#TRPBF datasheet, LTC3728LEUH#TRPBF pinout, LTC3728LEUH#TRPBF application, or LTC3728LEUH#TRPBF equivalent, key selection criteria include dual-phase current-mode control, OPTI-LOOP™ compensation for wide output capacitor/ESR tolerance, integrated 3.3V LDO, PGOOD monitoring, and FCB-selectable operating modes (Burst Mode®, constant-frequency, forced continuous).
Technical Context
The LTC3728LEUH#TRPBF implements a constant-frequency, current-mode architecture with dual independent error amplifiers, transconductance gm = 1.3 mmho, and GBW = 3 MHz per channel. Its phase-locked loop accepts external synchronization via PLLIN and enables frequency tuning (260–550 kHz) through PLLFLTR voltage (0–2.4 V), while OPTI-LOOP™ compensation allows stable loop response across diverse ceramic output capacitors.
Each channel integrates dedicated current sense comparators with ±90 µA total source current on SENSE± pins, 100 ns typical gate drive rise/fall times (TG/BG), and precise 0.8V feedback threshold with ±1% accuracy over –40°C to +85°C. The device includes independent RUN/SS pins enabling soft-start ramping and timed short-circuit shutdown, plus latched overvoltage protection that forces bottom-FET conduction until VOSENSE returns within ±7.5%.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5V to 28V - supports all common battery chemistries and industrial DC rails without external pre-regulation. |
| Output Voltage Reference | 0.800V ±1% - enables accurate 5V/3.3V regulation with standard resistor dividers; compatible with modern microprocessor VDD requirements. |
| Switching Frequency Range | 250kHz to 550kHz (phase-lockable) - balances efficiency vs. size; 180° interleaving reduces input ripple current by ~70% vs. single-phase. |
| Operating Temperature | –40°C to +85°C - qualified for industrial and extended-temperature embedded systems including telecom and portable instrumentation. |
| Shutdown Quiescent Current | 20µA - minimizes battery drain during system sleep states in portable applications. |
| Integrated 3.3V LDO | 3.35V ±2% at 10mA - powers auxiliary circuitry (e.g., level shifters, sensors) without requiring a separate regulator. |
| Power Good Threshold | ±7.5% of setpoint on both outputs - provides reliable system enable/disable signaling for sequenced power-up/down. |
Pinout & Package
32-lead (5mm × 5mm) plastic QFN package with exposed pad (SGND); RoHS-compliant, lead-free finish; thermal resistance θJA = 34°C/W.
| Pin | Circuit Role | Design Meaning |
|---|---|---|
| RUN/SS1, RUN/SS2 | Soft-start & short-circuit timer input | Capacitor-based ramp controls startup current slew rate; also discharges under 70% VOUT fault to trigger latchoff after programmable timeout. |
| SENSE1+, SENSE1− / SENSE2+, SENSE2− | Differential current sense inputs | Measure voltage across RSENSE to regulate peak inductor current; ±90 µA total source current enables low-loss sensing with 10 mΩ shunts. |
| VOSENSE1, VOSENSE2 | Feedback voltage input | Connects to resistive divider output; internal 0.8V reference ensures ±1% output accuracy; PGOOD asserts if either deviates >±7.5%. |
| TG1, TG2 / BG1, BG2 | Top/bottom N-MOSFET gate drivers | Drive external high-side (floating) and low-side (ground-referenced) FETs; 100 ns max transition time supports high-frequency operation. |
| PLLIN, PLLFLTR | External sync input & frequency control | PLLIN accepts TTL/CMOS clock for synchronization; PLLFLTR voltage (0–2.4V) sets oscillator frequency from 260–550 kHz without external components. |
| FCB | Forced continuous mode select | Pull <0.8V for PWM mode (no reverse current); 0.8–2.7V enables Burst Mode®; >4.3V disables burst for constant-frequency operation. |
| PGOOD | Open-drain status output | Active-low signal indicates both outputs are within ±7.5%; requires external pull-up to ≤7V; responds within 10 µs of fault clearance. |
| 3.3VOUT | Integrated linear regulator output | Supplies 10mA DC (50mA peak); eliminates need for discrete 3.3V rail in companion circuitry such as level translators or monitoring ICs. |
Key Features
| Feature | Design Value |
|---|---|
| 180° Interleaved Dual-Phase Control | Reduces RMS input capacitor current by ~70%, cuts required input capacitance, and lowers conducted EMI vs. single-phase designs. |
| OPTI-LOOP™ Compensation | Enables stable loop response across wide range of ceramic output capacitors (10–1000 µF) and ESR (0.5–50 mΩ) without redesign. |
| Three-Mode FCB Control | Selects between Burst Mode® (high light-load efficiency), constant-frequency (low noise), or forced continuous (bidirectional current capability). |
| Integrated 3.3V LDO + PGOOD | Provides auxiliary power and system-level power-good signaling in one IC - simplifies BOM and board layout for multi-rail systems. |
| Robust Fault Protection | Includes foldback current limiting, latched overvoltage shutdown (bottom-FET clamping), and programmable short-circuit timeout via RUN/SS caps. |
Applications
| High-Efficiency Notebook CPU Power | Telecom DC/DC Distribution |
|---|---|
Use Scenario: Dual-rail power delivery for Intel Core i-series or AMD Ryzen mobile processors requiring tightly regulated 1.0–1.35V core and 5V/3.3V I/O rails. IC Role / Device Role / Timing Role: Dual-phase synchronous buck controller managing two independent 5A channels with interleaved timing to minimize input ripple and thermal stress. Use Value: Achieves >92% peak efficiency at 5A/5V and 5A/3.3V; 180° phase shift halves input capacitor RMS current, allowing smaller 22µF ceramic input vs. 47µF in single-phase. |
Use Scenario: Intermediate bus conversion in 48V telecom systems powering multiple point-of-load regulators (e.g., FPGA, DSP, SerDes). IC Role / Device Role / Timing Role: Primary controller generating stable 12V/5V intermediate rails with precise sequencing and PGOOD coordination across distributed loads. Use Value: Wide 4.5–28V input accommodates 24V/48V backplane derating; ±1% reference and ±7.5% PGOOD window ensure reliable downstream regulator enablement. |
| Portable Test Instrumentation | Battery-Powered Industrial Controller |
Use Scenario: Multi-voltage power supply for handheld oscilloscopes or spectrum analyzers with analog front-end (±5V), digital logic (3.3V), and ADC reference (2.5V) rails. IC Role / Device Role / Timing Role: Dual-output controller delivering 5V/3.3V simultaneously; integrated 3.3V LDO powers auxiliary logic; RUN/SS enables controlled startup sequencing. Use Value: 20µA shutdown IQ extends battery life; Burst Mode® maintains >85% efficiency down to 10mA load; compact QFN saves PCB area in space-constrained enclosures. |
Use Scenario: Power management for ruggedized PLC modules operating from 12V/24V lead-acid or LiFePO₄ batteries in factory automation. IC Role / Device Role / Timing Role: High-reliability dual buck controller with –40°C to +85°C rating, undervoltage lockout (3.5V), and overvoltage protection to safeguard sensitive I/O circuitry. Use Value: Input UVLO prevents brownout-induced resets; latched OVP clamps faults without latchoff delay; EXTVCC support enables efficient self-biasing from 5V output. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual-phase synchronous buck controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MP2918GL-Z | Single-chip dual-phase controller with integrated MOSFET drivers only (no 3.3V LDO); fixed 500kHz frequency; no PLL sync capability. | Lacks PGOOD and 3.3V LDO - requires external components for system monitoring and auxiliary power. | Choose when cost-sensitive, fixed-frequency operation suffices and auxiliary rails are already available. |
| ISL95836IRZ | Intel VR12.5-compliant dual-phase controller; supports DVID, SVID interface; higher integration (integrated MOSFET drivers + telemetry). | Designed specifically for CPU voltage regulation with dynamic VID scaling - not suitable for generic 5V/3.3V fixed-rail use. | Choose only for Intel CPU core power applications requiring SVID communication and adaptive voltage positioning. |
Compared with MP2918GL-Z and ISL95836IRZ, the LTC3728LEUH#TRPBF offers broader input range (4.5–28V vs. 4.5–24V), integrated 3.3V LDO and PGOOD, and flexible frequency synchronization - making it uniquely suited for non-CPU, multi-rail industrial and portable systems requiring design flexibility and reliability.
Availability
LTC3728LEUH#TRPBF is available at Aetrix Electronics and suitable for notebook computing, telecom power distribution, and portable instrumentation requiring stable component supply, long-term lifecycle support, and guaranteed industrial temperature performance.
Supply support for LTC3728LEUH#TRPBF 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 full product support, documentation, and manufacturing continuity for all Linear ICs including the LTC3728 family.
The LTC3728L series was designed for high-efficiency, dual-phase synchronous buck conversion in space- and thermally-constrained applications such as notebooks, telecom equipment, and portable test gear - emphasizing precision regulation, fault resilience, and layout simplicity.
FAQ
What is the maximum supported switching frequency for LTC3728LEUH#TRPBF?
The LTC3728LEUH#TRPBF supports a phase-lockable switching frequency range from 250kHz to 550kHz. At VPLLFLTR ≥ 2.4V, the nominal frequency reaches 550kHz (typical), enabling compact magnetics and reduced output ripple. Operation above 550kHz is not specified and may compromise stability or protection timing.
Does LTC3728LEUH#TRPBF include an internal 3.3V regulator?
Yes, the LTC3728LEUH#TRPBF integrates a dedicated 3.3V linear regulator (3.3VOUT pin) delivering up to 10mA DC with 50mA peak capability. Its output is trimmed to 3.35V ±2% at no load and exhibits 0.5% load regulation from 0–10mA, eliminating the need for an external 3.3V LDO in many companion circuits.
How does the FCB pin affect operating mode selection in LTC3728LEUH#TRPBF?
The FCB pin on the LTC3728LEUH#TRPBF selects among three distinct modes: pulling FCB <0.8V forces continuous PWM operation; 0.8–2.7V enables Burst Mode® for high light-load efficiency; tying FCB >4.3V disables burst for constant-frequency discontinuous conduction mode. Each mode directly impacts efficiency, noise, and reverse-current behavior.
What is the purpose of the RUN/SS pins on LTC3728LEUH#TRPBF?
The LTC3728LEUH#TRPBF features two independent RUN/SS pins (RUN/SS1 and RUN/SS2) that serve dual functions: soft-start control via external capacitor ramping, and short-circuit detection using the same capacitor as a timing element. When either output drops below 70% of nominal, the corresponding RUN/SS capacitor discharges, triggering latchoff after programmable timeout.
Can LTC3728LEUH#TRPBF be synchronized to an external clock?
Yes, the LTC3728LEUH#TRPBF supports external synchronization via the PLLIN pin. Its internal phase-locked loop aligns the rising edge of TG1 to the rising edge of the external clock applied to PLLIN. The PLLIN pin has 50kΩ internal termination to SGND, and synchronization is maintained across the full 250–550kHz operating range without additional components.
LTC3728LEUH#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 32-WFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Output Type:
- Transistor Driver
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Number of Outputs:
- 2
- Output Phases:
- 2
- Voltage - Supply (Vcc/Vdd):
- 4.5V ~ 28V
- Frequency - Switching:
- 260kHz ~ 550kHz
- Duty Cycle (Max):
- 99.4%
- Synchronous Rectifier:
- Yes
- Clock Sync:
- No
- Serial Interfaces:
- -
- Control Features:
- Enable, Power Good, Soft Start
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 32-QFN (5x5)
LTC3728LEUH#TRPBF FAQ
1.How can I place an order for LTC3728LEUH#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3728LEUH#TRPBF 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 LTC3728LEUH#TRPBF reliable?
The price and inventory of LTC3728LEUH#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3728LEUH#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3728LEUH#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3728LEUH#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3728LEUH#TRPBF?
LTC3728LEUH#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3728LEUH#TRPBF 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 LTC3728LEUH#TRPBF?
For technical support, including LTC3728LEUH#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3728LEUH#TRPBF requirements.
6.How does Aetrix verify that LTC3728LEUH#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3728LEUH#TRPBF 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 LTC3728LEUH#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3728LEUH#TRPBF?
All LTC3728LEUH#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3728LEUH#TRPBF, 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 LTC3728LEUH#TRPBF part is unused and in its original packaging.
Return procedure for LTC3728LEUH#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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