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Analog Devices Inc. LTC3728LIUH#PBF
- Part No.:
- LTC3728LIUH#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 32-WFQFN Exposed Pad
- Datasheet:
-
LTC3728LIUH#PBF.pdf
- Description:
- IC REG CTRLR BUCK 32QFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,012
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Product details
Overview
LTC3728LIUH#PBF from Analog Devices (formerly Linear Technology) is a dual-phase, 550kHz synchronous step-down controller IC driving two independent N-channel MOSFET stages in 180° out-of-phase operation. It features ±1% output voltage accuracy (0.8V reference), 4.5V–28V input range, and integrated 3.3V/10mA linear regulator - designed for high-efficiency dual-output power supplies in space-constrained portable systems.
For engineers reviewing the LTC3728LIUH#PBF datasheet, LTC3728LIUH#PBF pinout, LTC3728LIUH#PBF application, or LTC3728LIUH#PBF equivalent, key selection criteria include phase synchronization capability, OPTI-LOOP™ compensation flexibility, FCB-selectable operating modes (Burst Mode®, constant-frequency, forced continuous), and dual-channel current-mode control with independent RUN/SS soft-start and short-circuit protection.
Technical Context
The LTC3728LIUH#PBF implements a constant-frequency, current-mode architecture with two fully independent control loops, each featuring an error amplifier (ITH1/ITH2), differential current sense inputs (SENSE1±/SENSE2±), and dedicated gate drivers (TG1/BG1, TG2/BG2). Phase alignment is achieved via PLLIN synchronization or internal oscillator tuning through PLLFLTR (260–550kHz range).
It integrates dual 5V/3.3V auxiliary regulation: INTVCC (5V LDO, 4.8–5.2V) powers internal circuitry, while 3.3VOUT delivers up to 10mA. Protection includes output overvoltage latch (VOSENSE > 0.84V), foldback current limiting, and RUN/SS-based timed short-circuit shutdown with latchoff defeat option.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5V to 28V - supports wide battery chemistries (Li-ion, LiPo, 12V rail) without external pre-regulation. |
| Output Voltage Accuracy | ±1% at VOSENSE (0.792V–0.808V) - ensures tight regulation for modern microprocessor core and I/O rails. |
| Switching Frequency | 260kHz to 550kHz (PLL-tunable) - enables optimized EMI filtering and inductor size trade-offs. |
| Operating Temperature | –40°C to +85°C - qualified for industrial and extended-temperature portable applications. |
| Shutdown Quiescent Current | 20µA - minimizes battery drain during system sleep states. |
| Power Good Threshold | ±7.5% on both outputs - provides reliable sequencing and fault detection for multi-rail systems. |
| Max Duty Cycle | 99.4% - supports ultra-low dropout operation (e.g., 5V→3.3V at high load). |
Pinout & Package
Package: 32-lead (5mm × 5mm) plastic QFN (UH), exposed pad soldered to SGND - provides low thermal resistance (θJA = 34°C/W) and compact footprint for high-density PCB layouts.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN | Main input supply connection | Accepts 4.5V–28V; bypass capacitor required to SGND for noise suppression and transient response. |
| TG1, TG2 | Top N-MOSFET gate drivers | Floating drivers with swing = INTVCC – 0.5V referenced to SWx; require external bootstrap capacitors. |
| BG1, BG2 | Bottom N-MOSFET gate drivers | Ground-referenced drivers (0V to INTVCC); enable synchronous rectification and high efficiency. |
| SENSE1+, SENSE1− SENSE2+, SENSE2− |
Differential current sense inputs | Measure RSENSE voltage drop; set peak current limit via ITH voltage and offset calibration. |
| VOSENSE1, VOSENSE2 | Feedback voltage inputs | Compare against 0.8V reference; support remote sensing to compensate for PCB trace IR drop. |
| RUN/SS1, RUN/SS2 | Soft-start and fault timer inputs | Capacitor-based ramp controls startup inrush; falling below 1.0V initiates shutdown; discharge triggers latchoff on sustained overcurrent. |
| FCB | Forced continuous/burst mode select | Voltage-controlled mode selector: <0.8V → PWM; 0.8–2.8V → Burst Mode®; >4.3V → constant-frequency. |
| PGOOD | Open-drain power-good indicator | Asserts low if either VOSENSE deviates >±7.5%; requires external pull-up to ≤7V. |
| 3.3VOUT | Integrated linear regulator output | Stable 3.3V/10mA supply for biasing external circuitry (e.g., level shifters, ADC references). |
| INTVCC | Internal 5V LDO output | Supplies gate drivers and control logic; can be bypassed by EXTVCC ≥4.7V for higher efficiency. |
Key Features
| Feature | Design Value |
|---|---|
| OPTI-LOOP™ compensation | Enables stable loop response across wide COUT/ESR variations - eliminates need for custom compensation per output capacitor type. |
| 180° interleaved dual-phase operation | Halves input ripple current vs single-phase design - reduces required input capacitance by ~70% and lowers EMI. |
| Three selectable operating modes | Burst Mode® (high light-load efficiency), constant-frequency (low-noise), or forced continuous (PWM) - configurable per application demand. |
| Dual independent RUN/SS control | Per-channel soft-start timing and short-circuit timeout - enables staggered power-up and selective fault isolation. |
| Integrated 3.3V/10mA LDO | Eliminates need for external standby regulator - simplifies BOM and saves board space in dual-rail systems. |
Applications
| Notebook Computer Core/IO Power | Telecom Line Card Dual-Rail Supply |
|---|---|
|
Use Scenario: Providing tightly regulated 5V/3.3V rails for CPU core, memory, and peripheral interfaces in ultraportable notebooks. IC Role / Device Role / Timing Role: Dual-phase synchronous controller managing two independent buck converters with phase interleaving and precise voltage tracking. Use Value: Reduces input capacitor count and volume by 50% versus single-phase solutions while maintaining <1% cross-regulation between rails. |
Use Scenario: Generating isolated 5V and 3.3V supplies for FPGA, transceivers, and management ASICs on telecom line cards. IC Role / Device Role / Timing Role: High-accuracy dual controller with PGOOD monitoring and temperature-stable reference for fault-tolerant power sequencing. Use Value: ±1% output accuracy and ±7.5% PGOOD window ensure compliance with GR-63-CORE telecom reliability requirements. |
| Battery-Powered Test Instrumentation | Industrial Embedded Controller Power |
|
Use Scenario: Powering precision analog front-ends and digital signal processors in handheld multimeters and oscilloscopes. IC Role / Device Role / Timing Role: Low-noise, constant-frequency buck controller with Burst Mode® disable for clean analog supply domains. Use Value: 20µA shutdown IQ extends battery life; 550kHz switching enables small 1µH inductors and ceramic output caps. |
Use Scenario: Delivering robust 5V/3.3V power to PLC I/O modules and motor control MCUs operating in harsh industrial environments. IC Role / Device Role / Timing Role: Wide-input (-40°C to +85°C) dual controller with overvoltage protection and latchoff recovery for unattended operation. Use Value: Output overvoltage latch (0.84V threshold) prevents damage to downstream logic during transient faults or feedback resistor failure. |
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 |
|---|---|---|---|
| LTC3728LEUH#PBF | Same pinout, identical electrical specs, but rated for –40°C to +85°C industrial temp range - no functional difference from LTC3728LIUH#PBF. | Identical use cases; selected when broader qualification documentation is required for industrial OEM programs. | Drop-in replacement where full industrial temp validation is mandated - no design change needed. |
| MP2918GL-Z | Single-chip dual-phase controller with integrated MOSFET drivers and PMBus interface; lacks 3.3VOUT LDO and PLLIN sync capability. | Targeted at digitally managed power systems requiring telemetry and dynamic margining - not suitable for analog-only or sync-critical designs. | Choose when digital control and telemetry outweigh need for analog sync or integrated 3.3V bias rail. |
Compared with LTC3728LEUH#PBF, the LTC3728LIUH#PBF offers identical performance but is specifically characterized for the –40°C to +85°C range with documented correlation to statistical process controls; versus MP2918GL-Z, it provides superior analog synchronization fidelity and integrated auxiliary regulation at the cost of digital configurability.
Availability
LTC3728LIUH#PBF is available at Aetrix Electronics and suitable for notebook computers, telecom line cards, portable instrumentation, and industrial embedded controllers requiring stable component supply, long-term lifecycle assurance, and guaranteed –40°C to +85°C operation.
Supply support for LTC3728LIUH#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 full product support, datasheet archives, and application engineering resources for legacy Linear parts including the LTC3728L family.
The LTC3728L series was designed as a high-performance dual-phase synchronous buck controller targeting portable and space-constrained power systems needing interleaved efficiency, precise voltage regulation, and flexible low-power operating modes.
FAQ
What is the maximum input voltage rating for the LTC3728LIUH#PBF?
The LTC3728LIUH#PBF has an absolute maximum input voltage rating of 30V on the VIN pin. Continuous operation is specified from 4.5V to 28V, making it compatible with 24V industrial rails and multi-cell Li-ion battery packs. Exceeding 30V risks permanent damage per Absolute Maximum Ratings.
Does the LTC3728LIUH#PBF support external frequency synchronization?
Yes, the LTC3728LIUH#PBF supports external synchronization via the PLLIN pin, which accepts a TTL/CMOS clock signal. The internal phase-locked loop aligns the rising edge of TG1 to the rising edge of the PLLIN signal, enabling deterministic timing across multiple converters or noise-sensitive systems.
How does the FCB pin affect operating mode selection in the LTC3728LIUH#PBF?
The FCB pin on the LTC3728LIUH#PBF selects among three modes: <0.8V forces continuous PWM operation; 0.8V–2.8V enables Burst Mode® for high light-load efficiency; >4.3V disables Burst Mode® for constant-frequency operation. This allows dynamic optimization of efficiency vs. EMI based on real-time load conditions.
What is the purpose of the 3.3VOUT pin on the LTC3728LIUH#PBF?
The 3.3VOUT pin on the LTC3728LIUH#PBF is an integrated linear regulator delivering up to 10mA DC (50mA peak) at 3.3V. It provides a clean, low-noise bias supply for external components such as level shifters, ADC references, or logic buffers - eliminating the need for a separate LDO in dual-rail designs.
Can the LTC3728LIUH#PBF operate with only one channel enabled?
Yes, the LTC3728LIUH#PBF supports independent channel control: pulling RUN/SS1 low disables Channel 1 while leaving Channel 2 active, and vice versa. Both channels must be enabled for interleaved operation, but single-channel use is fully supported with full feature retention per active channel.
LTC3728LIUH#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 32-WFQFN Exposed Pad
- Packaging:
- Tube
- 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)
LTC3728LIUH#PBF FAQ
1.How can I place an order for LTC3728LIUH#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3728LIUH#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 LTC3728LIUH#PBF reliable?
The price and inventory of LTC3728LIUH#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3728LIUH#PBF is usually 5 days.
3.What payment methods are accepted for LTC3728LIUH#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3728LIUH#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3728LIUH#PBF?
LTC3728LIUH#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3728LIUH#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 LTC3728LIUH#PBF?
For technical support, including LTC3728LIUH#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3728LIUH#PBF requirements.
6.How does Aetrix verify that LTC3728LIUH#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3728LIUH#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 LTC3728LIUH#PBF meets industry standards.
7.What is the process for return or replacement of LTC3728LIUH#PBF?
All LTC3728LIUH#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3728LIUH#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 LTC3728LIUH#PBF part is unused and in its original packaging.
Return procedure for LTC3728LIUH#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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