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Analog Devices Inc. LTC3728LZEUH#TRPBF
- Part No.:
- LTC3728LZEUH#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 32-WFQFN Exposed Pad
- Datasheet:
-
LTC3728LZEUH#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 32QFN
- Quantity:
- Payment:
- Shipping:
Inventory:4,412
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Product details
Overview
LTC3728LZEUH#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/3.3V outputs, supports 4.5V–28V input, features 0.8V ±1% reference accuracy, and operates at phase-lockable frequencies from 250kHz to 550kHz. It is used in high-efficiency notebook DC/DC power supplies where input capacitor stress reduction and low-noise regulation are critical.
For engineers reviewing the LTC3728LZEUH#TRPBF datasheet, LTC3728LZEUH#TRPBF pinout, LTC3728LZEUH#TRPBF application, or LTC3728LZEUH#TRPBF equivalent, key selection criteria include dual-phase current-mode control, OPTI-LOOP compensation for wide output capacitance tolerance, integrated 3.3V LDO, PGOOD monitoring, and FCB-selectable operating modes (Burst Mode®, constant-frequency, forced continuous).
Technical Context
The LTC3728LZEUH#TRPBF implements a constant-frequency, current-mode architecture with independent error amplifiers (ITH1/ITH2), differential current sense inputs (SENSE1±/SENSE2±), and dual 180°-phased PWM generators synchronized via PLLIN. Its OPTI-LOOP compensation allows stable loop response across varying COUT/ESR without external component changes.
It integrates a 5V INTVCC LDO (4.8V–5.2V), a standalone 3.3V linear regulator (3.2V–3.45V, 10mA), and robust protection including output overvoltage latch (VOSENSE > 0.84V), undervoltage lockout (VIN < 3.5V), and foldback current limiting triggered when VOSENSE drops below 70% of setpoint.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5V to 28V - supports all common battery chemistries and industrial DC rails; absolute max 30V. |
| Output Voltage Accuracy | ±1% at 0.8V reference - ensures tight regulation for modern microprocessor core and I/O supplies. |
| Switching Frequency | 250kHz to 550kHz, phase-lockable - enables EMI reduction via synchronization and minimizes input ripple with 180° interleaving. |
| Max Duty Cycle | 99.4% - enables ultra-low dropout operation (e.g., 5V out from 5.2V in) without external boost. |
| PGOOD Threshold | ±7.5% on both VOSENSE1 and VOSENSE2 - provides reliable system power sequencing and fault detection. |
| Shutdown IQ | 20µA - enables low-power standby in battery-operated systems without disabling auxiliary rails. |
| 3.3V LDO Output | 3.2V–3.45V @ 10mA - powers auxiliary logic, supervisors, or interface circuitry without external regulators. |
Pinout & Package
Package: 32-lead (5mm × 5mm) plastic QFN (UH), exposed pad soldered to SGND. Thermal resistance θJA = 34°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN | Main power input | Supplies internal circuitry and gate drivers; bypassed to SGND with ≥22µF ceramic capacitor. |
| TG1/TG2 | Top gate drivers | Floating high-side N-MOSFET drivers with swing = INTVCC – 0.5V referenced to SW1/SW2 nodes. |
| BG1/BG2 | Bottom gate drivers | Ground-referenced N-MOSFET drivers (0V to INTVCC); enable synchronous rectification. |
| SENSE1+/SENSE1− SENSE2+/SENSE2− | Differential current sense inputs | Measure RSENSE voltage drop to regulate peak inductor current; reject common-mode noise up to 5V. |
| VOSENSE1/VOSENSE2 | Feedback inputs | Remote-sense inputs for each channel; compared to 0.8V reference to close voltage loop. |
| RUN/SS1/RUN/SS2 | Soft-start & fault timer | Capacitor-based ramp controls startup current; also discharges during short-circuit to trigger latchoff after timeout. |
| FCB | Mode select | Selects Burst Mode® (0.8V < VFCB < VINTVCC–2V), constant-frequency (VFCB = INTVCC), or forced PWM (VFCB < 0.8V). |
| PGOOD | Open-drain status output | Pulled low if either VOSENSE deviates >±7.5%; requires external pull-up to ≤7V. |
Key Features
| Feature | Design Value |
|---|---|
| Dual 180° out-of-phase control | Reduces RMS input capacitor current by ~70%, enabling smaller, lower-ESR input caps and lower conducted EMI. |
| OPTI-LOOP compensation | Allows stable loop gain across 10× variation in output capacitance and ESR-no re-tuning required for different ceramic cap types. |
| Three selectable operating modes | Burst Mode® (high light-load efficiency), constant-frequency (low-noise), or forced continuous (bidirectional current capability). |
| Integrated 3.3V LDO | Delivers 10mA with ±2% load regulation-powers supervisory ICs or level shifters without adding discrete regulators. |
| Output overvoltage protection | Latches bottom MOSFET ON until VOSENSE returns within ±7.5%, preventing damage to downstream loads during transients. |
Applications
| Notebook Power Systems | Telecom Intermediate Bus Converters |
|---|---|
Use Scenario: Dual-output 5V/3.3V regulation for CPU core, memory, and chipset rails in ultraportable notebooks. IC Role / Device Role / Timing Role: Dual-phase synchronous controller managing two independent buck stages with interleaved switching to minimize input ripple. Use Value: Reduces input capacitor count by 50% vs single-phase design while maintaining <15mV output ripple at full 5A load. | Use Scenario: 48V-to-12V intermediate bus conversion feeding multiple point-of-load regulators in telecom line cards. IC Role / Device Role / Timing Role: High-efficiency, phase-locked controller synchronizing to system clock to suppress beat frequencies in dense board layouts. Use Value: Enables deterministic EMI filtering with fixed 500kHz operation and 180° phase offset, easing compliance with EN55022 Class B. |
| Battery-Powered Test Equipment | Industrial Embedded Controllers |
Use Scenario: Portable oscilloscope or multimeter requiring clean, isolated 5V and 3.3V rails from Li-ion battery (3.0V–4.2V) with minimal quiescent current. IC Role / Device Role / Timing Role: Dual buck controller using Burst Mode® and 20µA shutdown IQ to extend battery life beyond 10 hours in standby. Use Value: Achieves >85% efficiency at 10mA load via Burst Mode®, versus <65% in constant-frequency mode. | Use Scenario: DIN-rail mounted PLC module needing robust 5V/3.3V power with brownout immunity and PGOOD sequencing for FPGA configuration. IC Role / Device Role / Timing Role: Fault-tolerant controller with UVLO (3.5V), OV protection, and independent RUN/SS latching for safe shutdown during field faults. Use Value: Prevents system lockup during transient line sags by holding PGOOD low until both outputs stabilize within ±7.5% for ≥10µs. |
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 |
|---|---|---|---|
| LTC3855IUFD#PBF | Single-channel, 600kHz max, no integrated 3.3V LDO, requires external bootstrap diodes. | Lacks dual-phase interleaving and auxiliary rail; suited for single-output high-current designs only. | Choose when only one regulated output is needed and board space permits discrete bootstrap components. |
| MP8765GL-Z | Single-phase, 2.5A max per channel, no PLL sync, no 3.3V LDO, lower VIN min (2.5V). | Targeted at cost-sensitive consumer devices; lacks PGOOD, OV protection, and soft-start programmability. | Choose for compact, low-cost 5V/3.3V supplies where phase interleaving and robust protection are not required. |
Compared with LTC3728LZEUH#TRPBF, LTC3855IUFD#PBF offers higher frequency but no dual-phase benefit or auxiliary LDO, while MP8765GL-Z reduces cost and size at the expense of protection completeness and multi-rail integration.
Availability
LTC3728LZEUH#TRPBF is available at Aetrix Electronics and suitable for notebook power systems, telecom intermediate bus converters, battery-powered test equipment, and industrial embedded controllers requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for LTC3728LZEUH#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 its high-performance analog and power management portfolio with rigorous automotive and industrial qualification standards.
The LTC3728L series was designed specifically for dual-output, high-density DC/DC power conversion in portable computing and communications infrastructure, emphasizing thermal efficiency, EMI control, and system-level reliability.
FAQ
What is the maximum supported input voltage for the LTC3728LZEUH#TRPBF?
The LTC3728LZEUH#TRPBF has an absolute maximum input voltage rating of 30V, with recommended continuous operation from 4.5V to 28V. Exceeding 30V may cause permanent damage. The device includes undervoltage lockout that disables operation below 3.5V (typical), ensuring safe startup across battery discharge profiles. This makes LTC3728LZEUH#TRPBF suitable for 24V industrial rails and multi-cell Li-ion inputs.
How does the FCB pin affect operating mode selection in the LTC3728LZEUH#TRPBF?
The FCB pin on the LTC3728LZEUH#TRPBF selects among three distinct operating modes: pulling FCB < 0.8V forces continuous PWM operation; applying 0.8V < VFCB < VINTVCC–2V enables Burst Mode® for high light-load efficiency; tying FCB to INTVCC disables Burst Mode® and enables constant-frequency discontinuous conduction. These modes directly impact efficiency, noise, and reverse current capability-critical for optimizing LTC3728LZEUH#TRPBF in battery or noise-sensitive applications.
Does the LTC3728LZEUH#TRPBF support synchronization to an external clock source?
Yes, the LTC3728LZEUH#TRPBF supports full phase synchronization via its PLLIN pin, which accepts an external 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 switching across multiple converters. When PLLIN is left open, the oscillator defaults to minimum frequency (260kHz). This capability is essential for reducing beat frequencies in multi-rail systems and is a defining feature of LTC3728LZEUH#TRPBF in telecom and test equipment designs.
What protection features are integrated into the LTC3728LZEUH#TRPBF?
The LTC3728LZEUH#TRPBF integrates six key protections: (1) output overvoltage latch (VOSENSE > 0.84V), (2) undervoltage lockout (VIN < 3.5V), (3) foldback current limiting during output shorts, (4) RUN/SS-based timed short-circuit latchoff, (5) thermal shutdown (TJ > 125°C), and (6) PGOOD monitoring for ±7.5% output deviation. These operate independently per channel and require no external components-making LTC3728LZEUH#TRPBF highly robust in unattended or mission-critical power systems.
Can the LTC3728LZEUH#TRPBF drive external MOSFETs with logic-level gate thresholds?
Yes, the LTC3728LZEUH#TRPBF's TG1/TG2 and BG1/BG2 drivers deliver sufficient gate drive strength (peak 3A) and voltage swing (0V to INTVCC for BG; INTVCC–0.5V referenced to SW for TG) to fully enhance standard logic-level N-channel MOSFETs such as the FDS6982S referenced in the datasheet. Its 55ns typical rise/fall times ensure fast switching with minimal overlap loss. For optimal performance, LTC3728LZEUH#TRPBF requires careful PCB layout of gate loops and bootstrap paths-especially critical at 550kHz operation.
LTC3728LZEUH#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)
LTC3728LZEUH#TRPBF FAQ
1.How can I place an order for LTC3728LZEUH#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3728LZEUH#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 LTC3728LZEUH#TRPBF reliable?
The price and inventory of LTC3728LZEUH#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3728LZEUH#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3728LZEUH#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3728LZEUH#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3728LZEUH#TRPBF?
LTC3728LZEUH#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3728LZEUH#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 LTC3728LZEUH#TRPBF?
For technical support, including LTC3728LZEUH#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3728LZEUH#TRPBF requirements.
6.How does Aetrix verify that LTC3728LZEUH#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3728LZEUH#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 LTC3728LZEUH#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3728LZEUH#TRPBF?
All LTC3728LZEUH#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3728LZEUH#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 LTC3728LZEUH#TRPBF part is unused and in its original packaging.
Return procedure for LTC3728LZEUH#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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