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Analog Devices Inc. LTC3728LZEUH#PBF
- Part No.:
- LTC3728LZEUH#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 32-WFQFN Exposed Pad
- Datasheet:
-
LTC3728LZEUH#PBF.pdf
- Description:
- IC REG CTRLR BUCK 32QFN
- Quantity:
- Payment:
- Shipping:
Inventory:4,336
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Product details
Overview
LTC3728LZEUH#PBF 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 up to 550kHz. It is used in high-efficiency notebook CPU core power supplies requiring low input ripple and fast transient response.
For engineers reviewing the LTC3728LZEUH#PBF datasheet, LTC3728LZEUH#PBF pinout, LTC3728LZEUH#PBF application, or LTC3728LZEUH#PBF equivalent, key selection criteria include dual-phase current-mode control architecture, OPTI-LOOP™ compensation for wide output capacitor ESR tolerance, integrated 3.3V LDO regulator, PGOOD monitoring for dual-rail sequencing, and FCB-selectable operating modes (Burst Mode®, constant-frequency, forced continuous).
Technical Context
The LTC3728LZEUH#PBF implements a constant-frequency, current-mode control architecture with two independent error amplifiers (ITH1/ITH2), differential current sense inputs (SENSE1±/SENSE2±), and dual 180°-phased PWM generators synchronized via internal oscillator or external PLLIN. Its OPTI-LOOP™ compensation allows stable loop response across 10µF–1000µF ceramic output capacitors with ESR from 1mΩ to 100mΩ.
It integrates a 5V INTVCC LDO (4.8V–5.2V), a standalone 3.3V/10mA linear regulator (3.2V–3.45V), and dual gate drivers (TG/BG) with 55ns rise/fall times and 80ns dead-time control. Protection includes output overvoltage latching (VOSENSE > 0.84V), foldback current limiting during short-circuit, and RUN/SS-based timed latchoff with defeat option.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5V to 28V - supports 12V/19V adapter inputs and all common battery chemistries (Li-ion, LiFePO₄, lead-acid) |
| Output Voltage Accuracy | ±1% at 0.8V reference - ensures tight regulation for modern microprocessor VDD rails |
| Switching Frequency Range | 250kHz to 550kHz (phase-lockable) - enables EMI optimization and inductor size reduction |
| Max Duty Cycle | 99.4% - supports ultra-low dropout operation down to VIN − VOUT < 100mV |
| Shutdown Quiescent Current | 20µA - minimizes battery drain in portable standby states |
| PGOOD Threshold | ±7.5% of setpoint on both outputs - provides reliable power-rail sequencing indication |
| 3.3V LDO Output | 3.35V ±0.15V @ 10mA - powers auxiliary logic, SMBus controllers, or PMIC bias rails |
Pinout & Package
Package: 32-lead (5mm × 5mm) plastic QFN with exposed SGND pad (UH package). Thermal resistance θJA = 34°C/W. Exposed pad must be soldered to PCB and connected to PGND/SGND.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VOSENSE1 / VOSENSE2 | Error amplifier feedback input | Accepts remote-sense voltage from resistor divider; sets regulated output voltage with ±1% accuracy |
| TG1 / TG2, BG1 / BG2 | N-channel MOSFET gate drivers | TG drives high-side FET with bootstrapped swing; BG drives low-side FET from ground to INTVCC (5V) |
| SENSE1+ / SENSE1−, SENSE2+ / SENSE2− | Differential current sense inputs | Measure RSENSE voltage drop to enable cycle-by-cycle peak current limiting and foldback protection |
| RUN/SS1 / RUN/SS2 | Soft-start and short-circuit timer input | Capacitor-to-ground sets ramp time; falling below 1.0V shuts down respective channel; enables timed latchoff on sustained overcurrent |
| FCB | Forced continuous mode control | Pull <0.8V for continuous PWM; 0.8V–(INTVCC−2V) for Burst Mode®; tie to INTVCC for constant-frequency operation |
| PGOOD | Open-drain power-good indicator | Asserts low when either VOSENSE deviates >±7.5%; requires external pull-up to ≤7V |
| 3.3VOUT | Integrated linear regulator output | Supplies 10mA DC (50mA peak); eliminates need for external 3.3V bias rail in compact designs |
Key Features
| Feature | Design Value |
|---|---|
| 180° dual-phase interleaving | Reduces RMS input capacitor current by ~70%, cutting required CIN volume and lowering conducted EMI |
| OPTI-LOOP™ compensation | Enables stable loop gain with ceramic output caps from 10µF to 1000µF without external type-specific tuning |
| Three selectable operating modes | Burst Mode® (high efficiency at light load), constant-frequency (low noise), forced continuous (bidirectional current capability) |
| Integrated 3.3V/10mA LDO | Provides dedicated low-noise supply for system management ICs, eliminating discrete regulator and saving board space |
| Output overvoltage latching | Immediately disables top FET and enables bottom FET upon VOSENSE > 0.84V, preventing damage to downstream loads |
| Dropout recovery circuitry | Forces 400ns top-FET off every 10th cycle when duty >98%, ensuring bootstrap capacitor recharge under deep dropout |
Applications
| Notebook CPU Core Power | Telecom Line Card Bias |
|---|---|
Use Scenario: Dual-rail power delivery for Intel/AMD mobile processors requiring tightly regulated 1.0V–1.35V core and 1.8V I/O rails with fast load-step response. IC Role / Device Role / Timing Role: Dual-phase synchronous buck controller managing two independent output stages with shared clock synchronization and coordinated soft-start. Use Value: 180° interleaving cuts input ripple by 2× vs single-phase, reducing bulk capacitor count and enabling thinner laptop chassis designs. |
Use Scenario: Generating isolated 3.3V/5V bias rails from 48V telecom backplane in line cards with strict thermal and EMI constraints. IC Role / Device Role / Timing Role: High-voltage input controller regulating secondary windings via FCB-driven synchronous rectification and PLL-synchronized switching. Use Value: Wide 4.5V–28V input range accommodates 48V-derived intermediate bus; Burst Mode® extends hold-up time during brownouts. |
| Portable Test Instrumentation | Industrial Embedded Control |
Use Scenario: Powering FPGA, ADC/DAC, and RF front-end in handheld spectrum analyzers requiring ultra-low noise and precise voltage tracking. IC Role / Device Role / Timing Role: Dual-output controller delivering 1.2V FPGA core and 2.5V analog supply with independent PGOOD signaling for fault isolation. Use Value: ±1% reference accuracy and OPTI-LOOP™ ensure <10mV output deviation across temperature and load, critical for measurement integrity. |
Use Scenario: Distributed 5V/3.3V power for PLC I/O modules operating in harsh environments with wide ambient temperature swings (−40°C to +85°C). IC Role / Device Role / Timing Role: Robust dual-phase controller with latchoff disable, overvoltage protection, and industrial-grade temp rating (LTC3728LEUH variant). Use Value: RUN/SS-based short-circuit latchoff prevents thermal runaway during field wiring faults; exposed QFN pad improves thermal reliability. |
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; max fSW = 1MHz; supports digital PMBus interface | Requires external 3.3V bias; suited for systems needing telemetry and dynamic voltage scaling | Select MP2918GL-Z when digital control and higher frequency are prioritized over analog simplicity and integrated bias rail |
| ISL95812IRZ | Intel VR12.5-compliant dual-phase controller; supports adaptive voltage positioning (AVP); no integrated 3.3V LDO; requires external gate drivers | Targeted specifically at CPU VR applications with AVP; lacks standalone bias regulator | Select ISL95812IRZ only for Intel platform-specific CPU power delivery where AVP compliance is mandatory |
Compared with MP2918GL-Z and ISL95812IRZ, the LTC3728LZEUH#PBF offers unique integration of a 3.3V LDO and analog-only simplicity-reducing BOM count and eliminating firmware dependencies-while maintaining industrial temperature support and robust analog protection features essential for non-CPU embedded power.
Availability
LTC3728LZEUH#PBF is available at Aetrix Electronics and suitable for notebook computing, telecom infrastructure, portable instrumentation, and industrial embedded control applications requiring stable component supply, long-lifecycle assurance, and guaranteed industrial temperature performance.
Supply support for LTC3728LZEUH#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, datasheets, and application engineering for legacy Linear parts including the LTC3728L series.
The LTC3728L family was designed for high-efficiency, dual-phase DC/DC conversion in space-constrained portable and industrial systems-emphasizing low EMI, wide input range, and robust protection without digital complexity.
FAQ
What is the maximum supported switching frequency for LTC3728LZEUH#PBF?
The LTC3728LZEUH#PBF supports a phase-lockable switching frequency range of 250kHz to 550kHz. The upper limit of 550kHz is achieved when the PLLFLTR pin voltage is ≥2.4V. This maximum frequency enables compact magnetics design while maintaining stable current-mode control and sufficient gate drive timing margins.
Does LTC3728LZEUH#PBF include an integrated 3.3V regulator?
Yes, the LTC3728LZEUH#PBF includes a dedicated 3.3V linear regulator (3.3VOUT pin) capable of supplying 10mA DC with 50mA peak current. Its output voltage is specified as 3.35V ±0.15V at no load and exhibits ≤2% load regulation across 0–10mA, making it suitable for powering PMIC bias, SMBus transceivers, or supervisory circuits without external components.
How does the FCB pin affect operating mode selection in LTC3728LZEUH#PBF?
The FCB pin on the LTC3728LZEUH#PBF selects among three distinct operating modes: pulling FCB <0.8V forces continuous PWM; applying 0.8V–(INTVCC−2V) enables Burst Mode® for high light-load efficiency; tying FCB to INTVCC disables Burst Mode® and enables constant-frequency discontinuous conduction mode. This pin directly controls both channels simultaneously and can also regulate secondary windings in flyback-derived topologies.
What protection features are implemented in LTC3728LZEUH#PBF?
The LTC3728LZEUH#PBF implements output overvoltage latching (VOSENSE >0.84V), foldback current limiting during short-circuit, RUN/SS-based timed latchoff with optional disable, undervoltage lockout (UVLO at 3.5V), and dropout recovery forcing periodic top-FET off-cycles. All protections operate independently per channel and require no external components beyond standard RC networks on RUN/SS and FCB pins.
Can LTC3728LZEUH#PBF synchronize to an external clock source?
Yes, the LTC3728LZEUH#PBF supports external synchronization via the PLLIN pin. An external clock signal applied to PLLIN causes the internal phase-locked loop to align the rising edge of TG1 with the rising edge of the external signal. The PLLFLTR pin serves as both the phase detector output and DC frequency control input, allowing fine-tuning of oscillator frequency from 260kHz to 550kHz using a DC voltage between 0V and 2.4V.
LTC3728LZEUH#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)
LTC3728LZEUH#PBF FAQ
1.How can I place an order for LTC3728LZEUH#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3728LZEUH#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 LTC3728LZEUH#PBF reliable?
The price and inventory of LTC3728LZEUH#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3728LZEUH#PBF is usually 5 days.
3.What payment methods are accepted for LTC3728LZEUH#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3728LZEUH#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3728LZEUH#PBF?
LTC3728LZEUH#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3728LZEUH#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 LTC3728LZEUH#PBF?
For technical support, including LTC3728LZEUH#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3728LZEUH#PBF requirements.
6.How does Aetrix verify that LTC3728LZEUH#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3728LZEUH#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 LTC3728LZEUH#PBF meets industry standards.
7.What is the process for return or replacement of LTC3728LZEUH#PBF?
All LTC3728LZEUH#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3728LZEUH#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 LTC3728LZEUH#PBF part is unused and in its original packaging.
Return procedure for LTC3728LZEUH#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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