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Analog Devices Inc. LTC3728LIUH#TRPBF
- Part No.:
- LTC3728LIUH#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 32-WFQFN Exposed Pad
- Datasheet:
-
LTC3728LIUH#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 32QFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,888
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Product details
Overview
LTC3728LIUH#TRPBF 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#TRPBF datasheet, LTC3728LIUH#TRPBF pinout, LTC3728LIUH#TRPBF application, or LTC3728LIUH#TRPBF equivalent, key selection criteria include phase-lockable frequency (250–550kHz), OPTI-LOOP™ compensation for wide output capacitance/ESR tolerance, dual RUN/SS pins with soft-start and short-circuit latchoff, and FCB-selectable operating modes (Burst Mode®, constant-frequency, forced continuous).
Technical Context
The LTC3728LIUH#TRPBF implements a constant-frequency current-mode control architecture with two independent channels, each featuring an error amplifier (ITH1/ITH2), differential current sense inputs (SENSE1±/SENSE2±), and 180° phase offset to reduce input ripple current and capacitor stress. Its PLLIN/PLLFLTR interface enables external synchronization or DC voltage-controlled frequency tuning from 260kHz to 550kHz.
It integrates dual gate drivers (TG1/BG1 and TG2/BG2) optimized for N-channel MOSFETs, with 55ns/45ns typical rise/fall times, 80ns dead-time control, and dropout detection that forces periodic top-FET off-time to recharge bootstrap capacitors below 99% duty cycle. The 3.3VOUT linear regulator and INTVCC/EXTVCC power management support self-biasing from regulated outputs.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5V to 28V - supports all common battery chemistries (Li-ion, LiPo, 12V lead-acid) and industrial DC rails without external pre-regulation. |
| Output Voltage Accuracy | ±1% over temperature - ensures stable core/supply rail regulation for microprocessors and FPGAs requiring tight voltage margins. |
| Switching Frequency Range | 250kHz to 550kHz (phase-lockable) - enables EMI optimization and inductor size reduction while maintaining 180° interleaving benefits. |
| Current Sense Threshold | 62mV to 88mV (adjustable via RSENSE) - sets precise overcurrent protection point with foldback behavior during short-circuit conditions. |
| Shutdown Quiescent Current | 20µA - minimizes battery drain in standby mode for portable instrumentation and always-on subsystems. |
| Operating Temperature | –40°C to +85°C - qualified for industrial and automotive under-hood environments where thermal robustness is critical. |
| Package | 32-lead 5mm × 5mm QFN (UH) with exposed SGND pad - provides low thermal resistance (θJA = 34°C/W) and compact footprint for dense PCB layouts. |
Pinout & Package
Package: 32-lead (5mm × 5mm) plastic QFN (UH) with exposed pad soldered to SGND. Thermal performance: θJA = 34°C/W. Pin 33 = exposed pad = SGND.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN | Main input supply connection | Bypassed to SGND; powers internal LDO and logic; must be decoupled with ≥22µF ceramic capacitor. |
| TG1, TG2 | Top-gate drive outputs | Floating drivers for N-channel high-side MOSFETs; swing = INTVCC – 0.5V above SWx node; require external bootstrap diode/capacitor. |
| BG1, BG2 | Bottom-gate drive outputs | Ground-referenced drivers for N-channel synchronous rectifiers; swing = 0V to INTVCC; enable >95% efficiency at light loads. |
| SENSE1+, SENSE1− SENSE2+, SENSE2− |
Differential current sense inputs | Measure voltage across RSENSE to set peak inductor current limit; reject common-mode noise up to 5V. |
| VOSENSE1, VOSENSE2 | Feedback voltage inputs | Remote sensing of output voltage via resistive divider; referenced to 0.8V internal precision bandgap. |
| RUN/SS1, RUN/SS2 | Soft-start and fault timer inputs | Capacitor-connected pins control startup ramp time and provide timed short-circuit shutdown with latchoff defeat option. |
| FCB | Forced continuous/burst mode select | Voltage-controlled pin selecting between Burst Mode® (0.8V–INTVCC–2V), constant-frequency (tied to INTVCC), or PWM (grounded). |
| PGOOD | Open-drain power-good indicator | Asserts low when either VOSENSE is outside ±7.5% of setpoint; enables system sequencing and fault reporting. |
Key Features
| Feature | Design Value |
|---|---|
| 180° dual-phase interleaving | Reduces RMS input capacitor current by ~70% vs single-phase, enabling smaller input bulk capacitance and lower EMI. |
| OPTI-LOOP™ compensation | Allows stable loop response across wide COUT/ESR ranges (e.g., ceramic + polymer caps), eliminating need for custom compensation per design. |
| Three selectable operating modes | Burst Mode® (high light-load efficiency), constant-frequency (low-noise fixed switching), or forced PWM (continuous conduction for reverse-current capability). |
| Dual independent RUN/SS controls | Enables staggered startup, independent channel shutdown, and programmable short-circuit timeout per output without external logic. |
| Integrated 3.3V/10mA linear regulator | Provides clean bias for auxiliary circuitry (e.g., ADC references, level shifters) without requiring separate LDO or external components. |
Applications
| Notebook Dual-Rail Power | Telecom Intermediate Bus Converter |
|---|---|
Use Scenario: Generating 5V/5A and 3.3V/5A from a 12V or 19V adapter in ultrabook platforms with strict thermal and size constraints. IC Role / Device Role / Timing Role: Dual-phase synchronous buck controller managing two independent output rails with interleaved switching to minimize input ripple and heat generation. Use Value: Enables use of smaller input capacitors (22µF ceramic vs 100µF electrolytic) and achieves >92% peak efficiency at full load, extending battery runtime. |
Use Scenario: Converting 48V telecom bus to 5V/3.3V for line-card ASICs and FPGAs in carrier-grade equipment requiring high reliability and low noise. IC Role / Device Role / Timing Role: High-voltage-input dual controller providing tightly regulated, sequenced outputs with PGOOD monitoring for system-level power management. Use Value: Phase interleaving reduces conducted EMI at 550kHz, meeting EN55022 Class B limits without additional filtering; ±1% accuracy ensures ASIC core voltage compliance. |
| Portable Test Instrumentation | Industrial Embedded Control Unit |
Use Scenario: Powering mixed-signal circuits (ADCs, DACs, microcontrollers) in handheld multimeters and oscilloscopes using Li-ion battery input (7–28V). IC Role / Device Role / Timing Role: Dual-output controller delivering low-noise 3.3V analog rail and 5V digital rail with independent soft-start and fault handling. Use Value: Burst Mode® operation extends battery life >3× vs constant-frequency mode at standby; 3.3VOUT LDO supplies ultra-low-noise reference voltage. |
Use Scenario: Providing redundant 5V/3.3V supplies in DIN-rail mounted PLC modules operating continuously in factory environments (–40°C to +85°C). IC Role / Device Role / Timing Role: Industrial-grade dual controller with extended temperature rating, output overvoltage protection, and latchoff-capable short-circuit response. Use Value: Output OVP latches bottom MOSFET on during overvoltage events, preventing damage to downstream I/O modules; –40°C to +85°C rating ensures field 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 |
|---|---|---|---|
| LTC3728LEUH#TRPBF | Same pinout, identical electrical specs, but rated for –40°C to +85°C with different screening - no functional difference from LTC3728LIUH#TRPBF. | No application difference; both qualified for industrial temperature range. | Select LTC3728LEUH#TRPBF only if traceability to Linear's standard industrial grade is required; otherwise LTC3728LIUH#TRPBF is functionally identical. |
| MP2918GL-Z | Single-chip dual-phase controller with integrated MOSFET drivers but no 3.3V LDO; max VIN = 24V; lacks PLLIN sync and OPTI-LOOP™. | Suitable for cost-sensitive, non-temperature-extended designs where external LDO is acceptable and sync is not needed. | Choose MP2918GL-Z for simplified BOM and lower cost in commercial-temp applications; avoid where 28V input, 3.3V bias, or external sync is required. |
Compared with LTC3728LEUH#TRPBF, the LTC3728LIUH#TRPBF offers identical performance and industrial temperature qualification, while MP2918GL-Z trades integrated power stages and cost for reduced feature set - making it viable only where 3.3VOUT, 28V input, or PLL synchronization are unnecessary.
Availability
LTC3728LIUH#TRPBF is available at Aetrix Electronics and suitable for notebook computers, telecom power systems, and portable instrumentation requiring stable component supply, long-term lifecycle support, and guaranteed industrial temperature performance.
Supply support for LTC3728LIUH#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 the LTC portfolio.
The LTC3728L series was designed specifically for high-efficiency, dual-output, interleaved DC/DC conversion in portable and industrial systems - emphasizing thermal efficiency, layout simplicity, and robust fault protection.
FAQ
What is the maximum input voltage rating for the LTC3728LIUH#TRPBF?
The LTC3728LIUH#TRPBF has an absolute maximum input voltage (VIN) rating of 30V. Continuous operation is specified from 4.5V to 28V, making it compatible with 24V industrial rails and multi-cell Li-ion batteries. Exceeding 30V risks permanent damage per Absolute Maximum Ratings.
Does the LTC3728LIUH#TRPBF support external frequency synchronization?
Yes, the LTC3728LIUH#TRPBF supports external synchronization via the PLLIN pin. When driven with a clean square wave, the internal phase-locked loop aligns the rising edge of TG1 to the rising edge of the PLLIN signal. The PLLFLTR pin allows DC voltage tuning of oscillator frequency from 260kHz to 550kHz.
How does the FCB pin affect operating mode selection in the LTC3728LIUH#TRPBF?
The FCB pin selects among three modes: pulling FCB < 0.8V forces continuous PWM; 0.8V < FCB < (INTVCC – 2V) enables Burst Mode®; tying FCB to INTVCC disables Burst Mode® for constant-frequency operation. This single pin eliminates external mode-selection logic in the LTC3728LIUH#TRPBF design.
What is the purpose of the 3.3VOUT pin on the LTC3728LIUH#TRPBF?
The 3.3VOUT pin on the LTC3728LIUH#TRPBF delivers a regulated 3.3V output capable of 10mA DC (50mA peak), powered from the internal INTVCC rail. It provides clean, low-noise bias for auxiliary circuitry such as ADC references, level shifters, or microcontroller I/O, eliminating the need for an external LDO in many LTC3728LIUH#TRPBF implementations.
Can the LTC3728LIUH#TRPBF operate with only one channel enabled?
Yes, the LTC3728LIUH#TRPBF supports independent channel control: pulling RUN/SS1 low disables Channel 1 while Channel 2 remains active, and vice versa. Both channels must be enabled for dual-phase interleaving; single-channel operation is fully supported with identical regulation performance and protection features per active channel.
LTC3728LIUH#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)
LTC3728LIUH#TRPBF FAQ
1.How can I place an order for LTC3728LIUH#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3728LIUH#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 LTC3728LIUH#TRPBF reliable?
The price and inventory of LTC3728LIUH#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3728LIUH#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3728LIUH#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3728LIUH#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3728LIUH#TRPBF?
LTC3728LIUH#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3728LIUH#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 LTC3728LIUH#TRPBF?
For technical support, including LTC3728LIUH#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3728LIUH#TRPBF requirements.
6.How does Aetrix verify that LTC3728LIUH#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3728LIUH#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 LTC3728LIUH#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3728LIUH#TRPBF?
All LTC3728LIUH#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3728LIUH#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 LTC3728LIUH#TRPBF part is unused and in its original packaging.
Return procedure for LTC3728LIUH#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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