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Analog Devices Inc. LTC3728IUH#PBF
- Part No.:
- LTC3728IUH#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 32-WFQFN Exposed Pad
- Datasheet:
-
LTC3728IUH#PBF.pdf
- Description:
- IC REG CTRLR BUCK 32QFN
- Quantity:
- Payment:
- Shipping:
Inventory:146
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Product details
Overview
LTC3728IUH#PBF from Analog Devices (formerly Linear Technology) is a dual-phase, constant-frequency current-mode synchronous step-down controller driving two independent N-channel MOSFET stages. It operates at 250–550 kHz with 180° phase shift, delivers ±1% output voltage accuracy at 0.8 V reference, supports 3.5–36 V input, and integrates a 3.3 V/10 mA linear regulator - used in high-efficiency notebook DC/DC power rails for 5 V/3.3 V dual-output systems.
For engineers reviewing the LTC3728IUH#PBF datasheet, LTC3728IUH#PBF pinout, LTC3728IUH#PBF application, or LTC3728IUH#PBF equivalent, key selection criteria include dual-phase EMI reduction, OPTI-LOOP compensation adaptability across capacitor ESR, programmable operating modes (Burst/Continuous/PWM), and robust overvoltage/short-circuit protection with latched shutdown.
Technical Context
The LTC3728IUH#PBF implements two independent current-mode control loops with 180° interleaved switching to halve input ripple current and reduce required input capacitance. Each channel features a transconductance error amplifier (gm = 1.3 mmho, GBW = 3 MHz), precision 0.8 V reference (±1%), and ITH-controlled peak-current limiting.
Its phase-locked loop accepts external synchronization via PLLIN (50 kΩ internal termination) and allows frequency tuning from 250 kHz to 550 kHz using a DC voltage on PLLFLTR. The FCB pin selects among Burst Mode®, constant-frequency discontinuous mode, and forced continuous PWM - enabling optimization of light-load efficiency versus output ripple and noise.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.5 V to 36 V - supports wide battery chemistries (12 V, 24 V industrial, Li-ion stacks) without external pre-regulation. |
| Output Voltage Accuracy | ±1% at 0.8 V reference - ensures tight regulation for modern microprocessor core and I/O rails. |
| Switching Frequency | 250 kHz to 550 kHz, phase-lockable - enables EMI shaping and synchronization to system clocks. |
| Max Duty Cycle | 99.4% - supports ultra-low dropout operation (e.g., 5 V out from 5.2 V in) without external boost. |
| Quiescent Current | 20 μA in shutdown - critical for battery-backed standby and always-on subsystems. |
| PGOOD Threshold | ±7.5% window on both outputs - provides reliable power sequencing indication for FPGA/CPU power-up. |
| 3.3V LDO Output | 3.25–3.45 V at 10 mA - powers auxiliary circuitry (bias, monitoring ICs) without external regulator. |
Pinout & Package
Package: 32-lead (5 mm × 5 mm) plastic QFN with exposed thermal pad (SGND). Requires soldering of exposed pad to PCB ground for thermal performance (θJA = 68°C/W on 4-layer board).
| Pin | Circuit Role | Design Meaning |
|---|---|---|
| VOSENSE1 / VOSENSE2 | Differential feedback input | Accepts remote-sense voltage from output divider; enables precise regulation despite PCB trace IR drop. |
| SENSE1+/SENSE1− / SENSE2+/SENSE2− | Current sense differential inputs | Measure RSENSE voltage drop to set peak inductor current; support foldback during short-circuit. |
| TG1/TG2, BG1/BG2 | Top/bottom gate drivers | Drive N-MOSFET gates with 3 A peak current; TG swing = INTVCC − 0.5 V referenced to SW node. |
| RUN/SS1 / RUN/SS2 | Soft-start & latchoff timer control | Capacitor-based ramp sets startup time; falling edge below 1.0 V disables channel; discharge triggers timed shutdown. |
| FCB | Operating mode selector | Voltage < 0.8 V forces continuous PWM; 0.8–3.5 V enables Burst Mode®; >4.3 V enables constant-frequency mode. |
| PGOOD | Open-drain power-good indicator | Pulled low if either VOSENSE deviates >±7.5%; requires external pull-up to ≤7 V. |
Key Features
| Feature | Design Value |
|---|---|
| 180° interleaved dual-phase operation | Reduces RMS input ripple by ~70% vs. single-phase - cuts input capacitor size/cost and lowers EMI filter requirements. |
| OPTI-LOOP® compensation | Enables stable loop response across wide range of output capacitor values and ESR - eliminates need for custom compensation per design. |
| Three selectable operating modes | Burst Mode® (high light-load efficiency), constant-frequency (low-noise), or forced continuous (output sink capability) - configurable per application need. |
| Integrated 3.3 V/10 mA LDO | Provides clean bias for monitoring circuits or level-shifters - eliminates discrete LDO and saves board space. |
| Output overvoltage protection | Latches bottom MOSFET ON until VOSENSE returns within ±7.5% - prevents damage to downstream logic during transient faults. |
Applications
| High-Efficiency Notebook Power | Telecom Intermediate Bus Converter |
|---|---|
|
Use Scenario: Dual-output DC/DC conversion in ultraportable notebooks delivering 5 V@5 A and 3.3 V@5 A from 12–20 V battery or adapter input. IC Role / Device Role / Timing Role: Dual-phase synchronous buck controller managing interleaved switching, current sharing, and coordinated soft-start sequencing. Use Value: 180° phase shift halves input ripple current, allowing smaller, lower-cost input capacitors and reducing conducted EMI without shielding. |
Use Scenario: 48 V-to-12 V intermediate bus conversion in telecom line cards requiring high reliability and thermal headroom. IC Role / Device Role / Timing Role: High-voltage dual-phase controller with wide VIN range and robust overvoltage/overcurrent protection. Use Value: 36 V absolute max VIN rating and 99.4% duty cycle enable direct 48 V-to-12 V conversion with minimal dropout loss under load transients. |
| Portable Instrumentation Power | Battery-Operated Digital Systems |
|
Use Scenario: Precision analog/digital mixed-signal instruments powered from Li-ion packs (8.4–12.6 V) requiring low-noise, tightly regulated 3.3 V and 5 V rails. IC Role / Device Role / Timing Role: Dual-output controller with Burst Mode® for extended battery life and constant-frequency mode for ADC/DAC clocking stability. Use Value: ±1% output accuracy and 0.8 V reference ensure consistent ADC reference and digital logic thresholds across temperature and load. |
Use Scenario: Power management in handheld test equipment with deep sleep states and fast wake-up requirements. IC Role / Device Role / Timing Role: Low-IQ (20 μA shutdown) controller with programmable soft-start and PGOOD sequencing for system-level power management. Use Value: RUN/SS-controlled timed shutdown and foldback current limiting protect batteries during fault conditions while minimizing energy waste. |
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); 4.5–28 V VIN; fixed 500 kHz fSW. | Lacks integrated 3.3V LDO and programmable FCB modes; optimized for cost-sensitive, fixed-frequency applications. | Select when board space is constrained and auxiliary 3.3V rail is provided externally; verify compatibility with existing layout due to different pinout. |
| LTC3855EUH#PBF | Dual-phase controller with identical 32-pin QFN package, same 0.8 V reference and ±1% accuracy, but adds digital power system management (PMBus) interface. | Supports telemetry, fault logging, and dynamic VOUT adjustment - suited for server/industrial systems requiring remote monitoring. | Choose when firmware-configurable parameters (frequency, margins, sequencing) and telemetry are required; higher BOM cost and firmware overhead apply. |
Compared with MP2918GL-Z, the LTC3728IUH#PBF offers integrated 3.3V bias and flexible FCB mode selection for better light-load efficiency trade-offs; compared with LTC3855EUH#PBF, it provides simpler analog control without PMBus overhead - ideal for cost- and size-sensitive embedded designs where digital telemetry is unnecessary.
Availability
LTC3728IUH#PBF is available at Aetrix Electronics and suitable for notebook computers, telecom power systems, portable instrumentation, and battery-operated digital devices requiring stable component supply, long-term lifecycle support, and guaranteed industrial temperature range (–40°C to +85°C).
Supply support for LTC3728IUH#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, documentation, and manufacturing continuity for the LTC portfolio.
The LTC3728IUH#PBF belongs to Linear's high-performance power controller family, designed specifically for demanding dual-output, high-efficiency DC/DC conversion in portable and industrial systems where thermal density, EMI, and regulation accuracy are critical.
FAQ
What is the maximum input voltage rating for the LTC3728IUH#PBF?
The LTC3728IUH#PBF has an absolute maximum input voltage (VIN) rating of 36 V. Operation is specified from 3.5 V to 30 V, with transient tolerance up to 36 V. Exceeding 36 V risks permanent damage per Absolute Maximum Ratings. The LTC3728IUH#PBF is commonly used with 12 V, 24 V, and multi-cell Li-ion inputs within this safe operating window.
Does the LTC3728IUH#PBF support phase synchronization to an external clock?
Yes, the LTC3728IUH#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. The PLLFLTR pin serves as both the phase detector output and DC frequency control input, enabling frequency tuning from 250 kHz to 550 kHz.
How does the FCB pin affect operating mode selection in the LTC3728IUH#PBF?
The FCB pin on the LTC3728IUH#PBF selects among three operating modes: voltage < 0.8 V forces continuous PWM; 0.8–3.5 V enables Burst Mode® for high light-load efficiency; >4.3 V disables Burst Mode® and enables constant-frequency discontinuous conduction. This single-pin control simplifies mode selection without external logic.
What is the function of the RUN/SS pins on the LTC3728IUH#PBF?
RUN/SS1 and RUN/SS2 on the LTC3728IUH#PBF serve dual functions: soft-start timing (via external capacitor ramp) and short-circuit latchoff detection. Pulling either pin below 1.0 V disables its channel; sustained low voltage after startup triggers timed shutdown if output drops below 70% of nominal. The LTC3728IUH#PBF uses these pins for coordinated dual-rail sequencing and fault protection.
Is the 3.3V output on the LTC3728IUH#PBF internally regulated and load-capable?
Yes, the LTC3728IUH#PBF integrates a dedicated 3.3 V linear regulator (pin 10, 3.3VOUT) with ±2% load regulation (0–10 mA) and ±0.2% line regulation. It delivers up to 10 mA DC with 50 mA peak current, powering auxiliary circuitry such as supervisors, level shifters, or optocouplers - eliminating the need for an external LDO in many designs.
LTC3728IUH#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):
- 3.5V ~ 30V
- 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)
LTC3728IUH#PBF FAQ
1.How can I place an order for LTC3728IUH#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3728IUH#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 LTC3728IUH#PBF reliable?
The price and inventory of LTC3728IUH#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3728IUH#PBF is usually 5 days.
3.What payment methods are accepted for LTC3728IUH#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3728IUH#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3728IUH#PBF?
LTC3728IUH#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3728IUH#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 LTC3728IUH#PBF?
For technical support, including LTC3728IUH#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3728IUH#PBF requirements.
6.How does Aetrix verify that LTC3728IUH#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3728IUH#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 LTC3728IUH#PBF meets industry standards.
7.What is the process for return or replacement of LTC3728IUH#PBF?
All LTC3728IUH#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3728IUH#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 LTC3728IUH#PBF part is unused and in its original packaging.
Return procedure for LTC3728IUH#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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