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Analog Devices Inc. LTC3728EG#PBF
- Part No.:
- LTC3728EG#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 28-SSOP (0.209", 5.30mm Width)
- Datasheet:
-
LTC3728EG#PBF.pdf
- Description:
- IC REG CTRLR BUCK 28SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,534
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Product details
Overview
LTC3728EG#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, supports 3.5V–36V input, delivers ±1% output voltage accuracy at 0.8V reference, and integrates OPTI-LOOP compensation for wide output capacitance/ESR tolerance - used in high-efficiency dual-rail power supplies for notebook computers and telecom systems.
For engineers reviewing the LTC3728EG#PBF datasheet, LTC3728EG#PBF pinout, LTC3728EG#PBF application, or LTC3728EG#PBF equivalent, key selection criteria include dual-phase interleaving for reduced input ripple, programmable operating modes (Burst Mode®, constant-frequency PWM, forced continuous), remote sense capability, and integrated 3.3V LDO output for auxiliary biasing.
Technical Context
The LTC3728EG#PBF implements two independent current-mode control loops with 180° phase offset to minimize input capacitor RMS current and EMI. Each channel uses a transconductance error amplifier (gm = 1.3 mmho, GBW = 3 MHz) and precision 0.8V reference (±1% over temperature) with remote sensing inputs (VOSENSE1/2).
Its oscillator supports phase-lockable frequency tuning via PLLIN (50 kΩ input impedance) and PLLFLTR (DC voltage-controlled from 0–2.4V), enabling synchronization across multiple controllers or external clocks. The FCB pin selects among Burst Mode® (low-IQ), constant-frequency discontinuous conduction, and forced continuous PWM operation - with distinct foldback current limiting and latchoff behavior during short-circuit events.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.5V to 36V - supports wide battery chemistries (12V, 24V, Li-ion stacks) and industrial DC rails without external pre-regulation. |
| Output Voltage Accuracy | ±1% over temperature - ensures stable core logic supply for microprocessors and FPGAs requiring tight regulation. |
| Switching Frequency | 250 kHz to 550 kHz, phase-lockable - enables EMI reduction via spread-spectrum sync and allows optimization of magnetics size vs efficiency. |
| Phase Offset | 180° between channels - cuts input ripple current by ~70% vs single-phase, reducing required CIN and PCB footprint. |
| Reference Voltage | 0.800 V ±0.008 V - matches modern low-voltage CPU/GPU core requirements and enables precise resistor-divider setpoints. |
| Shutdown Quiescent Current | 20 μA - enables ultra-low-power standby in portable instruments and battery-operated devices. |
| Integrated 3.3V LDO | 3.35 V ±0.1 V, 10 mA load - powers auxiliary circuitry (e.g., level shifters, sensors) without external regulator. |
Pinout & Package
Package: 28-Lead Plastic SSOP (G package), exposed pad soldered to SGND for thermal and electrical integrity. Pin count and layout match industry-standard SSOP-28 footprint with 0.025" pitch.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| RUN/SS1, RUN/SS2 (Pins 1, 15) | Soft-start & short-circuit timer control | Capacitor-based ramp sets current slew rate; falling below 1.0V shuts down respective channel; latchoff triggered if VOSENSE drops <70% nominal. |
| SENSE1+/SENSE2+, SENSE1−/SENSE2− (Pins 2,14,13,12) | Differential current sense inputs | Measure RSENSE voltage drop to regulate peak inductor current; total source current ≤ –60 μA ensures minimal offset error. |
| VOSENSE1, VOSENSE2 (Pins 4, 12) | Remote feedback voltage inputs | Accept resistive divider output from load point - enables accurate regulation despite PCB trace IR drop. |
| ITH1, ITH2 (Pins 8, 11) | Error amplifier output / compensation node | Voltage controls current limit threshold; OPTI-LOOP allows direct RC network connection for stability across wide COUT/ESR range. |
| TG1, TG2, BG1, BG2 (Pins 27,16,23,19) | Top/bottom gate drivers | Drive N-MOSFET gates with 50 ns rise/fall times; TG swing = INTVCC – 0.5V referenced to SW node; BG swing = 0–INTVCC referenced to PGND. |
| PGOOD (Pin 28) | Open-drain power-good indicator | Pulls low if either VOSENSE deviates >±7.5% from setpoint - enables system-level sequencing and fault reporting. |
Key Features
| Feature | Design Value |
|---|---|
| Dual 180° phased controllers | Reduces input ripple RMS current by up to 70%, allowing smaller, lower-cost input capacitors and easing EMI filtering. |
| OPTI-LOOP® compensation | Enables stable loop response across 10× variation in output capacitance and ESR - eliminates need for re-tuning when changing bulk capacitor types. |
| Selectable operating modes | Burst Mode® (ultra-low IQ), constant-frequency (low-noise), or forced continuous (bidirectional current) - selectable per application load profile. |
| Integrated 3.3V linear regulator | Delivers 10 mA with ±0.5% line/load regulation - powers bias rails for ADCs, comparators, or level translators without external LDO. |
| Output overvoltage protection | Latches bottom MOSFET on until VOSENSE returns within ±7.5% - prevents damage to downstream logic during transient overshoot or feedback fault. |
Applications
| Notebook Power Management | Telecom DC/DC Conversion |
|---|---|
Use Scenario: Dual-rail 5V/3.3V power supply for CPU core and I/O in thin-and-light notebooks with strict thermal and ripple constraints. IC Role / Device Role / Timing Role: Dual-phase synchronous buck controller managing two independent 5A outputs with interleaved switching to minimize input ripple and heat generation. Use Value: 180° phase shift reduces input capacitor RMS current by ~70%, enabling use of smaller 22μF ceramic input caps instead of larger electrolytics - saving board space and cost. | Use Scenario: Intermediate bus converter in 48V telecom systems powering distributed 12V/5V loads across backplane. IC Role / Device Role / Timing Role: High-input-voltage dual controller regulating two isolated secondary rails with remote sensing to compensate for long PCB trace losses. Use Value: 3.5V–36V input range accommodates wide 48V-derived intermediate bus tolerances; ±1% output accuracy ensures reliable interface with SERDES and PHY ICs. |
| Portable Instrumentation | Battery-Powered Digital Systems |
Use Scenario: Precision analog front-end power in handheld test equipment requiring clean, low-noise 3.3V and 5V rails. IC Role / Device Role / Timing Role: Dual-output controller operating in constant-frequency mode to avoid audible noise and ensure predictable EMI spectrum. Use Value: Constant-frequency operation down to 1% load (vs Burst Mode) eliminates low-frequency ripple that could couple into sensitive analog measurements. | Use Scenario: Power management for Li-ion powered IoT edge nodes with deep sleep and burst transmit cycles. IC Role / Device Role / Timing Role: Controller using Burst Mode® at light load to achieve 20 μA shutdown IQ, then seamless transition to PWM under active load. Use Value: 20 μA quiescent current extends battery life in multi-year deployments; foldback current limiting protects battery during accidental short circuits. |
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 |
|---|---|---|---|
| LTC3727EG#PBF | Same pinout, identical feature set, but rated for –40°C to 125°C junction temperature (vs 85°C for LTC3728EG#PBF); higher thermal performance grade. | Suitable for extended-temperature industrial or automotive under-hood applications where ambient exceeds 85°C. | Select LTC3727EG#PBF when operating ambient exceeds 85°C or when AEC-Q200 qualification is required. |
| MP2918GL-Z | Single-chip dual-phase controller with integrated MOSFET drivers only (no external gate drive requirement); lacks 3.3V LDO and PLL sync capability. | Used in cost-sensitive consumer electronics where board space is critical and external sync is unnecessary. | Choose MP2918GL-Z when integrating drivers saves BOM cost and thermal design complexity, but accept loss of 3.3V bias rail and sync flexibility. |
Compared with LTC3727EG#PBF, the LTC3728EG#PBF offers identical functionality at lower temperature grade and cost, while MP2918GL-Z trades off programmability and auxiliary features for integration density - making LTC3728EG#PBF optimal for thermally constrained but functionally demanding industrial and computing applications.
Availability
LTC3728EG#PBF is available at Aetrix Electronics and suitable for notebook power management, telecom DC/DC conversion, and portable instrumentation requiring stable component supply, long-term lifecycle support, and guaranteed lead-free compliance.
Supply support for LTC3728EG#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 all Linear ICs including the LTC series.
The LTC3728 belongs to Linear's high-performance power controller family designed for demanding multi-rail, high-efficiency DC/DC conversion in computing, communications, and portable electronics - emphasizing precision regulation, thermal robustness, and flexible control architecture.
FAQ
What is the maximum input voltage rating for the LTC3728EG#PBF?
The LTC3728EG#PBF has an absolute maximum input voltage rating of 36V on the VIN pin. Continuous operation is specified from 3.5V to 30V, with transient tolerance up to 36V for short durations. Exceeding 36V risks permanent damage per Absolute Maximum Ratings. The LTC3728EG#PBF must be used with appropriate input clamping or pre-regulation in systems with uncontrolled surges above this threshold.
Does the LTC3728EG#PBF support remote voltage sensing?
Yes, the LTC3728EG#PBF supports true remote voltage sensing via dedicated VOSENSE1 and VOSENSE2 pins. These inputs accept feedback signals from resistive dividers placed directly at the load terminals, compensating for IR drop across PCB traces and connectors. This ensures ±1% output accuracy at the point-of-load - critical for powering sensitive microprocessors and high-speed interfaces in the LTC3728EG#PBF-based designs.
How does the FCB pin affect operating mode selection in the LTC3728EG#PBF?
The FCB pin on the LTC3728EG#PBF selects among three distinct operating modes: pulling it below 0.8V forces continuous PWM; holding it between 0.8V and (INTVCC – 1V) enables Burst Mode®; tying it to INTVCC disables Burst Mode for constant-frequency operation. This single-pin control allows dynamic efficiency/noise trade-offs without firmware or external logic - a key differentiator of the LTC3728EG#PBF in adaptive power systems.
What is the purpose of the 3.3VOUT pin on the LTC3728EG#PBF?
The 3.3VOUT pin on the LTC3728EG#PBF is the output of an integrated linear regulator delivering up to 10 mA with ±0.5% line and load regulation. It provides a clean, low-noise auxiliary supply for biasing level shifters, ADC references, or communication interfaces - eliminating the need for an external LDO and simplifying BOM in space-constrained LTC3728EG#PBF applications.
Can the LTC3728EG#PBF synchronize its switching frequency to an external clock?
Yes, the LTC3728EG#PBF supports full frequency synchronization via the PLLIN pin, which accepts an external clock signal (e.g., from a system master oscillator). Its internal phase-locked loop aligns the rising edge of TG1 to the PLLIN rising edge, enabling deterministic timing across multiple converters. This capability is essential for EMI reduction and noise-sensitive LTC3728EG#PBF implementations in dense PCB layouts.
LTC3728EG#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 28-SSOP (0.209", 5.30mm Width)
- 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:
- 28-SSOP
LTC3728EG#PBF FAQ
1.How can I place an order for LTC3728EG#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3728EG#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 LTC3728EG#PBF reliable?
The price and inventory of LTC3728EG#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3728EG#PBF is usually 5 days.
3.What payment methods are accepted for LTC3728EG#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3728EG#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3728EG#PBF?
LTC3728EG#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3728EG#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 LTC3728EG#PBF?
For technical support, including LTC3728EG#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3728EG#PBF requirements.
6.How does Aetrix verify that LTC3728EG#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3728EG#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 LTC3728EG#PBF meets industry standards.
7.What is the process for return or replacement of LTC3728EG#PBF?
All LTC3728EG#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3728EG#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 LTC3728EG#PBF part is unused and in its original packaging.
Return procedure for LTC3728EG#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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