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Analog Devices Inc. LT3975IMSE#PBF
- Part No.:
- LT3975IMSE#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 16-TFSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LT3975IMSE#PBF.pdf
- Description:
- IC REG BUCK ADJ 2.5A 16MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:165
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Product details
Overview
LT3975IMSE#PBF from Analog Devices (formerly Linear Technology) is a 42V, 2.5A monolithic synchronous step-down switching regulator with current-mode control, 2.7µA quiescent current in Burst Mode, and adjustable 200kHz–2MHz switching frequency. It features a 75mΩ internal NPN switch, power good flag, soft-start, and 500mV dropout voltage-designed for automotive cold-crank and battery-powered industrial systems.
For engineers reviewing the LT3975IMSE#PBF datasheet, LT3975IMSE#PBF pinout, LT3975IMSE#PBF application, or LT3975IMSE#PBF equivalent, key selection criteria include ultralow IQ at no load, guaranteed 2.5A output current with foldback protection, thermal shutdown, programmable UVLO via EN pin, and MSOP-16EP package with exposed GND pad for thermal management.
Technical Context
The LT3975IMSE#PBF employs an internally compensated current-mode architecture with fixed-frequency PWM and automatic transition to low-ripple Burst Mode below ~150mA load. Its oscillator is RT-resistor programmable (200kHz–2MHz), and it supports external synchronization (250kHz–2MHz) with pulse-skipping behavior when SYNC is driven.
It integrates a bipolar NPN main switch with 75mΩ typical RCE(SAT), a boost Schottky diode, and internal bias regulation that auto-switches between VIN and OUT (≥3.2V) for efficiency. Dropout operation maintains 500mV (min) VIN–VOUT differential while sustaining full saturation via boost capacitor charge management.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.3V to 42V - supports automotive battery transients including cold-crank (down to 4.3V) and load-dump immunity up to 42V. |
| Max Output Current | 2.5A continuous - limited by thermal design and current-limit foldback (3.3A at VFB = 0V) during short-circuit. |
| Quiescent Current | 2.7µA at no load - enables >1-year battery life in always-on IoT sensors and telematics modules. |
| Switching Frequency | 200kHz to 2MHz - set by RT resistor; allows optimization of inductor size (e.g., 3.3µH at 600kHz) vs. efficiency. |
| Feedback Reference | 1.197V ±1.2% - high-accuracy reference enables ±1.5% total output voltage tolerance with 1% resistors. |
| Dropout Voltage | 500mV (typical) - ensures regulation during VIN sag; enforced by internal comparator monitoring OUT pin. |
| Power Good Threshold | 91.6% of VOUT - open-drain PG pin asserts high only after stable regulation is achieved, with 8.4% hysteresis. |
| EN Threshold | 1.02V (falling), 1.08V (rising) - precise hysteresis enables reliable programmable undervoltage lockout without external circuitry. |
Pinout & Package
LT3975IMSE#PBF is housed in a thermally enhanced 16-lead plastic MSOP package with exposed GND pad (Pin 17), θJA = 40°C/W. The exposed pad must be soldered to PCB for thermal performance and electrical grounding.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| FB (1) | Feedback input | Regulated to 1.197V; connects to resistor divider tap; phase-lead capacitor (10pF) required for stability. |
| SS (2) | Soft-start control | Internal 1.8µA pull-up charges external capacitor; actively discharged during shutdown/UVLO for controlled startup. |
| OUT (3) | Output sense & bias source | Connects to regulated output (≤16V); supplies internal bias when ≥3.2V; input to dropout comparator. |
| BOOST (4) | Boost drive node | Drives external capacitor to generate >VIN voltage for NPN switch saturation; max 55V rating. |
| SW (5,6,7) | Switch node | High-current output of internal NPN switch; connects to inductor, catch diode, and boost capacitor. |
| NC (8,9) | No connect | Not bonded; must remain unconnected per datasheet. |
| VIN (10,11,12) | Main power input | Supplies internal circuitry and switch; requires local ceramic bypass (e.g., 10µF + 100nF). |
| EN (13) | Enable control | Hysteretic threshold (1.02V/1.08V); ties directly to MCU GPIO or resistor-divider for UVLO. |
| RT (14) | Frequency programming | Resistor to GND sets fSW; 78.7kΩ yields 600kHz, 41.2kΩ yields 1MHz, 294kΩ yields 200kHz. |
| PG (15) | Power good flag | Open-drain output; pulled low during startup/fault; valid only when VIN > 2V. |
| SYNC (16) | External clock input | Ground for Burst Mode; drive with CMOS clock (250kHz–2MHz) for synchronized pulse-skipping. |
| GND (17) | Power ground | Exposed thermal pad; must be soldered to large PCB copper area for thermal and electrical integrity. |
Key Features
| Feature | Design Value |
|---|---|
| Ultralow quiescent current | 2.7µA IQ enables >10-year shelf life in battery-backed industrial controllers and remote sensors. |
| Low-ripple Burst Mode | Maintains <15mVP-P output ripple at light loads while preserving >85% efficiency down to 1mA. |
| Thermal-enhanced MSOP-16EP | Exposed GND pad reduces θJA to 40°C/W - supports 2.5A continuous output at 70°C ambient with minimal heatsinking. |
| Current limit foldback | Reduces switch current limit from 5.4A to 3.3A during overload, limiting junction temperature rise and enabling safe short-circuit survival. |
| Accurate programmable UVLO | EN pin's 60mV hysteresis and 1.02V/1.08V thresholds allow precise system-level brownout detection without external comparators. |
| Dropout performance | Regulates with 500mV VIN–VOUT differential and sustains full switch saturation via active boost capacitor recharge. |
Applications
| Automotive Battery Regulation | Portable Medical Devices |
|---|---|
|
Use Scenario: Powering infotainment head units and ADAS cameras during engine cranking (VIN drops to 4.3V). IC Role / Device Role / Timing Role: Primary 3.3V/5V buck regulator delivering 2.5A with seamless dropout recovery and <15mV ripple. Use Value: Maintains system uptime without brownout resets; 2.7µA IQ extends backup battery life during vehicle sleep mode. |
Use Scenario: Supplying FPGA, ADC, and wireless SoC in handheld ultrasound or glucose monitors. IC Role / Device Role / Timing Role: Main system PMIC providing stable 1.8V/3.3V rails from single Li-ion cell (3.0–4.2V) or coin cell. Use Value: Burst Mode preserves battery capacity over multi-week clinical deployments; soft-start prevents inrush-induced sensor noise. |
| Industrial Sensor Nodes | Railway Signaling Modules |
|
Use Scenario: Powering LoRaWAN or NB-IoT edge nodes deployed in remote substations or pipelines. IC Role / Device Role / Timing Role: Primary DC/DC converter accepting wide-input 9–36V DC rail, delivering 3.3V @ 500mA with low EMI. Use Value: 42V absolute max rating withstands 36V rail transients; PG flag enables firmware-controlled power sequencing and fault logging. |
Use Scenario: Regulating 24V train battery supply to 5V logic for safety-critical signaling logic and LED drivers. IC Role / Device Role / Timing Role: High-reliability buck controller operating across –40°C to +125°C junction range with thermal shutdown. Use Value: I-grade qualification (–40°C to +125°C) and current foldback ensure fail-safe operation under sustained overload or ambient extremes. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar high-efficiency, wide-input buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT8610EMSE#PBF | 42V input, 3.5A, 2.5µA IQ, Silent Switcher architecture; higher cost, lower EMI, no BOOST pin. | Better for noise-sensitive analog/RF systems; lacks dropout comparator and OUT pin functionality. | Select when EMI compliance (CISPR 25 Class 5) is mandatory and layout space permits larger inductor. |
| TPS54240DGQR | 40V input, 2.5A, 145µA IQ, integrated MOSFETs; no Burst Mode, higher light-load IQ. | Suitable for cost-sensitive industrial supplies where >100µA IQ is acceptable. | Choose for simpler BOM (no external Schottky) and TI ecosystem support, but expect reduced battery runtime. |
Compared with LT8610EMSE#PBF and TPS54240DGQR, the LT3975IMSE#PBF uniquely balances ultralow IQ (2.7µA), robust dropout behavior (500mV), and integrated boost diode-making it optimal for automotive and long-life battery systems where both efficiency and regulation margin are critical.
Availability
LT3975IMSE#PBF is available at Aetrix Electronics and suitable for automotive battery regulation, portable medical devices, industrial sensor nodes, and railway signaling modules requiring stable component supply across extended temperature and lifecycle requirements.
Supply support for LT3975IMSE#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 all LT parts including the LT3975 series.
The LT3975 belongs to Linear's high-voltage monolithic buck regulator family, designed specifically for automotive, industrial, and battery-powered systems demanding ultralow quiescent current, wide input range, and robust thermal performance.
FAQ
What is the guaranteed operating temperature range for LT3975IMSE#PBF?
The LT3975IMSE#PBF is specified for –40°C to +125°C junction temperature and is qualified to the Industrial grade (I-grade). This range is fully tested and guaranteed - not just assured by design - making it suitable for under-hood automotive and outdoor industrial deployments where ambient temperatures exceed 85°C.
Can LT3975IMSE#PBF operate with input voltage below 4.3V?
No - the LT3975IMSE#PBF has a minimum input voltage specification of 4.3V under normal operation. Below this, internal UVLO activates and forces shutdown. The device will not regulate or deliver output current at 4.0V or lower, even if EN is asserted. This limit is defined by internal bias circuitry and cannot be overridden.
How does the LT3975IMSE#PBF achieve 500mV dropout performance?
The LT3975IMSE#PBF achieves 500mV dropout by using its OUT pin to monitor VIN–VOUT differential and dynamically extending duty cycle while maintaining sufficient BOOST capacitor voltage to saturate the internal NPN switch. This avoids linear-mode operation and preserves efficiency even when VIN approaches VOUT.
Is the LT3975IMSE#PBF pin-compatible with other LT3975 variants like LT3975EMSE#PBF or LT3975HMSE#PBF?
Yes - all LT3975 variants (E, I, H grades) share identical pinout, package (MSOP-16EP), and electrical interface. The only differences are temperature grading and associated reliability testing: E-grade (0°C–125°C), I-grade (–40°C–125°C), and H-grade (–40°C–150°C). LT3975IMSE#PBF may be used as a drop-in replacement for E-grade in new designs requiring wider temp range.
What external components are mandatory for basic LT3975IMSE#PBF operation?
Mandatory components for functional operation of the LT3975IMSE#PBF include: (1) input ceramic capacitor (≥10µF), (2) output capacitor (≥47µF low-ESR), (3) power inductor (e.g., 3.3µH), (4) catch Schottky diode (e.g., PDS560), (5) FB resistor divider, (6) BOOST capacitor (≥10nF), and (7) RT resistor for frequency setting. Omitting any of these prevents regulation or risks damage.
LT3975IMSE#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-TFSOP (0.118", 3.00mm Width) Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 4.3V
- Voltage - Input (Max):
- 42V
- Voltage - Output (Min/Fixed):
- 1.197V
- Voltage - Output (Max):
- 40.74V
- Current - Output:
- 2.5A
- Frequency - Switching:
- 200kHz ~ 2.25MHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-MSOP-EP
LT3975IMSE#PBF FAQ
1.How can I place an order for LT3975IMSE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3975IMSE#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 LT3975IMSE#PBF reliable?
The price and inventory of LT3975IMSE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3975IMSE#PBF is usually 5 days.
3.What payment methods are accepted for LT3975IMSE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3975IMSE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3975IMSE#PBF?
LT3975IMSE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3975IMSE#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 LT3975IMSE#PBF?
For technical support, including LT3975IMSE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3975IMSE#PBF requirements.
6.How does Aetrix verify that LT3975IMSE#PBF is sourced from the original manufacturer or authorized distributors?
All LT3975IMSE#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 LT3975IMSE#PBF meets industry standards.
7.What is the process for return or replacement of LT3975IMSE#PBF?
All LT3975IMSE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3975IMSE#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 LT3975IMSE#PBF part is unused and in its original packaging.
Return procedure for LT3975IMSE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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