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Analog Devices Inc. LT3975EMSE#PBF
- Part No.:
- LT3975EMSE#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 16-TFSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LT3975EMSE#PBF.pdf
- Description:
- IC REG BUCK ADJ 2.5A 16MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,053
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Product details
Overview
LT3975EMSE#PBF from Analog Devices (formerly Linear Technology) is a monolithic 42V, 2.5A synchronous step-down switching regulator with current-mode control, 2.7µA quiescent current, and adjustable 200kHz–2MHz switching frequency. It features low-ripple Burst Mode® operation (<15mVP-P), 500mV dropout voltage, and integrated 75mΩ NPN switch for automotive cold-crank and battery-powered industrial supplies.
For engineers reviewing the LT3975EMSE#PBF datasheet, LT3975EMSE#PBF pinout, LT3975EMSE#PBF application, or LT3975EMSE#PBF equivalent, key selection criteria include ultralow IQ at no load, programmable UVLO via EN pin (1.02V threshold), power good flag accuracy (±8.4% of VFB), soft-start control via SS pin, and thermal shutdown protection in the 16-lead MSOP package with exposed pad.
Technical Context
The LT3975EMSE#PBF employs an internally compensated current-mode topology with fixed-frequency PWM and automatic transition to low-ripple Burst Mode® below ~150mA load. Its oscillator supports RT-programmed frequencies from 200kHz to 2MHz, with synchronization capability (SYNC pin) and frequency foldback during startup or overload.
It integrates a saturating bipolar NPN main switch (75mΩ typical RCE(SAT)), internal boost Schottky diode, and bias regulator that auto-switches between VIN and OUT supply when VOUT > 3.2V. The dropout comparator enforces 500mV minimum (VIN – VOUT) with 25mV hysteresis, enabling stable regulation down to automotive cold-crank conditions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.3V to 42V - supports wide automotive and industrial input rails including cold-crank transients. |
| Max Output Current | 2.5A - sustained load capability with current limit foldback to constrain power dissipation during short circuit. |
| Quiescent Current | 2.7µA at no load - enables multi-year battery life in always-on IoT and telematics systems. |
| Switching Frequency | 200kHz to 2MHz (RT-programmable) - balances inductor size, efficiency, and EMI performance. |
| Feedback Reference | 1.197V ±1.2% - high-accuracy reference enables tight output regulation across temperature and line. |
| Dropout Voltage | 500mV (VIN – VOUT) - ensures regulation during low-input conditions without external LDO assist. |
| Power Good Threshold | 91.6% of regulated VOUT - open-drain PG flag signals valid output with ±8.4% tolerance relative to VFB. |
| Shutdown Current | 700nA - ultra-low leakage enables reliable system-level power gating. |
Pinout & Package
LT3975EMSE#PBF is housed in a thermally enhanced 16-lead plastic MSOP package with exposed GND pad (θJA = 40°C/W). The exposed pad (Pin 17) must be soldered to PCB for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| FB (1) | Feedback input | Regulated to 1.197V; connects to resistor divider tap for output voltage programming. |
| SS (2) | Soft-start control | Internal 1.8µA pull-up charges external capacitor to ramp peak current limit and limit inrush. |
| OUT (3) | Output sense / boost anode | Connects to output node ≤16V; supplies bias to internal regulator when VOUT > 3.2V. |
| BOOST (4) | Boost drive voltage | Provides >VIN voltage to fully saturate internal NPN switch; requires external capacitor to SW. |
| SW (5,6,7) | Switch node | Drives external inductor and catch diode; shared high-current path for power delivery. |
| NC (8,9) | No connect | Not bonded internally; must remain unconnected per datasheet. |
| VIN (10,11,12) | Main power input | Supplies internal circuitry and switch; requires local ceramic bypassing near pins. |
| EN (13) | Enable control | Hysteretic threshold (1.02V fall / 1.08V rise); accurate only when VIN ≥ 4.3V. |
| RT (14) | Frequency set | Resistor to GND programs switching frequency from 200kHz to 2MHz. |
| PG (15) | Power good flag | Open-drain output active low until VFB reaches 91.6% of target; valid when VIN > 2V. |
| SYNC (16) | External clock sync | Ground for Burst Mode; tie to external clock for pulse-skipping sync; do not float. |
| GND (17) | Ground reference | Exposed thermal pad; must be soldered to PCB ground plane for thermal and electrical performance. |
Key Features
| Feature | Design Value |
|---|---|
| Ultralow quiescent current | 2.7µA IQ enables >10-year battery life in always-on sensor nodes and telematics modules. |
| Low-ripple Burst Mode® | Maintains <15mVP-P output ripple while delivering single current pulses and sleeping between them. |
| Programmable undervoltage lockout | Accurate 1.02V EN threshold with 60mV hysteresis allows precise system-level brownout control. |
| Thermal derating with foldback | Current limit folds back under overload and thermal stress, limiting junction temperature rise. |
| Integrated boost Schottky | On-die diode eliminates external component count and reduces board area in compact designs. |
| Dropout performance | 500mV enforced dropout maintains regulation during automotive cold-crank (e.g., 4.5V start). |
Applications
| Automotive Battery Regulation | Portable Medical Devices |
|---|---|
|
Use Scenario: Powering infotainment head units and ADAS cameras from 12V battery with cold-crank immunity. IC Role / Device Role / Timing Role: Primary buck regulator providing stable 3.3V/5V rail during 4.5V–42V transients. Use Value: 500mV dropout and 2.7µA IQ ensure uninterrupted operation during engine cranking and extended parking modes. |
Use Scenario: Long-life portable glucose meters and wearable ECG monitors powered by coin cells. IC Role / Device Role / Timing Role: Main power converter delivering regulated 3.3V from single-cell Li-ion or alkaline. Use Value: 2.7µA no-load IQ extends battery service life beyond 5 years without compromising startup time. |
| Industrial Sensor Transmitters | Railway Signaling Modules |
|
Use Scenario: 4–20mA loop-powered pressure/temperature transmitters in hazardous zones. IC Role / Device Role / Timing Role: Efficient step-down regulator converting loop voltage to 3.3V for microcontroller and analog front-end. Use Value: Wide 4.3V–42V input range accommodates loop compliance drop while maintaining <15mV ripple for precision ADCs. |
Use Scenario: Onboard power for LED signal lamps and communication interfaces in rolling stock. IC Role / Device Role / Timing Role: Primary DC-DC converter accepting 24V–110V nominal rail with surge tolerance up to 150V. Use Value: 42V absolute max rating plus robust thermal shutdown protects against railway voltage spikes and overloads. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT8610EMSE#PBF | 42V input, 3.5A output, 2.5µA IQ, Silent Switcher® architecture; higher cost, lower EMI. | Better suited for noise-sensitive RF or audio subsystems where EMI must be minimized. | Select LT8610EMSE#PBF when radiated emissions compliance (CISPR 25 Class 5) is mandatory. |
| TPS54240DGQR | 40V input, 2.5A output, 110µA IQ, external MOSFETs; lower IQ spec but no Burst Mode®. | Requires external high-side/low-side FETs and compensation; less integrated, higher BOM count. | Choose TPS54240DGQR only if design requires adjustable current limit or external FET optimization. |
Compared with LT3975EMSE#PBF, LT8610EMSE#PBF delivers superior EMI performance at higher cost and complexity, while TPS54240DGQR trades integration and ultralow IQ for flexibility in FET selection and thermal management-neither offers direct pin compatibility or identical Burst Mode® behavior.
Availability
LT3975EMSE#PBF is available at Aetrix Electronics and suitable for automotive battery regulation, portable medical devices, industrial sensor transmitters, and railway signaling modules requiring stable component supply with long-term lifecycle assurance.
Supply support for LT3975EMSE#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, qualification, and manufacturing continuity for all LT® parts.
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 and robust transient performance.
FAQ
What is the guaranteed operating temperature range for LT3975EMSE#PBF?
The LT3975EMSE#PBF is specified for operation from –40°C to +125°C junction temperature. This E-grade variant is qualified across the full range with assured performance per datasheet Electrical Characteristics tables, including feedback voltage accuracy, current limit, and quiescent current. It is not rated for the extended H-grade (–40°C to +150°C) range.
Can LT3975EMSE#PBF operate with input voltage below 4.3V?
No-LT3975EMSE#PBF has a minimum input voltage of 4.3V under normal operation. Below this, the internal bias regulator cannot sustain control circuitry. If VIN drops below 3.9V, the part enters undervoltage lockout and shuts down. For sub-4.3V applications, consider a dedicated low-input buck such as the LT3692 or LTC3639.
How does the LT3975EMSE#PBF achieve 2.7µA quiescent current?
The LT3975EMSE#PBF achieves 2.7µA IQ through a combination of low-leakage internal circuitry, optimized bias paths, and intelligent Burst Mode® operation that powers down oscillator, error amplifier, and gate drivers between current pulses. This occurs only when SYNC is grounded; synchronizing externally raises IQ to ~11µA.
Is the LT3975EMSE#PBF pin-compatible with other LT3975 variants like LT3975IMSE#PBF?
Yes-LT3975EMSE#PBF shares identical pinout, package (16-lead MSOP), and electrical interface with LT3975IMSE#PBF and LT3975HMSE#PBF. The only difference is the guaranteed temperature grade: E-grade (–40°C to +125°C), I-grade (same range, tighter initial specs), and H-grade (–40°C to +150°C). No PCB changes are required for substitution within same grade requirements.
What is the purpose of the OUT pin on the LT3975EMSE#PBF?
The OUT pin on LT3975EMSE#PBF serves three functions: (1) it connects to the output node to enable dropout regulation (500mV min VIN–VOUT), (2) it supplies bias current to the internal regulator when VOUT > 3.2V (improving efficiency), and (3) it acts as the anode connection for the integrated boost Schottky diode. It must be connected to VOUT for proper dropout and bias operation.
LT3975EMSE#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
LT3975EMSE#PBF FAQ
1.How can I place an order for LT3975EMSE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3975EMSE#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 LT3975EMSE#PBF reliable?
The price and inventory of LT3975EMSE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3975EMSE#PBF is usually 5 days.
3.What payment methods are accepted for LT3975EMSE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3975EMSE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3975EMSE#PBF?
LT3975EMSE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3975EMSE#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 LT3975EMSE#PBF?
For technical support, including LT3975EMSE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3975EMSE#PBF requirements.
6.How does Aetrix verify that LT3975EMSE#PBF is sourced from the original manufacturer or authorized distributors?
All LT3975EMSE#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 LT3975EMSE#PBF meets industry standards.
7.What is the process for return or replacement of LT3975EMSE#PBF?
All LT3975EMSE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3975EMSE#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 LT3975EMSE#PBF part is unused and in its original packaging.
Return procedure for LT3975EMSE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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