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Analog Devices Inc. LT3975HMSE#PBF
- Part No.:
- LT3975HMSE#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 16-TFSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LT3975HMSE#PBF.pdf
- Description:
- IC REG BUCK ADJ 2.5A 16MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:118
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Product details
Overview
LT3975HMSE#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, adjustable 200kHz–2MHz switching frequency, and 500mV dropout voltage. It delivers regulated 3.3V/5V outputs for automotive cold-crank and industrial power rails.
For engineers reviewing the LT3975HMSE#PBF datasheet, LT3975HMSE#PBF pinout, LT3975HMSE#PBF application, or LT3975HMSE#PBF equivalent, key selection criteria include ultralow IQ operation, Burst Mode ripple performance (<15mVP-P), thermal grade (–40°C to 150°C), soft-start control via SS pin, and programmable UVLO using EN pin threshold (1.02V).
Technical Context
The LT3975HMSE#PBF employs an internally compensated current-mode topology with fast transient response and stable loop behavior across input voltages from 4.3V to 42V. Its 75mΩ integrated bipolar NPN switch and on-die boost Schottky diode enable high efficiency and low dropout operation.
It features dual-mode regulation: standard PWM above ~150mA load and low-ripple Burst Mode below that threshold-maintaining 2.7µA no-load supply current while holding output ripple under 15mVP-P in typical configurations. Frequency foldback and current limit foldback protect during startup and overload.
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. |
| Max Output Current | 2.5A - sustained delivery with thermal derating above 125°C junction temperature. |
| No-Load Quiescent Current | 2.7µA - enables >10-year battery life in always-on IoT sensors and telematics modules. |
| Switching Frequency Range | 200kHz to 2MHz - adjustable via RT resistor; enables compact magnetics at high fSW. |
| Dropout Voltage | 500mV - maintains regulation when VIN drops within 500mV of VOUT (e.g., 8.3V→7.8V). |
| Feedback Reference Voltage | 1.197V ±1.2% - sets output accuracy; used with external resistor divider for adjustable VOUT. |
| Junction Temperature Range | –40°C to 150°C - H-grade qualification for under-hood automotive and industrial edge computing. |
| Power Good Threshold | 91.6% of VOUT - open-drain PG flag asserts high when FB reaches 0.916 × VREF. |
Pinout & Package
LT3975HMSE#PBF is housed in a thermally enhanced 16-lead MSOP package with exposed GND pad (Pin 17), θJA = 40°C/W. The exposed pad 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 setting. |
| SS (2) | Soft-start control | Internal 1.8µA pull-up charges external capacitor to ramp peak current limit at startup. |
| OUT (3) | Output sense / bias source | Connects to output node; supplies internal regulator when VOUT > 3.2V; enables dropout comparator. |
| BOOST (4) | Switch driver boost rail | Drives internal NPN switch above VIN; requires external capacitor tied to SW. |
| SW (5,6,7) | Switch node | High-current output of internal power switch; connects to inductor, catch diode, and BOOST cap. |
| 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 bypassing (≥1µF). |
| EN (13) | Enable / UVLO input | Hysteretic threshold: 1.02V (falling), 1.08V (rising); accurate only when VIN ≥ 4.3V. |
| RT (14) | Frequency programming | Resistor to GND sets switching frequency from 200kHz to 2MHz (e.g., 78.7kΩ → 600kHz). |
| PG (15) | Power good flag | Open-drain output; pulled low until FB reaches 91.6% of target; valid when VIN > 2V. |
| SYNC (16) | External clock sync | Ground for Burst Mode; drive with external clock (250kHz–2MHz) for synchronized pulse-skipping. |
| GND (17) | Ground reference | Exposed thermal pad; must be soldered to PCB plane for thermal management and noise reduction. |
Key Features
| Feature | Design Value |
|---|---|
| Ultralow quiescent current | 2.7µA IQ at no load enables multi-year battery operation in always-on monitoring systems. |
| Low-ripple Burst Mode | Maintains <15mVP-P output ripple while achieving 2.7µA supply current-critical for noise-sensitive analog/RF subsystems. |
| Thermal grade H | Guaranteed operation from –40°C to 150°C junction temperature-qualified for engine bay and industrial control environments. |
| Programmable undervoltage lockout | Accurate 1.02V EN threshold with 60mV hysteresis allows precise system-level brownout protection. |
| Current limit foldback | Reduces switch current limit from 5.4A to 3.3A during short-circuit-limits power dissipation without thermal shutdown. |
| Soft-start override | SS pin voltage < 2V disables foldback during startup-ensures reliable inrush control without current limiting interference. |
Applications
| Automotive Battery Regulation | Portable Medical Sensors |
|---|---|
Use Scenario: Powering infotainment head units and ADAS cameras from 12V vehicle battery with cold-crank dips to 4.3V. IC Role / Device Role / Timing Role: Primary buck regulator delivering stable 5V/3.3V rails during wide VIN transients. Use Value: 500mV dropout ensures uninterrupted operation during cranking; 2.7µA IQ extends battery backup runtime. |
Use Scenario: Long-life wearable ECG monitors powered by coin cells or small Li-ion batteries. IC Role / Device Role / Timing Role: Main power converter enabling multi-year operation via ultralow IQ and efficient light-load regulation. Use Value: Burst Mode maintains <15mV ripple while drawing only 2.7µA-preserves signal integrity and battery capacity. |
| Industrial PLC I/O Modules | Smart Meter Data Acquisition |
Use Scenario: Providing isolated 3.3V logic supply in DIN-rail mounted controllers exposed to 85°C ambient temperatures. IC Role / Device Role / Timing Role: High-reliability DC-DC stage operating continuously at elevated junction temperatures. Use Value: H-grade (–40°C to 150°C) and thermal shutdown ensure robustness; 2.5A capability supports multiple digital loads. |
Use Scenario: Powering metrology ADCs and RF sub-GHz transceivers in utility meters requiring low-noise, long-life power. IC Role / Device Role / Timing Role: Low-ripple, low-IQ buck regulator feeding precision analog and wireless communication circuits. Use Value: 1.197V reference and <15mV ripple minimize measurement error; PG flag enables firmware health monitoring. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3639EMSE#PBF | 40V input, 1.5A output, 3.5µA IQ, fixed 3.3V/5V options only; no SYNC or PG pins. | Suitable for space-constrained designs where fixed output and lower current suffice; lacks programmability and status signaling. | Select when simplicity and minimal BOM count outweigh need for adjustable VOUT, PG flag, or synchronization. |
| MPQ4420AGL-AEC1-P | 40V input, 2A output, 17µA IQ, AEC-Q100 Grade 1 (–40°C to 125°C); no Burst Mode, higher IQ. | Automotive-qualified but limited to 125°C junction; lacks ultralow IQ and low-ripple light-load operation. | Select for AEC-Q100 compliance in cabin applications where 150°C operation and <3µA IQ are not required. |
Compared with LTC3639EMSE#PBF and MPQ4420AGL-AEC1-P, the LT3975HMSE#PBF uniquely combines H-grade thermal rating, 2.7µA IQ, programmable frequency/sync, and PG flag-making it optimal for high-reliability automotive under-hood and industrial edge nodes demanding both longevity and diagnostics.
Availability
LT3975HMSE#PBF is available at Aetrix Electronics and suitable for automotive battery regulation, portable medical sensors, industrial PLC I/O modules, and smart meter data acquisition requiring stable component supply across extended temperature and long-lifecycle programs.
Supply support for LT3975HMSE#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 LT® parts.
The LT3975 belongs to Linear's high-voltage monolithic buck regulator family, designed specifically for automotive, industrial, and battery-powered systems requiring ultralow quiescent current, wide input range, and robust thermal performance.
FAQ
What is the guaranteed operating junction temperature range for LT3975HMSE#PBF?
The LT3975HMSE#PBF is guaranteed over the full –40°C to 150°C junction temperature range. This H-grade qualification distinguishes it from the E- and I-grade variants (–40°C to 125°C) and enables deployment in under-hood automotive and high-ambient industrial environments where sustained 150°C operation is required. Derating curves in the datasheet define maximum load vs. ambient temperature.
How does LT3975HMSE#PBF achieve 2.7µA quiescent current while maintaining low output ripple?
The LT3975HMSE#PBF achieves 2.7µA quiescent current through low-ripple Burst Mode operation: it delivers discrete current pulses to the output capacitor, then enters deep sleep (consuming only 1.7µA), minimizing average supply current. Ripple remains <15mVP-P because pulse magnitude and timing are optimized-verified in typical 3.3V/5V applications with 47µF output capacitance and low-leakage Schottky diodes.
Can LT3975HMSE#PBF be synchronized to an external clock, and what is the supported frequency range?
Yes, LT3975HMSE#PBF supports external clock synchronization via the SYNC pin across 250kHz to 2MHz. When driven by an external clock, it operates in pulse-skipping mode at light loads (quiescent current rises to ~11µA), preserving timing determinism for noise-sensitive systems. Grounding SYNC enables native low-ripple Burst Mode with 2.7µA IQ. Floating SYNC is prohibited.
What is the function of the OUT pin on LT3975HMSE#PBF, and how must it be connected?
The OUT pin on LT3975HMSE#PBF serves three roles: (1) input to the dropout comparator (enabling 500mV minimum dropout), (2) anode connection for the internal boost Schottky diode, and (3) bias supply path for the internal regulator when VOUT > 3.2V. It must be connected directly to the output node for all applications where VOUT ≤ 16V-ensuring proper dropout behavior and efficiency optimization.
Does LT3975HMSE#PBF include thermal protection, and how does it interact with current limit foldback?
Yes, LT3975HMSE#PBF includes thermal shutdown protection that activates above 165°C junction temperature. It operates independently of current limit foldback: foldback reduces switch current limit from 5.4A to 3.3A during overload to limit power dissipation *before* thermal shutdown triggers. During startup, SS pin voltage < 2V overrides foldback to ensure reliable inrush-preventing premature current limiting.
LT3975HMSE#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 ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-MSOP-EP
LT3975HMSE#PBF FAQ
1.How can I place an order for LT3975HMSE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3975HMSE#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 LT3975HMSE#PBF reliable?
The price and inventory of LT3975HMSE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3975HMSE#PBF is usually 5 days.
3.What payment methods are accepted for LT3975HMSE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3975HMSE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3975HMSE#PBF?
LT3975HMSE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3975HMSE#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 LT3975HMSE#PBF?
For technical support, including LT3975HMSE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3975HMSE#PBF requirements.
6.How does Aetrix verify that LT3975HMSE#PBF is sourced from the original manufacturer or authorized distributors?
All LT3975HMSE#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 LT3975HMSE#PBF meets industry standards.
7.What is the process for return or replacement of LT3975HMSE#PBF?
All LT3975HMSE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3975HMSE#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 LT3975HMSE#PBF part is unused and in its original packaging.
Return procedure for LT3975HMSE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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