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Analog Devices Inc. LT3975EMSE#TRPBF
- Part No.:
- LT3975EMSE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 16-TFSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LT3975EMSE#TRPBF.pdf
- Description:
- IC REG BUCK ADJ 2.5A 16MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,150
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Product details
Overview
LT3975EMSE#TRPBF 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 power good flag - designed for automotive cold-crank and battery-powered industrial systems.
For engineers reviewing the LT3975EMSE#TRPBF datasheet, LT3975EMSE#TRPBF pinout, LT3975EMSE#TRPBF application, or LT3975EMSE#TRPBF equivalent, key selection criteria include ultralow IQ at no load, programmable UVLO via EN pin (1.02V threshold), soft-start control via SS pin, thermal shutdown protection, and compatibility with external synchronization (250kHz–2MHz range).
Technical Context
The LT3975EMSE#TRPBF employs an internally compensated current-mode architecture with fast transient response and stable loop behavior across wide input/output conditions. Its bipolar NPN power switch (75mΩ RCE(SAT)) is driven by a bootstrap circuit requiring external BOOST capacitor, enabling full saturation down to 500mV dropout.
Burst Mode® operation reduces no-load supply current to 2.7µA while maintaining output ripple below 15mVP-P; frequency foldback during startup or overload limits inrush and improves reliability. The device integrates soft-start override during current limit foldback, accurate 1.197V feedback reference, and open-drain PG flag signaling VOUT ≥ 91.6% of regulation target.
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 - sustained DC load capability with current-limit foldback during short-circuit to constrain thermal dissipation. |
| Quiescent Current | 2.7µA at no load - enables >10-year battery life in always-on IoT sensors and telematics modules. |
| Switching Frequency | 200kHz to 2MHz - adjustable via RT resistor; synchronizable externally from 250kHz to 2MHz for EMI reduction. |
| Feedback Reference | 1.197V ±1.2% - high-accuracy internal reference enabling ±1.5% output voltage tolerance with 1% resistors. |
| Dropout Voltage | 500mV - enforced minimum (VIN – VOUT) ensures boost capacitor remains charged and switch stays saturated during low-VIN operation. |
| Power Good Threshold | VOUT ≥ 91.6% of regulation - open-drain PG flag asserts high only after stable regulation is confirmed, not during soft-start. |
Pinout & Package
LT3975EMSE#TRPBF 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 | Regulates output by holding voltage at 1.197V; connects to resistor divider tap; requires 10pF phase-lead capacitor to VOUT for stability. |
| SS (2) | Soft-start control | Internal 1.8µA current source ramps peak switch current at startup; actively discharged during shutdown or UVLO. |
| OUT (3) | Output sense / bias path | Connects to regulated output (≤16V); supplies bias current to internal regulator when VOUT > 3.2V, improving efficiency. |
| BOOST (4) | Bootstrap drive | Drives internal NPN switch base above VIN; requires external capacitor between BOOST and SW pins. |
| SW (5,6,7) | Switch node | High-current output of internal bipolar switch; connects to inductor, catch diode cathode, and BOOST capacitor. |
| NC (8,9) | No connect | Not bonded internally; must remain unconnected on PCB. |
| VIN (10,11,12) | Main power input | Supplies internal circuitry and switch driver; requires local ceramic bypass (≥1µF) close to pins. |
| EN (13) | Enable / UVLO input | Hysteretic threshold (1.02V fall, 1.08V rise); accurate only when VIN ≥ 4.3V; ties directly to microcontroller GPIO. |
| RT (14) | Frequency programming | Resistor to GND sets switching frequency from 200kHz to 2MHz per datasheet Table 1. |
| PG (15) | Power good flag | Open-drain output; pulled low during startup, fault, or shutdown; valid only when VIN > 2V. |
| SYNC (16) | External clock input | Ground for Burst Mode; tie to external clock (250kHz–2MHz) for synchronized pulse-skipping; never float. |
| GND (17) | Ground reference | Exposed thermal pad; electrically and thermally connected to all internal GND nodes; must be soldered to PCB plane. |
Key Features
| Feature | Design Value |
|---|---|
| Ultralow quiescent current | 2.7µA IQ enables multi-year operation from coin cells or supercaps in always-on monitoring systems. |
| Low-ripple Burst Mode® | Maintains <15mVP-P output ripple at light loads while reducing IQ vs. standard pulse-skipping architectures. |
| Programmable undervoltage lockout | Accurate 1.02V EN threshold allows custom battery cutoff (e.g., 10.5V for 12V lead-acid) without external comparators. |
| Thermal-enhanced MSOP-16EP | Exposed pad and low θJA (40°C/W) support 2.5A continuous output without heatsink in compact layouts. |
| Integrated boost Schottky diode | On-die diode eliminates external component count and leakage path, reducing BOM cost and board area. |
| Current limit foldback with override | Foldback throttles switch current during overload; overridden during soft-start to prevent startup failure under heavy load. |
Applications
| Automotive Battery Regulation | Portable Medical Sensors |
|---|---|
Use Scenario: Powering infotainment head units and ADAS cameras during engine cranking (VIN dips to 4.3V). IC Role / Device Role / Timing Role: Primary buck regulator delivering stable 3.3V/5V from 6–16V nominal battery rail with cold-crank dropout recovery. Use Value: 500mV enforced dropout and 2.7µA IQ ensure uninterrupted operation and extended battery reserve during repeated start-stop cycles. |
Use Scenario: Long-life wearable ECG monitors powered by CR2032 coin cell. IC Role / Device Role / Timing Role: Efficient step-down converter generating 3.3V for ultra-low-power MCU and analog front-end. Use Value: 2.7µA no-load IQ and Burst Mode® extend battery life beyond 5 years while maintaining <15mV ripple for clean ADC reference. |
| Industrial IoT Edge Nodes | Railway Signaling Modules |
Use Scenario: Remote vibration sensor nodes deployed in oil/gas pipelines with 24VDC field bus supply. IC Role / Device Role / Timing Role: Primary 5V regulator supporting LoRaWAN radio, MEMS accelerometer, and flash memory. Use Value: 42V absolute max rating and robust UVLO enable reliable operation despite 40V transients on long cable runs. |
Use Scenario: Onboard power for LED signal lamps and CAN transceivers in rolling stock with 72–110VDC nominal supply. IC Role / Device Role / Timing Role: Pre-regulator stepping 72V down to 12V for downstream isolated DC/DC converters. Use Value: Wide 4.3–42V input range and thermal shutdown protect against overvoltage faults in harsh rail environments. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3631EMSE#PBF | Lower max input (36V), lower IQ (1.2µA), fixed 3.3V/5V outputs, no SYNC pin | Better for space-constrained, fixed-output, ultra-low-IQ designs where programmability is unnecessary | Select LTC3631EMSE#PBF if fixed output and sub-2µA IQ outweigh need for 42V rating and frequency sync. |
| MPQ4470AGL-Z | 40V max input, 3.5A output, 25µA IQ, integrated MOSFETs, no PG or SS pin | Suitable for higher-current, cost-sensitive industrial supplies where PG flag and soft-start are optional | Select MPQ4470AGL-Z if higher output current and integrated FETs justify 10× higher IQ and loss of PG/SS functionality. |
Compared with LTC3631EMSE#PBF and MPQ4470AGL-Z, LT3975EMSE#TRPBF uniquely balances 42V operation, 2.5A capability, 2.7µA IQ, and full feature set (PG, SS, SYNC, programmable UVLO) in a single MSOP-16EP package - making it optimal for automotive and ruggedized portable designs demanding both performance and reliability.
Availability
LT3975EMSE#TRPBF is available at Aetrix Electronics and suitable for automotive battery regulation, portable medical sensors, industrial IoT edge nodes, and railway signaling modules requiring stable component supply across extended temperature ranges (–40°C to +125°C).
Supply support for LT3975EMSE#TRPBF 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 LT® family of high-performance power management ICs.
The LT3975 belongs to Linear's ultralow-IQ buck regulator product line, engineered specifically for automotive, battery-powered, and industrial applications where extended runtime, cold-crank resilience, and EMI-controlled switching are critical design requirements.
FAQ
What is the absolute maximum input voltage rating for LT3975EMSE#TRPBF?
The LT3975EMSE#TRPBF has an absolute maximum VIN rating of 42V. Exceeding this voltage risks permanent damage. While the device can tolerate brief transients up to 42V, normal operation above ~36V may require derating due to thermal constraints and reduced duty cycle margin. Always verify operating conditions against the Absolute Maximum Ratings table in the official datasheet.
Does LT3975EMSE#TRPBF support true synchronous rectification?
No, LT3975EMSE#TRPBF does not use synchronous rectification. It integrates a bipolar NPN main switch and an on-die Schottky catch diode. The BOOST pin drives the NPN base for saturation, but there is no second actively controlled MOSFET for the low-side path. This architecture enables robust 500mV dropout but trades off some efficiency versus fully synchronous buck regulators.
How is soft-start configured on LT3975EMSE#TRPBF?
Soft-start on LT3975EMSE#TRPBF is implemented by connecting a capacitor between SS (Pin 2) and GND. An internal 1.8µA current source charges this capacitor, ramping the peak switch current limit linearly. Typical values range from 1nF to 100nF, yielding soft-start times from ~0.5ms to 50ms. Leaving SS floating disables soft-start; pulling SS low forces immediate shutdown.
Can LT3975EMSE#TRPBF operate with input voltage below 4.3V?
No - the LT3975EMSE#TRPBF requires a minimum input voltage of 4.3V to regulate. Below this, the internal bias regulator cannot sustain operation, and the device enters undervoltage lockout. During automotive cold-crank events where VIN dips below 4.3V, the part ceases switching and holds output via output capacitance until VIN recovers above threshold.
What is the purpose of the OUT pin on LT3975EMSE#TRPBF?
The OUT pin on LT3975EMSE#TRPBF serves three roles: (1) input to the dropout comparator (enforcing 500mV min VIN–VOUT), (2) anode connection for the internal boost Schottky diode, and (3) auxiliary bias supply path - when VOUT > 3.2V, the internal regulator draws power from OUT instead of VIN, improving conversion efficiency by ~0.5% at full load.
LT3975EMSE#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-TFSOP (0.118", 3.00mm Width) Exposed Pad
- Packaging:
- Tape & Reel (TR)
- 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#TRPBF FAQ
1.How can I place an order for LT3975EMSE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3975EMSE#TRPBF 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#TRPBF reliable?
The price and inventory of LT3975EMSE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3975EMSE#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3975EMSE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3975EMSE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3975EMSE#TRPBF?
LT3975EMSE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3975EMSE#TRPBF 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#TRPBF?
For technical support, including LT3975EMSE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3975EMSE#TRPBF requirements.
6.How does Aetrix verify that LT3975EMSE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3975EMSE#TRPBF 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#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3975EMSE#TRPBF?
All LT3975EMSE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3975EMSE#TRPBF, 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#TRPBF part is unused and in its original packaging.
Return procedure for LT3975EMSE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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