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Analog Devices Inc. LT3975IMSE#TRPBF
- Part No.:
- LT3975IMSE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 16-TFSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LT3975IMSE#TRPBF.pdf
- Description:
- IC REG BUCK ADJ 2.5A 16MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,616
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Product details
Overview
LT3975IMSE#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 LT3975IMSE#TRPBF datasheet, LT3975IMSE#TRPBF pinout, LT3975IMSE#TRPBF application, or LT3975IMSE#TRPBF equivalent, key selection criteria include ultralow IQ at no load, programmable UVLO via EN pin, soft-start control via SS pin, thermal shutdown, and current-limit foldback for short-circuit robustness in 12V/24V automotive and portable power rails.
Technical Context
The LT3975IMSE#TRPBF uses an internally compensated current-mode topology with a 75mΩ saturating bipolar NPN switch and integrated boost Schottky diode. Its oscillator is RT-resistor-programmable (200kHz–2MHz) and synchronizable (250kHz–2MHz), enabling precise EMI control and multi-rail coordination.
It implements low-ripple Burst Mode® operation below ~150mA load, reducing no-load supply current to 2.7µA while maintaining output ripple <15mVP-P; during dropout, it enforces a 500mV minimum (VIN – VOUT) and extends duty cycle up to ~98% using boost capacitor charge recycling to sustain regulation down to 4.3V input.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.3V to 42V - supports automotive battery transients including cold-crank (down to 3V with dropout mode active) |
| Max Output Current | 2.5A - sustained continuous load capability with thermal derating above 125°C junction |
| 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 - set by RT resistor; allows optimization of inductor size vs. efficiency vs. EMI |
| Feedback Reference | 1.197V ±1.2% - high-accuracy internal reference enables ±1.5% output voltage tolerance with 1% resistors |
| Dropout Voltage | 500mV - enforced minimum (VIN – VOUT) ensures stable regulation and boost capacitor recharge during low-input conditions |
| Power Good Threshold | 91.6% of VOUT - open-drain PG flag asserts when output reaches regulation, valid above 2V VIN |
Pinout & Package
LT3975IMSE#TRPBF is housed in a thermally enhanced 16-lead 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 - determines output voltage with ±1.5% accuracy |
| SS (2) | Soft-start control | Internal 1.8µA pull-up charges external capacitor; controls inrush current and overrides foldback during startup |
| OUT (3) | Output sense / bias source | Connects to output node ≤16V; supplies internal bias when >3.2V, enabling higher efficiency in buck configurations |
| BOOST (4) | Switch driver boost supply | Drives internal NPN switch fully saturated; requires external capacitor charged above VIN for low VCE(SAT) |
| 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 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 / UVLO input | Hysteretic threshold (1.02V↓ / 1.08V↑); accurate only when VIN ≥4.3V - enables programmable undervoltage lockout |
| RT (14) | Frequency programming | Resistor to GND sets switching frequency from 200kHz to 2MHz - enables EMI tuning and layout optimization |
| PG (15) | Power good flag | Open-drain output; pulled low when FB <91.6% of target - used for system sequencing and fault monitoring |
| SYNC (16) | External clock sync | Accepts 250kHz–2MHz external clock; disables Burst Mode and enables pulse-skipping for synchronized multi-rail designs |
| GND (17) | Ground / thermal pad | Exposed pad is internal GND - mandatory PCB soldering required for thermal performance and noise immunity |
Key Features
| Feature | Design Value |
|---|---|
| Ultralow quiescent current | 2.7µA IQ enables >10-year battery life in always-on automotive and industrial monitoring nodes |
| Low-ripple Burst Mode® | Maintains <15mVP-P output ripple at light loads while sustaining 2.7µA IQ - critical for noise-sensitive analog/sensor rails |
| Programmable undervoltage lockout | Accurate 1.02V EN threshold with 60mV hysteresis allows custom battery cutoff without external comparators |
| Current limit foldback | Reduces switch current from 5.4A to 3.3A during overload - limits power dissipation and enables safe short-circuit survival |
| Thermal shutdown protection | Activates at ~165°C junction; latches off until cooldown - prevents permanent damage in enclosed or high-ambient environments |
| Soft-start override | SS pin voltage <2V disables current limit foldback during startup - avoids premature current limiting in high-capacitance outputs |
Applications
| Automotive Battery Regulation | Portable Medical Sensors |
|---|---|
Use Scenario: Powering infotainment, ADAS camera modules, and body control units from 12V vehicle battery with cold-crank (down to 3.5V) and load-dump (up to 42V) transients. IC Role / Device Role / Timing Role: Primary 3.3V/5V buck regulator delivering 2.5A with ultralow IQ to minimize parasitic drain during vehicle sleep mode. Use Value: 2.7µA quiescent current and 500mV dropout ensure reliable start-up after extended parking; Burst Mode maintains <15mV ripple for camera image sensors. | Use Scenario: Long-life wearable ECG and glucose monitors powered by coin-cell or Li-SOCl₂ batteries requiring multi-year operation without replacement. IC Role / Device Role / Timing Role: Main system power supply converting 3.6V battery to regulated 3.3V rail for ultra-low-power MCU and analog front-end. Use Value: 2.7µA IQ extends battery life beyond 10 years; soft-start prevents inrush-induced brownout during wake-up from deep sleep. |
| Industrial Process Transmitters | Smart Building Controllers |
Use Scenario: 4–20mA loop-powered field instruments (pressure, temperature, flow) operating from 24V DC supply with wide ambient temperature range (–40°C to +85°C). IC Role / Device Role / Timing Role: Isolated auxiliary supply generating 3.3V/5V for microcontroller, ADC, and wireless transceiver from limited loop power budget. Use Value: 4.3V min input and 2.5A output support full functionality under worst-case loop voltage drop; thermal shutdown protects against enclosure overheating. | Use Scenario: HVAC controllers and lighting gateways deployed in commercial buildings with 24V AC/DC power supplies subject to brownouts and surges. IC Role / Device Role / Timing Role: Robust primary DC-DC converter powering ARM Cortex-M7 MCU, Ethernet PHY, and Zigbee/BLE radios. Use Value: 42V absolute max rating and current foldback withstand 100V+ transients; PG flag enables graceful firmware reset on undervoltage events. |
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 | Higher 60V input rating; lower 1.5A output current; 3.5µA IQ; no PG flag; same MSOP-16 package | Better suited for 48V industrial PoE-powered devices; less ideal for 2.5A automotive loads | Select LTC3639EMSE#PBF only if 60V input margin is required and 1.5A output suffices - not a drop-in replacement |
| TPS54240DGQR | 42V input, 2.5A output, but 73µA IQ; no Burst Mode; no PG flag; 10-pin MSOP package | Higher IQ increases battery drain; lacks low-noise light-load operation needed for sensor rails | Choose TPS54240DGQR only for cost-sensitive non-battery applications where 73µA IQ is acceptable and PG signaling is unnecessary |
Compared with LTC3639EMSE#PBF and TPS54240DGQR, LT3975IMSE#TRPBF uniquely delivers 2.5A output with 2.7µA IQ and integrated PG flag in a 16-pin MSOP - making it optimal for automotive and long-life battery systems requiring both high current and ultralow standby consumption.
Availability
LT3975IMSE#TRPBF is available at Aetrix Electronics and suitable for automotive battery regulation, portable medical sensors, industrial process transmitters, and smart building controllers requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LT3975IMSE#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, Inc. (ADI) is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, formed through the acquisition of Linear Technology in 2017.
The LT3975 belongs to ADI's high-voltage monolithic buck regulator product line, engineered specifically for automotive, industrial, and battery-powered applications demanding ultralow quiescent current, wide input range, and robust fault protection.
FAQ
What is the guaranteed operating junction temperature range for LT3975IMSE#TRPBF?
The LT3975IMSE#TRPBF is guaranteed over the full –40°C to +125°C junction temperature range. This I-grade rating makes it suitable for under-hood automotive and industrial environments where ambient temperatures exceed 85°C. The device includes thermal shutdown that activates at approximately 165°C to prevent permanent damage, and its 16-lead MSOP package with exposed pad provides θJA = 40°C/W for effective heat dissipation when properly soldered to PCB copper.
How does LT3975IMSE#TRPBF achieve 2.7µA quiescent current, and what conditions must be met?
The LT3975IMSE#TRPBF achieves 2.7µA quiescent current in low-ripple Burst Mode® operation with SYNC pin grounded, no load, and VIN ≥4.3V. This requires disabling synchronization (SYNC = GND), using large-value feedback resistors (>1MΩ), and selecting a low-leakage Schottky catch diode (<1µA reverse current). Under these conditions, the IC enters deep sleep between current pulses, minimizing input current while maintaining regulation and <15mVP-P ripple. If SYNC is driven externally, IQ rises to ~11µA.
Can LT3975IMSE#TRPBF operate with input voltage below 4.3V, and how does dropout mode function?
Yes - the LT3975IMSE#TRPBF can regulate down to ~3.5V input in dropout mode, though its specified minimum operating voltage is 4.3V. When VIN drops below VOUT + 500mV, the device enforces a minimum (VIN – VOUT) of 500mV by extending duty cycle up to ~98%, skipping switch-off periods to maintain boost capacitor charge. This preserves regulation during automotive cold-crank events, with VOUT tracking VIN – 500mV until VIN recovers above the normal operating range.
What is the purpose of the OUT pin on LT3975IMSE#TRPBF, and how should it be connected?
The OUT pin on LT3975IMSE#TRPBF serves two functions: (1) it connects to the anode of the internal boost Schottky diode, and (2) it supplies bias current to the internal regulator when voltage exceeds 3.2V. For standard buck operation with VOUT ≤16V, OUT must be connected directly to the output node. This connection enables efficient bias sourcing from the regulated output - improving overall efficiency - and ensures proper dropout comparator operation. Leaving OUT unconnected or connecting it to a different node invalidates regulation and may cause failure.
Does LT3975IMSE#TRPBF require an external catch diode, and why?
Yes - the LT3975IMSE#TRPBF requires an external Schottky catch diode connected from SW to VOUT. Although it integrates a boost Schottky diode (between BOOST and SW), it does not integrate the main power path catch diode. The external diode provides the return path for inductor current during switch-off periods. A low-forward-voltage, low-leakage Schottky (e.g., PDS560) is mandatory to preserve ultralow IQ performance - reverse leakage >1µA directly increases apparent load current and degrades no-load efficiency. Diode selection directly impacts achievable quiescent current and thermal performance.
LT3975IMSE#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
LT3975IMSE#TRPBF FAQ
1.How can I place an order for LT3975IMSE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3975IMSE#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 LT3975IMSE#TRPBF reliable?
The price and inventory of LT3975IMSE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3975IMSE#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3975IMSE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3975IMSE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3975IMSE#TRPBF?
LT3975IMSE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3975IMSE#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 LT3975IMSE#TRPBF?
For technical support, including LT3975IMSE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3975IMSE#TRPBF requirements.
6.How does Aetrix verify that LT3975IMSE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3975IMSE#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 LT3975IMSE#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3975IMSE#TRPBF?
All LT3975IMSE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3975IMSE#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 LT3975IMSE#TRPBF part is unused and in its original packaging.
Return procedure for LT3975IMSE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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