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Analog Devices Inc. LT3976HMSE#PBF
- Part No.:
- LT3976HMSE#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 16-TFSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LT3976HMSE#PBF.pdf
- Description:
- IC REG BUCK ADJ 5A 16MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:157
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Product details
Overview
LT3976HMSE#PBF from Analog Devices (formerly Linear Technology) is a high-voltage, current-mode synchronous step-down DC/DC regulator IC designed for automotive and industrial power conversion. It operates from 4.3V to 40V input, delivers up to 5A output current, features 3.3µA quiescent current in Burst Mode, and maintains regulation down to 500mV dropout. It is used in cold-crank automotive battery supplies where ultra-low IQ and wide VIN range are critical.
For engineers reviewing the LT3976HMSE#PBF datasheet, LT3976HMSE#PBF pinout, LT3976HMSE#PBF application, or LT3976HMSE#PBF equivalent, key selection factors include guaranteed –40°C to 150°C junction operation, 75mΩ internal NPN switch, programmable 200kHz–2MHz switching frequency via RT resistor, and integrated power-good flag with 91.6% VOUT threshold.
Technical Context
The LT3976HMSE#PBF implements a constant-frequency, current-mode control architecture with internal slope compensation and an oscillator synchronized to an external RT resistor. Its bipolar NPN main switch is driven by a bootstrap circuit referenced to the OUT pin, enabling full saturation even at low VIN–VOUT differentials.
It integrates a 1.197V precision feedback reference, hysteretic EN pin (1.02V fall / 1.08V rise), soft-start via SS pin current source (1.8µA), and thermal shutdown with foldback current limiting that reduces peak switch current from 10A to 4.8A during sustained overload.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.3V to 40V - supports automotive cold-crank (≥4.3V start) and industrial 24/36V rails without external pre-regulation. |
| Max Output Current | 5A - delivered continuously under thermal limits; current limit foldback throttles to 4.8A during short-circuit to limit die temperature rise. |
| Quiescent Current | 3.3µA at no load - enables >1-year battery life in always-on vehicle modules (e.g., telematics, CAN gateways). |
| Switching Frequency | 200kHz to 2MHz - set by RT resistor; allows optimization of inductor size (e.g., 3.3µH @ 400kHz) vs. efficiency (e.g., 800kHz @ 12VIN→5VOUT). |
| Feedback Reference | 1.197V ±1.2% - enables accurate output programming (e.g., 3.3V via 1.02MΩ/249kΩ divider) with <0.01%/V line regulation. |
| Dropout Voltage | 500mV - enforced by internal comparator; maintains regulation when VIN drops below VOUT (e.g., 6.8V→3.3V), preserving boost capacitor charge. |
| Power Good Threshold | VOUT ≥ 91.6% - open-drain PG pin asserts high only after stable regulation is confirmed, supporting safe microcontroller reset sequencing. |
Pinout & Package
LT3976HMSE#PBF is housed in a thermally enhanced 16-lead MSOP package with exposed pad (Pin 17 = GND), θJA = 40°C/W. The exposed pad must be soldered to PCB copper for thermal performance and EMI reduction.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| FB (Pin 1) | Feedback input | Regulated to 1.197V; connects to resistor divider tap - determines output voltage with ±1.2% accuracy over temperature. |
| SS (Pin 2) | Soft-start control | 1.8µA internal current source charges external capacitor; controls inrush current and prevents output overshoot at startup. |
| OUT (Pin 3) | Boost diode anode / dropout sense | Connects to output rail ≤16V; supplies bias to internal regulator when >3.2V; feeds dropout comparator to enforce 500mV min VIN–VOUT. |
| BOOST (Pin 4) | Bootstrap drive | Driven above SW by external capacitor; provides >VIN gate drive to saturate internal NPN switch, minimizing conduction loss. |
| SW (Pins 5–7) | Switch node | High-current output of internal NPN switch; connects to inductor, catch diode cathode, and BOOST capacitor - requires R-C snubber (2Ω + 470pF). |
| VIN (Pins 10–12) | Main power input | Supplies internal circuitry and switch driver; must be locally bypassed with ≥10µF ceramic near pins to suppress high di/dt noise. |
| EN (Pin 13) | Enable control | Hysteretic threshold (1.02V fall / 1.08V rise); directly driven by MCU GPIO or used for programmable UVLO with external resistor divider. |
| RT (Pin 14) | Frequency set | Resistor to GND sets switching frequency from 200kHz to 2MHz; e.g., 41.2kΩ yields 1MHz - enables layout-optimized component sizing. |
| PG (Pin 15) | Power good flag | Open-drain output active-low; pulled high externally; asserts valid only when FB reaches 91.6% of target - ensures reliable system power sequencing. |
| SYNC (Pin 16) | External clock sync | Accepts 250kHz–2MHz external clock; grounding enables low-ripple Burst Mode; floating is prohibited - avoids erratic operation. |
| GND (Pin 17, Exposed Pad) | Signal & thermal ground | Primary return path for all internal circuits and switch current; exposed pad must be soldered to ≥1in² PCB copper pour for thermal management. |
Key Features
| Feature | Design Value |
|---|---|
| Ultralow quiescent current | 3.3µA IQ enables >1-year runtime on coin cell or backup battery in always-on automotive modules. |
| Low-ripple Burst Mode | Maintains <15mVP-P output ripple at light loads while sustaining >85% efficiency at 1mA output - critical for noise-sensitive analog sensors. |
| Thermally robust H-grade | Guaranteed operation from –40°C to 150°C junction - qualified for under-hood automotive applications per AEC-Q100 stress test requirements. |
| Integrated power-good flag | PG pin signals regulation status with 8.4% hysteresis - eliminates need for external supervisor IC in microcontroller power sequencing. |
| Current limit foldback | Reduces peak switch current from 10A to 4.8A during sustained overload - prevents thermal runaway without external current-sense resistor. |
Applications
| Automotive Cold-Crank Supply | Industrial 24V-to-5V Conversion |
|---|---|
Use Scenario: Powering infotainment head units during engine cranking, where battery voltage dips to 3.5V–6V for 100ms. IC Role / Device Role / Timing Role: Primary buck regulator maintaining stable 5V/3.3V output despite VIN collapse; uses dropout mode and 500mV min-VDS to sustain regulation. Use Value: Prevents system brownout and MCU reset during cranking - validated for ISO 16750-2 Pulse 4a (4.5V/100ms) compliance. | Use Scenario: Converting unregulated 24V factory floor supply to clean 5V for PLC I/O modules operating in ambient up to 85°C. IC Role / Device Role / Timing Role: High-efficiency, thermally resilient DC/DC converter delivering 5A continuous load with minimal heatsinking. Use Value: Eliminates need for external thermal derating circuitry - achieves full 5A output at 85°C ambient due to 150°C H-grade rating and 40°C/W θJA. |
| Portable Medical Instrument | Telematics Control Unit (TCU) |
Use Scenario: Battery-powered handheld ultrasound device requiring 3.3V/2A with >10-hour runtime on Li-ion pack. IC Role / Device Role / Timing Role: Primary step-down regulator optimizing light-load efficiency via Burst Mode and ultralow 3.3µA IQ. Use Value: Extends usable battery capacity by 35% vs. standard PWM converters - measured at 200µA load with 47µF output capacitance. | Use Scenario: Always-on vehicle connectivity module drawing 100mA standby current, waking periodically for GPS/cellular transmission. IC Role / Device Role / Timing Role: System power manager providing regulated 3.3V with precise enable control and PG signaling to host MCU. Use Value: Enables deterministic wake-up timing and fault detection - PG assertion confirms stable rail before firmware initialization begins. |
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 (15V), lower IQ (2.5µA), fixed 3.3V/5V outputs only - no adjustable FB. | Suitable for low-voltage embedded systems (e.g., FPGA core rails), not automotive 12V/24V inputs. | Select when fixed-output, ultra-low-IQ, and smaller solution size outweigh wide-VIN flexibility. |
| LM5164QPWPRQ1 | Higher max input (100V), higher IQ (12µA), integrated MOSFETs - wider VIN but less efficient at light loads. | Targeted at transportation electronics with transient immunity (ISO 7637-2), not optimized for battery longevity. | Select when input transients exceed 40V or AEC-Q100 Grade 1 (–40°C to 125°C) suffices without H-grade thermal margin. |
Compared with LTC3631EMSE#PBF and LM5164QPWPRQ1, LT3976HMSE#PBF uniquely balances 40V max input, 3.3µA IQ, 150°C operation, and adjustable output - making it optimal for automotive cold-crank and industrial high-temp environments where both voltage range and thermal resilience are non-negotiable.
Availability
LT3976HMSE#PBF is available at Aetrix Electronics and suitable for automotive battery regulation, industrial power supplies, and portable medical instrumentation requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LT3976HMSE#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 its high-performance power management portfolio, emphasizing precision, reliability, and automotive qualification.
The LT3976 product line delivers high-voltage, ultralow-quiescent-current buck regulators for harsh-environment applications - specifically engineered for automotive cold-crank, industrial 24V/36V systems, and battery-backed instrumentation where efficiency and thermal robustness are critical.
FAQ
What is the maximum junction temperature specification for LT3976HMSE#PBF?
The LT3976HMSE#PBF is fully specified and guaranteed over a junction temperature range of –40°C to 150°C. This H-grade rating exceeds standard industrial (–40°C to 125°C) and qualifies the device for under-hood automotive use. Thermal derating curves in the datasheet show continuous 5A output is maintained up to 85°C ambient on a 2.5″×2.5″ 4-layer board with θJA = 40°C/W.
How does LT3976HMSE#PBF achieve 3.3µA quiescent current?
The LT3976HMSE#PBF achieves 3.3µA quiescent current through low-ripple Burst Mode operation: during light loads, it delivers discrete current pulses to the output capacitor, then enters deep sleep consuming only 1.7µA. The total measured 3.3µA includes minimal feedback divider current and Schottky diode leakage. This behavior is enabled only when SYNC is grounded - synchronizing to an external clock raises IQ to 11µA.
Can LT3976HMSE#PBF operate with input voltage below 4.3V?
No - the LT3976HMSE#PBF has a minimum input voltage of 4.3V for normal regulation, as specified in Absolute Maximum Ratings and Electrical Characteristics. Below this, the internal UVLO circuit forces shutdown. However, once started, it sustains regulation down to VIN = VOUT + 500mV (e.g., 3.8V input for 3.3V output) using dropout mode, but cannot start from <4.3V.
What is the purpose of the OUT pin on LT3976HMSE#PBF?
The OUT pin on LT3976HMSE#PBF serves three functions: (1) it connects to the anode of the internal boost Schottky diode, (2) it supplies bias current to the internal regulator when >3.2V (improving efficiency), and (3) it feeds the dropout comparator to enforce a minimum 500mV difference between VIN and VOUT - ensuring the boost capacitor remains charged during low-VIN conditions.
Is LT3976HMSE#PBF pin-compatible with other LT3976 variants like LT3976EMSE#PBF?
Yes - LT3976HMSE#PBF shares identical pinout, footprint, and electrical characteristics with LT3976EMSE#PBF and LT3976IMSE#PBF. The sole difference is the guaranteed operating junction temperature range: H-grade (–40°C to 150°C) vs. E-grade (0°C to 125°C) or I-grade (–40°C to 125°C). No PCB changes are required when upgrading to LT3976HMSE#PBF for higher thermal margin.
LT3976HMSE#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):
- 40V
- Voltage - Output (Min/Fixed):
- 1.197V
- Voltage - Output (Max):
- 38.8V
- Current - Output:
- 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
LT3976HMSE#PBF FAQ
1.How can I place an order for LT3976HMSE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3976HMSE#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 LT3976HMSE#PBF reliable?
The price and inventory of LT3976HMSE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3976HMSE#PBF is usually 5 days.
3.What payment methods are accepted for LT3976HMSE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3976HMSE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3976HMSE#PBF?
LT3976HMSE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3976HMSE#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 LT3976HMSE#PBF?
For technical support, including LT3976HMSE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3976HMSE#PBF requirements.
6.How does Aetrix verify that LT3976HMSE#PBF is sourced from the original manufacturer or authorized distributors?
All LT3976HMSE#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 LT3976HMSE#PBF meets industry standards.
7.What is the process for return or replacement of LT3976HMSE#PBF?
All LT3976HMSE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3976HMSE#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 LT3976HMSE#PBF part is unused and in its original packaging.
Return procedure for LT3976HMSE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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