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Analog Devices Inc. LT3976IUDD#TRPBF
- Part No.:
- LT3976IUDD#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 24-WFQFN Exposed Pad
- Datasheet:
-
LT3976IUDD#TRPBF.pdf
- Description:
- IC REG BUCK ADJ 5A 24QFN
- Quantity:
- Payment:
- Shipping:
Inventory:4,688
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Product details
Overview
LT3976IUDD#TRPBF from Analog Devices (formerly Linear Technology) is a monolithic 40V, 5A synchronous step-down DC/DC regulator with current-mode control, 3.3µA quiescent current, and adjustable 200kHz–2MHz switching frequency. It features low-ripple Burst Mode operation (<15mVP-P), 500mV dropout voltage, power good flag, and soft-start-designed for automotive cold-crank and battery-powered industrial systems.
For engineers reviewing the LT3976IUDD#TRPBF datasheet, LT3976IUDD#TRPBF pinout, LT3976IUDD#TRPBF application, or LT3976IUDD#TRPBF equivalent, key selection criteria include ultralow IQ at no load, thermal performance in QFN-24 package, programmable UVLO via EN pin, and validated 5A output capability under 125°C junction temperature.
Technical Context
The LT3976IUDD#TRPBF implements an internally compensated current-mode architecture with fast transient response and stable loop behavior across input voltages from 4.3V to 40V. Its bipolar NPN main switch (75mΩ RDS(on)-equivalent) is driven by a bootstrap circuit requiring external BST capacitor and Schottky diode.
It integrates a 1.197V reference, accurate EN threshold (1.02V falling), PG comparator (91.6% VOUT trip), and RT-programmable oscillator with frequency foldback during startup/overload. The device supports synchronization (250kHz–2MHz) and enters low-ripple Burst Mode below ~150mA load to maintain <3.3µA supply current.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.3V to 40V - supports automotive battery transients including cold-crank (down to 3.5V with dropout mode). |
| Max Output Current | 5A - sustained delivery with current-limit foldback and thermal shutdown protection. |
| Quiescent Current | 3.3µA at no load - enables >10-year battery life in always-on IoT sensors and telematics. |
| Switching Frequency | 200kHz to 2MHz - adjustable via RT resistor; enables compact magnetics and EMI optimization. |
| Feedback Reference | 1.197V ±1.2% - high-accuracy regulation with <0.01%/V line regulation. |
| Dropout Voltage | 500mV - maintains regulation when VIN drops below VOUT (e.g., 6V→3.3V), critical for automotive start-stop. |
| Power Good Threshold | 91.6% of VOUT - open-drain PG flag signals valid output with 8.4% hysteresis. |
Pinout & Package
LT3976IUDD#TRPBF is housed in a thermally enhanced 24-lead 3mm × 5mm plastic QFN package with exposed pad (Pin 25 = GND). Thermal resistance θJA = 46°C/W on standard 4-layer PCB.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| FB (Pins 23,24) | Feedback input | Regulates output by sensing divider voltage; internal 1.197V reference sets VOUT = 1.197V × (1 + R1/R2). |
| SS (Pin 1) | Soft-start control | Internal 1.8µA current source ramps VC node; capacitor value sets inrush current slew rate. |
| OUT (Pin 2) | Boost diode anode / dropout sense | Connects to output for bias supply (>3.2V) and enables 500mV dropout comparator. |
| BOOST (Pin 4) | Bootstrap drive | Drives switch base above VIN via external capacitor/diode; enables full saturation of NPN switch. |
| SW (Pins 6,7,8) | Switch node | High-current output to inductor/catch diode; requires snubber (2Ω + 470pF) for EMI robustness. |
| EN (Pin 16) | Enable input | Hysteretic threshold (1.02V fall / 1.08V rise); directly interfaces microcontroller GPIO for programmable UVLO. |
| RT (Pin 18) | Frequency set | Resistor to GND programs fSW from 200kHz–2MHz; 41.2kΩ = 1MHz typical. |
| PG (Pin 19) | Power good flag | Open-drain output pulled low until FB reaches 91.6% of target; valid only when VIN > 2V. |
| SYNC (Pin 20) | External clock sync | Ground for Burst Mode; connect to external clock (250kHz–2MHz) for synchronized pulse-skipping. |
| GND (Pins 21,25) | Signal & thermal ground | Exposed pad (Pin 25) must be soldered to PCB plane for thermal and electrical integrity. |
Key Features
| Feature | Design Value |
|---|---|
| Ultralow quiescent current | 3.3µA at no load enables multi-year operation from coin-cell or LiSOCl₂ batteries. |
| Low-ripple Burst Mode | Maintains <15mVP-P output ripple while delivering single current pulses - avoids audible noise and EMI spikes. |
| Programmable undervoltage lockout | Accurate 1.02V EN threshold allows custom battery cutoff (e.g., 10.5V for 12V lead-acid) without external comparators. |
| Thermally enhanced QFN | 24-pin 3mm×5mm package with exposed pad achieves 46°C/W θJA, supporting 5A continuous in compact layouts. |
| Current limit foldback | Reduces switch current from 10A to 4.8A during short-circuit - limits power dissipation and enables self-recovery. |
Applications
| Automotive Battery Regulation | Industrial Sensor Node Power |
|---|---|
Use Scenario: 12V vehicle battery powering infotainment display during engine cranking (VIN dips to 3.5V). IC Role / Device Role / Timing Role: Step-down regulator maintaining 3.3V/5V rail with 500mV dropout and seamless transition to Burst Mode at idle. Use Value: Prevents system reset during cold-crank; 3.3µA IQ extends parked battery life beyond 6 months. | Use Scenario: Remote vibration sensor powered by primary lithium battery (3.6V) with 10-year field life requirement. IC Role / Device Role / Timing Role: Primary DC/DC converter enabling ultra-low-power sleep cycles and fast wake-up with controlled inrush. Use Value: Achieves sub-µA average system current; soft-start prevents voltage sag during MCU wake-up bursts. |
| Portable Medical Monitor | Smart Building Controller |
Use Scenario: Handheld ECG device using dual-cell Li-ion (6–8.4V) to generate isolated 3.3V logic and 5V analog rails. IC Role / Device Role / Timing Role: High-efficiency buck regulator supplying 5A peak for ADC sampling and wireless transmission bursts. Use Value: 95% peak efficiency at 2A load extends clinical use time; PG flag validates rail stability before data acquisition. | Use Scenario: DIN-rail mounted HVAC controller operating from 24VAC/DC with wide ambient (-40°C to +85°C). IC Role / Device Role / Timing Role: Main 5V/3A supply with thermal derating support and SYNC input for EMI-controlled switching in noisy environments. Use Value: Guaranteed operation up to 125°C junction; 2MHz sync capability reduces conducted EMI in shared power bus. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM5164QPWPRQ1 | 4.5V–65V input, 3.5A max, 1.5µA IQ, integrated MOSFETs, no PG flag | Better HV range and lower IQ, but lacks power good signal and fixed 1.5A current limit | Choose LM5164QPWPRQ1 for higher input voltage tolerance and automotive AEC-Q100 qualification; avoid if PG monitoring is required. |
| MP2451DT-LF-Z | 4.5V–36V input, 0.6A max, 26µA IQ, 8-pin SOIC, no SS or SYNC | Lower cost and smaller footprint, but insufficient current rating and higher quiescent current | Choose MP2451DT-LF-Z only for sub-600mA loads where board space and BOM cost outweigh efficiency and feature requirements. |
Compared with LM5164QPWPRQ1 and MP2451DT-LF-Z, the LT3976IUDD#TRPBF delivers verified 5A output with integrated PG, soft-start, and 3.3µA IQ in a thermally optimized QFN - making it uniquely suited for high-reliability automotive and industrial applications demanding both high current and ultralow standby power.
Availability
LT3976IUDD#TRPBF is available at Aetrix Electronics and suitable for automotive battery regulation, portable medical monitors, industrial sensor nodes, and smart building controllers requiring stable component supply across extended temperature and lifecycle demands.
Supply support for LT3976IUDD#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 its high-performance power management portfolio with rigorous automotive and industrial qualification standards.
The LT3976 product line was designed specifically for demanding automotive and industrial DC/DC conversion - emphasizing ultralow quiescent current, wide input range, thermal robustness, and functional safety features like PG and thermal shutdown.
FAQ
What is the maximum output current capability of the LT3976IUDD#TRPBF?
The LT3976IUDD#TRPBF delivers up to 5A of continuous output current under proper thermal conditions (e.g., 4-layer PCB with exposed pad soldered). Its current limit is 10A typical with foldback to 4.8A during short-circuit, and thermal shutdown activates above 150°C junction temperature. Derating curves in the datasheet confirm 5A operation at 125°C ambient with appropriate layout.
Does the LT3976IUDD#TRPBF support synchronization to an external clock?
Yes, the LT3976IUDD#TRPBF supports external clock synchronization via the SYNC pin (Pin 20), accepting frequencies from 250kHz to 2MHz. When synchronized, it operates in pulse-skipping mode at light loads (increasing IQ to ~11µA), unlike Burst Mode (3.3µA) which requires SYNC grounded. Do not leave SYNC floating - tie to GND or a clean clock source.
How does the LT3976IUDD#TRPBF achieve 500mV dropout voltage?
The LT3976IUDD#TRPBF achieves 500mV dropout by monitoring the OUT pin (connected to output) and reducing switching frequency when VIN approaches VOUT. This maintains sufficient boost capacitor voltage to saturate the internal NPN switch, enabling low VCE(sat) conduction even at high duty cycles. Dropout behavior is guaranteed per Electrical Characteristics table (430–570mV threshold).
What is the purpose of the OUT pin on the LT3976IUDD#TRPBF?
The OUT pin on the LT3976IUDD#TRPBF serves three functions: (1) it connects to the anode of the internal boost Schottky diode, (2) it supplies bias current to the IC's internal regulator when VOUT > 3.2V (improving efficiency), and (3) it feeds the dropout comparator that enforces the 500mV minimum VIN–VOUT differential. It must be connected to the output for all these features to operate correctly.
Can the LT3976IUDD#TRPBF be used in automotive cold-crank applications?
Yes, the LT3976IUDD#TRPBF is explicitly qualified for automotive cold-crank operation. With 4.3V minimum input, 500mV dropout, and guaranteed operation from –40°C to +125°C junction temperature, it maintains regulation during battery dips to 3.5V. Its 3.3µA quiescent current also minimizes parasitic drain during long parking periods - a key requirement for modern automotive electronics.
LT3976IUDD#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 24-WFQFN 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):
- 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 ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 24-QFN (3x5)
LT3976IUDD#TRPBF FAQ
1.How can I place an order for LT3976IUDD#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3976IUDD#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 LT3976IUDD#TRPBF reliable?
The price and inventory of LT3976IUDD#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3976IUDD#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3976IUDD#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3976IUDD#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3976IUDD#TRPBF?
LT3976IUDD#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3976IUDD#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 LT3976IUDD#TRPBF?
For technical support, including LT3976IUDD#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3976IUDD#TRPBF requirements.
6.How does Aetrix verify that LT3976IUDD#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3976IUDD#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 LT3976IUDD#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3976IUDD#TRPBF?
All LT3976IUDD#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3976IUDD#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 LT3976IUDD#TRPBF part is unused and in its original packaging.
Return procedure for LT3976IUDD#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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