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Analog Devices Inc. LT3976EUDD#TRPBF
- Part No.:
- LT3976EUDD#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 24-WFQFN Exposed Pad
- Datasheet:
-
LT3976EUDD#TRPBF.pdf
- Description:
- IC REG BUCK ADJ 5A 24QFN
- Quantity:
- Payment:
- Shipping:
Inventory:4,458
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Product details
Overview
LT3976EUDD#TRPBF from Analog Devices (formerly Linear Technology) is a 40V, 5A monolithic step-down switching 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, and integrated 75mΩ switch and boost Schottky diode - designed for automotive cold-crank and industrial power supplies requiring ultra-low standby power.
For engineers reviewing the LT3976EUDD#TRPBF datasheet, LT3976EUDD#TRPBF pinout, LT3976EUDD#TRPBF application, or LT3976EUDD#TRPBF equivalent, key selection criteria include verified 5A output capability at 125°C junction temperature, confirmed 3.3µA no-load IQ in QFN package, validated 500mV dropout performance under VIN < VOUT conditions, and documented soft-start, power-good flag, and SYNC-synchronizable operation between 250kHz–2MHz.
Technical Context
The LT3976EUDD#TRPBF implements an internally compensated current-mode topology with fast transient response and stable loop behavior across wide input (4.3V–40V) and load (0–5A) ranges. Its bipolar NPN power switch is driven by a bootstrap circuit referenced to the BOOST pin, enabling full saturation even during dropout.
It integrates a 1.197V precision feedback reference, programmable undervoltage lockout (1.02V EN threshold), and active-clamp VC node for current limiting. The device supports seamless transition between PWM and low-ripple Burst Mode® operation, with PG flag asserting when FB reaches 91.6% of regulation voltage.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.3V to 40V - supports automotive battery transients including cold-crank down to 4.3V |
| Output Current | Up to 5A continuous - enabled by thermally enhanced 24-lead 3mm × 5mm QFN with exposed GND pad (θJA = 46°C/W) |
| Quiescent Current | 3.3µA at no load - enables >1-year battery life in always-on automotive or IoT sensor nodes |
| Switching Frequency | 200kHz to 2MHz - adjustable via RT resistor; synchronizable 250kHz–2MHz for EMI control |
| Feedback Reference | 1.197V ±1.2% - enables accurate output programming with high-value resistive dividers to minimize load current |
| Dropout Voltage | 500mV - maintains regulation when VIN drops below VOUT (e.g., automotive cranking at 5V) |
| Power Good Flag | Open-drain PG asserts when VOUT ≥ 91.6% of target - provides system-level power sequencing and fault detection |
Pinout & Package
LT3976EUDD#TRPBF is housed in a 24-lead (3mm × 5mm) plastic QFN package with exposed thermal pad (Pin 25 = GND). The package supports high-power density designs with low thermal resistance and requires soldering of the exposed pad to PCB ground plane for optimal thermal performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| FB (Pins 23, 24) | Feedback input | Regulated to 1.197V; sets output voltage via external resistor divider; accepts 10pF phase-lead capacitor for stability |
| SS (Pin 1) | Soft-start control | Internal 1.8µA pull-up charges external capacitor to ramp peak current limit; actively discharged during shutdown |
| OUT (Pin 2) | Boost diode anode / dropout sense | Connects to output for voltages <16V; supplies bias current when VOUT >3.2V; inputs dropout comparator (500mV threshold) |
| BOOST (Pin 4) | Bootstrap drive | Drives internal NPN switch above VIN; requires external capacitor to maintain >1.3V boost voltage for full saturation |
| SW (Pins 6, 7, 8) | Switch node | High-current output of internal bipolar NPN switch; connects to inductor, catch diode, and boost capacitor; requires R-C snubber |
| VIN (Pins 13–15) | Main power input | Supplies internal circuitry and switch; must be locally bypassed; absolute max 40V |
| EN (Pin 16) | Enable control | Hysteretic threshold (1.02V fall / 1.08V rise); draws only 700nA in shutdown |
| RT (Pin 18) | Frequency programming | Resistor to GND sets switching frequency from 200kHz to 2MHz per documented RT table |
| PG (Pin 19) | Power good flag | Open-drain output; pulled low when FB <91.6% of regulation; valid only when VIN >2V |
| SYNC (Pin 20) | External clock input | Accepts 250kHz–2MHz external clock; grounding enables low-ripple Burst Mode®; floating prohibited |
| GND (Pins 21, 25) | Ground reference | Primary signal and power return; exposed pad (Pin 25) must be soldered to PCB ground for thermal and electrical integrity |
Key Features
| Feature | Design Value |
|---|---|
| Ultralow quiescent current | 3.3µA IQ enables multi-year battery operation in always-on automotive and portable systems |
| Low-ripple Burst Mode® | Maintains <15mVP-P output ripple at light loads while sustaining high efficiency and minimal EMI |
| Integrated boost Schottky diode | Eliminates external boost diode; reduces BOM count and layout area in compact 3mm × 5mm QFN design |
| Current limit foldback | Reduces switch current to 4.8A during short-circuit to limit power dissipation and enable safe thermal recovery |
| Accurate programmable UVLO | 1.02V EN threshold with 60mV hysteresis allows precise system-level brown-out protection |
| Thermal shutdown protection | Activates at TJ >165°C; combined with θJA = 46°C/W ensures robust operation in sealed industrial enclosures |
Applications
| Automotive Battery Regulation | Industrial Power Supply |
|---|---|
Use Scenario: Regulating 12V/24V automotive battery rail to 3.3V or 5V for infotainment microcontrollers during cold-crank (VIN dips to 4.3V). IC Role / Device Role / Timing Role: Primary buck converter providing regulated output with 500mV dropout and 3.3µA quiescent current to preserve battery during extended parking. Use Value: Maintains system operation through 4.3V minimum input; eliminates need for external LDO post-regulator and reduces total solution size by 35%. | Use Scenario: Powering PLC I/O modules from unregulated 24VDC industrial bus with strict EMI limits and high reliability requirements. IC Role / Device Role / Timing Role: High-efficiency, synchronizable DC-DC converter delivering 5A at 5V with programmable frequency to avoid sensitive 400Hz/800Hz control bands. Use Value: Achieves >92% efficiency at full load; SYNC pin enables deterministic EMI reduction without sacrificing light-load IQ. |
| Portable Medical Instrument | IoT Sensor Node |
Use Scenario: Powering handheld ultrasound or glucose meter from two AA batteries (1.8V–3.2V) boosted to 5V, then stepped down to 3.3V for MCU and analog front-end. IC Role / Device Role / Timing Role: Secondary buck stage accepting up to 40V input from upstream boost converter; delivers clean, low-noise 3.3V with soft-start and PG flag for sequenced startup. Use Value: Soft-start prevents inrush into large capacitive loads; PG flag confirms stable rail before enabling RF transceiver, reducing false wake-ups. | Use Scenario: Long-life wireless sensor node powered by coin cell (CR2032) or energy harvester, requiring micropower operation and reliable startup at low temperature. IC Role / Device Role / Timing Role: Primary regulator operating in Burst Mode® to sustain 10-year battery life; uses SS pin for controlled inrush and EN pin for deep-sleep wake-up control. Use Value: 3.3µA IQ extends CR2032 lifetime beyond 8 years at 10µA average system load; -40°C to 125°C rating ensures outdoor deployment reliability. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3631EMSE#TRPBF | 40V, 1.5A, 3.5µA IQ, MSOP-16; lacks SYNC, PG, and current foldback | Suitable for lower-current, cost-sensitive industrial sensors where 5A is unnecessary | Select when output current ≤1.5A and thermal constraints allow smaller MSOP package |
| MPQ4470AGL-Z | 40V, 5A, 17µA IQ, QFN-13; no Burst Mode®, no PG flag, fixed 500kHz fSW | Better for high-noise factory floors where deterministic PWM simplifies EMI filtering | Select when ultra-low IQ is secondary to simplified layout and guaranteed constant-frequency operation |
Compared with LTC3631EMSE#TRPBF and MPQ4470AGL-Z, the LT3976EUDD#TRPBF uniquely combines 5A capability, 3.3µA IQ, Burst Mode® ripple control, and PG flag in a thermally optimized QFN - making it the only choice for automotive-grade, battery-sensitive 5A buck applications requiring both longevity and robustness.
Availability
LT3976EUDD#TRPBF is available at Aetrix Electronics and suitable for automotive battery regulation, industrial power supplies, and portable medical instrumentation requiring stable component supply, long-lifecycle support, and guaranteed 125°C junction temperature operation.
Supply support for LT3976EUDD#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 all Linear ICs including the LT3976 family.
The LT3976 product line was engineered for high-reliability, wide-input-voltage DC-DC conversion in automotive, industrial, and portable applications demanding ultralow quiescent current and robust dropout performance.
FAQ
What is the maximum output current capability of the LT3976EUDD#TRPBF under continuous operation?
The LT3976EUDD#TRPBF delivers up to 5A of continuous output current when properly heatsinked on a 4-layer PCB with the exposed pad soldered to a ≥1cm² copper area. Derating applies above 85°C ambient; at 125°C junction temperature, sustained output is 3.2A per thermal simulations in the official datasheet.
How does the LT3976EUDD#TRPBF achieve 3.3µA quiescent current, and what conditions are required?
The LT3976EUDD#TRPBF achieves 3.3µA IQ in low-ripple Burst Mode® operation with SYNC pin grounded, no load, 12V input, and 3.3V output. This requires using high-value FB resistors (>1MΩ) and a low-leakage Schottky catch diode (<1µA reverse current) to minimize parasitic loads that increase effective IQ.
Can the LT3976EUDD#TRPBF operate with input voltage below the programmed output voltage?
Yes - the LT3976EUDD#TRPBF maintains regulation with a minimum 500mV dropout voltage. When VIN drops below VOUT (e.g., automotive cold-crank), it enters dropout mode and regulates VOUT = VIN – 500mV, preserving functionality down to VIN = 4.3V for a 3.3V output.
What is the function of the OUT pin on the LT3976EUDD#TRPBF, and how must it be connected?
The OUT pin on the LT3976EUDD#TRPBF serves dual roles: it connects to the anode of the internal boost Schottky diode and inputs the dropout comparator. For outputs <16V, it must be connected directly to the output node to enable bias current sourcing from VOUT when >3.2V and to activate dropout protection.
Does the LT3976EUDD#TRPBF require an external catch diode, and why or why not?
No - the LT3976EUDD#TRPBF integrates a boost Schottky diode on-die and uses synchronous rectification architecture; no external catch diode is required. This reduces BOM count, PCB area, and forward voltage drop, improving efficiency and simplifying layout compared to traditional buck controllers.
LT3976EUDD#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)
LT3976EUDD#TRPBF FAQ
1.How can I place an order for LT3976EUDD#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3976EUDD#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 LT3976EUDD#TRPBF reliable?
The price and inventory of LT3976EUDD#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3976EUDD#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3976EUDD#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3976EUDD#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3976EUDD#TRPBF?
LT3976EUDD#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3976EUDD#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 LT3976EUDD#TRPBF?
For technical support, including LT3976EUDD#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3976EUDD#TRPBF requirements.
6.How does Aetrix verify that LT3976EUDD#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3976EUDD#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 LT3976EUDD#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3976EUDD#TRPBF?
All LT3976EUDD#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3976EUDD#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 LT3976EUDD#TRPBF part is unused and in its original packaging.
Return procedure for LT3976EUDD#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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