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Analog Devices Inc. LT3976EUDD#PBF
- Part No.:
- LT3976EUDD#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 24-WFQFN Exposed Pad
- Datasheet:
-
LT3976EUDD#PBF.pdf
- Description:
- IC REG BUCK ADJ 5A 24QFN
- Quantity:
- Payment:
- Shipping:
Inventory:146
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Product details
Overview
LT3976EUDD#PBF 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 supply applications.
For engineers reviewing the LT3976EUDD#PBF datasheet, LT3976EUDD#PBF pinout, LT3976EUDD#PBF application, or LT3976EUDD#PBF equivalent, key selection criteria include ultralow IQ at no load, programmable UVLO via EN pin (1.02V threshold), soft-start via SS pin, power-good flag (PG), and thermal shutdown with current-limit foldback - all in a thermally enhanced 24-lead 3mm × 5mm QFN package.
Technical Context
The LT3976EUDD#PBF implements an internally compensated current-mode architecture for fast transient response and stable loop behavior across wide input (4.3V–40V) and output (adjustable down to 1.2V) ranges. Its bipolar NPN main switch is driven by a bootstrap circuit referenced to the BOOST pin, enabling full saturation even during dropout conditions.
It supports three operating modes: continuous PWM (above ~150mA load), low-ripple Burst Mode® (SYNC grounded, IQ = 3.3µA typical), and pulse-skipping synchronization (SYNC driven externally, IQ = 11µA no-load). The device includes active soft-start override during fault recovery and VC-clamp-based current limiting with foldback below 4.8A under short-circuit.
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) and load-dump immunity up to 40V. |
| Max Output Current | 5A - sustained delivery with thermal derating above 125°C junction temperature; foldback limits peak current to 4.8A during overload. |
| Quiescent Current | 3.3µA at no load - enables >10-year battery life in always-on automotive or IoT sensor nodes. |
| Switching Frequency | 200kHz to 2MHz - adjustable via RT resistor; synchronizable 250kHz–2MHz externally; enables compact magnetics and EMI optimization. |
| Feedback Reference | 1.197V ±1.2% - high-accuracy internal reference enables ±1.5% output regulation over line, load, and temperature. |
| Dropout Voltage | 500mV - maintains regulation when VIN drops within 500mV of VOUT, critical for automotive start-stop systems. |
| Power Good Flag | Open-drain PG asserts when VOUT reaches 91.6% of target - provides system-level power sequencing and fault detection. |
Pinout & Package
LT3976EUDD#PBF is housed in a 24-lead, 3mm × 5mm plastic QFN package with exposed thermal pad (Pin 25 = GND). The package delivers θJA = 46°C/W and requires soldering of the exposed pad to PCB ground plane for thermal integrity and EMI reduction.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| FB (Pins 23,24) | Feedback input | Regulates output by sensing divider voltage; clamped to 1.197V reference; requires 10pF phase-lead capacitor for stability. |
| SS (Pin 1) | Soft-start control | Internal 1.8µA current source ramps VC node; capacitor value sets inrush current slew rate and startup time. |
| OUT (Pin 2) | Boost diode anode / dropout sense | Connects to output rail ≤16V; supplies bias to internal regulator when VOUT > 3.2V; enables low-dropout operation. |
| BOOST (Pin 4) | Bootstrap drive | Drives internal NPN switch gate above VIN; requires external 0.47µF ceramic capacitor to SW for full saturation. |
| SW (Pins 6,7,8) | Switch node | High-current output of internal bipolar switch; connects to inductor, catch diode, and boost cap; requires R-C snubber (2Ω + 470pF). |
| VIN (Pins 13–15) | Main power input | Supplies IC bias and switch current; must be locally bypassed with ≥10µF ceramic + bulk capacitance. |
| EN (Pin 16) | Enable control | Hysteretic threshold (1.02V fall / 1.08V rise); accurate UVLO programming; tie to VIN if always-on operation required. |
| RT (Pin 18) | Frequency set | Resistor to GND programs fSW from 200kHz–2MHz; 11.8kΩ yields ~2MHz; 294kΩ yields ~200kHz. |
| PG (Pin 19) | Power good flag | Open-drain output pulled low until FB reaches 91.6% of regulation; valid only when VIN > 2V. |
| SYNC (Pin 20) | External clock sync | Ground for Burst Mode; drive with 250kHz–2MHz square wave for synchronized pulse-skipping; do not float. |
| GND (Pins 21,25) | Signal & thermal ground | Exposed pad (Pin 25) is primary thermal path and must be soldered to large PCB copper area. |
Key Features
| Feature | Design Value |
|---|---|
| Ultralow quiescent current | 3.3µA IQ enables >10-year battery life in always-on automotive modules and remote sensors. |
| Low-ripple Burst Mode® | Maintains <15mVP-P output ripple at light loads while sustaining >85% efficiency at 1mA output. |
| Integrated boost Schottky | On-die 730mV forward drop diode eliminates external component and reduces board space by ~30%. |
| Programmable undervoltage lockout | EN pin with 1.02V threshold and 60mV hysteresis allows precise system-level brown-out protection. |
| Thermal shutdown + current foldback | Combines junction temperature cutoff (>165°C) with foldback current limit (4.8A) to prevent thermal runaway during short-circuit. |
Applications
| Automotive Battery Regulation | Industrial Power Supply |
|---|---|
Use Scenario: Regulating 12V/24V automotive battery to 3.3V/5V for infotainment microcontrollers during cold-crank (VIN dips to 4.3V). IC Role / Device Role / Timing Role: Primary buck controller maintaining regulation through 500mV dropout; manages inrush via SS pin; signals readiness via PG. Use Value: Eliminates need for pre-regulator stage; sustains operation below 5V input; meets ISO 16750-2 pulse 4 requirements. | Use Scenario: Providing 5V/3A to PLC I/O modules in factory automation with wide-input 18–36V DC bus. IC Role / Device Role / Timing Role: High-efficiency primary converter with 2MHz switching to minimize filter size; uses SYNC for EMI spread-spectrum alignment. Use Value: Reduces total solution footprint by 40% vs. 500kHz alternatives; achieves >92% efficiency at full load across input range. |
| Portable Medical Instrument | Smart Sensor Node |
Use Scenario: Powering low-noise analog front-end and BLE SoC in handheld diagnostic device powered by single Li-ion cell (3.0–4.2V) + boost-capable backup. IC Role / Device Role / Timing Role: Step-down regulator delivering 1.8V/2A with ultra-low noise; operates in Burst Mode between measurements. Use Value: Extends battery runtime to >12 months per charge; <15mV ripple avoids ADC quantization errors. | Use Scenario: Always-on environmental sensor node harvesting energy from solar or vibration, requiring micropower operation. IC Role / Device Role / Timing Role: Primary regulator converting variable harvester output (5–30V) to stable 3.3V; leverages 3.3µA IQ and soft-start for intermittent wake-up. Use Value: Enables operation on <10µW average input power; PG signal triggers MCU wake-up only after stable VOUT. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3630EMSE#PBF | Lower max current (3A), higher IQ (12µA), fixed 3.3V/5V options only; no PG or SYNC. | Suitable for space-constrained, lower-power applications where programmability and diagnostics are secondary. | Select LTC3630EMSE#PBF only when output voltage is fixed and 5A capability is unnecessary. |
| MPQ4420AGL-AEC1-Z | Automotive-grade (AEC-Q100), 40V/2A, 17µA IQ, no Burst Mode; integrated MOSFETs but no boost diode. | Targeted at ASIL-B automotive subsystems requiring qualification; lacks ultralow IQ and low-ripple light-load performance. | Choose MPQ4420AGL-AEC1-Z only when AEC-Q100 compliance is mandatory and 5A output is not required. |
Compared with LTC3630EMSE#PBF and MPQ4420AGL-AEC1-Z, the LT3976EUDD#PBF uniquely combines 5A capability, 3.3µA IQ, programmable frequency/sync, PG flag, and integrated boost diode - making it optimal for high-reliability, wide-input, ultralow-power industrial and automotive systems where both peak current and standby efficiency are critical.
Availability
LT3976EUDD#PBF is available at Aetrix Electronics and suitable for automotive battery regulation, industrial power supplies, and portable medical instrumentation requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.
Supply support for LT3976EUDD#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 full product support, documentation, and manufacturing continuity for the LT3976 series.
The LT3976 product line was engineered for high-voltage, high-efficiency, ultralow-quiescent-current DC/DC conversion in automotive, industrial, and portable applications demanding robustness across extreme input transients and ambient temperatures.
FAQ
What is the maximum output current capability of the LT3976EUDD#PBF?
The LT3976EUDD#PBF delivers up to 5A of continuous output current under proper thermal management (θJA = 46°C/W, 2-layer PCB). Current limit foldback reduces peak switch current to 4.8A during short-circuit, protecting the device. Derating begins above 125°C junction temperature, with thermal shutdown activating at >165°C.
How does the LT3976EUDD#PBF achieve 3.3µA quiescent current?
The LT3976EUDD#PBF achieves 3.3µA quiescent current by entering low-ripple Burst Mode® operation at light loads - cycling between active bursts (delivering discrete current pulses) and deep sleep (consuming only 1.7µA). This mode requires SYNC pin grounded and is optimized for minimal feedback resistor leakage and low-diode reverse current.
Can the LT3976EUDD#PBF operate with input voltage below 5V?
Yes - the LT3976EUDD#PBF operates down to 4.3V input, enabling use in automotive cold-crank scenarios. Below this, internal UVLO disables regulation. When VIN drops within 500mV of the programmed VOUT, the device enters dropout mode, maintaining regulation with reduced duty cycle while keeping the boost capacitor charged.
What is the purpose of the OUT pin on the LT3976EUDD#PBF?
The OUT pin on the LT3976EUDD#PBF serves dual functions: (1) it connects to the anode of the internal boost Schottky diode, enabling efficient switch drive; and (2) it feeds the internal bias regulator when VOUT > 3.2V, improving efficiency by reducing VIN current draw. It must be connected to the output rail for voltages ≤16V.
Does the LT3976EUDD#PBF require an external Schottky diode?
No - the LT3976EUDD#PBF integrates a Schottky diode on-die (forward voltage ≈730mV at 100mA), eliminating the need for an external catch diode. This reduces BOM count, PCB area, and thermal losses. External diodes are unnecessary unless specific reliability or thermal isolation requirements mandate them.
LT3976EUDD#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 24-WFQFN 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 ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 24-QFN (3x5)
LT3976EUDD#PBF FAQ
1.How can I place an order for LT3976EUDD#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3976EUDD#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 LT3976EUDD#PBF reliable?
The price and inventory of LT3976EUDD#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3976EUDD#PBF is usually 5 days.
3.What payment methods are accepted for LT3976EUDD#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3976EUDD#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3976EUDD#PBF?
LT3976EUDD#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3976EUDD#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 LT3976EUDD#PBF?
For technical support, including LT3976EUDD#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3976EUDD#PBF requirements.
6.How does Aetrix verify that LT3976EUDD#PBF is sourced from the original manufacturer or authorized distributors?
All LT3976EUDD#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 LT3976EUDD#PBF meets industry standards.
7.What is the process for return or replacement of LT3976EUDD#PBF?
All LT3976EUDD#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3976EUDD#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 LT3976EUDD#PBF part is unused and in its original packaging.
Return procedure for LT3976EUDD#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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