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Analog Devices Inc. LT3973EDD-5#PBF
- Part No.:
- LT3973EDD-5#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 10-WFDFN Exposed Pad
- Datasheet:
-
LT3973EDD-5#PBF.pdf
- Description:
- IC REG BUCK 5V 750MA 10DFN
- Quantity:
- Payment:
- Shipping:
Inventory:138
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Product details
Overview
LT3973EDD-5#PBF from Analog Devices (formerly Linear Technology) is a 42V, 750mA monolithic step-down regulator with integrated boost and catch diodes, 2.5µA quiescent current, fixed 5V output, and operation down to 4.2V input - designed for automotive cold-crank and industrial power supply applications where ultra-low IQ and dropout robustness are critical.
For engineers reviewing the LT3973EDD-5#PBF datasheet, LT3973EDD-5#PBF pinout, LT3973EDD-5#PBF application, or LT3973EDD-5#PBF equivalent, this page delivers verified specifications, thermal-aware package details, real-world load regulation behavior, and validated alternative options for 5V automotive/industrial DC-DC conversion.
Technical Context
The LT3973EDD-5#PBF implements constant-frequency current-mode control with programmable switching frequency (200kHz–2.2MHz) and automatic Burst Mode® operation below ~100mA load to maintain <10mVP-P output ripple while sustaining 1.8µA no-load IQ. Its bipolar NPN internal switch requires external BOOST capacitor biasing for full saturation.
It features dual current limiting (1.65A switch peak / 1.15A catch diode valley), 530mV enforced minimum dropout voltage, accurate 90% power-good flag, and programmable EN/UVLO with 30mV hysteresis - all operating across –40°C to +125°C junction temperature in the thermally enhanced 10-lead 3mm × 3mm DFN package with exposed GND pad.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 5.00V ±1.2%, tightly regulated over line, load, and temperature - eliminates external feedback resistors and ensures stable 5V rail for MCU peripherals. |
| Input Voltage Range | 4.2V to 42V continuous - supports 12V/24V automotive battery systems including cold-crank (down to ~4.5V) and industrial wide-input supplies. |
| Quiescent Current | 2.5µA at 12VIN → 5VOUT; drops to 1.8µA in Burst Mode - enables always-on subsystems with multi-year battery life in portable/remote sensors. |
| Max Output Current | 750mA continuous at TJ ≤ 125°C (θJA = 40°C/W) - sufficient for powering microcontrollers, CAN transceivers, and analog front-ends without external heatsinking. |
| Switching Frequency | Adjustable 200kHz–2.2MHz via RT resistor - allows optimization of inductor size (e.g., 15µH @ 600kHz) vs. EMI vs. light-load efficiency trade-offs. |
| Dropout Performance | 530mV minimum VIN–VOUT differential maintained during dropout - guarantees regulation continuity and boost capacitor recharge even when input sags near output voltage. |
| Thermal Rating | –40°C to +125°C operating junction temperature - qualified for under-hood automotive and harsh industrial environments. |
Pinout & Package
LT3973EDD-5#PBF uses a 10-lead (3mm × 3mm) plastic DFN package with exposed thermal pad (Pin 11 = GND), optimized for high-power density and PCB-level thermal dissipation (θJA = 40°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 FB/VOUT | Feedback reference input / Fixed-output sense | Internally connected to 5V regulation divider - no external resistor required; ties directly to output for closed-loop stability. |
| 2 OUT | Dropout regulation node | Must be tied to VOUT to enable 530mV dropout enforcement and boost capacitor refresh during low-VIN conditions. |
| 3 EN/UVLO | Enable and undervoltage lockout input | Active-high enable with 1.19V rising threshold and 30mV hysteresis - supports programmable brown-out protection down to 4.2V input. |
| 4 VIN | Main power input | Supplies internal circuitry and switch; rated to 42V absolute max - requires local 4.7µF X7R ceramic bypassing. |
| 5 GND | Signal and power ground | Pin 5 + exposed pad (Pin 11) must be soldered to large PCB copper area for thermal and EMI performance. |
| 6 SW | Switch node | Drives external inductor; connects to internal NPN collector - requires low-inductance layout to minimize switching losses and EMI. |
| 7 BOOST | Bootstrap drive voltage source | Accepts external capacitor to generate >VIN voltage - essential for full NPN saturation and low RCE(SAT) (~250mV). |
| 8 BD | Bias diode anode input | Enables auxiliary bias from regulated output (≥3.2V) to improve light-load efficiency and reduce VIN current draw. |
| 9 PG | Power good open-drain flag | Asserts high when VOUT reaches 90% of 5V (i.e., ≥4.5V); requires external pull-up - used for system sequencing and fault monitoring. |
| 10 RT | Frequency setting input | Resistor-to-GND sets switching frequency (e.g., 215kΩ = 600kHz); enables EMI tuning and inductor size reduction. |
Key Features
| Feature | Design Value |
|---|---|
| Ultralow quiescent current | 2.5µA IQ at 12VIN→5VOUT enables >10-year battery life in always-on IoT nodes and automotive body electronics. |
| Integrated boost and catch diodes | Eliminates two external Schottky diodes - reduces BOM count, PCB area, and reverse leakage path failures in high-temp environments. |
| Low-ripple Burst Mode® operation | Maintains <10mVP-P output ripple at light loads while achieving 1.8µA no-load IQ - critical for noise-sensitive analog/RF circuits. |
| Accurate programmable UVLO | EN/UVLO threshold (1.19V ±30mV) with hysteresis prevents oscillation during battery sag - supports reliable cold-crank startup. |
| Thermally enhanced DFN package | 3mm × 3mm footprint with exposed GND pad achieves θJA = 40°C/W - enables 750mA output without heatsink in compact enclosures. |
| Power good flag with 90% threshold | PG asserts when VOUT ≥4.5V - provides precise system power sequencing signal for MCUs, FPGAs, and PMICs without external comparators. |
Applications
| Automotive Body Control Module (BCM) | Industrial PLC I/O Power Supply |
|---|---|
Use Scenario: Powering CAN transceivers, door-lock actuators, and LED drivers in 12V vehicle electrical systems experiencing cold-crank dips to 4.5V. IC Role / Device Role / Timing Role: Primary 5V buck regulator delivering stable rail despite wide input transients and ambient temperatures up to 125°C. Use Value: 530mV dropout enforcement and 2.5µA IQ ensure uninterrupted operation during engine start and multi-year standby battery life. |
Use Scenario: Generating isolated 5V logic supply for digital I/O modules in factory automation cabinets with 24V DC input and high EMI noise. IC Role / Device Role / Timing Role: Compact, thermally robust DC-DC converter providing clean 5V for microcontroller and level-shifter ICs. Use Value: Integrated diodes eliminate external component failure points; 42V rating accommodates 24V surge transients per IEC 61000-4-5. |
| Portable Medical Sensor Hub | Gated Power for RF Front-End |
Use Scenario: Battery-powered wearable device requiring long-life 5V rail for ADC, Bluetooth SoC, and display backlight driver. IC Role / Device Role / Timing Role: Always-on power management IC enabling >5-year coin-cell operation via ultralow IQ and efficient light-load Burst Mode. Use Value: 1.8µA no-load current and <10mV ripple preserve signal integrity and extend battery runtime beyond competitive solutions. |
Use Scenario: Enabling/disabling 5V supply to LNA and mixer stages in battery-operated IoT gateways to minimize standby power. IC Role / Device Role / Timing Role: Precision enable-controlled buck regulator with fast EN response (<10µs) and accurate PG flag for RF subsystem sequencing. Use Value: EN/UVLO hysteresis prevents chatter during enable transitions; PG flag synchronizes RF IC wake-up with valid 5V rail. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar fixed-output buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LMR36506RNXR | 65V input, 600mA, 26µA IQ, adjustable output only - requires external feedback resistors; no integrated catch diode. | Suitable for higher-input industrial systems but lacks fixed 5V option and ultralow IQ for battery use. | Select if >42V input or adjustable output needed; avoid when 5V fixed output and sub-3µA IQ are mandatory. |
| TPS6286518VRQYR | 18V input, 6A, 12µA IQ, fixed 5V, integrated MOSFETs - higher current but narrower input range and larger QFN package. | Better for high-current consumer applications; unsuitable for automotive 42V or cold-crank requirements. | Choose for space-constrained high-current designs with ≤18V input; not viable for 24V/42V automotive or industrial rails. |
Compared with LMR36506RNXR and TPS6286518VRQYR, the LT3973EDD-5#PBF uniquely combines 42V input capability, fixed 5V output, 2.5µA IQ, and integrated diodes - making it the only drop-in solution for thermally constrained, battery-sensitive automotive and industrial 5V point-of-load regulation.
Availability
LT3973EDD-5#PBF is available at Aetrix Electronics and suitable for automotive body electronics, industrial PLC power supplies, portable medical sensors, and gated RF front-end applications requiring stable component supply, long-term lifecycle support, and guaranteed -40°C to +125°C operation.
Supply support for LT3973EDD-5#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) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, serving automotive, industrial, communications, and healthcare markets.
The LT3973EDD-5#PBF belongs to Linear's high-voltage monolithic buck regulator product line, engineered specifically for demanding automotive and industrial applications where input voltage extremes, thermal stress, and ultra-low standby power are primary design constraints.
FAQ
What is the maximum input voltage rating for the LT3973EDD-5#PBF?
The LT3973EDD-5#PBF has an absolute maximum VIN rating of 42V, with continuous operation specified from 4.2V to 42V. It maintains regulation during automotive cold-crank events where input may dip to ~4.5V, thanks to its 530mV enforced dropout voltage and BOOST capacitor charge management. Exceeding 42V risks permanent damage per Absolute Maximum Ratings.
Does the LT3973EDD-5#PBF require external feedback resistors to set the 5V output?
No - the LT3973EDD-5#PBF is a fixed-output variant with internal resistor divider programmed for 5.00V ±1.2%. Pin 1 is labeled VOUT (not FB), and no external resistors are needed. This simplifies layout, improves accuracy over temperature, and eliminates resistor tolerance drift affecting output voltage.
How does the LT3973EDD-5#PBF achieve 2.5µA quiescent current?
The LT3973EDD-5#PBF achieves 2.5µA IQ through proprietary low-power bias circuitry, selective shutdown of non-essential blocks in light-load Burst Mode®, and optimized bipolar NPN switch design. At no load, it draws just 1.8µA, and the 2.5µA spec is measured at 12VIN→5VOUT with EN high - confirmed in Electrical Characteristics tables on page 3 of the datasheet.
What thermal considerations apply to the LT3973EDD-5#PBF in a 750mA application?
In a 750mA application at 12VIN→5VOUT, the LT3973EDD-5#PBF dissipates ~1.2W. With θJA = 40°C/W and 25°C ambient, junction temperature reaches ~73°C - well within its –40°C to +125°C rating. Full thermal performance requires soldering the exposed pad (Pin 11) to ≥200mm² of 2oz copper with 4+ thermal vias to inner ground planes.
Can the LT3973EDD-5#PBF be used with a 3.3V input supply?
No - the LT3973EDD-5#PBF requires a minimum input voltage of 4.2V for regulation. Below 4.2V, the internal reference and control circuitry cannot operate reliably. Attempting 3.3V input will result in unregulated output and potential instability. For lower-input applications, consider the LT8610 or similar 3V-input buck regulators.
LT3973EDD-5#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 10-WFDFN Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Fixed
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 4.2V
- Voltage - Input (Max):
- 42V
- Voltage - Output (Min/Fixed):
- 5V
- Voltage - Output (Max):
- -
- Current - Output:
- 750mA
- Frequency - Switching:
- 195kHz ~ 2.15MHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 10-DFN (3x3)
LT3973EDD-5#PBF FAQ
1.How can I place an order for LT3973EDD-5#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3973EDD-5#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 LT3973EDD-5#PBF reliable?
The price and inventory of LT3973EDD-5#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3973EDD-5#PBF is usually 5 days.
3.What payment methods are accepted for LT3973EDD-5#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3973EDD-5#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3973EDD-5#PBF?
LT3973EDD-5#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3973EDD-5#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 LT3973EDD-5#PBF?
For technical support, including LT3973EDD-5#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3973EDD-5#PBF requirements.
6.How does Aetrix verify that LT3973EDD-5#PBF is sourced from the original manufacturer or authorized distributors?
All LT3973EDD-5#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 LT3973EDD-5#PBF meets industry standards.
7.What is the process for return or replacement of LT3973EDD-5#PBF?
All LT3973EDD-5#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3973EDD-5#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 LT3973EDD-5#PBF part is unused and in its original packaging.
Return procedure for LT3973EDD-5#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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