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Analog Devices Inc. LT3973EDD#TRPBF
- Part No.:
- LT3973EDD#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 10-WFDFN Exposed Pad
- Datasheet:
-
LT3973EDD#TRPBF.pdf
- Description:
- IC REG BUCK ADJ 750MA 10DFN
- Quantity:
- Payment:
- Shipping:
Inventory:7,107
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Product details
Overview
LT3973EDD#TRPBF from Analog Devices (formerly Linear Technology) is a 42V, 750mA monolithic step-down DC/DC regulator with integrated power switch, catch diode, and boost diode. It delivers fixed 5V output at up to 750mA, operates from 4.2V–42V input, consumes only 2.5µA quiescent current, and maintains <10mVP-P output ripple in Burst Mode - ideal for automotive cold-crank battery regulation and low-power industrial supplies.
For engineers reviewing the LT3973EDD#TRPBF datasheet, LT3973EDD#TRPBF pinout, LT3973EDD#TRPBF application, or LT3973EDD#TRPBF equivalent, key selection criteria include its 530mV minimum dropout voltage, programmable UVLO threshold (1.19V), 200kHz–2.2MHz adjustable switching frequency, integrated diodes eliminating external components, and thermal shutdown protection in the 3mm × 3mm DFN package.
Technical Context
The LT3973EDD#TRPBF implements constant-frequency current-mode control with internal slope compensation, enabling fast transient response and stable loop behavior across wide input/output ratios. Its bipolar NPN main switch is driven by an on-chip charge pump (BOOST pin), allowing full saturation even at high duty cycles - critical for automotive dropout performance.
Burst Mode operation reduces quiescent current to 1.8µA at light loads while maintaining <10mVP-P output ripple; the power-good (PG) flag asserts when VOUT reaches 90% of regulation, and the catch diode current limit (1.15A typ.) provides fault protection during shorted-output conditions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.2V to 42V - supports automotive battery transients including cold-crank (down to ~3.5V start-up) and 24V/36V industrial rails. |
| Output Voltage | Fixed 5V ±1.2% - internally trimmed; no external feedback resistors required for standard 5V rail generation. |
| Max Output Current | 750mA - limited by internal switch and catch diode current limits; derated above 125°C junction temperature. |
| Quiescent Current | 2.5µA at 12VIN/3.3VOUT; 1.9µA at 12VIN - enables always-on systems with multi-year battery life. |
| Switching Frequency | 200kHz to 2.2MHz - set via RT-to-GND resistor; higher frequencies allow smaller magnetics but reduce max VIN/VOUT ratio. |
| Minimum Dropout Voltage | 530mV - enforced by internal comparator; ensures stable regulation and boost capacitor recharge during deep dropout. |
| Output Ripple (Burst Mode) | <10mVP-P - achieved without external LC filtering, simplifying EMI design in space-constrained applications. |
Pinout & Package
LT3973EDD#TRPBF is housed in a thermally enhanced 10-lead (3mm × 3mm) plastic DFN package with exposed pad (Pin 11 = GND). The exposed pad must be soldered to PCB for thermal and electrical integrity (θJA = 40°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Pin 1 (FB/VOUT) | Feedback / Fixed Output Sense | For LT3973EDD#TRPBF (5V variant), this pin is VOUT - internally connected to fixed 5V divider; no external resistors needed. |
| Pin 2 (OUT) | Dropout Regulation Node | Monitors output for dropout condition; ties to VOUT to enforce 530mV min. dropout; must be grounded if VOUT >14V. |
| Pin 3 (EN/UVLO) | Enable / Programmable Undervoltage Lockout | Active-high enable; 1.19V rising threshold with 30mV hysteresis; draws only 0.75µA in shutdown. |
| Pin 4 (VIN) | Main Power Input | Supplies internal circuitry and switch; requires local 4.7µF ceramic bypass; absolute max = 42V. |
| Pin 5 & 11 (GND) | Signal & Power Ground | Pin 5 = signal GND; Pin 11 = exposed thermal pad = GND - must be soldered to large copper area. |
| Pin 6 (SW) | Switch Node | Connects to inductor; carries high di/dt switching current; layout critical for EMI and efficiency. |
| Pin 7 (BOOST) | Charge Pump Drive | Drives external bootstrap capacitor to generate >VIN voltage for NPN switch saturation; max 55V rating. |
| Pin 8 (BD) | Boost Diode Anode Input | Accepts external bias (≥3.2V) to power internal regulator - improves efficiency vs. VIN-derived bias. |
| Pin 9 (PG) | Power Good Flag | Open-drain output; pulls low until VOUT reaches 90% of 5V (i.e., 4.5V); valid only when VIN >4.2V and EN high. |
| Pin 10 (RT) | Frequency Set | Resistor to GND sets switching frequency from 200kHz (732kΩ) to 2.2MHz (36.5kΩ). |
Key Features
| Feature | Design Value |
|---|---|
| Integrated Boost & Catch Diodes | Eliminates 2 external diodes - reduces BOM count, PCB area, and thermal stress in compact 3mm × 3mm DFN. |
| Low-Ripple Burst Mode | Maintains <10mVP-P output ripple at µA load currents - avoids audible noise and meets tight analog supply specs. |
| Accurate Programmable UVLO | 1.19V enable threshold with 30mV hysteresis - enables precise battery undervoltage cutoff without external comparators. |
| 530mV Minimum Dropout | Guarantees regulation during automotive cold-crank (e.g., 5.5VIN → 5VOUT) while sustaining boost capacitor charge. |
| Thermal Shutdown Protection | Activates at ~165°C junction temperature - prevents permanent damage during overload or poor heatsinking. |
Applications
| Automotive Battery Regulation | Industrial Sensor Power Supply |
|---|---|
|
Use Scenario: Powering CAN transceivers and microcontrollers in 12V vehicle systems during cold-crank (input drops to 3.5V–5V). IC Role / Device Role / Timing Role: Primary 5V buck regulator with ultra-low IQ and enforced dropout margin to sustain logic supply through cranking transients. Use Value: Maintains 5V output down to 5.5VIN with 530mV dropout; 2.5µA quiescent current extends battery life in parked-state monitoring. |
Use Scenario: Providing stable 5V rail to low-power industrial sensors (e.g., pressure, temperature) in remote 24V loop-powered installations. IC Role / Device Role / Timing Role: High-efficiency, low-noise DC/DC converter operating from wide-input industrial bus with minimal heat dissipation. Use Value: Delivers 750mA at >90% efficiency across 12V–36V input; integrated diodes eliminate layout-sensitive external components. |
| Portable Medical Device Power | Gate Drive Bias Supply |
|
Use Scenario: Generating clean 5V for microcontroller and ADC in battery-operated handheld diagnostics equipment. IC Role / Device Role / Timing Role: Always-on power management IC with Burst Mode for extended standby time and low-noise regulation during measurement cycles. Use Value: <10mVP-P ripple avoids ADC reference noise coupling; 1.9µA no-load IQ enables multi-year coin-cell operation. |
Use Scenario: Biasing high-side gate drivers in motor control inverters where isolated 5V is needed from main DC bus (e.g., 24V–42V). IC Role / Device Role / Timing Role: Compact, robust auxiliary supply with high input voltage tolerance and fast transient response to driver switching demands. Use Value: Withstands 42V transients; 750mA output supports multiple gate drivers; thermal shutdown protects against MOSFET shoot-through faults. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT8609SIV#TRPBF | 42V input, 2.5A output, 2.5µA IQ, synchronous rectification, 3mm × 4mm LQFN | Higher current, lower dropout (250mV), but requires external sync FET and has different pinout | Choose for >750mA loads or tighter dropout; not pin-compatible - requires PCB redesign. |
| TPS54340DDAR | 42V input, 3.5A output, 145µA IQ, external diode, SO-8 package | Higher current, higher IQ, no integrated catch diode - needs external Schottky and more board space | Choose for cost-sensitive high-current designs where 145µA IQ is acceptable; larger footprint and extra component. |
Compared with LT3973EDD#TRPBF, LT8609SIV offers higher current and lower dropout but lacks integrated diodes and requires layout changes, while TPS54340DDAR delivers triple the current at higher quiescent draw and external component overhead - making LT3973EDD#TRPBF optimal for space-constrained 5V/750mA applications demanding ultralow IQ and minimal BOM.
Availability
LT3973EDD#TRPBF is available at Aetrix Electronics and suitable for automotive battery regulation, industrial sensor power supplies, and portable medical device power requiring stable component supply with guaranteed long-term availability and traceable sourcing.
Supply support for LT3973EDD#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 the LT3973 family.
The LT3973 series was designed specifically for high-input-voltage, ultralow-quiescent-current DC/DC conversion in automotive and industrial environments where reliability under voltage transients and long battery life are critical.
FAQ
What is the output voltage of the LT3973EDD#TRPBF?
The LT3973EDD#TRPBF is the fixed 5V variant of the LT3973 family. Its output is precisely regulated to 5V ±1.2% over temperature and line/load conditions, with no external feedback resistors required - Pin 1 functions as VOUT, not FB, simplifying design and improving accuracy.
Does the LT3973EDD#TRPBF require external diodes?
No. The LT3973EDD#TRPBF integrates both the catch diode and boost diode on-die, eliminating the need for two external Schottky diodes. This reduces component count, PCB area, and potential failure points - a key advantage over controllers like the TPS54340DDAR that require external diodes.
What is the minimum input voltage required for the LT3973EDD#TRPBF to regulate 5V output?
The LT3973EDD#TRPBF requires a minimum input voltage of 5.53V to maintain 5V regulation under full load, based on its 530mV enforced dropout voltage (VIN ≥ VOUT + 530mV). It can start switching as low as ~3V, but regulation is only guaranteed above 5.53V when delivering 750mA.
How does the LT3973EDD#TRPBF achieve ultralow quiescent current?
The LT3973EDD#TRPBF achieves 2.5µA quiescent current through optimized bipolar process design, low-leakage internal circuitry, and intelligent Burst Mode operation - where non-essential blocks (oscillator, error amp, drivers) are fully powered down between switching bursts, reducing VIN current to just 1.8µA at no load.
Is the LT3973EDD#TRPBF pin-compatible with other LT3973 variants?
Yes - all LT3973 DFN-package variants (e.g., LT3973EDD#TRPBF, LT3973EDD-3.3#TRPBF, LT3973EDD-5#TRPBF) share identical 10-lead (3mm × 3mm) DFN pinouts and thermal pad layout. Only the internal feedback network differs: Pin 1 is VOUT (5V) for LT3973EDD#TRPBF, enabling drop-in replacement within the same output voltage family.
LT3973EDD#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 10-WFDFN 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):
- 4.2V
- Voltage - Input (Max):
- 42V
- Voltage - Output (Min/Fixed):
- 1.21V
- Voltage - Output (Max):
- 24V
- 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#TRPBF FAQ
1.How can I place an order for LT3973EDD#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3973EDD#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 LT3973EDD#TRPBF reliable?
The price and inventory of LT3973EDD#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3973EDD#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3973EDD#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3973EDD#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3973EDD#TRPBF?
LT3973EDD#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3973EDD#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 LT3973EDD#TRPBF?
For technical support, including LT3973EDD#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3973EDD#TRPBF requirements.
6.How does Aetrix verify that LT3973EDD#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3973EDD#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 LT3973EDD#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3973EDD#TRPBF?
All LT3973EDD#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3973EDD#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 LT3973EDD#TRPBF part is unused and in its original packaging.
Return procedure for LT3973EDD#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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