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Analog Devices Inc. LT3973EDD-3.3#TRPBF
- Part No.:
- LT3973EDD-3.3#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 10-WFDFN Exposed Pad
- Datasheet:
-
LT3973EDD-3.3#TRPBF.pdf
- Description:
- IC REG BUCK 3.3V 750MA 10DFN
- Quantity:
- Payment:
- Shipping:
Inventory:3,181
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Product details
Overview
LT3973EDD-3.3#TRPBF from Analog Devices (formerly Linear Technology) is a 42V, 750mA monolithic step-down regulator with fixed 3.3V output, integrated boost and catch diodes, and ultralow 2.5µA quiescent current at 12VIN. It employs current-mode control for fast transient response and maintains regulation down to 530mV dropout-critical for automotive cold-crank scenarios.
For engineers reviewing the LT3973EDD-3.3#TRPBF datasheet, LT3973EDD-3.3#TRPBF pinout, LT3973EDD-3.3#TRPBF application, or LT3973EDD-3.3#TRPBF equivalent, key selection criteria include its 3.3V fixed output accuracy (±1.2% over temperature), 10-lead 3mm × 3mm DFN package with exposed thermal pad, Burst Mode® operation for <10mVP-P ripple at light load, and programmable UVLO via EN/UVLO pin.
Technical Context
The LT3973EDD-3.3#TRPBF uses a constant-frequency current-mode architecture with adjustable switching frequency (200kHz–2.2MHz) set by an external RT resistor. Its internal bipolar NPN switch is driven by a charge-pump boosted gate voltage, enabling full saturation even during low-VIN dropout conditions.
It integrates both catch and boost Schottky diodes, eliminating external components while supporting low-ripple Burst Mode® operation below ~100mA load. A dedicated power-good (PG) open-drain flag asserts when VOUT reaches 90% of regulation, and thermal shutdown plus catch-diode current limiting provide fault protection.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 3.3V ±1.2% over –40°C to 125°C junction range; eliminates external feedback resistors. |
| Input Voltage Range | 4.2V to 42V continuous; supports wide automotive and industrial supply rails. |
| Quiescent Current | 2.5µA at 12VIN/3.3VOUT; enables always-on systems with multi-year battery life. |
| Max Output Current | 750mA DC; limited by switch peak current (1.65A typ.) and catch diode valley current (1.15A typ.). |
| Switching Frequency | Programmable 200kHz–2.2MHz via RT pin; allows optimization of size vs. efficiency vs. EMI. |
| Dropout Voltage | 530mV minimum (VIN – VOUT); ensures regulation during automotive cold-crank (e.g., 5.5VIN → 3.3VOUT). |
| Output Ripple | <10mVP-P in Burst Mode®; meets noise-sensitive analog and RF supply requirements. |
Pinout & Package
LT3973EDD-3.3#TRPBF is housed in a thermally enhanced 10-lead (3mm × 3mm) plastic DFN package with exposed GND pad (Pin 11), requiring PCB soldering for thermal and electrical integrity. θJA = 40°C/W, θJC = 5°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VOUT (Pin 1) | Fixed-output voltage reference node | Internally regulated to 3.3V; connects directly to output capacitor-no external divider needed. |
| OUT (Pin 2) | Dropout regulation and boost capacitor charging node | Tied to VOUT to enable 530mV dropout mode; supplies current to charge BOOST capacitor during startup. |
| EN/UVLO (Pin 3) | Enable and programmable undervoltage lockout input | Active-high enable; threshold 1.19V rising with 30mV hysteresis; sets shutdown current to 0.75µA. |
| VIN (Pin 4) | Main power input | Supplies internal circuitry and switch; must be locally bypassed with ≥4.7µF ceramic capacitor. |
| GND (Pin 5 & Exposed Pad 11) | Power and signal ground reference | Exposure pad is electrically GND and mandatory for thermal performance and noise immunity. |
| SW (Pin 6) | Internal switch drain node | Connects to inductor; switches between VIN and GND; carries high di/dt current-requires short, low-inductance trace. |
| BOOST (Pin 7) | Charge-pump bootstrap drive voltage | Driven by external capacitor to ~VIN + 10V; ensures full saturation of internal bipolar NPN switch. |
| BD (Pin 8) | Boost diode anode and bias regulator input | Accepts external bias >3.2V (e.g., from VOUT) to improve efficiency by powering internal regulator externally. |
| PG (Pin 9) | Open-drain power-good flag | Asserts high (via external pull-up) when VOUT reaches 90% of 3.3V; valid only if VIN >4.2V and EN/UVLO high. |
| RT (Pin 10) | Frequency-setting resistor connection | Resistor to GND programs switching frequency; e.g., 215kΩ sets 600kHz per datasheet Table 1. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated boost and catch Schottky diodes | Eliminates 2 external diodes, reduces BOM count and board area, and improves reliability in harsh environments. |
| Burst Mode® operation | Maintains <10mVP-P output ripple at light loads while drawing only 1.8µA input current-ideal for IoT sleep modes. |
| Accurate programmable UVLO | EN/UVLO pin allows system-level brown-out detection with 30mV hysteresis, preventing erratic startup in fluctuating supplies. |
| Thermal shutdown and current limiting | Combines catch-diode valley current limit (1.15A typ.) and thermal foldback to protect against short-circuit and overload faults. |
| Power-good (PG) flag with hysteresis | Provides clean, glitch-free system reset signaling with 0.8% hysteresis-enables safe microcontroller boot sequencing. |
Applications
| Automotive Body Control Module | Industrial Sensor Node Power |
|---|---|
Use Scenario: Powering CAN transceiver, microcontroller, and LIN interface in door module under cold-crank (5.5VIN) and load-dump (42VIN) conditions. IC Role / Device Role / Timing Role: Primary 3.3V system rail regulator with dropout recovery and transient robustness. Use Value: Maintains 3.3V regulation down to 5.5VIN (530mV dropout), survives 42V transients, and draws only 2.5µA in sleep-extending battery backup life. |
Use Scenario: Supplying low-power MCU, ADC, and wireless SoC in remote environmental sensor with 10-year battery target. IC Role / Device Role / Timing Role: Always-on 3.3V buck converter operating in Burst Mode® during 99% duty-cycle sleep. Use Value: 1.8µA no-load current and <10mVP-P ripple ensure stable ADC references and low-noise RF transmission without compromising battery life. |
| Portable Medical Diagnostic Device | Gate Drive Bias Supply |
Use Scenario: Powering precision analog front-end (AFE), display controller, and Bluetooth LE radio in handheld ultrasound probe. IC Role / Device Role / Timing Role: Low-noise, fixed 3.3V supply with tight output tolerance and fast load transient response. Use Value: ±1.2% output accuracy and 200ns typical response to 100mA load steps ensure stable AFE bias and accurate signal acquisition. |
Use Scenario: Generating isolated 3.3V bias for high-side gate drivers in motor inverter control stage. IC Role / Device Role / Timing Role: Compact, high-reliability auxiliary supply decoupled from main DC bus. Use Value: Integrated diodes and 42V input rating allow direct derivation from 24V or 48V bus; DFN package enables dense layout near gate driver ICs. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT8609SIS8E#TRPBF | 42V input, 3.3V fixed, 2A output; synchronous rectification; 2.5µA IQ; 3mm × 4mm SOIC-8 package. | Higher output current and smaller footprint; lacks integrated boost diode-requires external bootstrap cap. | Select when >750mA load or tighter layout constraints exist; verify external bootstrap design for dropout operation. |
| TPS54332DDAR | 28V input, 3.3V fixed, 3A output; external MOSFETs; 19µA IQ; 8-pin SOIC package. | Higher current and lower cost; significantly higher quiescent current limits battery-life applications. | Choose for cost-sensitive industrial supplies where 19µA IQ is acceptable and 28V max input suffices. |
Compared with LT3973EDD-3.3#TRPBF, LT8609SIS8E#TRPBF delivers 2x output current in a slightly larger but more thermally efficient package, while TPS54332DDAR offers higher current at the expense of 7.6× higher quiescent current-making LT3973EDD-3.3#TRPBF optimal for ultra-low-power, high-input-voltage, space-constrained designs.
Availability
LT3973EDD-3.3#TRPBF is available at Aetrix Electronics and suitable for automotive body electronics, industrial sensor nodes, portable medical diagnostics, and gate drive bias supplies requiring stable component supply across extended temperature ranges (–40°C to 125°C).
Supply support for LT3973EDD-3.3#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, Inc. (ADI) acquired Linear Technology in 2017 and continues to develop high-performance power management ICs with emphasis on efficiency, integration, and ruggedness.
The LT3973 family was designed specifically for demanding automotive and industrial applications requiring wide input voltage range, ultralow quiescent current, and robust fault protection-without external diodes or complex compensation.
FAQ
What is the guaranteed output voltage accuracy of the LT3973EDD-3.3#TRPBF over temperature?
The LT3973EDD-3.3#TRPBF guarantees a 3.3V output with ±1.2% accuracy across its full operating junction temperature range of –40°C to 125°C, as specified in the Electrical Characteristics table (VOUT = 3.26V to 3.366V). This accuracy is achieved using an internal trimmed feedback divider, eliminating external resistor tolerance errors.
Can the LT3973EDD-3.3#TRPBF operate with input voltages below 4.2V?
Yes-the LT3973EDD-3.3#TRPBF begins switching at ~3V input but does not regulate to 3.3V until VIN exceeds 4.2V. Below this threshold, the FB reference degrades and output voltage drops proportionally; regulation resumes fully once VIN rises above 4.2V, as confirmed in the Typical Performance Characteristics (Figure G22).
How does the LT3973EDD-3.3#TRPBF achieve 530mV dropout performance?
The LT3973EDD-3.3#TRPBF achieves 530mV dropout by tying the OUT pin to VOUT, which activates an internal comparator that enforces a minimum (VIN – VOUT) difference. This ensures the boost capacitor remains charged during low-VIN conditions, allowing the internal bipolar NPN switch to stay saturated and maintain regulation-even at 5.5VIN → 3.3VOUT.
Is an external boost capacitor required for the LT3973EDD-3.3#TRPBF?
Yes-an external 15pF ceramic capacitor is required between BOOST and SW pins. This capacitor forms the charge pump that generates the boosted gate drive voltage (~VIN + 10V) necessary to fully saturate the internal bipolar NPN switch, especially critical during dropout and high-current operation.
Does the LT3973EDD-3.3#TRPBF support synchronization to an external clock?
No-the LT3973EDD-3.3#TRPBF does not support external clock synchronization. Its switching frequency is set solely by the resistor connected between RT and GND, with a programmable range of 200kHz to 2.2MHz. Synchronization capability is absent in the block diagram, pin functions, and Applications Information sections of the datasheet.
LT3973EDD-3.3#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:
- Fixed
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 4.2V
- Voltage - Input (Max):
- 42V
- Voltage - Output (Min/Fixed):
- 3.3V
- 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-3.3#TRPBF FAQ
1.How can I place an order for LT3973EDD-3.3#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3973EDD-3.3#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-3.3#TRPBF reliable?
The price and inventory of LT3973EDD-3.3#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-3.3#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3973EDD-3.3#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3973EDD-3.3#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3973EDD-3.3#TRPBF?
LT3973EDD-3.3#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3973EDD-3.3#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-3.3#TRPBF?
For technical support, including LT3973EDD-3.3#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3973EDD-3.3#TRPBF requirements.
6.How does Aetrix verify that LT3973EDD-3.3#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3973EDD-3.3#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-3.3#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3973EDD-3.3#TRPBF?
All LT3973EDD-3.3#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3973EDD-3.3#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-3.3#TRPBF part is unused and in its original packaging.
Return procedure for LT3973EDD-3.3#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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