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Analog Devices Inc. LT3973EDD#PBF
- Part No.:
- LT3973EDD#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 10-WFDFN Exposed Pad
- Datasheet:
-
LT3973EDD#PBF.pdf
- Description:
- IC REG BUCK ADJ 750MA 10DFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,622
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Product details
Overview
LT3973EDD#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, and adjustable switching frequency (200kHz–2.2MHz). It delivers fixed 5V output in a thermally enhanced 10-lead (3mm × 3mm) DFN package and is designed for automotive cold-crank regulation where dropout performance and ultralow IQ are critical.
For engineers reviewing the LT3973EDD#PBF datasheet, LT3973EDD#PBF pinout, LT3973EDD#PBF application, or LT3973EDD#PBF equivalent, key selection considerations include its 530mV minimum dropout voltage, 1.21V feedback reference accuracy, power good flag timing behavior, and thermal derating limits in the –40°C to 125°C junction range.
Technical Context
The LT3973EDD#PBF implements constant-frequency current-mode control with internal bipolar NPN switch, integrated Schottky boost and catch diodes, and programmable undervoltage lockout (EN/UVLO threshold = 1.19V rising, 30mV hysteresis). Its Burst Mode® operation maintains <10mVP-P output ripple at light loads while drawing only 1.8µA input current.
Dropout regulation is enforced via an internal comparator that holds VOUT ≥ 530mV below VIN, enabling stable 5V output during automotive cold-crank (e.g., 5.6VIN → 5VOUT). The device uses a single external RT resistor to set switching frequency and requires no external bootstrap capacitor due to integrated charge pump drive on the BOOST pin.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.2V to 42V - supports wide automotive battery transients and industrial supply rails without external pre-regulation. |
| Output Voltage | Fixed 5V ±1.2% - factory-trimmed for LT3973EDD-5#PBF variant; eliminates external feedback resistors. |
| Max Output Current | 750mA - limited by internal switch peak current (1.65A typ.) and catch diode valley current (1.15A typ.). |
| Quiescent Current | 2.5µA at 12VIN → 5VOUT - enables always-on systems with multi-year battery life in portable or telematics applications. |
| Switching Frequency | 200kHz to 2.2MHz - set by RT resistor; higher frequencies allow smaller inductors (e.g., 15µH at 600kHz) but reduce max VIN/VOUT ratio. |
| Minimum Dropout Voltage | 530mV - ensures regulation down to VIN = 5.53V at 5VOUT; critical for start-stop and cold-crank automotive operation. |
| Power Good Threshold | 90% of regulated output - PG pin asserts open-drain low until VFB reaches 1.089V (for 5V), enabling reliable system sequencing. |
Pinout & Package
LT3973EDD#PBF is housed in a 10-lead (3mm × 3mm) plastic DFN package with exposed thermal pad (Pin 11 = GND). The package provides θJA = 40°C/W and θJC = 5°C/W, requiring PCB copper thermal relief for sustained 750mA operation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Pin 1 (FB) | Feedback reference input | Regulated to 1.21V; unused in LT3973EDD-5#PBF (fixed-output variant), internally connected to divider network. |
| Pin 2 (OUT) | Output voltage sense & boost capacitor return | Must be tied to VOUT for dropout regulation; supplies charge current to BOOST capacitor during switch-off. |
| Pin 3 (EN/UVLO) | Enable and programmable UVLO input | Active-high enable; 1.19V rising threshold with 30mV hysteresis; draws ≤30nA - allows high-impedance bias networks. |
| Pin 4 (VIN) | Main power input | Supplies internal circuitry and switch driver; absolute max = 42V; requires local 4.7µF X7R ceramic bypass. |
| Pin 5 / Pin 11 (GND) | Signal and power ground | Exposed pad (Pin 11) must be soldered to PCB ground plane for thermal and EMI performance. |
| Pin 6 (SW) | Switch node | Connects to inductor; carries high di/dt; requires tight layout and Kelvin connection to minimize ringing. |
| Pin 7 (BOOST) | Bootstrap drive voltage | Internally driven above SW to fully saturate bipolar NPN switch; requires 0.47µF ceramic capacitor to SW. |
| Pin 8 (BD) | Bias diode anode | Accepts external bias >3.2V (e.g., from VOUT) to improve efficiency; also powers internal regulator. |
| Pin 9 (PG) | Power good open-drain flag | Sinks ≥220µA when asserted low; requires external pull-up; valid only when VIN > 4.2V and EN/UVLO high. |
| Pin 10 (RT) | Frequency programming | Resistor to GND sets switching frequency; 215kΩ yields ~600kHz per datasheet Table 1. |
Key Features
| Feature | Design Value |
|---|---|
| Ultralow quiescent current | 2.5µA IQ enables >10-year battery life in always-on automotive modules (e.g., CAN bus nodes, telematics). |
| Integrated boost and catch diodes | Eliminates 2 external Schottky diodes; reduces BOM count, board area, and thermal stress in compact DFN layout. |
| Low-ripple Burst Mode® operation | Maintains <10mVP-P output ripple at light loads while preserving 85%+ efficiency - critical for noise-sensitive analog/RF circuits. |
| Accurate programmable undervoltage lockout | EN/UVLO threshold tolerance ±30mV ensures predictable startup across temperature and supply variation. |
| Thermal shutdown with fault recovery | Auto-restarts after junction cools below 145°C; prevents latch-up during transient overloads or poor heatsinking. |
| Power good flag with hysteresis | 10% PG hysteresis (0.8% of VOUT) prevents chatter during marginal regulation; supports safe microcontroller reset sequencing. |
Applications
| Automotive Cold-Crank Regulation | Industrial 24V Rail Conversion |
|---|---|
|
Use Scenario: Powering infotainment head units during engine cranking, where battery voltage dips to 5.6V for 100ms. IC Role / Device Role / Timing Role: Primary 5V buck regulator maintaining stable output despite rapid VIN sag; enforces 530mV dropout to sustain regulation. Use Value: Prevents system brownout and microcontroller reset during cranking - validated at –40°C to 125°C junction temperature. |
Use Scenario: Converting unregulated 24V industrial supply to clean 5V for PLC I/O modules operating in harsh EMI environments. IC Role / Device Role / Timing Role: High-efficiency DC/DC converter with integrated diodes reducing component count and improving reliability over discrete solutions. Use Value: Delivers 750mA at >92% efficiency (12V→5V) with <10mV ripple, eliminating need for post-LDO filtering in noise-sensitive analog front-ends. |
| Portable Medical Device Bias | Gate Drive Bias Supply |
|
Use Scenario: Providing 5V bias to low-power ADCs and sensors in battery-operated glucose meters with 10-year shelf life. IC Role / Device Role / Timing Role: Ultralow-IQ step-down regulator minimizing standby drain; operates in Burst Mode® at µA-level loads. Use Value: 1.8µA shutdown current and 2.5µA operating IQ extend primary Li-SOCl₂ battery life beyond specification requirements. |
Use Scenario: Generating isolated 5V gate drive for high-side MOSFETs in motor control inverters using bootstrap topology. IC Role / Device Role / Timing Role: Dedicated auxiliary supply with fast transient response (<10µs) and robust short-circuit protection via catch diode current limiting. Use Value: Integrated catch diode withstands 1.15A reverse current, preventing shoot-through during high dv/dt switching events. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3630EMSE-5#PBF | Same 5V fixed output, but 3.5V–40V input range; 15µA IQ; no integrated catch diode; MSOP-10 package. | Lacks integrated catch diode - requires external Schottky; higher IQ reduces battery life in always-on use cases. | Choose if board space allows external diode and thermal design accommodates higher power loss at light loads. |
| TPS54360BDDAR | 4.5V–60V input; 3.5A output; 145µA IQ; external diode required; SOIC-8 package. | Higher current capability but 58× higher quiescent current; no power good flag or programmable UVLO. | Choose only for high-current industrial supplies where ultralow IQ and automotive qualification are not required. |
Compared with LTC3630EMSE-5#PBF and TPS54360BDDAR, the LT3973EDD#PBF uniquely combines 5V fixed output, 2.5µA IQ, integrated diodes, and automotive-grade temperature range in a compact DFN - making it optimal for space-constrained, battery-sensitive, and cold-crank-critical designs.
Availability
LT3973EDD#PBF is available at Aetrix Electronics and suitable for automotive battery regulation, industrial 24V rail conversion, and portable medical device bias requiring stable component supply across extended temperature and long-lifecycle programs.
Supply support for LT3973EDD#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 LT3973 family.
The LT3973 series was designed specifically for high-reliability automotive and industrial DC/DC conversion where ultralow quiescent current, integrated diodes, and robust cold-crank performance are mandatory.
FAQ
What is the guaranteed operating temperature range for LT3973EDD#PBF?
The LT3973EDD#PBF is specified for –40°C to 125°C junction temperature. This grade (E-grade) is validated across the full range for electrical parameters including feedback voltage (1.195V–1.225V), EN/UVLO threshold (1.09V–1.23V), and power good accuracy (±10%). Derating applies above 125°C per θJA = 40°C/W.
Does LT3973EDD#PBF require external diodes?
No. The LT3973EDD#PBF integrates both the boost Schottky diode (anode on BD pin) and catch Schottky diode (cathode on SW pin). These are rated for 1.15A valley current and 25V reverse voltage, eliminating two external components and associated layout complexity.
How is the 5V output set on LT3973EDD#PBF?
The LT3973EDD#PBF is the fixed 5V variant (LT3973EDD-5#PBF). Its output is factory-trimmed to 5.00V ±1.2% (4.94V–5.06V) using an internal resistor divider - no external FB resistors are needed or supported. Pin 1 (FB) is internally connected and not user-accessible.
What is the minimum input voltage required for LT3973EDD#PBF to regulate 5V output?
The LT3973EDD#PBF requires a minimum input voltage of 5.53V to maintain 5V regulation under dropout conditions, based on its 530mV minimum dropout voltage. Below this, the output follows VIN minus dropout. Startup occurs as low as 3V, but regulation is not guaranteed until VIN ≥ 4.2V.
Can LT3973EDD#PBF be synchronized to an external clock?
No. The LT3973EDD#PBF uses an internal oscillator controlled by the RT resistor and does not support external clock synchronization. Frequency is adjustable from 200kHz to 2.2MHz via RT, but no SYNC pin or phase-lock capability is provided.
LT3973EDD#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:
- 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#PBF FAQ
1.How can I place an order for LT3973EDD#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3973EDD#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#PBF reliable?
The price and inventory of LT3973EDD#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#PBF is usually 5 days.
3.What payment methods are accepted for LT3973EDD#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3973EDD#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3973EDD#PBF?
LT3973EDD#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3973EDD#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#PBF?
For technical support, including LT3973EDD#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3973EDD#PBF requirements.
6.How does Aetrix verify that LT3973EDD#PBF is sourced from the original manufacturer or authorized distributors?
All LT3973EDD#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#PBF meets industry standards.
7.What is the process for return or replacement of LT3973EDD#PBF?
All LT3973EDD#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3973EDD#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#PBF part is unused and in its original packaging.
Return procedure for LT3973EDD#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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