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Analog Devices Inc. LT3973HDD-5#PBF
- Part No.:
- LT3973HDD-5#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 10-WFDFN Exposed Pad
- Datasheet:
-
LT3973HDD-5#PBF.pdf
- Description:
- IC REG BUCK 5V 750MA 10DFN
- Quantity:
- Payment:
- Shipping:
Inventory:3,803
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Product details
Overview
LT3973HDD-5#PBF from Analog Devices (formerly Linear Technology) is a 42V, 750mA monolithic step-down DC/DC regulator with integrated boost and catch diodes, 2.5µA quiescent current, fixed 5V output, and operation up to 150°C junction temperature - designed for automotive cold-crank battery regulation and industrial power supplies.
For engineers reviewing the LT3973HDD-5#PBF datasheet, LT3973HDD-5#PBF pinout, LT3973HDD-5#PBF application, or LT3973HDD-5#PBF equivalent, key selection criteria include its 530mV minimum dropout voltage, programmable undervoltage lockout, low-ripple Burst Mode® operation, and thermal robustness in 3mm × 3mm DFN packaging.
Technical Context
The LT3973HDD-5#PBF implements constant-frequency current-mode control with adjustable switching frequency (200kHz–2.2MHz via RT pin), enabling fast transient response and stable loop behavior across wide input ranges. Its internal bipolar NPN switch is driven by a charge-pump boosted gate voltage, sustaining full saturation even during automotive dropout events.
Burst Mode® operation reduces quiescent current to 1.8µA at light loads while maintaining output ripple below 10mVP-P; the power-good flag asserts when VOUT reaches 90% of 5V, and an integrated catch diode current limit (1.15A typ.) provides short-circuit protection without external components.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 5.0V ±1.2% over –40°C to 150°C; enables direct replacement of LDOs in 5V rail generation. |
| Input Voltage Range | 4.2V to 42V; supports 12V/24V/36V automotive and industrial battery inputs including cold-crank transients. |
| Quiescent Current | 2.5µA at 12VIN → 5VOUT; sustains ultra-low standby power in always-on systems. |
| Switching Frequency | 200kHz–2.2MHz (RT-programmable); allows optimization of inductor size vs. EMI vs. efficiency. |
| Max Output Current | 750mA continuous; limited by thermal design and internal switch/catch diode current limits. |
| Minimum Dropout | 530mV at full load; maintains regulation down to VIN = 5.53V, critical for automotive start-stop operation. |
| Operating Temp | –40°C to +150°C junction; qualified for under-hood automotive and high-temp industrial environments. |
Pinout & Package
LT3973HDD-5#PBF uses a thermally enhanced 10-lead (3mm × 3mm) plastic DFN package with exposed pad (Pin 11) soldered to PCB ground for optimal thermal performance (θJA = 40°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| FB/VOUT (Pin 1) | Feedback / Fixed-output sense | For LT3973HDD-5#PBF, this is VOUT pin - internally connected to fixed 5V divider; no external resistors required. |
| OUT (Pin 2) | Dropout regulation node | Tied to VOUT to enforce ≥530mV dropout; must be grounded if output >14V (not applicable here). |
| EN/UVLO (Pin 3) | Enable & programmable UVLO input | Active-high enable with 1.19V rising threshold and 30mV hysteresis; supports battery undervoltage detection. |
| VIN (Pin 4) | Main power input | Supplies internal circuitry and switch; rated to 42V absolute max; requires local 4.7µF ceramic bypass. |
| GND (Pin 5 & Exposed Pad 11) | Power and signal reference | Exposure pad is GND and must be soldered to PCB thermal plane for reliability and thermal derating. |
| SW (Pin 6) | Switch node | Connects to inductor; carries high di/dt switching current; layout critical for EMI and efficiency. |
| BOOST (Pin 7) | Charge-pump bootstrap supply | Drives internal NPN switch base above VIN; requires 0.47µF ceramic capacitor to SW. |
| BD (Pin 8) | Bias diode anode input | Accepts external bias (≥3.2V) to improve efficiency; otherwise draws from VIN. |
| PG (Pin 9) | Open-drain power-good flag | Asserts high when VOUT ≥ 4.5V (90% of 5V); requires external pull-up for system monitoring. |
| RT (Pin 10) | Frequency set resistor | Resistor to GND sets switching frequency; e.g., 215kΩ yields ~600kHz per datasheet table. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated boost & catch diodes | Eliminates 2 external diodes, reducing BOM count, board area, and forward-drop losses. |
| Low-ripple Burst Mode® | Maintains <10mVP-P output ripple at light loads while drawing only 1.8µA, ideal for sensor sleep modes. |
| Accurate programmable UVLO | EN/UVLO threshold (1.19V ±70mV) enables precise battery brown-out detection without external comparators. |
| Thermal shutdown & current limiting | Combines catch diode valley-current limit (1.15A) and thermal shutdown to protect against shorts and overloads. |
| Power-good flag with hysteresis | PG asserts at 90% of 5V (4.5V) with 0.8% hysteresis, providing clean system reset signaling without external supervision ICs. |
Applications
| Automotive Battery Regulation | Industrial Power Supply |
|---|---|
Use Scenario: Regulating 12V/24V vehicle battery to stable 5V for infotainment MCU, CAN transceivers, and sensors during cold-crank (down to 3.5V battery). IC Role / Device Role / Timing Role: Primary buck regulator with dropout recovery, UVLO monitoring, and PG signaling for system sequencing. Use Value: 530mV dropout ensures uninterrupted 5V operation at VIN = 5.53V; 150°C rating supports under-hood placement. | Use Scenario: Generating 5V from unregulated 24V factory-floor power bus for PLC I/O modules and fieldbus interfaces. IC Role / Device Role / Timing Role: High-reliability DC/DC converter with integrated protection, immune to line surges and thermal stress. Use Value: 42V abs-max input withstands 36V transients; 2.5µA IQ extends backup battery life in fail-safe controllers. |
| Gate Drive Bias Supply | Portable Product Power |
Use Scenario: Providing isolated 5V bias for high-side MOSFET drivers in motor-control half-bridges powered from 12–42V battery packs. IC Role / Device Role / Timing Role: Compact, efficient auxiliary supply with low noise and fast transient response to support gate charging. Use Value: Integrated diodes eliminate reverse-recovery noise; Burst Mode® prevents idle power waste during PWM dead-time. | Use Scenario: Powering 5V microcontrollers and wireless SoCs in battery-operated test equipment with multi-year shelf life requirements. IC Role / Device Role / Timing Role: Ultra-low-IQ step-down regulator enabling long-term storage and instant wake-up capability. Use Value: 1.8µA Burst Mode® current extends primary Li-ion battery life beyond 10 years in deep-sleep states. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3973IDD-5#PBF | Same electrical specs but rated for –40°C to 125°C junction; lower thermal robustness than H-grade. | Suitable for cabin electronics or non-under-hood industrial use where ambient <125°C. | Select when cost sensitivity outweighs need for 150°C operation; identical pinout and layout. |
| LM5164QPWPRQ1 | 4.5–65V input, 500mA, 1.5µA IQ, but no integrated catch diode; requires external Schottky. | Better for higher-input-voltage automotive apps (>42V), but adds BOM cost and layout complexity. | Choose only if input exceeds 42V or if external diode control is preferred; not pin-compatible. |
Compared with LT3973IDD-5#PBF, the LT3973HDD-5#PBF delivers guaranteed 150°C operation and superior thermal margin; versus LM5164QPWPRQ1, it offers lower system-level cost and smaller footprint due to integrated diodes and simpler layout, despite narrower input range.
Availability
LT3973HDD-5#PBF is available at Aetrix Electronics and suitable for automotive battery regulation, industrial power supplies, gate drive bias, and portable product power requiring stable component supply across extended temperature ranges.
Supply support for LT3973HDD-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 and continues to develop high-performance analog, power management, and mixed-signal ICs for demanding applications.
The LT3973 family was designed specifically for high-input-voltage, low-quiescent-current buck conversion in automotive and industrial environments where reliability under thermal and voltage stress is critical.
FAQ
What is the maximum input voltage rating for LT3973HDD-5#PBF?
The LT3973HDD-5#PBF has an absolute maximum VIN rating of 42V. It operates continuously from 4.2V to 42V, making it suitable for 12V/24V/36V automotive and industrial systems. Transient overvoltage tolerance is limited by internal clamp structures - sustained operation above 42V may cause permanent damage.
Does LT3973HDD-5#PBF require external feedback resistors?
No. The LT3973HDD-5#PBF is the fixed 5V variant; its FB/VOUT pin (Pin 1) connects internally to a precision resistor divider. Unlike the adjustable LT3973, no external R1/R2 network is needed - simplifying design and improving output accuracy over temperature.
How does the power-good (PG) flag behave on LT3973HDD-5#PBF?
The PG pin on LT3973HDD-5#PBF is an open-drain output that pulls low until VOUT reaches 4.5V (90% of 5V). It remains valid only when EN/UVLO is high and VIN > 4.2V. A typical 10kΩ pull-up to 5V provides clean reset signaling for microcontrollers or FPGAs.
What thermal considerations apply to LT3973HDD-5#PBF in a 150°C environment?
LT3973HDD-5#PBF is specified for –40°C to +150°C junction temperature. To achieve this, the exposed pad (Pin 11) must be soldered to a minimum 200mm² copper thermal pad with ≥4 thermal vias. Derating is required above 125°C - consult the datasheet's lifetime vs. TJ curve for reliability modeling.
Can LT3973HDD-5#PBF operate in dropout mode, and what is its minimum dropout voltage?
Yes. When the OUT pin is tied to VOUT, LT3973HDD-5#PBF enforces a minimum dropout voltage of 530mV (typ.) - meaning it regulates down to VIN = 5.53V. This is achieved via internal dropout comparator and extended duty cycle control, ensuring stable 5V output during automotive cranking events.
LT3973HDD-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 ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 10-DFN (3x3)
LT3973HDD-5#PBF FAQ
1.How can I place an order for LT3973HDD-5#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3973HDD-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 LT3973HDD-5#PBF reliable?
The price and inventory of LT3973HDD-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 LT3973HDD-5#PBF is usually 5 days.
3.What payment methods are accepted for LT3973HDD-5#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3973HDD-5#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3973HDD-5#PBF?
LT3973HDD-5#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3973HDD-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 LT3973HDD-5#PBF?
For technical support, including LT3973HDD-5#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3973HDD-5#PBF requirements.
6.How does Aetrix verify that LT3973HDD-5#PBF is sourced from the original manufacturer or authorized distributors?
All LT3973HDD-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 LT3973HDD-5#PBF meets industry standards.
7.What is the process for return or replacement of LT3973HDD-5#PBF?
All LT3973HDD-5#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3973HDD-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 LT3973HDD-5#PBF part is unused and in its original packaging.
Return procedure for LT3973HDD-5#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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