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Analog Devices Inc. LT3973HDD-5#TRPBF
- Part No.:
- LT3973HDD-5#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 10-WFDFN Exposed Pad
- Datasheet:
-
LT3973HDD-5#TRPBF.pdf
- Description:
- IC REG BUCK 5V 750MA 10DFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,296
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Product details
Overview
LT3973HDD-5#TRPBF from Analog Devices (formerly Linear Technology) is a 42V, 750mA monolithic step-down DC/DC regulator with integrated boost and catch Schottky diodes, 2.5µA quiescent current, and fixed 5V output. It operates from 4.2V to 42V input, maintains regulation down to 530mV dropout, and delivers stable power in automotive cold-crank and industrial supply applications.
For engineers reviewing the LT3973HDD-5#TRPBF datasheet, LT3973HDD-5#TRPBF pinout, LT3973HDD-5#TRPBF application, or LT3973HDD-5#TRPBF equivalent, key selection criteria include its H-grade 150°C junction rating, low-ripple Burst Mode™ operation (<10mVP-P), programmable UVLO, power-good flag, and thermally enhanced 3mm × 3mm DFN package with exposed pad.
Technical Context
The LT3973HDD-5#TRPBF implements constant-frequency current-mode control with adjustable switching frequency (200kHz–2.2MHz) via external RT resistor. Its bipolar NPN internal switch is driven by a charge-pump boosted gate voltage, enabling full saturation even at high duty cycles up to ~97.5%.
It integrates dual protection mechanisms: catch diode valley-current limiting (1.15A typ.) for short-circuit fault containment, and thermal shutdown. The device uses an internal 1.21V reference for feedback regulation and features accurate 90% power-good detection referenced to output voltage.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 5.00V ±1.2% over –40°C to 150°C; enables direct replacement of linear regulators without external feedback resistors. |
| Input Voltage Range | 4.2V to 42V continuous; supports wide automotive battery transients including cold-crank (down to ~3.8V start-up). |
| Quiescent Current | 2.5µA at 12VIN/5VOUT; sustains ultra-low-power standby in always-on systems like telematics or ECU wake logic. |
| Max Output Current | 750mA continuous; limited by thermal design and switch/catch diode current limits (1.65A peak / 1.15A valley). |
| Dropout Voltage | 530mV minimum (VIN – VOUT); ensures regulation during deep input sags while maintaining boost capacitor charge. |
| Switching Frequency | Programmable 200kHz–2.2MHz via RT pin; allows optimization of inductor size vs. efficiency for space-constrained designs. |
| Operating Junction Temp | –40°C to +150°C (H-grade); qualified for under-hood automotive and high-ambient industrial environments. |
Pinout & Package
LT3973HDD-5#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 |
|---|---|---|
| FB/VOUT (Pin 1) | Fixed-output voltage sense node | Internally connected to 5V feedback divider; no external resistors required-simplifies layout and improves accuracy. |
| OUT (Pin 2) | Dropout regulation reference | Enables minimum dropout enforcement (530mV) when tied to output; critical for cold-crank performance. |
| EN/UVLO (Pin 3) | Enable and undervoltage lockout input | 1.19V rising threshold with 45mV hysteresis; allows precise system-level power sequencing and brown-out protection. |
| VIN (Pin 4) | Main power input | Supplies internal circuitry and switch; must be locally bypassed with ≥4.7µF X7R ceramic for stability. |
| GND (Pin 5 & 11) | Power and signal ground | Exposed pad (Pin 11) is mandatory GND connection-failure to solder degrades thermal performance and reliability. |
| SW (Pin 6) | Switch node | Drives external inductor; high dv/dt node requiring tight layout and minimized loop area to reduce EMI. |
| BOOST (Pin 7) | Charge-pump bootstrap supply | Requires external 0.47µF ceramic capacitor to SW; enables full NPN switch saturation across full input range. |
| BD (Pin 8) | Bias diode anode | Accepts external bias >3.2V (e.g., from VOUT) to improve light-load efficiency by powering internal regulator. |
| PG (Pin 9) | Open-drain power-good flag | Asserts high when VOUT reaches 90% of 5V; used for system reset, sequencing, or fault monitoring. |
| RT (Pin 10) | Frequency programming input | Resistor-to-GND sets switching frequency; e.g., 215kΩ yields ~600kHz-balances efficiency and component size. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated boost & catch Schottky diodes | Eliminates 2 external diodes, reduces BOM count and board area, and guarantees matched thermal behavior. |
| Low-ripple Burst Mode™ operation | Maintains <10mVP-P output ripple at light loads while drawing only 1.8µA, preserving signal integrity in noise-sensitive analog circuits. |
| Accurate programmable UVLO | EN/UVLO threshold (1.19V ±70mV) with 45mV hysteresis enables robust power sequencing in multi-rail systems. |
| Thermal shutdown with H-grade rating | Guaranteed operation to +150°C junction temperature; supports under-hood automotive, motor drives, and industrial controls. |
| Power-good flag with 90% threshold | Provides deterministic system startup timing and fault indication without external comparators or dividers. |
Applications
| Automotive Battery Regulation | Industrial Power Supply |
|---|---|
Use Scenario: Powering infotainment head units and ADAS sensors during engine cranking (VIN drops to 3.5V). IC Role / Device Role / Timing Role: Primary 5V buck regulator maintaining stable output despite wide input transients. Use Value: 530mV dropout and 4.2V min operating voltage ensure uninterrupted operation during cold-crank events. |
Use Scenario: Providing isolated 5V bias for PLC I/O modules in factory automation cabinets (85°C ambient). IC Role / Device Role / Timing Role: High-reliability DC/DC converter delivering regulated 5V from 24V rail. Use Value: H-grade 150°C junction rating and integrated thermal shutdown prevent field failures in sealed enclosures. |
| Portable Medical Instrumentation | Gate Drive Bias Supply |
Use Scenario: Powering low-noise ADCs and microcontrollers in handheld ultrasound devices with battery life constraints. IC Role / Device Role / Timing Role: Ultra-low-IQ 5V supply enabling multi-week standby without recharge. Use Value: 2.5µA quiescent current extends battery runtime; Burst Mode™ preserves signal integrity below 10mV ripple. |
Use Scenario: Generating clean 5V gate drive for SiC MOSFET half-bridges in motor inverters. IC Role / Device Role / Timing Role: Dedicated auxiliary supply decoupled from main power stage noise. Use Value: Integrated catch diode and low EMI SW node simplify layout; PG flag synchronizes gate driver enable timing. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3631EMSE-5#PBF | Same 5V fixed output, but 36V max input, 500mA output, and no integrated catch diode; requires external Schottky. | Suitable for lower-power, cost-sensitive industrial sensors where 750mA is not required. | Select when input voltage stays ≤36V and thermal budget permits external diode placement. |
| MP2451DT-LF-Z | 5V fixed output, 36V max input, 600mA output, no integrated diodes, higher 25µA IQ, no PG flag or UVLO programming. | Fits basic consumer electronics where automotive qualification and ultra-low IQ are not needed. | Choose for non-automotive, non-critical applications prioritizing lowest BOM cost over precision features. |
Compared with LTC3631EMSE-5#PBF and MP2451DT-LF-Z, LT3973HDD-5#TRPBF provides superior automotive robustness (42V/150°C), integrated diodes reducing layout complexity, and critical system features like PG flag and programmable UVLO-making it optimal for safety-critical or thermally demanding deployments.
Availability
LT3973HDD-5#TRPBF is available at Aetrix Electronics and suitable for automotive battery regulation, industrial power supplies, portable medical instrumentation, and gate drive bias applications requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LT3973HDD-5#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) is a global leader in high-performance analog, mixed-signal, and power management ICs, serving automotive, industrial, communications, and healthcare markets.
The LT3973 family was designed specifically for high-input-voltage, ultra-low-quiescent-current DC/DC conversion in harsh environments-emphasizing reliability, integrated protection, and seamless cold-crank operation.
FAQ
What is the maximum junction temperature rating for LT3973HDD-5#TRPBF?
The LT3973HDD-5#TRPBF is rated for operation up to +150°C junction temperature (H-grade), verified across the full –40°C to +150°C ambient range. This rating is guaranteed per datasheet specifications and enables deployment in under-hood automotive locations and high-ambient industrial settings where standard E- or I-grade parts would derate or fail.
Does LT3973HDD-5#TRPBF require external feedback resistors to set the 5V output?
No, LT3973HDD-5#TRPBF does not require external feedback resistors. It is a fixed-output variant with internal resistor divider connected to Pin 1 (VOUT), delivering 5.00V ±1.2% over temperature. This eliminates tuning errors, reduces component count, and improves long-term stability compared to adjustable versions like the base LT3973.
How does the LT3973HDD-5#TRPBF maintain regulation during automotive cold-crank conditions?
The LT3973HDD-5#TRPBF maintains regulation during cold-crank by combining three features: (1) a minimum operating input voltage of 4.2V, (2) a 530mV enforced dropout voltage when OUT is tied to VOUT, and (3) extended duty cycle capability (~97.5%) enabled by BOOST capacitor charge management. Together, these allow stable 5V output even as VIN sags to ~3.5V transiently.
What is the purpose of the BD pin on LT3973HDD-5#TRPBF, and how should it be used?
The BD pin on LT3973HDD-5#TRPBF connects to the anode of the external boost diode and also serves as an auxiliary bias input. When biased above 3.2V (e.g., from the regulated 5V output), it powers the internal regulator instead of VIN-reducing input current and improving light-load efficiency. If unused, BD must be left unconnected or tied to SW through the boost diode.
Can LT3973HDD-5#TRPBF be used without the exposed thermal pad (Pin 11) soldered to the PCB?
No, the exposed pad (Pin 11) of LT3973HDD-5#TRPBF must be soldered to a thermally robust GND plane on the PCB. It is electrically GND and thermally critical-θJA degrades from 40°C/W to >100°C/W if unsoldered, risking thermal shutdown or premature failure at rated load. Manufacturer documentation explicitly states "MUST BE SOLDERED TO PCB".
LT3973HDD-5#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):
- 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#TRPBF FAQ
1.How can I place an order for LT3973HDD-5#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3973HDD-5#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 LT3973HDD-5#TRPBF reliable?
The price and inventory of LT3973HDD-5#TRPBF 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#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3973HDD-5#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3973HDD-5#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3973HDD-5#TRPBF?
LT3973HDD-5#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3973HDD-5#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 LT3973HDD-5#TRPBF?
For technical support, including LT3973HDD-5#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3973HDD-5#TRPBF requirements.
6.How does Aetrix verify that LT3973HDD-5#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3973HDD-5#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 LT3973HDD-5#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3973HDD-5#TRPBF?
All LT3973HDD-5#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3973HDD-5#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 LT3973HDD-5#TRPBF part is unused and in its original packaging.
Return procedure for LT3973HDD-5#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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