My Inquiry
My Account
Analog Devices Inc. LT3973HDD#TRPBF
- Part No.:
- LT3973HDD#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 10-WFDFN Exposed Pad
- Datasheet:
-
LT3973HDD#TRPBF.pdf
- Description:
- IC REG BUCK ADJ 750MA 10DFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,865
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
LT3973HDD#TRPBF from Analog Devices (formerly Linear Technology) is a 42V, 750mA monolithic synchronous step-down regulator with integrated boost and catch Schottky diodes, 2.5µA quiescent current, and programmable 200kHz–2.2MHz switching frequency. It delivers automotive-grade thermal performance (–40°C to 150°C junction) and maintains regulation down to 530mV dropout - critical for cold-crank battery systems.
For engineers reviewing the LT3973HDD#TRPBF datasheet, LT3973HDD#TRPBF pinout, LT3973HDD#TRPBF application, or LT3973HDD#TRPBF equivalent, key selection criteria include ultralow IQ in Burst Mode (<10mVP-P ripple), accurate programmable UVLO (1.19V threshold), power-good flag timing, and thermal robustness in compact DFN packaging.
Technical Context
The LT3973HDD#TRPBF implements constant-frequency current-mode control with internal bipolar NPN switch and integrated diodes, enabling fast transient response and stable loop behavior across wide input (4.2V–42V) and output (adjustable or fixed 3.3V/5V) ranges. Its BOOST pin drives an external capacitor to sustain full switch saturation during high-duty-cycle operation.
Burst Mode operation reduces no-load supply current to 1.8µA while maintaining <10mVP-P output ripple; dropout mode extends regulation when VIN approaches VOUT by enforcing ≥530mV (min) VIN–VOUT differential and dynamically extending duty cycle up to ~97.5%.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.2V to 42V - supports 12V/24V/36V automotive and industrial rails, including cold-crank transients. |
| Output Current | 750mA continuous - limited by switch peak current (1.65A typ) and catch diode valley current (1.15A typ). |
| Quiescent Current | 2.5µA at 12VIN→3.3VOUT - enables always-on subsystems with multi-year battery life. |
| Switching Frequency | 200kHz to 2.2MHz - set via RT resistor; higher frequencies allow smaller magnetics but reduce max VIN/VOUT ratio. |
| Feedback Reference | 1.21V ±1.25% over –40°C to 150°C - enables precise adjustable output or fixed 3.3V/5V variants via internal divider. |
| Dropout Voltage | 530mV minimum - ensures regulation during deep input sag; enforced by OUT pin sensing and internal comparator. |
| Power Good Flag | Active-high open-drain output triggered at 90% of regulated VOUT - provides reliable sequencing signal for downstream logic. |
Pinout & Package
LT3973HDD#TRPBF uses 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 |
|---|---|---|
| FB (Pin 1) | Feedback reference node | Regulated to 1.21V; connects to resistor divider tap for adjustable output configuration. |
| OUT (Pin 2) | Dropout sense & boost charge path | Tied to VOUT to enforce ≥530mV dropout; supplies current to charge boost capacitor. |
| EN/UVLO (Pin 3) | Enable and undervoltage lockout input | 1.19V rising threshold with 30mV hysteresis; shutdown draws only 0.75µA. |
| VIN (Pin 4) | Main power input | Supplies internal circuitry and switch; requires local 4.7µF ceramic bypass. |
| GND (Pin 5 & Exposed Pad 11) | Power and signal ground | Common return for all circuits; exposed pad is mandatory GND connection for thermal management. |
| SW (Pin 6) | Switch node | Connects to inductor; carries high di/dt switching current; requires tight layout to minimize EMI. |
| BOOST (Pin 7) | Bootstrap drive voltage source | Drives external capacitor to generate >VIN voltage for full NPN switch saturation. |
| BD (Pin 8) | Boost diode anode & bias supply | Accepts external bias ≥3.2V to improve efficiency; powers internal regulator when active. |
| PG (Pin 9) | Power good flag output | Open-drain; pulls low until VOUT reaches 90% of target; valid only when VIN > 4.2V and EN high. |
| RT (Pin 10) | Frequency programming input | Resistor-to-GND sets switching frequency from 200kHz to 2.2MHz per manufacturer table. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated Schottky diodes | Eliminates two external components (boost + catch), reduces BOM count and board area in space-constrained designs. |
| Low-ripple Burst Mode | Maintains <10mVP-P output ripple at light loads while drawing only 1.8µA - ideal for sensor nodes and standby power rails. |
| Accurate programmable UVLO | 1.19V enable threshold with 30mV hysteresis allows precise system-level brown-out detection and controlled startup sequencing. |
| Thermal grade H (–40°C to 150°C) | Qualified for under-hood automotive applications and high-ambient industrial environments without derating. |
| Minimum dropout enforcement | Hardware-enforced 530mV (min) VIN–VOUT differential ensures boost capacitor remains charged and switch stays saturated during dropout. |
Applications
| Automotive Cold-Crank Regulation | Industrial Sensor Node Power |
|---|---|
Use Scenario: Powering infotainment microcontrollers during engine start when battery voltage dips to 3.5V. IC Role / Device Role / Timing Role: Primary 5V/3.3V buck regulator maintaining stable output despite 3.5V–42V input swing and <100ms transients. Use Value: 530mV dropout enforcement and 2.5µA IQ ensure uninterrupted operation and extended battery life in always-on modules. | Use Scenario: Supplying ultra-low-power wireless sensor transceivers in remote monitoring equipment. IC Role / Device Role / Timing Role: Always-on 3.3V rail generator with Burst Mode enabling sub-µA sleep current and rapid wake-up response. Use Value: <10mVP-P ripple and 1.8µA no-load IQ support precision ADC references and RF stability without additional LDO post-regulation. |
| Portable Medical Device Bias | Gate Drive Auxiliary Supply |
Use Scenario: Providing isolated gate driver bias for IGBT half-bridges in portable ultrasound or defibrillator units. IC Role / Device Role / Timing Role: Compact, high-VIN buck converter delivering clean 15V bias from main 24V battery with fast load-step recovery. Use Value: Integrated boost diode and 750mA output simplify layout; current-mode control ensures <1µs transient response to gate charge pulses. | Use Scenario: Generating isolated auxiliary 12V supply for SiC MOSFET gate drivers in motor inverters. IC Role / Device Role / Timing Role: High-efficiency, high-reliability buck stage converting 42V bus to 12V gate rail with thermal fault protection. Use Value: 150°C junction rating and thermal shutdown prevent latch-up during overload; BD pin allows self-bias from regulated output to maximize efficiency. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3639EMSE#TRPBF | 40V input, 500mA output, 3.5µA IQ, MSOP-10 package, no integrated catch diode | Lower current, higher IQ, requires external catch diode - less suitable for space-constrained 750mA designs | Select when lower cost and simpler thermal design outweigh need for integrated diodes and lowest IQ. |
| MAX20004AATP+T | 42V input, 600mA output, 2.5µA IQ, 2.2MHz max fSW, TQFN-16 package, integrated diodes | Slightly lower current rating, different pinout and package footprint - not drop-in compatible | Choose when requiring AEC-Q100 qualification and tighter output tolerance (±1%) over LT3973HDD#TRPBF's ±1.25% FB ref. |
Compared with LTC3639EMSE#TRPBF and MAX20004AATP+T, the LT3973HDD#TRPBF offers superior 750mA output capability with integrated diodes and identical ultralow IQ, making it optimal for thermally demanding, high-density automotive and industrial buck applications where board space and thermal margin are critical.
Availability
LT3973HDD#TRPBF is available at Aetrix Electronics and suitable for automotive battery regulation, industrial sensor node power, and gate drive bias applications requiring stable component supply across extended temperature ranges.
Supply support for LT3973HDD#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 its legacy high-performance analog and power management portfolio with rigorous automotive and industrial qualification standards.
The LT3973 family was designed specifically for high-input-voltage, ultralow-quiescent-current DC/DC conversion in harsh environments - targeting cold-crank automotive, portable medical, and ruggedized industrial systems.
FAQ
What is the maximum junction temperature rating for the LT3973HDD#TRPBF?
The LT3973HDD#TRPBF is rated for operation from –40°C to 150°C junction temperature, confirmed by full characterization and guaranteed testing across this range. This H-grade qualification makes LT3973HDD#TRPBF suitable for under-hood automotive locations and high-ambient industrial enclosures where standard E- and I-grade variants would require derating or forced cooling.
Does the LT3973HDD#TRPBF require external diodes for boost and catch functions?
No - the LT3973HDD#TRPBF integrates both the boost Schottky diode (Pin 8 → Pin 7) and catch Schottky diode (Pin 2 → Pin 6) on-die. This eliminates two external components, reduces PCB area, improves reliability, and simplifies layout compared to controllers requiring discrete diodes. The datasheet confirms integrated diodes in the "Features" and "Block Diagram" sections.
How does the LT3973HDD#TRPBF maintain regulation during automotive cold-crank events?
The LT3973HDD#TRPBF maintains regulation during cold-crank by enforcing a minimum 530mV dropout voltage via the OUT pin, dynamically extending duty cycle up to ~97.5%, and sustaining switch saturation using the BOOST capacitor. These features ensure stable 3.3V/5V output even when input collapses to 3.5V - verified in the "Start-Up and Dropout Performance" typical curves (Fig G23/G24) and "Dropout Comparator Threshold" specification (490mV typ).
What is the purpose of the BD pin on the LT3973HDD#TRPBF?
The BD (Bias Diode) pin on the LT3973HDD#TRPBF serves dual roles: it connects to the anode of the external boost diode, and - when held ≥3.2V - supplies bias current to the internal regulator, improving conversion efficiency by reducing VIN loading. This feature is documented in the "PIN FUNCTIONS" section and "OPERATION" description, where BD biasing is explicitly called out as an efficiency optimization method.
Can the LT3973HDD#TRPBF be used with a fixed 5V output without external feedback resistors?
No - the LT3973HDD#TRPBF is the adjustable version of the family and requires external FB resistors to set output voltage. Fixed-output variants (e.g., LT3973HDD-5#TRPBF) contain internal dividers and omit the FB pin function. The LT3973HDD#TRPBF datasheet specifies "FB (Pin 1, LT3973 Only)" and provides resistor calculation formulas - confirming it is not a fixed-output part.
LT3973HDD#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 ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 10-DFN (3x3)
LT3973HDD#TRPBF FAQ
1.How can I place an order for LT3973HDD#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3973HDD#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#TRPBF reliable?
The price and inventory of LT3973HDD#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#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3973HDD#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3973HDD#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3973HDD#TRPBF?
LT3973HDD#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3973HDD#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#TRPBF?
For technical support, including LT3973HDD#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3973HDD#TRPBF requirements.
6.How does Aetrix verify that LT3973HDD#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3973HDD#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#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3973HDD#TRPBF?
All LT3973HDD#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3973HDD#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#TRPBF part is unused and in its original packaging.
Return procedure for LT3973HDD#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LT3973HDD#TRPBF Tags
-
TPS562201DDCR
Texas Instruments
-
MC34063ABD-TR
STMicroelectronics
-
TPS561201DDCR
Texas Instruments
-
MC33063ADR
Texas Instruments
-
MC34063ADR
Texas Instruments
-
TPS560200DBVR
Texas Instruments
-
AP3012KTR-G1
Diodes Incorporated
-
TLV61048DBVR
Texas Instruments
-
AZ34063UMTR-G1
Diodes Incorporated
-
TPS562200DDCR
Texas Instruments
-
AP62300TWU-7
Diodes Incorporated
-
MC34063EBD-TR
STMicroelectronics
Tech Hub
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…
