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Analog Devices Inc. LT3973HMSE-3.3#PBF
- Part No.:
- LT3973HMSE-3.3#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LT3973HMSE-3.3#PBF.pdf
- Description:
- IC REG BUCK 3.3V 750MA 10MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:105
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Product details
Overview
LT3973HMSE-3.3#PBF from Analog Devices (formerly Linear Technology) is a 42V, 750mA monolithic step-down regulator with fixed 3.3V output, integrated boost and catch diodes, 2.5µA quiescent current, and operation down to –40°C to +150°C junction temperature - designed for automotive cold-crank battery regulation and industrial power supplies.
For engineers reviewing the LT3973HMSE-3.3#PBF datasheet, LT3973HMSE-3.3#PBF pinout, LT3973HMSE-3.3#PBF application, or LT3973HMSE-3.3#PBF equivalent, key selection criteria include its 530mV minimum dropout voltage, 3.3V ±1.2% output accuracy over temperature, 10-lead MSOP package with exposed thermal pad, and low-ripple Burst Mode™ operation maintaining <10mVP-P output ripple at light load.
Technical Context
The LT3973HMSE-3.3#PBF implements constant-frequency current-mode control with programmable 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, integrated Schottky boost and catch diodes, and dedicated BD pin for external bias sourcing support high-efficiency operation under varying load and input conditions.
It features dual current limiting: peak switch current limit (1.65A typical) and valley catch diode current limit (1.15A typical), providing robust short-circuit protection. The device maintains regulation during automotive cold-crank by enforcing a 530mV minimum dropout voltage and extending duty cycle up to ~97.5% when boost capacitor voltage permits.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 3.3V ±1.2% over –40°C to +150°C; eliminates external feedback resistors and reduces BOM count. |
| Input Voltage Range | 4.2V to 42V continuous; supports 12V/24V/36V automotive and industrial bus systems including cold-crank transients. |
| Quiescent Current | 2.5µA at 12VIN → 3.3VOUT; enables always-on subsystems in battery-powered applications without rapid drain. |
| Maximum Output Current | 750mA DC; sustained delivery limited by thermal performance in MSOP package (θJA = 45°C/W). |
| Switching Frequency | Programmable 200kHz–2.2MHz via RT-to-GND resistor; balances inductor size, efficiency, and EMI in space-constrained designs. |
| Output Ripple | <10mVP-P in Burst Mode™; meets low-noise requirements for RF, sensor, and precision analog circuitry. |
| Power Good Flag | Open-drain PG asserts when VOUT reaches 90% of 3.3V; provides reliable power sequencing signal for microcontrollers and FPGAs. |
Pinout & Package
LT3973HMSE-3.3#PBF uses a thermally enhanced 10-lead plastic MSOP package with exposed GND pad (Pin 11), rated for –40°C to +150°C operating junction temperature. The exposed pad must be soldered to PCB copper for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VOUT (Pin 1) | Fixed-output regulation node | Internally connected to 3.3V feedback divider; connects directly to output capacitor and load. |
| OUT (Pin 2) | Dropout regulation & boost capacitor charge path | Enables minimum dropout operation; ties to VOUT for standard use; must be grounded if VOUT >14V. |
| EN/UVLO (Pin 3) | Enable and programmable undervoltage lockout input | Active-high enable with 1.19V rising threshold and 30mV hysteresis; supports battery brownout detection. |
| VIN (Pin 4) | Main power input | Supplies internal circuitry and switch; requires local 4.7µF ceramic bypass capacitor. |
| GND (Pin 5 & Pin 11) | Signal and power ground reference | Pin 5 is signal GND; Pin 11 is exposed thermal pad - both must connect to system ground plane. |
| SW (Pin 6) | Internal switch node | Connects to inductor; carries high di/dt switching current - requires tight layout and Kelvin return path. |
| BOOST (Pin 7) | Boost capacitor drive node | Generates >VIN voltage to fully saturate internal bipolar switch; requires 0.47µF ceramic capacitor to SW. |
| BD (Pin 8) | Bias diode anode input | Accepts external bias ≥3.2V (e.g., from VOUT) to improve efficiency by powering internal regulator externally. |
| PG (Pin 9) | Power good open-drain flag | Sinks current when VOUT < 2.97V; requires external pull-up for logic-level signaling to host controller. |
| RT (Pin 10) | Frequency programming input | Resistor to GND sets switching frequency; e.g., 215kΩ yields 600kHz per datasheet Table 1. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated boost and catch Schottky diodes | Eliminates 2 external diodes, reduces board area and thermal stress, and ensures matched timing with internal switch. |
| Low-ripple Burst Mode™ operation | Maintains <10mVP-P output ripple at light loads while achieving 2.5µA IQ - critical for noise-sensitive analog/RF stages. |
| Accurate programmable undervoltage lockout | EN/UVLO threshold (1.19V) with 30mV hysteresis enables precise battery monitoring without external comparators. |
| Thermal shutdown and current limiting | Combines switch peak current limit (1.65A), catch diode valley limit (1.15A), and thermal shutdown for comprehensive fault protection. |
| Minimum dropout voltage of 530mV | Guarantees regulation during automotive cold-crank (e.g., VIN drops to 4.5V with 3.3V output) without output collapse. |
Applications
| Automotive Battery Regulation | Industrial Power Supply |
|---|---|
Use Scenario: Powering infotainment head units and ADAS sensors from 12V vehicle battery subject to cold-crank dips to 3.5V. IC Role / Device Role / Timing Role: Primary 3.3V buck regulator delivering stable rail despite wide VIN variation and high ambient temperature. Use Value: Maintains 3.3V output with <10mV ripple and no dropout during 4.2V–42V transients, supporting ASIL-B functional safety compliance. |
Use Scenario: Providing isolated 3.3V supply for PLC I/O modules operating continuously in 70°C cabinet environments. IC Role / Device Role / Timing Role: High-reliability DC-DC converter with extended temperature grade (–40°C to +150°C) and thermal derating support. Use Value: Delivers 750mA at full spec over temperature with 2.5µA quiescent current, minimizing self-heating and improving long-term stability. |
| Portable Medical Instrumentation | Gate Drive Bias Supply |
Use Scenario: Powering low-power ECG front-end ASICs in handheld diagnostic devices powered by Li-ion batteries (3.0V–4.2V). IC Role / Device Role / Timing Role: Efficient step-down regulator enabling multi-day battery life via ultralow IQ and Burst Mode™. Use Value: Draws only 2.5µA from battery at no load, extending runtime without compromising 3.3V accuracy or noise performance. |
Use Scenario: Generating clean 3.3V bias for high-side gate drivers in motor control inverters using 24V/48V DC bus. IC Role / Device Role / Timing Role: Dedicated auxiliary supply with fast transient response and low EMI for sensitive gate driver ICs. Use Value: Delivers 750mA with <10mV ripple and 70ns minimum on-time, ensuring reliable MOSFET turn-on even during bus transients. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3973HMSE#PBF | Adjustable output (via FB pin); requires external resistor divider; same package, temp grade, and core specs. | Used where flexible output voltage (e.g., 2.5V, 3.3V, 5V) is needed across multiple product variants. | Select LT3973HMSE#PBF when output voltage flexibility outweighs BOM simplification from fixed 3.3V. |
| LT3973HDD-3.3#PBF | Same 3.3V fixed output and H-grade temp range, but in 3mm × 3mm DFN package (θJA = 40°C/W vs. 45°C/W). | Preferred for higher power density layouts where thermal resistance and footprint are prioritized over MSOP compatibility. | Choose LT3973HDD-3.3#PBF when PCB real estate is constrained and thermal performance margin allows DFN use. |
Compared with LT3973HMSE#PBF, the LT3973HMSE-3.3#PBF saves two resistors and improves output accuracy by eliminating external divider errors; versus LT3973HDD-3.3#PBF, it offers easier hand-soldering and legacy MSOP footprint compatibility at slightly higher thermal resistance.
Availability
LT3973HMSE-3.3#PBF is available at Aetrix Electronics and suitable for automotive battery regulation, industrial power supplies, and portable medical instrumentation requiring stable component supply with guaranteed long-term availability and extended temperature support.
Supply support for LT3973HMSE-3.3#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, Inc. (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and power management semiconductors for precision, power, and signal processing applications.
The LT3973 family was designed specifically for high-input-voltage, ultralow-quiescent-current DC-DC conversion in harsh environments - targeting automotive, industrial, and portable equipment where reliability, efficiency, and thermal resilience are critical.
FAQ
What is the guaranteed operating temperature range for LT3973HMSE-3.3#PBF?
The LT3973HMSE-3.3#PBF is specified for –40°C to +150°C junction temperature, with full electrical performance guaranteed across this range. This H-grade rating makes it suitable for under-hood automotive and high-ambient industrial applications where standard commercial or industrial grades would fail.
Does LT3973HMSE-3.3#PBF require external feedback resistors?
No. The LT3973HMSE-3.3#PBF integrates the feedback divider for a fixed 3.3V output, so no external resistors are needed on the VOUT pin. This reduces component count, improves output accuracy (±1.2% over temperature), and eliminates resistor tolerance and drift errors inherent in adjustable versions like LT3973HMSE#PBF.
How does LT3973HMSE-3.3#PBF achieve low output ripple in light-load conditions?
The LT3973HMSE-3.3#PBF uses proprietary Burst Mode™ operation that shuts down internal control circuitry between switching bursts, reducing quiescent current to 1.8µA while maintaining output ripple below 10mVP-P. This is achieved without external compensation and preserves regulation accuracy across load steps from 1mA to 750mA.
What is the purpose of the BD pin on LT3973HMSE-3.3#PBF?
The BD pin on LT3973HMSE-3.3#PBF accepts an external bias voltage ≥3.2V (e.g., from VOUT) to power the internal regulator, bypassing VIN. This improves conversion efficiency by reducing input current draw and associated losses - especially beneficial in high-VIN, low-VOUT applications like 24V-to-3.3V conversion.
Can LT3973HMSE-3.3#PBF operate during automotive cold-crank events?
Yes. The LT3973HMSE-3.3#PBF maintains regulation down to 4.2V input and enforces a 530mV minimum dropout voltage, allowing it to sustain 3.3V output even when battery voltage dips to 3.8V during cold-crank. Its current-mode architecture and extended duty cycle (~97.5%) ensure uninterrupted operation without reset or brownout.
LT3973HMSE-3.3#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width) 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):
- 3.3V
- 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-MSOP-EP
LT3973HMSE-3.3#PBF FAQ
1.How can I place an order for LT3973HMSE-3.3#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3973HMSE-3.3#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 LT3973HMSE-3.3#PBF reliable?
The price and inventory of LT3973HMSE-3.3#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3973HMSE-3.3#PBF is usually 5 days.
3.What payment methods are accepted for LT3973HMSE-3.3#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3973HMSE-3.3#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3973HMSE-3.3#PBF?
LT3973HMSE-3.3#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3973HMSE-3.3#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 LT3973HMSE-3.3#PBF?
For technical support, including LT3973HMSE-3.3#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3973HMSE-3.3#PBF requirements.
6.How does Aetrix verify that LT3973HMSE-3.3#PBF is sourced from the original manufacturer or authorized distributors?
All LT3973HMSE-3.3#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 LT3973HMSE-3.3#PBF meets industry standards.
7.What is the process for return or replacement of LT3973HMSE-3.3#PBF?
All LT3973HMSE-3.3#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3973HMSE-3.3#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 LT3973HMSE-3.3#PBF part is unused and in its original packaging.
Return procedure for LT3973HMSE-3.3#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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