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Analog Devices Inc. LT3973EMSE#PBF
- Part No.:
- LT3973EMSE#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LT3973EMSE#PBF.pdf
- Description:
- IC REG BUCK ADJ 750MA 10MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:180
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Product details
Overview
LT3973EMSE#PBF from Analog Devices (formerly Linear Technology) is a 42V, 750mA monolithic step-down switching regulator with integrated boost and catch diodes, 2.5µA quiescent current, and adjustable switching frequency (200kHz–2.2MHz). It delivers fixed 5V output in MSOP-10 package and is engineered for automotive cold-crank regulation where input may dip to 4.2V while maintaining regulated output.
For engineers reviewing the LT3973EMSE#PBF datasheet, LT3973EMSE#PBF pinout, LT3973EMSE#PBF application, or LT3973EMSE#PBF equivalent, key selection considerations include its 530mV minimum dropout voltage, low-ripple Burst Mode operation (<10mVP-P), programmable UVLO threshold (1.19V rising), and thermal shutdown with exposed-pad MSOP package for enhanced power dissipation.
Technical Context
The LT3973EMSE#PBF employs constant-frequency current-mode control with internal slope compensation for stable loop dynamics and fast transient response. Its bipolar NPN power switch is driven via an external BOOST capacitor to ensure full saturation across wide input ranges, enabling robust dropout performance down to 4.2V input.
It integrates dual Schottky diodes (boost and catch), error amplifier, oscillator, and power-good comparator. The device enters low-ripple Burst Mode at light loads-reducing quiescent current to 1.8µA-while maintaining output regulation and keeping VOUT ripple below 10mVP-P in typical applications.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.2V to 42V - supports automotive battery systems including cold-crank (≥4.2V start-up) |
| Output Current | 750mA - maximum continuous load without thermal derating in MSOP-10 at TA ≤ 85°C |
| Quiescent Current | 2.5µA at 12VIN/3.3VOUT - enables always-on subsystems with ultra-low standby power |
| Switching Frequency | 200kHz to 2.2MHz - set by RT resistor; allows optimization of inductor size vs. efficiency |
| Feedback Reference | 1.21V ±1.2% - precise internal reference enabling accurate output regulation |
| Power Good Threshold | 90% of regulated output - open-drain PG flag asserts when VFB reaches 90% of 1.21V |
| Minimum Dropout Voltage | 530mV - ensures regulation during VIN-to-VOUT collapse (e.g., automotive cranking) |
Pinout & Package
LT3973EMSE#PBF is housed in a thermally enhanced 10-lead plastic MSOP package with exposed pad (Pin 11 = GND), θJA = 45°C/W, θJC = 10°C/W. The exposed pad must be soldered to PCB for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| FB (Pin 1) | Feedback input | Regulated to 1.21V; connects to resistor divider for adjustable output (not used in LT3973EMSE#PBF - fixed 5V variant) |
| OUT (Pin 2) | Dropout regulation node | Tied to VOUT; enforces ≥530mV dropout margin and maintains BOOST capacitor charge during low-VIN operation |
| EN/UVLO (Pin 3) | Enable & undervoltage lockout | Active-high enable; 1.19V rising threshold with 30mV hysteresis; shuts down device drawing only 0.75µA |
| 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 & 11) | Ground reference | Pins 5 and 11 (exposed pad) are internally connected; pad must be soldered for thermal performance |
| SW (Pin 6) | Switch node | Connects to inductor; drives internal bipolar NPN switch; peak voltage = VIN + VBOOST |
| BOOST (Pin 7) | Bootstrap drive supply | Drives switch base above VIN via external capacitor; rated to 55V max; requires 0.47µF ceramic |
| BD (Pin 8) | Bias diode anode | Accepts external bias ≥3.2V (e.g., from VOUT) to improve efficiency by powering internal regulator |
| PG (Pin 9) | Power good flag | Open-drain output; pulled low until VFB ≥ 90% of 1.21V; valid only when VIN > 4.2V and EN high |
| RT (Pin 10) | Frequency programming | Resistor to GND sets switching frequency; e.g., 215kΩ yields ~600kHz per datasheet Table 1 |
Key Features
| Feature | Design Value |
|---|---|
| Integrated boost & catch diodes | Eliminates 2 external Schottky diodes, reducing BOM count and layout area in space-constrained designs |
| Low-ripple Burst Mode | Maintains <10mVP-P output ripple at light loads while drawing only 1.8µA, critical for noise-sensitive analog circuits |
| Accurate programmable UVLO | EN/UVLO threshold (1.19V rising) with 30mV hysteresis enables precise system-level brown-out detection and sequencing |
| Thermally enhanced MSOP | 10-lead MSOP with exposed pad achieves θJC = 10°C/W - enables 750mA operation without heatsink in industrial ambient |
| Internal catch diode current limit | 1.15A valley current limit protects against shorted outputs and overvoltage faults without external sensing components |
Applications
| Automotive Battery Regulation | Industrial Power Supplies |
|---|---|
Use Scenario: Regulating 12V/24V vehicle battery rail to stable 5V for infotainment microcontrollers during cold-crank (VIN dips to 4.2V). IC Role / Device Role / Timing Role: Primary buck regulator with dropout recovery; maintains 5V output despite VIN collapse using OUT-pin enforcement and BOOST capacitor hold-up. Use Value: Enables uninterrupted MCU operation during engine start; eliminates need for external LDO backup or complex power sequencing. | Use Scenario: Providing 5V bias for PLC I/O modules operating from unregulated 18–36V DC industrial bus. IC Role / Device Role / Timing Role: Fixed-output DC/DC converter with programmable UVLO and PG flag for system health monitoring. Use Value: Delivers 750mA at >90% efficiency across wide input range; PG signal enables host controller fault logging and graceful shutdown. |
| Portable Product Power | Gate Drive Bias Supply |
Use Scenario: Powering 5V logic and sensors in handheld test equipment powered by 2-cell Li-ion (6–8.4V) or 9V alkaline. IC Role / Device Role / Timing Role: High-efficiency step-down regulator with ultralow 2.5µA quiescent current to extend battery life in sleep mode. Use Value: Achieves >85% efficiency at 10mA load and extends shelf life - critical for battery-backed data loggers and IoT edge nodes. | Use Scenario: Generating isolated 5V gate drive for high-side N-channel MOSFETs in motor control inverters. IC Role / Device Role / Timing Role: Compact, low-noise 5V source with fast transient response to support gate charging/discharging pulses. Use Value: Integrated diodes and 750mA capability eliminate external components; low EMI Burst Mode prevents interference with PWM timing signals. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT8609SIS8#PBF | 42V input, 2.5A output, 2.5µA IQ, Silent Switcher architecture; no integrated catch diode | Higher current, lower EMI, but requires external catch diode and larger layout footprint | Preferred for noise-sensitive applications (e.g., RF modules) where 2.5A output is needed |
| TPS54332DR | 28V input, 3.5A output, 120µA IQ, external diode required; no PG or UVLO programming | Higher current but significantly higher quiescent current - unsuitable for always-on automotive modules | Cost-optimized alternative for non-automotive industrial supplies where standby power is not critical |
Compared with LT3973EMSE#PBF, LT8609SIS8#PBF offers higher output current and superior EMI performance but lacks integrated diodes and requires more board space; TPS54332DR provides higher current at lower cost but consumes 48× more quiescent current, making it unsuitable for battery-backed or automotive cold-crank applications.
Availability
LT3973EMSE#PBF is available at Aetrix Electronics and suitable for automotive battery regulation, industrial power supplies, and portable product power requiring stable component supply, long-term lifecycle support, and guaranteed lead-free compliance.
Supply support for LT3973EMSE#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 and support its high-performance power management portfolio.
The LT3973 product line was designed for high-input-voltage, low-quiescent-current DC/DC conversion in harsh environments - especially automotive, industrial, and portable systems demanding reliable regulation under wide VIN transients and ultra-low standby power.
FAQ
What is the output voltage of the LT3973EMSE#PBF?
The LT3973EMSE#PBF is the fixed 5V output variant of the LT3973 family. It regulates to 4.94V to 5.10V over temperature and line, with typical accuracy of ±1.2% at 25°C. Unlike the adjustable LT3973, it does not require external feedback resistors - the internal divider sets VOUT directly at Pin 1 (VOUT), not FB.
Does the LT3973EMSE#PBF require an external catch diode?
No, the LT3973EMSE#PBF integrates both the boost and catch Schottky diodes on-die. This eliminates two external components, reduces board area, and improves reliability. The integrated catch diode supports up to 1.15A valley current and exhibits 550mV forward voltage at 200mA, as specified in the Electrical Characteristics table.
What is the purpose of the OUT pin on the LT3973EMSE#PBF?
The OUT pin on the LT3973EMSE#PBF enforces a minimum dropout voltage of 530mV between VIN and VOUT. When tied to the output, it enables the device to maintain regulation during automotive cold-crank events where VIN drops near VOUT. It also sources current to recharge the BOOST capacitor during extended duty cycles, ensuring switch saturation even at high duty ratios.
How is switching frequency set on the LT3973EMSE#PBF?
Switching frequency on the LT3973EMSE#PBF is set by connecting a resistor from the RT pin (Pin 10) to GND. The value determines frequency from 200kHz to 2.2MHz - for example, a 215kΩ resistor yields ~600kHz. The relationship is monotonic and documented in Table 1 of the datasheet; no external clock or configuration register is required.
What thermal considerations apply to the LT3973EMSE#PBF in MSOP package?
The LT3973EMSE#PBF uses a 10-lead MSOP with exposed thermal pad (Pin 11 = GND). For reliable 750mA operation, the pad must be fully soldered to a ≥100mm² copper pour. With proper PCB layout, θJA is 45°C/W - meaning at 750mA and 12VIN/5VOUT, junction temperature rise is ~25°C above ambient, well within the –40°C to 125°C operating range.
LT3973EMSE#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:
- 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-MSOP-EP
LT3973EMSE#PBF FAQ
1.How can I place an order for LT3973EMSE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3973EMSE#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 LT3973EMSE#PBF reliable?
The price and inventory of LT3973EMSE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3973EMSE#PBF is usually 5 days.
3.What payment methods are accepted for LT3973EMSE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3973EMSE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3973EMSE#PBF?
LT3973EMSE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3973EMSE#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 LT3973EMSE#PBF?
For technical support, including LT3973EMSE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3973EMSE#PBF requirements.
6.How does Aetrix verify that LT3973EMSE#PBF is sourced from the original manufacturer or authorized distributors?
All LT3973EMSE#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 LT3973EMSE#PBF meets industry standards.
7.What is the process for return or replacement of LT3973EMSE#PBF?
All LT3973EMSE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3973EMSE#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 LT3973EMSE#PBF part is unused and in its original packaging.
Return procedure for LT3973EMSE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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