My Inquiry
My Account
Analog Devices Inc. LT3973IDD#PBF
- Part No.:
- LT3973IDD#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 10-WFDFN Exposed Pad
- Datasheet:
-
LT3973IDD#PBF.pdf
- Description:
- IC REG BUCK ADJ 750MA 10DFN
- Quantity:
- Payment:
- Shipping:
Inventory:334
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
LT3973IDD#PBF 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 adjustable switching frequency (200kHz–2.2MHz). It delivers fixed 5V output in DFN-10 package and is engineered for automotive cold-crank regulation where input may dip to 4.2V while maintaining 530mV dropout.
For engineers reviewing the LT3973IDD#PBF datasheet, LT3973IDD#PBF pinout, LT3973IDD#PBF application, or LT3973IDD#PBF equivalent, key selection considerations include ultralow IQ operation at light load, Burst Mode® ripple control (<10mVP-P), programmable UVLO, power-good flag timing, and thermal performance in –40°C to 125°C industrial/automotive environments.
Technical Context
The LT3973IDD#PBF employs current-mode control with internal bipolar NPN switch and integrated diodes-eliminating external catch/boost diodes. Its minimum on-time (70ns) and extended duty cycle (up to 97.5%) enable stable 5V regulation down to 4.2V input, critical for automotive battery transients.
Burst Mode® operation maintains high efficiency at microamp loads by disabling control circuitry between switching bursts, reducing total supply current to 1.8µA. The power-good flag asserts when FB reaches 90% of 1.21V reference, and EN/UVLO provides accurate 1.19V rising threshold with 30mV hysteresis.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.2V to 42V - supports full automotive battery range including cold-crank (≥4.2V start-up) |
| Output Voltage | Fixed 5V ±1.2% - internally trimmed; no external feedback resistors required |
| Max Output Current | 750mA - limited by switch peak current (1.65A typ.) and catch diode valley current (1.15A typ.) |
| Quiescent Current | 2.5µA at 12VIN/5VOUT - enables always-on systems with multi-year battery life |
| Switching Frequency | 200kHz to 2.2MHz - set by RT resistor; higher frequencies allow smaller magnetics |
| Dropout Voltage | 530mV min - ensures regulation during VIN-to-VOUT collapse (e.g., engine cranking) |
| Power Good Flag | Open-drain PG with 90% VOUT threshold - provides reliable system reset sequencing |
Pinout & Package
LT3973IDD#PBF is housed in a thermally enhanced 10-lead (3mm × 3mm) plastic DFN package with exposed pad (Pin 11) soldered to PCB ground for optimal thermal dissipation (θJA = 40°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| FB/VOUT (Pin 1) | Feedback / Fixed-output sense | For LT3973IDD#PBF (5V variant), this pin connects to internal 5V divider - no external resistors needed |
| OUT (Pin 2) | Output voltage reference node | Internally tied to regulated 5V; used for dropout comparator and boost capacitor charging |
| EN/UVLO (Pin 3) | Enable and undervoltage lockout input | Active-high enable; 1.19V rising threshold with 30mV hysteresis - programmable UVLO for battery monitoring |
| VIN (Pin 4) | Main power input | Supplies internal bias and switch driver; rated to 42V absolute max |
| GND (Pin 5 & Exposed Pad 11) | Power and signal ground | Exposure pad must be soldered to PCB ground plane for thermal and electrical integrity |
| SW (Pin 6) | Switch node | Connects to inductor; carries pulsed current up to 1.65A peak - requires low-inductance layout |
| BOOST (Pin 7) | Bootstrap drive voltage | Drives internal NPN switch base; requires external capacitor to generate >VIN voltage |
| BD (Pin 8) | Boost diode anode | Connects to boost diode cathode; supplies bias to internal regulator when >3.2V |
| PG (Pin 9) | Power-good open-drain output | Sinks 350µA max; pulled high externally; asserts when VOUT ≥ 4.5V (90% of 5V) |
| RT (Pin 10) | Frequency programming | Resistor to GND sets switching frequency; 768kΩ yields ~195kHz, 158kΩ yields ~790kHz |
Key Features
| Feature | Design Value |
|---|---|
| Integrated boost & catch diodes | Eliminates 2 external Schottky diodes - reduces BOM count, board area, and layout complexity |
| Low-ripple Burst Mode® | Maintains <10mVP-P output ripple at light loads while achieving 1.8µA shutdown-like IQ |
| Accurate programmable UVLO | EN/UVLO pin allows custom battery brown-out detection with 30mV hysteresis - prevents erratic restarts |
| Thermal shutdown protection | Internal overtemperature circuit disables switching above 165°C junction - safeguards against sustained overload |
| Minimum dropout voltage enforcement | Guarantees ≥530mV (VIN − VOUT) during dropout - preserves boost capacitor charge for reliable recovery |
Applications
| Automotive Battery Regulation | Industrial Power Supplies |
|---|---|
Use Scenario: Regulating 5V rail from 12V/24V vehicle battery subject to cold-crank dips to 4.2V and load-dump spikes to 42V. IC Role / Device Role / Timing Role: Primary buck controller delivering stable 5V to infotainment, ADAS sensors, and CAN transceivers. Use Value: 530mV enforced dropout and 2.5µA IQ ensure continuous operation during cranking and ultra-low standby drain. | Use Scenario: Providing isolated 5V bias for PLC I/O modules, motor drives, and fieldbus interfaces in harsh factory environments. IC Role / Device Role / Timing Role: Main 5V DC-DC converter powering microcontrollers, ADCs, and digital isolators. Use Value: Wide 4.2V–42V input range accommodates unregulated industrial rails; DFN package enables compact, convection-cooled designs. |
| Portable Medical Devices | Gate Drive Bias Supply |
Use Scenario: Powering handheld ultrasound, glucose meters, or portable ECG monitors operating from single-cell Li-ion or alkaline batteries. IC Role / Device Role / Timing Role: Efficient 5V source for analog front-ends and BLE/Wi-Fi SoCs requiring low-noise, low-IQ supply. Use Value: Burst Mode® delivers <10mV ripple at µA loads - avoids interference with sensitive analog measurements. | Use Scenario: Generating clean 5V gate drive for SiC MOSFETs or IGBTs in inverters and servo drives. IC Role / Device Role / Timing Role: Auxiliary bias supply decoupled from main power stage, ensuring robust gate turn-on during fast transients. Use Value: Integrated boost diode and low VCE(SAT) (250mV) minimize losses and improve gate drive stability under high dV/dt. |
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 12µA IQ - lacks integrated boost diode and Burst Mode® ripple control | Lower current and input voltage capability; suitable only for non-automotive, lower-power applications | Select if cost sensitivity outweighs need for 42V rating or ultralow IQ |
| TPS54560QPWPRQ1 | 42V input, 5V fixed output, 500mA, 145µA IQ - uses external diodes, no integrated boost/catch diodes, no Burst Mode® | Higher IQ and external diode requirement increase board area and reduce light-load efficiency | Select if AEC-Q100 qualification is mandatory and 750mA output is not required |
Compared with LTC3631EMSE-5#PBF and TPS54560QPWPRQ1, LT3973IDD#PBF uniquely combines 42V/750mA capability, 2.5µA IQ, integrated diodes, and sub-10mV ripple Burst Mode® - making it optimal for space-constrained, battery-sensitive automotive and industrial 5V rails.
Availability
LT3973IDD#PBF is available at Aetrix Electronics and suitable for automotive battery regulation, industrial power supplies, and portable medical devices requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LT3973IDD#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 maintains its legacy of high-performance analog ICs for precision power, signal conditioning, and timing applications.
The LT3973 family was designed specifically for high-input-voltage, ultralow-quiescent-current DC-DC conversion in automotive, industrial, and portable systems where reliability under wide VIN transients is critical.
FAQ
What is the guaranteed operating temperature range for LT3973IDD#PBF?
The LT3973IDD#PBF is specified for –40°C to 125°C junction temperature. This "I-grade" rating ensures reliable operation in under-hood automotive environments and industrial enclosures without derating. Thermal performance is supported by the exposed-pad DFN package (θJA = 40°C/W), and internal thermal shutdown activates above 165°C to prevent damage. The LT3973IDD#PBF datasheet confirms full electrical specifications across this range.
Does LT3973IDD#PBF require external feedback resistors to set the 5V output?
No. The LT3973IDD#PBF is the fixed 5V variant - its internal resistor divider is factory-trimmed to deliver 5V ±1.2% at the VOUT/FB pin. Unlike the adjustable LT3973, no external R1/R2 network is needed. Pin 1 functions as VOUT (not FB), eliminating design error risk and saving board space. This simplifies layout and improves long-term stability versus discrete resistor networks.
How does LT3973IDD#PBF achieve 2.5µA quiescent current while maintaining regulation?
The LT3973IDD#PBF achieves 2.5µA IQ through optimized bias circuitry and Burst Mode® operation: during light loads, the controller shuts down oscillator, error amplifier, and gate drivers between switching bursts, drawing only essential bias current. At 12VIN/5VOUT, this results in 2.5µA typical IQ. The 1.8µA shutdown current (0.75µA with EN/UVLO low) further extends battery life. All specifications are measured and guaranteed per the LT3973IDD#PBF datasheet.
Can LT3973IDD#PBF operate with input voltage below 4.2V?
The LT3973IDD#PBF begins switching below 4.2V (down to ~3V), but regulation is not guaranteed. Its minimum regulated input is 4.2V - the point where internal reference and control loops stabilize. Below 4.2V, FB voltage drops nonlinearly (per G05 curve), causing VOUT to fall. For cold-crank scenarios, the 530mV enforced dropout ensures regulation as long as VIN stays ≥ (5V + 0.53V) = 5.53V. Thus, LT3973IDD#PBF is not intended for sub-4.2V operation.
What is the purpose of the OUT pin (Pin 2) on LT3973IDD#PBF?
The OUT pin (Pin 2) on LT3973IDD#PBF serves three critical roles: (1) it connects to the regulated 5V output, (2) it feeds the dropout comparator that enforces ≥530mV (VIN − VOUT), and (3) it sources current to recharge the boost capacitor during light-load intervals. When VOUT exceeds 14V, Pin 2 must be tied to GND to prevent overstress - but for the 5V LT3973IDD#PBF, it is directly connected to the output rail per standard application schematics.
LT3973IDD#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:
- 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-DFN (3x3)
LT3973IDD#PBF FAQ
1.How can I place an order for LT3973IDD#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3973IDD#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 LT3973IDD#PBF reliable?
The price and inventory of LT3973IDD#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3973IDD#PBF is usually 5 days.
3.What payment methods are accepted for LT3973IDD#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3973IDD#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3973IDD#PBF?
LT3973IDD#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3973IDD#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 LT3973IDD#PBF?
For technical support, including LT3973IDD#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3973IDD#PBF requirements.
6.How does Aetrix verify that LT3973IDD#PBF is sourced from the original manufacturer or authorized distributors?
All LT3973IDD#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 LT3973IDD#PBF meets industry standards.
7.What is the process for return or replacement of LT3973IDD#PBF?
All LT3973IDD#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3973IDD#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 LT3973IDD#PBF part is unused and in its original packaging.
Return procedure for LT3973IDD#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LT3973IDD#PBF 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…
