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Analog Devices Inc. LT3990IDD#PBF
- Part No.:
- LT3990IDD#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 10-WFDFN Exposed Pad
- Datasheet:
-
LT3990IDD#PBF.pdf
- Description:
- IC REG BUCK ADJ 350MA 10DFN
- Quantity:
- Payment:
- Shipping:
Inventory:457
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Product details
Overview
LT3990IDD#PBF from Analog Devices is a 62V, 350mA monolithic step-down regulator with integrated boost and catch diodes, 2.5µA quiescent current at 12VIN→3.3VOUT, low-ripple Burst Mode operation (<5mVP-P), and programmable undervoltage lockout (1.19V threshold). It serves as a primary DC/DC power stage in automotive battery regulation and industrial supplies where wide input range and ultra-low IQ are critical.
For engineers reviewing the LT3990IDD#PBF datasheet, LT3990IDD#PBF pinout, LT3990IDD#PBF application, or LT3990IDD#PBF equivalent, key selection criteria include its 10-lead DFN (3mm × 3mm) thermal performance, 4.2V–62V input range, fixed 5V output variant, and AEC-Q100 qualification for automotive-grade reliability.
Technical Context
The LT3990IDD#PBF implements constant-frequency current-mode control with adjustable switching frequency (200kHz–2.2MHz via RT resistor), enabling fast transient response and stable loop behavior across wide VIN/VOUT ratios. Its internal bipolar NPN switch, integrated Schottky boost and catch diodes, and 1.21V reference-based feedback architecture eliminate external components while supporting precise output regulation.
Burst Mode operation reduces input current to 1.8µA at light loads while maintaining <5mVP-P output ripple; the power good (PG) flag asserts when VOUT reaches 90% of regulation, and the EN/UVLO pin provides accurate 1.19V threshold with 35mV hysteresis for controlled startup under varying battery conditions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.2V to 62V - supports direct connection to 12V/24V/48V automotive and industrial bus systems without pre-regulation. |
| Output Current | 350mA - maximum continuous load capability limited by switch and catch diode current limits (700mA peak / 450mA valley). |
| Quiescent Current | 2.5µA at 12VIN→3.3VOUT - enables >10-year battery life in always-on monitoring systems. |
| Switching Frequency | 200kHz to 2.2MHz - set externally via RT-to-GND resistor; higher frequencies allow smaller magnetics but reduce max VIN/VOUT ratio. |
| Output Ripple | <5mVP-P in Burst Mode - meets noise-sensitive analog and RF subsystem requirements without additional filtering. |
| Feedback Reference | 1.21V ±1.2% over –40°C to 125°C - ensures stable 5V output accuracy (±1.2%) across full operating temperature range. |
| Power Good Threshold | 90% of regulated output - open-drain PG pin signals valid regulation only after VOUT stabilizes within tolerance. |
Pinout & Package
LT3990IDD#PBF is housed in a thermally enhanced 10-lead (3mm × 3mm) plastic DFN package with exposed pad (Pin 11) soldered to PCB for optimal thermal dissipation (θJA = 45°C/W). The package supports high-density layouts and automotive-grade reflow profiles.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Pin 1: FB | Feedback input | Regulates internal reference to 1.21V; connects to resistor divider for adjustable output or unused in fixed-output variants. |
| Pin 2: PG | Power good flag | Open-drain output active low until VFB ≥ 90% of target; requires external pull-up for system sequencing. |
| Pin 3: BD | Boost diode anode | Supplies bias current to internal regulator when >3.2V; improves efficiency by sourcing control power from VOUT. |
| Pin 4: BOOST | Bootstrap drive | Provides >VIN voltage to fully saturate internal bipolar NPN switch; requires external capacitor to SW node. |
| Pin 5: SW | Switch node | Connects to inductor; carries pulsed high-current switching waveform; layout critical for EMI and efficiency. |
| Pin 6: FB/VOUT | Feedback or output sense | In LT3990-5 variants like LT3990IDD#PBF, this pin is internally connected to fixed 5V regulation path (not FB). |
| Pin 7: EN/UVLO | Enable & undervoltage lockout | Active-high enable with 1.19V threshold and 35mV hysteresis; ties to VIN for always-on operation. |
| Pin 8: VIN | Main power input | Supplies internal circuitry and switch; must be locally bypassed with ≥1µF X7R ceramic capacitor. |
| Pins 9,10,11: GND | Ground return | Three ground connections including exposed thermal pad (Pin 11); all must be low-impedance to PCB ground plane. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated Schottky diodes | Eliminates two external diodes (boost + catch), reducing BOM count, board area, and forward drop losses. |
| FMEA fault-tolerant design | Output remains ≤ regulation voltage during adjacent-pin shorts or floating pins - certified for automotive safety-critical systems. |
| AEC-Q100 Grade I | Qualified for –40°C to +125°C junction operation; supports engine bay and ADAS power rail applications. |
| Low-ripple Burst Mode | Maintains <5mVP-P output ripple at µA-level loads - avoids audible noise and preserves signal integrity in sensor interfaces. |
| Programmable UVLO | EN/UVLO pin allows custom startup voltage (1.19V typ.) with hysteresis - prevents brownout oscillation in weak battery conditions. |
Applications
| Automotive Battery Regulation | Industrial Power Supplies |
|---|---|
|
Use Scenario: Regulating 12V–48V vehicle battery rails to stable 5V for infotainment head units and body control modules. IC Role / Device Role / Timing Role: Primary buck converter delivering 350mA at 5V with 62V transient tolerance and AEC-Q100 compliance. Use Value: Survives load dump (ISO 7637-2 Pulse 5a) up to 62V without external TVS; 2.5µA IQ extends backup battery life in parked mode. |
Use Scenario: Powering PLC I/O modules and field transmitters in 24V industrial control cabinets. IC Role / Device Role / Timing Role: Fixed 5V point-of-load regulator with programmable UVLO for brownout immunity during line sags. Use Value: Integrated diodes reduce component count vs. discrete solutions; thermal DFN package sustains 350mA at 85°C ambient. |
| Portable Medical Devices | Remote Sensing Nodes |
|
Use Scenario: Providing 5V power to portable ECG monitors and glucose meters powered by single-cell Li-ion batteries. IC Role / Device Role / Timing Role: High-efficiency buck regulator operating from 3.6V–62V input, supporting wide battery voltage swing. Use Value: 1.8µA Burst Mode IQ enables multi-year operation on coin cells; low ripple avoids interference with analog front-end measurements. |
Use Scenario: Powering LoRaWAN or NB-IoT sensor nodes deployed in utility metering or environmental monitoring. IC Role / Device Role / Timing Role: Ultra-low-power 5V supply for microcontroller, radio, and analog sensors in intermittent wake-up cycles. Use Value: 0.7µA shutdown current and accurate PG flag simplify power sequencing; small DFN footprint fits compact enclosures. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3990EMSE-5#PBF | 16-pin MSOP package; higher θJA (40°C/W) and larger footprint; identical electrical specs and AEC-Q100 rating. | Preferred for prototyping or manual assembly; less suitable for high-density automotive PCBs. | Select LT3990EMSE-5#PBF when thermal margin exceeds 10°C or hand-soldering is required. |
| LT8609SIS8#PBF | 42V input, 3A output, 2.5µA IQ, same DFN-10 package; synchronous rectification replaces catch diode; no boost diode. | Better efficiency above 100mA; lacks BD pin for bias-from-VOUT optimization; not AEC-Q100 qualified. | Choose LT8609SIS8#PBF for higher current or non-automotive applications where synchronous efficiency outweighs fault tolerance. |
Compared with LT3990EMSE-5#PBF, LT3990IDD#PBF offers superior thermal density in space-constrained automotive modules; versus LT8609SIS8#PBF, it trades peak current capability for FMEA-compliant fault behavior and integrated diode robustness in harsh environments.
Availability
LT3990IDD#PBF is available at Aetrix Electronics and suitable for automotive battery regulation, industrial power supplies, and remote sensing nodes requiring stable component supply with long lifecycle assurance and AEC-Q100 traceability.
Supply support for LT3990IDD#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) is a global leader in high-performance analog, mixed-signal, and power management ICs, serving automotive, industrial, and communications markets with precision, reliability, and longevity.
The LT3990 product line delivers high-voltage, ultra-low-IQ buck regulators for automotive and industrial applications where input transients, thermal constraints, and functional safety are critical design factors.
FAQ
What is the output voltage configuration of LT3990IDD#PBF?
The LT3990IDD#PBF is the fixed 5V output variant of the LT3990 family. Unlike the adjustable LT3990, it uses internal feedback resistors to regulate VOUT to 5.0V ±1.2% over –40°C to 125°C. Pin 6 functions as VOUT (not FB), and no external resistor divider is required - simplifying design and improving accuracy.
Does LT3990IDD#PBF require an external boost capacitor?
Yes, LT3990IDD#PBF requires an external ceramic capacitor (typically 10nF–100nF, X7R) between the BOOST and SW pins. This capacitor generates the boosted gate drive voltage needed to fully saturate the internal bipolar NPN switch. Omitting it causes excessive VCE(SAT) and thermal failure under load.
How does the power good (PG) pin operate on LT3990IDD#PBF?
The PG pin on LT3990IDD#PBF is an open-drain output that remains low until the regulated 5V output reaches 90% (4.5V) of final value. It becomes high-impedance only when EN/UVLO is high and VIN > 4.2V. An external pull-up resistor (e.g., 10kΩ to 5V) is required to generate a logic-high signal for system power sequencing.
Is LT3990IDD#PBF compatible with hot-plug input conditions?
LT3990IDD#PBF can withstand hot-plug events up to its absolute maximum VIN rating (62V), but ringing caused by input cable inductance + ceramic capacitor may exceed this. To ensure safe hot-plugging, add a series damping resistor (1–3Ω) and/or TVS clamp at the VIN input per Analog Devices Application Note 142.
What thermal considerations apply to LT3990IDD#PBF in continuous 350mA operation?
At 350mA and 12VIN→5VOUT, LT3990IDD#PBF dissipates ~1.2W. With θJA = 45°C/W and 4cm² 2-oz copper, junction temperature rises ~54°C above ambient. For 125°C max TJ, limit ambient to ≤71°C. Soldering the exposed pad (Pin 11) to ≥2cm² thermal pad is mandatory for rated performance.
LT3990IDD#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):
- 62V
- Voltage - Output (Min/Fixed):
- 1.21V
- Voltage - Output (Max):
- 25V
- Current - Output:
- 350mA
- Frequency - Switching:
- 210kHz ~ 2.3MHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 10-DFN (3x3)
LT3990IDD#PBF FAQ
1.How can I place an order for LT3990IDD#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3990IDD#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 LT3990IDD#PBF reliable?
The price and inventory of LT3990IDD#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3990IDD#PBF is usually 5 days.
3.What payment methods are accepted for LT3990IDD#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3990IDD#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3990IDD#PBF?
LT3990IDD#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3990IDD#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 LT3990IDD#PBF?
For technical support, including LT3990IDD#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3990IDD#PBF requirements.
6.How does Aetrix verify that LT3990IDD#PBF is sourced from the original manufacturer or authorized distributors?
All LT3990IDD#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 LT3990IDD#PBF meets industry standards.
7.What is the process for return or replacement of LT3990IDD#PBF?
All LT3990IDD#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3990IDD#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 LT3990IDD#PBF part is unused and in its original packaging.
Return procedure for LT3990IDD#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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