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Analog Devices Inc. LT8611IUDD#PBF
- Part No.:
- LT8611IUDD#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 24-WFQFN Exposed Pad
- Datasheet:
-
LT8611IUDD#PBF.pdf
- Description:
- IC REG BUCK ADJ 2.5A 24QFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,086
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Product details
Overview
LT8611IUDD#PBF from Analog Devices is a 42V, 2.5A synchronous step-down regulator with integrated current sense amplifier, 2.5µA quiescent current in Burst Mode, 50ns minimum on-time, and ±9% power-good accuracy. It operates across 3.4V–42V input, delivers up to 2.5A output, and supports adjustable switching frequency from 200kHz to 2.2MHz. It is used in automotive infotainment power supplies requiring low-noise, high-efficiency regulation under wide VIN and light-load conditions.
For engineers reviewing the LT8611IUDD#PBF datasheet, LT8611IUDD#PBF pinout, LT8611IUDD#PBF application, or LT8611IUDD#PBF equivalent, key selection criteria include ultralow IQ at light load, rail-to-rail current sense capability, programmable soft-start via TR/SS, SYNC-based frequency synchronization, and AEC-Q100 qualification for automotive-grade reliability.
Technical Context
The LT8611IUDD#PBF implements peak current mode control with internal compensation, enabling fast transient response and stable operation with small inductors. Its 50ns minimum on-time supports high VIN-to-low VOUT conversion (e.g., 42V→3.3V) without duty cycle limitation.
It integrates dual NMOS power switches (120mΩ top / 65mΩ bottom), a rail-to-rail current sense amplifier (ISP/ISN), IMON monitor output (20× VISP–ISN), and ICTRL-adjustable current limit (50mV default). The EN/UV pin features 1.00V rising threshold with 40mV hysteresis, and PG asserts open-drain when VOUT deviates >±9% from regulation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.4V to 42V - supports automotive cold-crank (4.5V) and load-dump (42V) transients without external protection. |
| Output Current | 2.5A continuous - limited by bottom FET current rating (3.3A typ) and thermal design in 3mm × 5mm QFN. |
| Quiescent Current | 2.5µA at 12VIN → 3.3VOUT - enables >10-year battery life in always-on automotive modules. |
| Switching Frequency | 200kHz to 2.2MHz - set by RT resistor; allows EMI optimization and compact magnetics selection. |
| Current Sense Accuracy | ±2mV offset (typ) - enables precise input/output current limiting and monitoring down to 10mV sense voltage. |
| Power-Good Threshold | ±9% of FB reference (0.97V) - provides reliable system reset signaling with built-in hysteresis. |
| Minimum On-Time | 50ns - supports high step-down ratios (e.g., 42V→3.3V @ ~8% duty) without pulse-skipping instability. |
Pinout & Package
LT8611IUDD#PBF is housed in a thermally enhanced 24-lead 3mm × 5mm QFN package with exposed pad (Pin 25 = GND), θJA = 40°C/W, θJC(PAD) = 5°C/W. The exposed pad must be soldered to PCB ground for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SYNC (1) | External clock input | Enables synchronization to external clock or selects Burst Mode (low) vs pulse-skipping (high); disables frequency foldback when asserted. |
| TR/SS (2) | Soft-start & tracking control | Programs output ramp rate via capacitor; enables voltage tracking when <0.97V; pulled low during fault/shutdown. |
| RT (3) | Frequency programming | Resistor to GND sets switching frequency from 200kHz to 2.2MHz; determines minimum load for full-frequency operation. |
| EN/UV (4) | Enable & undervoltage lockout | 1.00V rising threshold with 40mV hysteresis; shuts down IC drawing only 1µA when low. |
| VIN (5,6) | Main power input | Supplies internal circuitry and top FET; requires local high-frequency bypassing near pins. |
| PGND (7,8) | Power switch return | Low-inductance return path for bottom FET; must tie directly to input capacitor negative terminal. |
| SW (13–15) | Switch node | Drives external inductor; multiple pins reduce parasitic inductance and improve EMI performance. |
| BST (16) | Bootstrap supply | Requires 0.1µF ceramic cap to SW; enables efficient gate drive for top FET above VIN. |
| INTVCC (17) | Internal 3.4V regulator output | Bypass with ≥1µF ceramic; powers control logic; sourced from BIAS if VBIAS > 3.1V. |
| BIAS (18) | Efficiency-optimized bias supply | Connect to VOUT ≥3.3V to reduce VIN current draw and improve full-load efficiency. |
| PG (19) | Power-good flag | Open-drain output active low when VFB outside ±9% window or fault detected; valid above 3.4V VIN. |
| FB (20) | Feedback reference input | Regulated to 0.970V ±0.003V; connects to resistor divider; phase-lead cap (4.7–10pF) recommended. |
| ISP (21) / ISN (22) | Current sense differential inputs | Rail-to-rail inputs monitor external sense resistor; support bidirectional sensing and accurate current limiting. |
| IMON (23) | Current monitor output | Sources VIMON = 20 × (VISP – VISN); enables system-level current telemetry without external op-amp. |
| ICTRL (24) | Current limit adjustment | Modulates ISP–ISN threshold from 5mV to 50mV; float or tie to INTVCC for default 50mV limit. |
| GND (25) | Exposed thermal pad | Must be soldered to PCB ground plane; primary thermal path and low-impedance return for PGND/VIN loops. |
Key Features
| Feature | Design Value |
|---|---|
| Ultralow quiescent current | 2.5µA IQ in regulation enables >10-year standby in automotive always-on systems (e.g., telematics, ADAS sensors). |
| Rail-to-rail current sense amplifier | Supports ISP/ISN common-mode range from 0V to >VIN, enabling input current limiting, output current monitoring, or battery charge control. |
| Adjustable soft-start & tracking | TR/SS pin allows controlled VOUT ramp-up and seamless power sequencing with other rails via external voltage source. |
| AEC-Q100 qualified | Rated for –40°C to +125°C junction temperature; qualified per automotive reliability standards for under-hood and infotainment applications. |
| Low-EMI Silent Switcher® architecture | Integrated split-VIN and symmetric SW layout minimizes dI/dt loop area, reducing radiated emissions without shielding. |
Applications
| Automotive Infotainment Power Supply | Industrial Sensor Node Regulator |
|---|---|
|
Use Scenario: Powers display controller, audio codec, and MCU in vehicle head unit with 12V battery input subject to cold-crank and load-dump events. IC Role / Device Role / Timing Role: Primary 3.3V/2.5A synchronous buck regulator with current monitoring for overcurrent protection and diagnostics. Use Value: 2.5µA IQ extends backup battery life; 42V max input eliminates need for upstream TVS; ±9% PG ensures safe MCU boot sequencing. |
Use Scenario: Powers low-power wireless sensor (LoRaWAN, NB-IoT) in remote industrial monitoring with coin-cell or energy-harvesting input. IC Role / Device Role / Timing Role: High-efficiency step-down converter delivering regulated 3.3V from variable 5–24V input with programmable current limit. Use Value: Burst Mode maintains >85% efficiency at 100µA load; IMON pin enables self-diagnostic current reporting; TR/SS supports wake-up sequencing. |
| Automotive Camera Module Supply | Test Equipment Auxiliary Rail |
|
Use Scenario: Supplies image sensor and serializer in ADAS camera with strict EMI limits and thermal constraints inside compact housing. IC Role / Device Role / Timing Role: Low-noise, high-PWM-frequency (2.2MHz) buck converter with synchronized switching to avoid band interference. Use Value: Silent Switcher layout meets CISPR-25 Class 5; 50ns min on-time supports 12V→1.8V core rail; BIAS connection improves full-load efficiency by 1.2%. |
Use Scenario: Generates precision 5V auxiliary rail in automated test equipment where stability, current limiting, and fast transient response are critical. IC Role / Device Role / Timing Role: Programmable current-limited regulator with ISP/ISN sense for real-time load monitoring and fault logging. Use Value: Adjustable ICTRL sets 1.5A limit for DUT protection; PG flag triggers system fault interrupt; RT pin enables EMI-tuned 700kHz operation. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT8640SIV#PBF | Higher 4A output, 3.4µA IQ, same 42V input, but no IMON/ICTRL current monitor interface. | Lacks integrated current telemetry; suited for higher-current apps where sensing is handled externally. | Select when >2.5A output is required and current monitoring is implemented separately. |
| MPQ4420AGL-AEC1-Z | 2.5A, 45V input, 17µA IQ, no current sense amplifier or IMON output; AEC-Q100 qualified. | No rail-to-rail ISP/ISN or programmable current limit; simpler feature set, lower cost. | Select for cost-sensitive automotive apps where current monitoring is unnecessary and 17µA IQ is acceptable. |
Compared with LT8611IUDD#PBF, LT8640SIV#PBF offers higher current and identical voltage ratings but omits current telemetry, while MPQ4420AGL-AEC1-Z trades ultralow IQ and sensing capability for lower BOM cost and AEC-Q100 compliance-making LT8611IUDD#PBF optimal for applications demanding both efficiency and diagnostic visibility.
Availability
LT8611IUDD#PBF is available at Aetrix Electronics and suitable for automotive infotainment, industrial sensor nodes, and ADAS camera modules requiring stable component supply, AEC-Q100 qualification, and ultralow quiescent current performance.
Supply support for LT8611IUDD#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 is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving precision instrumentation, communications, and automotive markets.
The LT8611IUDD#PBF belongs to Analog Devices' Silent Switcher® monolithic DC/DC regulator product line, designed specifically for noise-sensitive automotive and industrial applications requiring high efficiency, low EMI, and robust current monitoring.
FAQ
What is the maximum input voltage rating for the LT8611IUDD#PBF?
The LT8611IUDD#PBF has an absolute maximum input voltage rating of 42V on VIN, EN/UV, PG, ISP, and ISN pins. Its operational input range is specified from 3.4V to 42V, making it suitable for 12V and 24V automotive systems including load-dump conditions. Exceeding 42V risks permanent damage per Absolute Maximum Ratings.
How does the LT8611IUDD#PBF achieve 2.5µA quiescent current?
The LT8611IUDD#PBF achieves 2.5µA quiescent current through optimized Burst Mode® operation: during light loads, it delivers discrete energy pulses to the output capacitor and enters deep sleep between bursts, disabling most internal circuitry. This behavior is enabled by grounding the SYNC pin and is validated at 12VIN → 3.3VOUT with no load.
Can the LT8611IUDD#PBF be synchronized to an external clock?
Yes, the LT8611IUDD#PBF supports external clock synchronization via the SYNC pin (Pin 1). Applying a logic-level clock signal (0.8V–2.4V thresholds) synchronizes switching to the external frequency and disables frequency foldback. This feature reduces EMI peaks and enables deterministic timing in multi-rail systems using LT8611IUDD#PBF.
What is the function of the ICTRL pin on the LT8611IUDD#PBF?
The ICTRL pin (Pin 24) on the LT8611IUDD#PBF adjusts the ISP–ISN current sense threshold from 5mV to 50mV. Tying ICTRL to GND sets minimum limit; floating or connecting to INTVCC selects default 50mV. This enables precise programmable overcurrent protection without changing the sense resistor value in LT8611IUDD#PBF designs.
Is the LT8611IUDD#PBF qualified for automotive applications?
Yes, the LT8611IUDD#PBF is AEC-Q100 qualified for automotive applications, rated over –40°C to +125°C junction temperature. It undergoes stress testing per automotive reliability standards and is manufactured with controlled processes-making it suitable for infotainment, ADAS, and body electronics where long-term reliability under harsh conditions is mandatory.
LT8611IUDD#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 24-WFQFN 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):
- 3.4V
- Voltage - Input (Max):
- 42V
- Voltage - Output (Min/Fixed):
- 0.97V
- Voltage - Output (Max):
- 40V
- Current - Output:
- 2.5A
- Frequency - Switching:
- 200kHz ~ 2.2MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 24-QFN (3x5)
LT8611IUDD#PBF FAQ
1.How can I place an order for LT8611IUDD#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8611IUDD#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 LT8611IUDD#PBF reliable?
The price and inventory of LT8611IUDD#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT8611IUDD#PBF is usually 5 days.
3.What payment methods are accepted for LT8611IUDD#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8611IUDD#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8611IUDD#PBF?
LT8611IUDD#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8611IUDD#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 LT8611IUDD#PBF?
For technical support, including LT8611IUDD#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8611IUDD#PBF requirements.
6.How does Aetrix verify that LT8611IUDD#PBF is sourced from the original manufacturer or authorized distributors?
All LT8611IUDD#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 LT8611IUDD#PBF meets industry standards.
7.What is the process for return or replacement of LT8611IUDD#PBF?
All LT8611IUDD#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8611IUDD#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 LT8611IUDD#PBF part is unused and in its original packaging.
Return procedure for LT8611IUDD#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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