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Analog Devices Inc. LT8609AHDDM#PBF
- Part No.:
- LT8609AHDDM#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 10-WFDFN Exposed Pad
- Datasheet:
-
LT8609AHDDM#PBF.pdf
- Description:
- IC REG BUCK ADJ 3A 10DFN
- Quantity:
- Payment:
- Shipping:
Inventory:105
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Product details
Overview
LT8609AHDDM#PBF from Analog Devices is a 42V, 3A synchronous step-down regulator with 2.5µA quiescent current in Burst Mode, peak current mode control, and internal compensation. It delivers regulated 5V output from 6–40V input in fixed-output configuration, supports spread-spectrum EMI reduction via SYNC pin, and operates up to 150°C junction temperature in automotive-grade DFN package.
For engineers reviewing the LT8609AHDDM#PBF datasheet, LT8609AHDDM#PBF pinout, LT8609AHDDM#PBF application, or LT8609AHDDM#PBF equivalent, key selection criteria include its 5V fixed output, 2.5µA no-load IQ, ±7.5% power-good accuracy, 45ns minimum on-time, and AEC-Q100 qualification for automotive power systems requiring low EMI and high thermal reliability.
Technical Context
The LT8609AHDDM#PBF implements peak current mode control with internal 0.782V reference and fixed 5V output via integrated feedback divider (8.95MΩ). Its oscillator frequency is set by external RT resistor (18.2kΩ typical for 2MHz) and supports synchronization or spread-spectrum modulation via SYNC pin - enabling precise EMI management without external clocking circuitry.
Burst Mode operation maintains <10mVP-P output ripple at light loads while drawing only 2.5µA from VIN, and EN/UV pin provides accurate 1.05V rising threshold with 50mV hysteresis for programmable input UVLO or shutdown. The device integrates top/bottom NMOS switches (185mΩ/115mΩ), PG flag with ±7.5% VOUT tolerance monitoring, and TR/SS pin for soft-start and tracking control.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 5.0V ±1.5% over full temperature range - eliminates external feedback resistors and simplifies layout for stable 5V rail generation. |
| Input Voltage Range | 3.0V to 42V - supports wide automotive battery transients including cold-crank (4.5V) and load-dump (40V) conditions. |
| Quiescent Current | 2.5µA at 12VIN → 5VOUT, no load - enables always-on systems (e.g., telematics, ADAS sensors) with multi-year battery life. |
| Switching Frequency | Adjustable 200kHz to 2.2MHz via RT pin; 2MHz typical with 18.2kΩ - allows use of compact 2.2µH inductors and reduces solution size. |
| Continuous Output Current | 3A - sufficient for powering microcontrollers, CAN transceivers, and sensor signal chains in automotive ECUs. |
| Power-Good Accuracy | ±7.5% on VOUT - ensures reliable system reset and sequencing when 5V rail reaches valid operating window. |
| Minimum On-Time | 45ns - enables high step-down ratios (e.g., 40V→5V at 2MHz) without pulse-skipping instability. |
Pinout & Package
LT8609AHDDM#PBF uses a 10-lead (3mm × 3mm) plastic side-wettable DFN package with exposed thermal pad (Pin 11 = GND). The package supports automated optical inspection (AOI) and offers θJA = 45°C/W, enabling high-power-density designs in space-constrained automotive modules.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN | Main input power supply | Accepts 3.0–42V; requires local 1µF ceramic bypass to GND for stability and EMI suppression. |
| BST | Bootstrap capacitor connection | Drives high-side NMOS gate; requires 0.1µF ceramic capacitor between BST and SW for proper top-switch operation. |
| SW | Switch node | Connects to inductor and BST capacitor; must be minimized in PCB area to reduce radiated EMI. |
| INTVCC | Internal 3.5V regulator bypass | Decoupled with ≥1µF low-ESR ceramic; powers internal logic and gate drivers - not for external loading. |
| RT | Oscillator frequency setting | Resistor to GND sets fSW (e.g., 18.2kΩ = 2MHz); determines inductor size and efficiency trade-off. |
| SYNC | External clock/spectrum control | Ground for Burst Mode; float for pulse-skipping; 3.2–5V for spread-spectrum - critical for CISPR 25 Class 5 compliance. |
| EN/UV | Enable and input UVLO control | 1.05V rising threshold with 50mV hysteresis - enables programmable brown-out protection using resistor divider from VIN. |
| PG | Power-good open-drain flag | Pulled low until VOUT within ±7.5%; drives MCU reset or sequencer enable with external pull-up. |
| TR/SS | Soft-start and tracking control | Capacitor sets output ramp rate; enables controlled startup and voltage sequencing with other rails. |
| VOUT | Regulated 5V output | Fixed 5V output pin with internal 8.95MΩ divider - connects directly to load and output capacitor (47µF typical). |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q100 Grade H qualification | Rated for –40°C to +150°C junction temperature - validated for under-hood automotive applications including engine control and body electronics. |
| Spread-spectrum frequency modulation | Reduces peak EMI by >10dB across 1–100MHz band - meets stringent automotive EMC requirements without added shielding or filters. |
| Ultralow 2.5µA quiescent current | Enables >10-year battery life in always-on vehicle modules (e.g., GPS trackers, toll tags) with minimal self-discharge. |
| 45ns minimum on-time | Supports direct 40V-to-5V conversion at 2MHz - eliminates need for pre-regulator stages and reduces BOM count. |
| Integrated 5V fixed-output topology | Removes external feedback network - improves accuracy, reduces layout sensitivity, and accelerates design validation. |
Applications
| Automotive Telematics | GSM Transceiver Power |
|---|---|
Use Scenario: Powering LTE/GNSS modules in connected car infotainment and fleet management units with battery backup. IC Role / Device Role / Timing Role: Primary 5V buck converter supplying modem baseband processor and RF front-end. Use Value: 2.5µA IQ extends backup battery life during ignition-off periods; AEC-Q100 H-grade ensures operation at 125°C ambient under dash. | Use Scenario: Providing clean, low-noise 5V rail to GSM/GPRS transceivers in emergency call (eCall) systems. IC Role / Device Role / Timing Role: High-efficiency DC/DC regulator delivering burst-current capable 3A peak to RF power amplifier stages. Use Value: Spread-spectrum modulation suppresses switching noise near 900/1800MHz bands - avoids desensitization of cellular receiver. |
| ADAS Camera ECU | Body Control Module (BCM) |
Use Scenario: Powering image sensor, ISP, and CAN interface in rear-view or surround-view camera modules mounted near exhaust or wheel wells. IC Role / Device Role / Timing Role: Main 5V supply with PG flag enabling safe boot sequencing and fault reporting to host MCU. Use Value: 45ns min-on-time supports 12V→5V conversion at 2MHz - minimizes inductor size for tight camera housing constraints. | Use Scenario: Regulating 5V for microcontroller, LIN transceivers, and LED drivers in door modules and lighting controllers. IC Role / Device Role / Timing Role: Compact, thermally robust buck regulator replacing discrete solutions in cost-sensitive, high-volume BCMs. Use Value: Side-wettable DFN package enables AOI and high-yield reflow; ±7.5% PG accuracy ensures deterministic MCU reset timing. |
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 |
|---|---|---|---|
| LT8609AEMSE#PBF | Same IC die, but in 10-lead MSOP package (θJA = 40°C/W) and rated for –40°C to +125°C junction. | Suitable for non-automotive industrial or consumer applications where thermal performance margin exceeds requirement. | Select when board space permits larger MSOP and ambient temperature stays below 105°C. |
| LT8609AJDDM#PBF | Identical DFN package and 150°C rating, but with adjustable output (FB pin) instead of fixed 5V (VOUT pin). | Required when system needs programmable output voltage (e.g., 3.3V, 2.5V) or dynamic voltage scaling. | Choose when flexibility in output voltage outweighs simplicity of fixed 5V; adds external resistor divider. |
Compared with LT8609AEMSE#PBF, LT8609AHDDM#PBF offers superior thermal performance in high-density layouts and extended temperature capability for under-hood use; versus LT8609AJDDM#PBF, it eliminates feedback components and guarantees factory-trimmed 5V accuracy but forfeits output adjustability.
Availability
LT8609AHDDM#PBF is available at Aetrix Electronics and suitable for automotive telematics, ADAS camera ECUs, and body control modules requiring stable component supply with AEC-Q100 qualification and long-term production support.
Supply support for LT8609AHDDM#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 automotive, industrial, communications, and healthcare markets.
The LT8609A product line delivers ultralow-IQ synchronous buck regulators optimized for automotive subsystems demanding high efficiency at light loads, low EMI, and extended temperature operation - especially in always-on and safety-critical applications.
FAQ
What is the guaranteed operating junction temperature range for LT8609AHDDM#PBF?
The LT8609AHDDM#PBF is guaranteed over the full –40°C to +150°C junction temperature range per Analog Devices' datasheet Rev. J. This Grade H qualification makes it suitable for under-hood automotive applications such as engine control units and transmission control modules where ambient temperatures exceed 105°C.
Does LT8609AHDDM#PBF require external feedback resistors to set the output voltage?
No, LT8609AHDDM#PBF does not require external feedback resistors. It is a fixed 5V output variant with an internal 8.95MΩ feedback divider connected to the VOUT pin. This eliminates component count, improves accuracy, and removes layout sensitivity associated with external resistor networks.
How does the SYNC pin function on LT8609AHDDM#PBF, and what are its valid states?
The SYNC pin on LT8609AHDDM#PBF supports three modes: grounded for low-ripple Burst Mode operation; floated for pulse-skipping mode; or biased to 3.2–5.0V for spread-spectrum frequency modulation. It does not accept external clock signals - unlike some other LT86xx variants - and is not a true synchronization input for external clock alignment.
What is the purpose of the TR/SS pin on LT8609AHDDM#PBF, and how is it used in practice?
The TR/SS pin on LT8609AHDDM#PBF controls soft-start ramp rate and enables output voltage tracking. A capacitor from TR/SS to GND sets the output slew rate (e.g., 100nF ≈ 1.5ms rise time); connecting it to another rail's SS node allows coordinated power sequencing. During faults, TR/SS is actively pulled low via internal 300Ω MOSFET.
Can LT8609AHDDM#PBF be used in designs requiring compliance with CISPR 25 Class 5 radiated emissions limits?
Yes, LT8609AHDDM#PBF supports CISPR 25 Class 5 compliance through its spread-spectrum modulation feature. When the SYNC pin is biased to 3.2–5.0V, the switching frequency dithers ±10% at 1–6kHz, reducing peak EMI by >10dB - a key enabler for automotive infotainment and telematics modules without added filtering or shielding.
LT8609AHDDM#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):
- 3V
- Voltage - Input (Max):
- 42V
- Voltage - Output (Min/Fixed):
- 0.782V
- Voltage - Output (Max):
- 42V
- Current - Output:
- 3A
- Frequency - Switching:
- 200kHz ~ 2.2MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount, Wettable Flank
- Supplier Device Package:
- 10-DFN (3x3)
LT8609AHDDM#PBF FAQ
1.How can I place an order for LT8609AHDDM#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8609AHDDM#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 LT8609AHDDM#PBF reliable?
The price and inventory of LT8609AHDDM#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT8609AHDDM#PBF is usually 5 days.
3.What payment methods are accepted for LT8609AHDDM#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8609AHDDM#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8609AHDDM#PBF?
LT8609AHDDM#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8609AHDDM#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 LT8609AHDDM#PBF?
For technical support, including LT8609AHDDM#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8609AHDDM#PBF requirements.
6.How does Aetrix verify that LT8609AHDDM#PBF is sourced from the original manufacturer or authorized distributors?
All LT8609AHDDM#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 LT8609AHDDM#PBF meets industry standards.
7.What is the process for return or replacement of LT8609AHDDM#PBF?
All LT8609AHDDM#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8609AHDDM#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 LT8609AHDDM#PBF part is unused and in its original packaging.
Return procedure for LT8609AHDDM#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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