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Analog Devices Inc. LT8640HUDC#PBF
- Part No.:
- LT8640HUDC#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 20-WFQFN, 18 Leads, Exposed Pad
- Datasheet:
-
LT8640HUDC#PBF.pdf
- Description:
- IC REG BUCK ADJ 5A 20QFN
- Quantity:
- Payment:
- Shipping:
Inventory:3,019
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Product details
Overview
LT8640HUDC#PBF from Analog Devices is a 42V, 5A synchronous step-down Silent Switcher regulator with 2.5µA quiescent current in regulation, 30ns minimum on-time, and AEC-Q100 H-grade (–40°C to 150°C) qualification - deployed in automotive infotainment power rails, industrial PLC I/O modules, and GSM RF power amplifiers.
For engineers reviewing the LT8640HUDC#PBF datasheet, LT8640HUDC#PBF pinout, LT8640HUDC#PBF application, or LT8640HUDC#PBF equivalent, key selection criteria include ultralow EMI performance (<10mVP-P ripple), forced continuous mode capability (via SYNC/MODE pin), thermal robustness up to 150°C junction, and compatibility with 3MHz switching using 1µH inductors.
Technical Context
The LT8640HUDC#PBF implements peak current-mode control with an internal 0.970V reference and programmable oscillator (200kHz–3MHz via RT resistor). Its Silent Switcher architecture uses symmetrical layout and integrated input capacitors to suppress common-mode EMI without external filters.
It supports four operating modes via the SYNC/MODE pin: Burst Mode (ultralow IQ), pulse-skipping (LT8640 variant), spread spectrum modulation (±22% frequency dither), and external clock synchronization - all while maintaining <100mV dropout at 1A and safe inductor saturation tolerance during overload transients.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.4V to 42V - supports 12V/24V/36V automotive and industrial bus inputs without pre-regulation. |
| Continuous Output Current | 5A - delivers full-rated load with thermal derating above 125°C junction temperature. |
| Quiescent Current | 2.5µA in regulation - enables >10-year battery life in always-on telematics modules. |
| Minimum On-Time | 30ns - enables high-frequency (up to 3MHz), high-VIN-to-low-VOUT conversion (e.g., 42V → 3.3V). |
| Output Ripple | <10mVP-P - meets stringent analog supply noise requirements for ADCs and RF ICs. |
| Thermal Grade | H-grade (–40°C to 150°C) - qualified per AEC-Q100 Rev G for under-hood automotive applications. |
| EMI Performance | CISPR 25 Class 5 compliant - passes radiated/ conducted EMI tests with minimal external filtering. |
Pinout & Package
LT8640HUDC#PBF uses an 18-lead 3mm × 4mm plastic QFN package with exposed SW pads (pins 21, 22) for thermal enhancement. The package is side-wettable capable (UDC variant) and RoHS-compliant.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| BIAS (1) | Internal regulator bias supply | Reduces VIN current draw when tied to VOUT ≥3.3V; enables higher efficiency across load range. |
| INTVCC (2) | Internal 3.4V LDO output | Bypassed with ≥1µF ceramic capacitor; powers gate drivers and control logic - not for external loading. |
| BST (3) | Bootstrap voltage node | Drives top NMOS gate via 0.1µF capacitor; critical for high-side switch turn-on integrity. |
| VIN1/VIN2 (4,13) | Dual input power entry | Each requires dedicated 1µF local ceramic bypass; reduces high-frequency input current loop area for EMI control. |
| GND1/GND2 (6,7,10,11) | Power ground return paths | Separate low-impedance paths for bottom switch and input caps - must be tied together and to PCB ground plane. |
| SW (8,9,21,22) | Switch node connection | High dv/dt node; pins 21/22 are exposed pad - soldered to SW copper for thermal and EMI performance. |
| EN/UV (14) | Enable and undervoltage lockout | Hysteretic threshold (0.94V–1.06V) enables programmable VIN brownout protection via resistor divider. |
| RT (15) | Oscillator frequency programming | Resistor to GND sets fSW from 200kHz to 3MHz - determines inductor size and efficiency trade-offs. |
| TR/SS (16) | Soft-start and output tracking | 1.9µA internal current source enables controlled VOUT ramp rate; supports power sequencing with other rails. |
| SYNC/MODE (17) | Operating mode selection | Selects Burst Mode (GND), FCM (float), spread spectrum (INTVCC), or external sync - defines light-load behavior. |
| GND (18) | System ground reference | Connects to system ground and PCB ground plane - completes control circuit return path. |
| PG (19) | Power good open-drain output | Asserts high when FB is within ±7.5% of 0.970V and no fault - used for system power sequencing. |
| FB (20) | Feedback voltage sense | Regulated to 0.970V ±0.006V; connects to resistor divider - accuracy directly impacts output voltage tolerance. |
Key Features
| Feature | Design Value |
|---|---|
| Silent Switcher® architecture | Integrated input capacitors + symmetrical layout reduce radiated EMI by >30dB vs conventional buck regulators. |
| Ultralow 2.5µA quiescent current | Enables >10-year standby operation in battery-backed systems without compromising regulation stability. |
| 30ns minimum on-time | Supports direct 42V→3.3V conversion at 2MHz, eliminating intermediate stages and reducing BOM count. |
| AEC-Q100 H-grade qualification | Validated for –40°C to 150°C operation - suitable for engine control units, ADAS camera modules, and transmission ECUs. |
| Forced Continuous Mode (FCM) | Eliminates low-load frequency variation and improves transient response - essential for FPGA core supplies. |
| Spread spectrum modulation | ±22% triangular dither reduces peak EMI amplitude - simplifies compliance testing for automotive EMC standards. |
Applications
| Automotive Infotainment Power Supply | Industrial PLC I/O Module |
|---|---|
|
Use Scenario: Powers DSP, audio codec, and display interface in head unit with 12V battery input and strict CISPR 25 Class 5 EMI limits. IC Role / Device Role / Timing Role: Primary 5V/3.3V buck converter delivering regulated rail with <10mVP-P ripple and burst-mode IQ optimization. Use Value: Eliminates need for external EMI filters and secondary LDOs - reduces board space by 35% and cost by $1.20/BOM. |
Use Scenario: Supplies isolated digital I/O channels in factory automation controller with 24V DC bus and wide ambient temperature swing. IC Role / Device Role / Timing Role: High-reliability 5V/5A point-of-load regulator supporting hot-swap and brownout recovery. Use Value: Maintains regulation down to 3.4V input and survives 7A pulsed loads - extends mean time between failures (MTBF) by 4.2×. |
| GSM RF Power Amplifier Bias | Telematics Control Unit (TCU) |
|
Use Scenario: Generates clean 3.3V/5A bias for LTE PA in vehicle-mounted cellular modem with aggressive thermal constraints. IC Role / Device Role / Timing Role: Low-noise, fast-transient buck converter synchronized to baseband clock to avoid intermodulation. Use Value: Spread spectrum + FCM eliminates PA spectral regrowth - improves ACLR by 8dB and passes 3GPP conformance. |
Use Scenario: Powers GPS receiver, CAN transceiver, and MCU in always-on vehicle tracking device with coin-cell backup. IC Role / Device Role / Timing Role: Dual-role regulator: delivers 5V@2A during active mode and sustains 3.3V@100µA in deep sleep. Use Value: 2.5µA IQ extends 120mAh coin-cell life to 14 months - exceeds ISO 16750-2 cold-cranking requirements. |
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 |
|---|---|---|---|
| LT8640-1HUDC#PBF | Forced Continuous Mode (FCM) enabled by default; no pulse-skipping option; identical pinout and package. | Better transient response for FPGA/CPU cores; higher light-load IQ (≈100µA) than LT8640HUDC#PBF's Burst Mode (2.5µA). | Choose LT8640-1HUDC#PBF when fast load-step response outweighs ultra-low-IQ requirements. |
| MPQ4433AGL-AEC1-Z | 45V/6A AEC-Q100 Grade 1 (–40°C to 125°C); no spread spectrum; 17µA IQ in skip mode; different pinout. | Lacks Silent Switcher EMI suppression - requires larger input filter for CISPR 25; lower thermal grade limits under-hood use. | Consider MPQ4433AGL-AEC1-Z only for cost-sensitive non-under-hood applications where EMI margin is available. |
Compared with LT8640-1HUDC#PBF and MPQ4433AGL-AEC1-Z, the LT8640HUDC#PBF uniquely balances ultralow IQ, automotive H-grade reliability, and certified EMI performance - making it optimal for safety-critical, space-constrained, and emission-sensitive designs.
Availability
LT8640HUDC#PBF is available at Aetrix Electronics and suitable for automotive infotainment systems, industrial PLCs, and telematics control units requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LT8640HUDC#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 industrial, automotive, communications, and healthcare markets since 1965.
The LT8640/LT8640-1 belongs to Analog Devices' Silent Switcher family - engineered specifically for ultra-low EMI, high-efficiency DC/DC conversion in automotive and industrial environments where thermal stress and electromagnetic compliance are critical.
FAQ
What is the maximum junction temperature rating for the LT8640HUDC#PBF?
The LT8640HUDC#PBF is rated for operation up to 150°C junction temperature and is qualified per AEC-Q100 Grade H (–40°C to 150°C). Its thermal resistance θJA is 40°C/W, and θJC(PAD) is 12°C/W - enabling reliable operation in under-hood automotive locations when properly mounted to a thermal pad. Derating begins above 125°C to ensure lifetime reliability.
Does the LT8640HUDC#PBF support external clock synchronization?
Yes, the LT8640HUDC#PBF supports external clock synchronization via its SYNC/MODE pin (pin 17). When driven with a clean CMOS clock signal between 200kHz and 3MHz, the device locks its internal oscillator and operates in pulse-skipping mode - enabling deterministic timing for noise-sensitive systems like radar or high-speed data converters.
How does the LT8640HUDC#PBF achieve ultralow EMI performance?
The LT8640HUDC#PBF achieves ultralow EMI through Silent Switcher architecture: integrated input capacitors minimize high-di/dt loop area, symmetrical internal layout cancels magnetic fields, and optional spread spectrum modulation (±22%) smears spectral peaks. It meets CISPR 25 Class 5 limits without ferrite beads or shielded inductors on standard demo boards.
Can the LT8640HUDC#PBF operate with a 1µH inductor at 3MHz switching frequency?
Yes - the LT8640HUDC#PBF supports 3MHz operation with a 1µH inductor, enabled by its 30ns minimum on-time and robust current-mode control. At 12VIN→5VOUT, this configuration delivers >90% efficiency at 2A load and maintains stable regulation across line and load variations per datasheet Figure 8640 G01.
What is the function of the BIAS pin on the LT8640HUDC#PBF?
The BIAS pin (pin 1) supplies the internal LDO that powers gate drivers and control circuits. When tied to VOUT ≥3.3V, it reduces input supply current and improves light-load efficiency. If unused, it must be tied to GND; if connected to an external supply, a 1µF bypass capacitor is required - ensuring stable operation across temperature and load.
LT8640HUDC#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- Silent Switcher®1
- Package/Case:
- 20-WFQFN, 18 Leads, 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):
- 42V
- Current - Output:
- 5A
- Frequency - Switching:
- 210kHz ~ 2MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-QFN (3x4)
LT8640HUDC#PBF FAQ
1.How can I place an order for LT8640HUDC#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8640HUDC#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 LT8640HUDC#PBF reliable?
The price and inventory of LT8640HUDC#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT8640HUDC#PBF is usually 5 days.
3.What payment methods are accepted for LT8640HUDC#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8640HUDC#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8640HUDC#PBF?
LT8640HUDC#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8640HUDC#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 LT8640HUDC#PBF?
For technical support, including LT8640HUDC#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8640HUDC#PBF requirements.
6.How does Aetrix verify that LT8640HUDC#PBF is sourced from the original manufacturer or authorized distributors?
All LT8640HUDC#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 LT8640HUDC#PBF meets industry standards.
7.What is the process for return or replacement of LT8640HUDC#PBF?
All LT8640HUDC#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8640HUDC#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 LT8640HUDC#PBF part is unused and in its original packaging.
Return procedure for LT8640HUDC#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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