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Analog Devices Inc. LT8640EUDC#PBF
- Part No.:
- LT8640EUDC#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 20-WFQFN, 18 Leads, Exposed Pad
- Datasheet:
-
LT8640EUDC#PBF.pdf
- Description:
- IC REG BUCK ADJ 5A 20QFN
- Quantity:
- Payment:
- Shipping:
Inventory:6,275
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Product details
Overview
LT8640EUDC#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 integrated power MOSFETs. It delivers up to 96% efficiency at 1MHz (12VIN→5VOUT), supports 3.4V–42V input, and targets automotive infotainment power rails requiring low EMI and high light-load efficiency.
For engineers reviewing the LT8640EUDC#PBF datasheet, LT8640EUDC#PBF pinout, LT8640EUDC#PBF application, or LT8640EUDC#PBF equivalent, key selection criteria include ultralow IQ for battery-backed systems, spread spectrum EMI reduction, forced continuous mode compatibility (via LT8640-1 variants), thermal performance in 3mm×4mm QFN, and AEC-Q100 qualification for automotive use.
Technical Context
The LT8640EUDC#PBF implements peak current mode control with an internal 0.97V reference and programmable oscillator (200kHz–3MHz via RT resistor). Its Silent Switcher architecture uses symmetrical layout and integrated bypass capacitors to suppress radiated EMI without external filters.
It features dual input pins (VIN1/VIN2), side-wettable QFN-compatible 18-lead package, and SYNC/MODE pin-configurable operation: Burst Mode (ground), pulse-skipping (floating), spread spectrum (INTVCC-high), or external clock sync. The BIAS pin enables efficiency optimization by sourcing INTVCC from VOUT ≥3.3V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.4V to 42V - supports wide automotive battery transients and industrial 24/36V rails. |
| Max Continuous Output Current | 5A - sufficient for powering SoCs, FPGAs, or multi-rail PMICs from single-stage conversion. |
| Quiescent Current (IQ) | 2.5µA at full regulation - enables >10-year battery life in always-on telematics modules. |
| Min On-Time | 30ns - allows high-frequency, high-VIN-to-low-VOUT conversion (e.g., 42V→3.3V at 2MHz). |
| Switching Frequency Range | 200kHz to 3MHz - adjustable via RT resistor; enables compact magnetics and noise avoidance in sensitive RF bands. |
| Output Ripple | <10mVP-P - meets stringent analog supply requirements for ADCs, sensors, and RF front-ends. |
| Thermal Performance | θJA = 40°C/W - enables 5A operation at ≤70°C ambient without heatsink in standard 2-layer PCB layouts. |
Pinout & Package
LT8640EUDC#PBF uses an 18-lead 3mm × 4mm plastic QFN (UDC) package with exposed SW pads (pins 21, 22) for thermal conduction. Pin 5 and pin 12 are omitted; top-side marking "LGNJ" identifies this variant.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| BIAS (1) | Internal regulator bias supply | Connect to VOUT (≥3.3V) to reduce VIN current draw and improve light-load efficiency. |
| INTVCC (2) | Internal 3.4V LDO output | Bypass with ≥1µF ceramic capacitor; do not load externally-powers gate drivers and control logic. |
| BST (3) | Bootstrap capacitor node | Requires 0.1µF ceramic capacitor between BST and SW to drive high-side NMOS gate above VIN. |
| VIN1 (4), VIN2 (13) | Dual input power inputs | Each requires dedicated 1µF local ceramic bypass; reduces high-frequency input current loop area and EMI. |
| GND1 (6,7), GND2 (10,11), GND (18) | Power and signal ground returns | Must be tied together and connected to solid ground plane; critical for EMI suppression and thermal dissipation. |
| SW (8,9,21,22) | Power switch node | Exposed pads (21,22) must be soldered to SW trace for optimal thermal performance and low-inductance switching path. |
| EN/UV (14) | Enable and undervoltage lockout | Hysteresis of 40mV; rising threshold 1.00V - enables programmable input UVLO using resistor divider from VIN. |
| RT (15) | Oscillator frequency set | Resistor to GND sets fSW: 221kΩ → 210kHz, 60.4kΩ → 700kHz, 18.2kΩ → 2.0MHz. |
| TR/SS (16) | Soft-start and tracking control | 1.9µA internal pull-up enables capacitor-programmed slew rate; voltage below 0.97V forces FB tracking. |
| SYNC/MODE (17) | Operating mode select | Ground = Burst Mode; float = pulse-skipping; INTVCC-high = spread spectrum; driven clock = sync - defines light-load behavior and EMI profile. |
| FB (20) | Feedback reference input | Regulated to 0.970V ±0.6%; connect resistor divider tap here; add 4.7pF–22pF phase-lead cap to VOUT for stability. |
| PG (19) | Power good open-drain output | Active-high when FB is within ±7.5% of target and no fault; valid only when VIN >3.4V. |
Key Features
| Feature | Design Value |
|---|---|
| Silent Switcher® Architecture | Reduces radiated EMI by >30dB vs conventional buck converters-meets CISPR 25 Class 5 limits without shielding or ferrites. |
| Ultralow 2.5µA Quiescent Current | Enables direct connection to vehicle battery in always-on domains (e.g., CAN wake-up circuits) without parasitic drain. |
| 30ns Minimum On-Time | Supports 42V→3.3V conversion at 2MHz, enabling smaller inductors (e.g., 1µH) and faster transient response. |
| Spread Spectrum Modulation | ±22% frequency dithering spreads EMI energy across bandwidth-reduces peak emissions while maintaining average fSW. |
| AEC-Q100 Qualified (Grade E) | Rated for –40°C to +125°C junction temperature-validated for under-hood automotive applications including ADAS camera modules. |
| Fast Minimum Off-Time (80ns) | Enables stable operation at high duty cycles (e.g., 36V→5V @ 1MHz), minimizing dropout during cold-crank conditions. |
Applications
| Automotive Infotainment Power Supply | Industrial PLC I/O Module |
|---|---|
Use Scenario: Powers DSP, display controller, and USB PHY in head-unit with 12V/24V battery input and strict CISPR 25 EMI limits. IC Role / Device Role / Timing Role: Primary 5V/5A DC/DC converter with integrated MOSFETs, Silent Switcher EMI suppression, and soft-start sequencing. Use Value: Eliminates need for external EMI filters and reduces board area by 40% vs discrete controller+MOSFET solution. | Use Scenario: Supplies isolated RS-485 transceivers and analog sensor front-ends in factory automation controllers operating from 24V rail. IC Role / Device Role / Timing Role: High-efficiency, low-noise 3.3V/3A point-of-load regulator with robust input UVLO and thermal shutdown. Use Value: Maintains regulation during 24V brownouts down to 3.4V and survives 60V load-dump transients via internal 42V rating. |
| GSM Base Station Bias Rail | Medical Portable Diagnostic Device |
Use Scenario: Generates clean 5V bias for PA driver stages and RF synthesizers in small-cell BTS where spectral purity is critical. IC Role / Device Role / Timing Role: Low-ripple, spread-spectrum synchronized buck converter with <10mVP-P output noise and programmable fSW. Use Value: Prevents switching artifacts from folding into 900MHz/1800MHz transmit bands-verified via conducted/radiated EMI testing. | Use Scenario: Powers ADC, microcontroller, and OLED display in handheld ultrasound probe with Li-ion battery (3.0–4.2V) and 10-year shelf-life requirement. IC Role / Device Role / Timing Role: Ultra-low-IQ step-down regulator delivering 3.3V/1A with 2.5µA quiescent current in regulation. Use Value: Extends battery runtime by 3.2× vs typical 20µA-Q buck converters-validated over full –40°C to +85°C operating range. |
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 |
|---|---|---|---|
| LT8640-1EUDC#PBF | Forced Continuous Mode (FCM) instead of pulse-skipping; higher light-load IQ (~100µA); identical pinout and package. | Better transient response for CPU/FPGA loads; unsuitable for ultra-low-power always-on monitoring. | Select LT8640-1EUDC#PBF when fast load-step recovery is required; retain LT8640EUDC#PBF for lowest standby power. |
| MPQ4420AGL-A-Z | 36V max input, 2A output, 17µA IQ, no spread spectrum, QFN-10 package. | Limited to lower-power applications; lacks AEC-Q100 qualification and Silent Switcher EMI performance. | Use MPQ4420AGL-A-Z only in cost-sensitive non-automotive designs where EMI filtering is acceptable. |
Compared with LT8640-1EUDC#PBF and MPQ4420AGL-A-Z, the LT8640EUDC#PBF uniquely balances ultralow 2.5µA IQ, 42V input capability, AEC-Q100 Grade E qualification, and certified CISPR 25 Class 5 EMI performance-making it the sole choice for automotive infotainment and industrial edge nodes demanding both efficiency and regulatory compliance.
Availability
LT8640EUDC#PBF is available at Aetrix Electronics and suitable for automotive infotainment systems, industrial PLC power supplies, and medical portable diagnostics requiring stable component supply, long-term lifecycle support, and AEC-Q100-compliant sourcing.
Supply support for LT8640EUDC#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 LT8640 series belongs to Analog Devices' Silent Switcher DC/DC regulator product line, engineered specifically for automotive and industrial applications demanding ultra-low EMI, high efficiency across load ranges, and robust operation in harsh electrical environments.
FAQ
What is the maximum input voltage rating for the LT8640EUDC#PBF?
The LT8640EUDC#PBF has an absolute maximum input voltage rating of 42V on VIN1 and VIN2 pins. It operates continuously over 3.4V to 42V, making it suitable for automotive 12V/24V systems with load dump protection and industrial 36V rails. Exceeding 42V risks permanent damage per Absolute Maximum Ratings.
Does the LT8640EUDC#PBF support spread spectrum modulation, and how is it enabled?
Yes, the LT8640EUDC#PBF supports spread spectrum modulation to reduce peak EMI emissions. To enable it, tie the SYNC/MODE pin (pin 17) to INTVCC (~3.4V) or an external 3V–4V supply. This configures the device for pulse-skipping mode with ±22% triangular frequency dithering-verified to meet CISPR 25 Class 5 radiated limits on DC2202A demo board.
Can the LT8640EUDC#PBF be used in forced continuous mode (FCM)?
No-the LT8640EUDC#PBF implements pulse-skipping mode when SYNC/MODE is floating. Forced Continuous Mode (FCM) is exclusive to the LT8640-1 variant (e.g., LT8640EUDC-1#PBF). Using LT8640EUDC#PBF in applications requiring FCM will result in degraded transient response and potential output voltage deviation under dynamic loads.
What is the thermal resistance (θJA) of the LT8640EUDC#PBF package, and how does it affect thermal design?
The LT8640EUDC#PBF in its 3mm×4mm QFN (UDC) package has θJA = 40°C/W per JEDEC 51-7. With 5A output at 12VIN→5VOUT and 95% efficiency, power dissipation is ~0.26W, resulting in ~10.4°C junction-to-ambient rise. Proper PCB layout-including 2oz copper, thermal vias under the exposed SW pad, and adequate ground plane-is essential to maintain TJ ≤125°C at full load.
Is the LT8640EUDC#PBF AEC-Q100 qualified, and which grade does it meet?
Yes, the LT8640EUDC#PBF is AEC-Q100 qualified for automotive applications. Per Analog Devices' ordering information, the "E" suffix denotes Grade E, rated for –40°C to +125°C operating junction temperature. This qualification covers stress testing for temperature cycling, humidity, and ESD-making it suitable for engine control, ADAS, and infotainment subsystems.
LT8640EUDC#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 ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-QFN (3x4)
LT8640EUDC#PBF FAQ
1.How can I place an order for LT8640EUDC#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8640EUDC#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 LT8640EUDC#PBF reliable?
The price and inventory of LT8640EUDC#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT8640EUDC#PBF is usually 5 days.
3.What payment methods are accepted for LT8640EUDC#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8640EUDC#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8640EUDC#PBF?
LT8640EUDC#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8640EUDC#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 LT8640EUDC#PBF?
For technical support, including LT8640EUDC#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8640EUDC#PBF requirements.
6.How does Aetrix verify that LT8640EUDC#PBF is sourced from the original manufacturer or authorized distributors?
All LT8640EUDC#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 LT8640EUDC#PBF meets industry standards.
7.What is the process for return or replacement of LT8640EUDC#PBF?
All LT8640EUDC#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8640EUDC#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 LT8640EUDC#PBF part is unused and in its original packaging.
Return procedure for LT8640EUDC#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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