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Analog Devices Inc. LT8640EUDC-1#PBF
- Part No.:
- LT8640EUDC-1#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 20-WFQFN, 18 Leads, Exposed Pad
- Datasheet:
-
LT8640EUDC-1#PBF.pdf
- Description:
- IC REG BUCK ADJ 5A 20QFN
- Quantity:
- Payment:
- Shipping:
Inventory:825
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Product details
Overview
LT8640EUDC-1#PBF from Analog Devices is a 42V, 5A synchronous step-down Silent Switcher regulator with forced continuous mode (FCM), 2.5µA quiescent current in regulation, 30ns minimum on-time, and AEC-Q100 qualification for automotive power supplies delivering stable 3.3V/5V outputs from wide-input industrial or vehicle battery rails.
For engineers reviewing the LT8640EUDC-1#PBF datasheet, LT8640EUDC-1#PBF pinout, LT8640EUDC-1#PBF application, or LT8640EUDC-1#PBF equivalent, key selection criteria include FCM operation for fast load transients, ultralow IQ at light loads, spread-spectrum EMI reduction, and QFN thermal performance in space-constrained automotive ECUs and industrial controllers.
Technical Context
The LT8640EUDC-1#PBF implements peak current-mode control with an internal 0.970V reference and programmable oscillator (200kHz–3MHz via RT resistor). Its SYNC/MODE pin configures Burst Mode, forced continuous mode (FCM), spread-spectrum modulation, or external clock synchronization - with FCM enabled by floating the pin.
It integrates dual power MOSFETs (67mΩ top / 28mΩ bottom), supports BIAS pin operation for improved efficiency at VOUT ≥ 3.3V, and features robust protection including overtemperature shutdown, VIN UVLO (3.4V), and PG monitoring with ±8% output voltage window.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.4V to 42V - supports 12V/24V/36V automotive and industrial battery inputs without pre-regulation. |
| Continuous Output Current | 5A - delivers full-rated current with thermal derating above 125°C junction temperature. |
| Quiescent Current (IQ) | 2.5µA at 12VIN → 3.3VOUT - enables >10-year battery life in always-on automotive modules. |
| Minimum On-Time | 30ns - enables 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; supports compact magnetics and EMI filtering. |
| Feedback Reference Voltage | 0.970V ±0.006V - precise setpoint enabling accurate output regulation across temperature and load. |
| Output Ripple | <10mVP-P - low noise critical for RF, sensor, and ADC power domains. |
| Thermal Performance | θJA = 40°C/W - validated on standard 2-layer PCB; exposed SW pad improves heat transfer. |
Pinout & Package
LT8640EUDC-1#PBF uses an 18-lead 3mm × 4mm plastic QFN package (UDC) with exposed SW pads (pins 21, 22) requiring solder connection to PCB for thermal and electrical integrity. Pin 5 and pin 12 are omitted per JEDEC outline mismatch.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| BIAS (1) | Internal regulator auxiliary 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; powers control circuitry when BIAS < 3.1V. |
| BST (3) | Bootstrap gate drive supply | Requires 0.1µF ceramic capacitor between BST and SW for top MOSFET gate drive. |
| VIN1 (4), VIN2 (13) | Main input power inputs | Each requires dedicated 1µF local bypass; shared bulk capacitor connects to both. |
| GND1 (6,7), GND2 (10,11) | Power switch return paths | Must be tied together and connected to low-impedance ground plane near input caps. |
| SW (8,9,21,22) | Switch node | Exposed pads (21,22) must be soldered to SW trace; critical for EMI and thermal performance. |
| EN/UV (14) | Enable and undervoltage lockout | Hysteresis of 40mV; rising threshold = 1.00V - enables programmable input brownout. |
| RT (15) | Oscillator frequency programming | Resistor to GND sets fSW: 221kΩ = 210kHz, 60.4kΩ = 700kHz, 18.2kΩ = 2.0MHz. |
| TR/SS (16) | Soft-start and output tracking | 1.9µA internal pull-up enables capacitor-programmed slew rate; pulled low during fault. |
| SYNC/MODE (17) | Operating mode control | Float = FCM; GND = Burst Mode; INTVCC = FCM + spread spectrum; external clock = sync. |
| GND (18) | System ground reference | Connect to system ground plane; separate from power GNDs but tied at single point. |
| PG (19) | Power good open-drain output | Active-high when FB is within ±8% of 0.970V and no faults - used for sequencing or monitoring. |
| FB (20) | Feedback input | Regulated to 0.970V; connect resistor divider tap and 4.7–22pF phase-lead capacitor to VOUT. |
Key Features
| Feature | Design Value |
|---|---|
| Silent Switcher® architecture | Reduces radiated/conducted EMI to meet CISPR 25 Class 5 limits without shielding or ferrites. |
| Forced Continuous Mode (FCM) | Enables fast transient response and consistent switching frequency across 0–5A load range. |
| Spread-spectrum modulation | ±20% frequency dithering lowers peak EMI amplitude by up to 10dB in narrowband measurements. |
| AEC-Q100 Grade E qualification | Rated for –40°C to +125°C junction temperature - qualified for under-hood automotive applications. |
| Low dropout performance | 100mV dropout at 1A load - maintains regulation during cold-crank (6V input) at 5V output. |
| Inductor saturation tolerance | Safely handles inductor saturation during overload without latch-up or damage. |
Applications
| Automotive Body Control Module (BCM) | Industrial PLC I/O Power Supply |
|---|---|
|
Use Scenario: Powering microcontroller, CAN transceiver, and sensor interfaces in BCM with 12V battery input subject to load dump and cold-crank. IC Role / Device Role / Timing Role: Primary 5V/3.3V buck converter providing regulated, low-noise, EMI-compliant power with fast transient recovery during ignition pulses. Use Value: 2.5µA IQ extends battery standby time; FCM ensures stable 5V rail during 100mA→3A load steps; AEC-Q100 ensures reliability over 15-year vehicle life. |
Use Scenario: Generating isolated 5V logic supply from 24V DC field bus in modular PLC backplane with strict EMC requirements. IC Role / Device Role / Timing Role: High-efficiency, spread-spectrum-enabled buck regulator feeding downstream LDOs and digital isolators. Use Value: 42V max input withstands 24V bus transients; <10mVP-P ripple prevents data corruption; QFN package fits dense backplane layouts. |
| GSM Base Station RF Power Amplifier Bias | Medical Portable Diagnostic Device |
|
Use Scenario: Providing clean, dynamically adjustable bias voltage to GaN/GaAs RF power amplifiers in small-cell base stations. IC Role / Device Role / Timing Role: High-frequency (2MHz) buck converter with precise soft-start and tracking for amplifier enable sequencing. Use Value: 30ns min on-time enables 28V→5V conversion at 2MHz; TR/SS pin allows controlled ramp to avoid RF burst artifacts. |
Use Scenario: Powering ARM Cortex-M7 MCU, ADC, and wireless BLE module in handheld ultrasound or glucose monitor with coin-cell backup. IC Role / Device Role / Timing Role: Primary buck regulator operating in Burst Mode during sleep, switching to FCM during measurement bursts. Use Value: 2.5µA IQ maximizes battery runtime; 5A capability supports short-duration high-power imaging cycles; low EMI avoids interference with analog front-end. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT8640EUDC#PBF | Pulse-skipping mode instead of FCM; SYNC/MODE pin floats for pulse-skipping, not FCM. | Better light-load efficiency in always-on systems where transient speed is secondary to IQ. | Select when lowest possible quiescent current dominates over transient response - e.g., battery-powered sensors. |
| MPQ4433AGL-AEC1-Z | 3.5A rated, 45V max input, 17µA IQ in shutdown, no spread spectrum, AEC-Q100 Grade 1 (–40°C to +125°C). | Limited peak current and higher IQ make it unsuitable for 5A automotive ECUs or ultra-low-power wake-up circuits. | Choose for cost-sensitive, lower-current automotive body electronics where EMI filtering is handled externally. |
Compared with LT8640EUDC#PBF and MPQ4433AGL-AEC1-Z, the LT8640EUDC-1#PBF uniquely combines 5A FCM operation, 2.5µA IQ, and integrated spread-spectrum EMI reduction - making it optimal for next-generation automotive ADAS domain controllers requiring both responsiveness and regulatory compliance.
Availability
LT8640EUDC-1#PBF is available at Aetrix Electronics and suitable for automotive body control modules, industrial PLC power supplies, GSM RF amplifier biasing, and portable medical diagnostics requiring stable component supply, AEC-Q100 qualification, and low-EMI DC/DC conversion.
Supply support for LT8640EUDC-1#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, Inc. is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and healthcare markets.
The LT8640/LT8640-1 product line was designed specifically for automotive and industrial applications demanding ultralow EMI, high efficiency across wide load ranges, and robust operation in harsh environments - exemplified by the LT8640EUDC-1#PBF's Silent Switcher architecture and AEC-Q100 qualification.
FAQ
What is the primary difference between LT8640EUDC-1#PBF and LT8640EUDC#PBF?
The LT8640EUDC-1#PBF operates in forced continuous mode (FCM) when the SYNC/MODE pin is floated, enabling fast transient response and consistent switching frequency across all loads. In contrast, the LT8640EUDC#PBF enters pulse-skipping mode under light loads when SYNC/MODE is floated, prioritizing ultralow quiescent current over transient speed. Both share identical pinout, package, and core specifications, but their default light-load behavior differs fundamentally - making LT8640EUDC-1#PBF ideal for automotive ECUs requiring rapid load steps.
Does LT8640EUDC-1#PBF require external compensation components?
No, the LT8640EUDC-1#PBF uses internal compensation and does not require external Type II or Type III compensation networks. Its error amplifier and VC node are fully integrated, simplifying design. However, a 4.7pF–22pF capacitor between FB and VOUT is mandatory for phase lead compensation and stability across all operating conditions - this is specified in the datasheet and validated on the DC2202A demo board.
Can LT8640EUDC-1#PBF operate with a 3.3V input voltage?
No, the LT8640EUDC-1#PBF has a minimum input voltage of 3.4V per absolute maximum ratings and electrical characteristics tables. Operation below 3.4V is not guaranteed and may result in failure to start or regulation loss. For 3.3V input applications, consider alternative regulators such as the LT8609S or LTC3637, which support true 2.8V or 3.0V minimum VIN.
How is spread-spectrum modulation enabled on LT8640EUDC-1#PBF?
Spread-spectrum modulation on the LT8640EUDC-1#PBF is enabled by applying a DC voltage of 3V to 4V (typically INTVCC ≈ 3.4V) to the SYNC/MODE pin. This configures the device to operate in forced continuous mode with ±20% triangular frequency dithering - reducing peak EMI emissions without affecting average switching frequency or output regulation. No external clock source is required for this mode.
Is LT8640EUDC-1#PBF pin-compatible with other Silent Switcher buck regulators?
No, the LT8640EUDC-1#PBF is not pin-compatible with earlier Silent Switcher devices like the LT8610 or LT8645S due to differences in pin count, function assignment (e.g., dual VIN/GND pins, dedicated BIAS and TR/SS), and internal architecture. Its 18-lead UDC QFN layout is unique to the LT8640 family. Migration requires PCB redesign and validation - though schematic-level similarities simplify requalification.
LT8640EUDC-1#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-1#PBF FAQ
1.How can I place an order for LT8640EUDC-1#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8640EUDC-1#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-1#PBF reliable?
The price and inventory of LT8640EUDC-1#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-1#PBF is usually 5 days.
3.What payment methods are accepted for LT8640EUDC-1#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8640EUDC-1#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8640EUDC-1#PBF?
LT8640EUDC-1#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8640EUDC-1#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-1#PBF?
For technical support, including LT8640EUDC-1#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8640EUDC-1#PBF requirements.
6.How does Aetrix verify that LT8640EUDC-1#PBF is sourced from the original manufacturer or authorized distributors?
All LT8640EUDC-1#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-1#PBF meets industry standards.
7.What is the process for return or replacement of LT8640EUDC-1#PBF?
All LT8640EUDC-1#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8640EUDC-1#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-1#PBF part is unused and in its original packaging.
Return procedure for LT8640EUDC-1#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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