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Analog Devices Inc. LT8640IUDC-1#PBF
- Part No.:
- LT8640IUDC-1#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 20-WFQFN, 18 Leads, Exposed Pad
- Datasheet:
-
LT8640IUDC-1#PBF.pdf
- Description:
- IC REG BUCK ADJ 5A 20QFN
- Quantity:
- Payment:
- Shipping:
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Product details
Overview
LT8640IUDC-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 LT8640IUDC-1#PBF datasheet, LT8640IUDC-1#PBF pinout, LT8640IUDC-1#PBF application, or LT8640IUDC-1#PBF equivalent, key selection criteria include ultralow EMI performance in automotive ECU designs, FCM-enabled fast load transient response in ADAS camera modules, and compatibility with 3mm × 4mm QFN PCB layouts requiring thermal pad soldering to SW node.
Technical Context
The LT8640IUDC-1#PBF implements peak current mode control with internal 0.97V reference and programmable oscillator (200kHz–3MHz via RT resistor). Its forced continuous mode eliminates pulse skipping, enabling consistent switching frequency and negative inductor current capability for improved light-load transient recovery.
Silent Switcher architecture integrates split VIN and GND paths with internal BST capacitor routing to minimize loop area; spread spectrum modulation (±22% frequency dither) further reduces radiated emissions without external filters. The BIAS pin supports efficiency optimization by sourcing internal circuitry from VOUT when ≥3.3V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.4V to 42V - supports cold-crank (4.5V) and load-dump (40V) conditions in 12V/24V automotive systems. |
| Continuous Output Current | 5A - delivers full-rated power without derating at TJ ≤ 125°C with proper PCB copper area. |
| Quiescent Current | 2.5µA at 12VIN → 3.3VOUT - enables >10-year battery life in always-on telematics modules. |
| Minimum On-Time | 30ns - enables high-frequency (≥2MHz) operation with low duty-cycle conversion (e.g., 42V→3.3V). |
| Feedback Reference | 0.970V ±0.006V - ensures ±1% output accuracy across –40°C to 125°C junction temperature range. |
| EMI Performance | CISPR 25 Class 5 compliant - meets automotive radiated emission limits without external EMI filter in typical layout. |
| Thermal Rating | –40°C to 125°C operating junction - qualified per AEC-Q100 Grade I for engine bay and infotainment applications. |
Pinout & Package
LT8640IUDC-1#PBF uses an 18-lead 3mm × 4mm plastic QFN package with exposed SW pads (Pins 21, 22) requiring solder connection to PCB for thermal and electrical performance. Pin count and layout match JEDEC MO-220, though Pins 5 and 12 are omitted.
| 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 cap; powers gate drivers and control logic-no external loading permitted. |
| BST (3) | Bootstrap capacitor node | Requires 0.1µF ceramic cap between BST and SW to drive high-side NMOS gate above VIN. |
| VIN1/VIN2 (4,13) | Main input power inputs | Each requires dedicated 1µF local ceramic bypass; both tied to common input bulk capacitor. |
| GND1/GND2 (6,7,10,11) | Power switch return paths | Must be shorted together and connected to low-impedance ground plane near input capacitors. |
| SW (8,9,21,22) | Switch node outputs | All SW pins-including exposed thermal pads-must connect directly to inductor and BST cap; critical for EMI control. |
| EN/UV (14) | Enable and input undervoltage lockout | Hysteretic threshold (0.96V/1.00V) allows programmable VIN start-up via resistor divider. |
| 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 current source enables voltage ramp control; pulled low during fault/shutdown. |
| SYNC/MODE (17) | Operating mode selection | Float = Forced Continuous Mode; GND = Burst Mode; INTVCC = Spread Spectrum FCM; clock input = sync mode. |
| GND (18) | System ground reference | Connect to main system ground plane; separate from power GNDs but tied at single point. |
| PG (19) | Power good open-drain output | Asserts high when FB is within ±7.5% of 0.97V and VIN > 3.4V; 2kΩ pull-up required externally. |
| FB (20) | Feedback voltage sense | Regulates to 0.970V; connect resistor divider tap here and add 4.7pF–22pF phase-lead cap to VOUT. |
Key Features
| Feature | Design Value |
|---|---|
| Forced Continuous Mode (FCM) | Enables zero-current crossover and negative inductor current for <50µs load-step recovery in ADAS vision systems. |
| Silent Switcher Architecture | Reduces peak radiated EMI by >30dB vs conventional buck regulators-eliminates need for metal shielding cans. |
| Spread Spectrum Modulation | ±22% triangular dither of switching frequency spreads energy across 30–100MHz band, easing CISPR 25 compliance. |
| Ultralow Dropout | 100mV dropout at 1A load allows stable 3.3V output even during 12V battery sag to 4.5V. |
| AEC-Q100 Grade I Qualification | Validated for automotive use including HTOL, TC, UHAST, and ESD testing-supports ASIL-B functional safety systems. |
| Robust Overload Protection | Tolerates inductor saturation up to 7A peak transient without latch-off; resumes regulation after current decay. |
Applications
| Automotive Engine Control Unit (ECU) | Industrial IoT Sensor Hub |
|---|---|
Use Scenario: Powering microcontroller, CAN transceiver, and analog front-end from 12V vehicle battery with cold-crank (4.5V) and load-dump (40V) transients. IC Role / Device Role / Timing Role: Primary 5V/3.3V point-of-load regulator with FCM ensuring stable clock domain during rapid load changes. Use Value: 2.5µA IQ extends battery backup runtime; Silent Switcher meets OEM EMI specs without added filtering cost. |
Use Scenario: Supplying ultra-low-power MCU, LoRaWAN radio, and environmental sensors in remote solar-powered monitoring nodes. IC Role / Device Role / Timing Role: High-efficiency buck converter maintaining regulation across 8V–42V PV input range and µA-level sleep currents. Use Value: Burst Mode achieves 90%+ efficiency at 100µA load; 30ns on-time supports 2MHz switching for compact magnetics. |
| ADAS Camera Module | Medical Portable Diagnostic Device |
Use Scenario: Generating clean 1.8V/3.3V rails for image sensor and ISP in rear-view camera with strict EMI limits near RF receivers. IC Role / Device Role / Timing Role: Low-noise power stage with spread spectrum and integrated compensation to avoid interference with 5GHz WiFi coexistence. Use Value: Radiated EMI < Class 5 peak limits at 10cm distance; PG signal synchronizes sensor startup sequence. |
Use Scenario: Providing isolated, ripple-free 5V/3.3V for precision ADC, touch controller, and Bluetooth LE radio in handheld ultrasound probe. IC Role / Device Role / Timing Role: Medical-grade DC/DC with <10mVP-P output ripple and AEC-Q100 reliability for Class II equipment. Use Value: Output ripple < 8mVP-P at 5A ensures SNR > 95dB in 24-bit ADC; thermal shutdown protects against enclosure overheating. |
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 |
|---|---|---|---|
| LT8640EUDC-1#PBF | Same silicon, –40°C to 125°C grade (E) vs –40°C to 125°C (I); identical electrical specs and pinout. | No automotive qualification; suitable for commercial/industrial environments without AEC-Q100 requirement. | Select LT8640IUDC-1#PBF when AEC-Q100 Grade I validation is mandatory for production release. |
| LT8643S-2#PBF | Supports external compensation and higher 7A peak current; requires external bootstrap capacitor; no internal caps. | Targeted at higher-power applications needing custom loop tuning or >5A continuous output with external MOSFETs. | Choose LT8640IUDC-1#PBF for drop-in replacement in existing 5A designs with minimal layout change and internal compensation. |
Compared with LT8640EUDC-1#PBF, the LT8640IUDC-1#PBF provides identical performance with certified automotive reliability; versus LT8643S-2#PBF, it offers faster time-to-market via internal compensation and reduced BOM count despite lower peak current rating.
Availability
LT8640IUDC-1#PBF is available at Aetrix Electronics and suitable for automotive ECU power supplies, ADAS camera modules, and industrial IoT sensor hubs requiring stable component supply with AEC-Q100 traceability and long-term lifecycle support.
Supply support for LT8640IUDC-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 is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving automotive, industrial, communications, and healthcare markets since 1965.
The LT8640/LT8640-1 product line delivers high-efficiency, low-EMI power conversion for automotive and harsh-environment applications where reliability, small size, and regulatory compliance are critical design constraints.
FAQ
What is the maximum ambient temperature for reliable operation of the LT8640IUDC-1#PBF?
The LT8640IUDC-1#PBF is rated for –40°C to 125°C junction temperature. With θJA = 40°C/W and typical PCB copper, maximum ambient temperature depends on power dissipation. At 5A output with 12VIN→5VOUT, ambient must remain ≤85°C to maintain TJ ≤125°C. Derating is required above 100°C ambient.
Does the LT8640IUDC-1#PBF require external compensation components?
No, the LT8640IUDC-1#PBF features internal compensation and requires no external Type II or Type III compensation network. Only standard input/output capacitors, BST capacitor, and RT resistor are needed for basic operation-reducing design complexity and BOM count.
How does the SYNC/MODE pin configure forced continuous mode on the LT8640IUDC-1#PBF?
On the LT8640IUDC-1#PBF, floating the SYNC/MODE pin (leakage <1µA) enables forced continuous mode. This configures the regulator to operate at full switching frequency across all load conditions, allowing negative inductor current and improving transient response over pulse-skipping alternatives.
Can the LT8640IUDC-1#PBF safely operate with a 48V input transient?
No-the absolute maximum VIN rating is 42V. While the LT8640IUDC-1#PBF withstands automotive load-dump transients up to 40V per ISO 7637-2, sustained operation above 42V risks permanent damage. External TVS clamping or input filtering is required for 48V system integration.
What is the purpose of the exposed SW pads (Pins 21, 22) on the LT8640IUDC-1#PBF package?
The exposed SW pads on the LT8640IUDC-1#PBF must be soldered to the PCB's SW trace-not left floating-to provide low-inductance, high-current return path for the internal power switches and enhance thermal conduction. Omitting this connection degrades efficiency, increases EMI, and raises junction temperature by up to 25°C.
LT8640IUDC-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)
LT8640IUDC-1#PBF FAQ
1.How can I place an order for LT8640IUDC-1#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8640IUDC-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 LT8640IUDC-1#PBF reliable?
The price and inventory of LT8640IUDC-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 LT8640IUDC-1#PBF is usually 5 days.
3.What payment methods are accepted for LT8640IUDC-1#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8640IUDC-1#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8640IUDC-1#PBF?
LT8640IUDC-1#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8640IUDC-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 LT8640IUDC-1#PBF?
For technical support, including LT8640IUDC-1#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8640IUDC-1#PBF requirements.
6.How does Aetrix verify that LT8640IUDC-1#PBF is sourced from the original manufacturer or authorized distributors?
All LT8640IUDC-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 LT8640IUDC-1#PBF meets industry standards.
7.What is the process for return or replacement of LT8640IUDC-1#PBF?
All LT8640IUDC-1#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8640IUDC-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 LT8640IUDC-1#PBF part is unused and in its original packaging.
Return procedure for LT8640IUDC-1#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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