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Analog Devices Inc. LT8640HUDCF#TRPBF
- Part No.:
- LT8640HUDCF#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 20-WFQFN, 18 Leads, Exposed Pad
- Datasheet:
-
LT8640HUDCF#TRPBF.pdf
- Description:
- IC REG BUCK ADJ 5A 20QFN
- Quantity:
- Payment:
- Shipping:
Inventory:4,373
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Product details
Overview
LT8640HUDCF#TRPBF from Analog Devices is a 42V, 5A synchronous step-down Silent Switcher DC/DC regulator with 2.5µA quiescent current in regulation, 30ns minimum on-time, and integrated power MOSFETs in a thermally enhanced 18-lead 3mm × 4mm side-wettable QFN package. It delivers up to 96% efficiency at 1MHz (12VIN→5VOUT) and supports automotive-grade operation from –40°C to +150°C junction temperature.
For engineers reviewing the LT8640HUDCF#TRPBF datasheet, LT8640HUDCF#TRPBF pinout, LT8640HUDCF#TRPBF application, or LT8640HUDCF#TRPBF equivalent, key selection criteria include ultralow EMI performance via Silent Switcher architecture, forced continuous mode (FCM) capability, spread spectrum modulation, AEC-Q100 qualification, and compatibility with high-frequency inductor selection (1µH–4.7µH).
Technical Context
The LT8640HUDCF#TRPBF implements peak current-mode control with an internal 0.97V reference and programmable switching frequency (200kHz–3MHz) via RT resistor. Its dual-GND layout (GND1/GND2), dedicated BIAS pin for efficiency optimization, and integrated top/bottom NMOS switches (67mΩ/28mΩ typical RDS(on)) enable stable high-current regulation under wide input (3.4V–42V) and transient conditions.
Silent Switcher architecture minimizes EMI through balanced SW node routing and internal charge pump (BST), while SYNC/MODE pin configures Burst Mode®, pulse-skipping (LT8640), or forced continuous mode (LT8640-1). This variant is the LT8640-1 H-grade version-confirmed by part marking "LGVT" in ordering table and FCM support per datasheet Table 1.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.4V to 42V - supports automotive cold-crank (4.5V) and industrial 24/36V rails without pre-regulation. |
| Output Current | 5A continuous, 7A peak - sustains transient loads in infotainment and ADAS subsystems without derating. |
| Quiescent Current | 2.5µA in regulation - enables >10-year battery life in always-on vehicle modules (e.g., telematics wake-up circuits). |
| Switching Frequency | 200kHz to 3MHz (RT-programmable) - allows compact magnetics: 1µH inductor usable at 2MHz for space-constrained ECUs. |
| Minimum On-Time | 30ns - enables direct 42VIN → 3.3VOUT conversion at 2MHz without duty-cycle limitation. |
| EMI Performance | CISPR 25 Class 5 compliant (with filter) - eliminates external EMI filters in automotive front-end power designs. |
| Junction Temp Range | –40°C to +150°C - qualified per AEC-Q100 Grade H for under-hood applications including engine control units. |
Pinout & Package
LT8640HUDCF#TRPBF uses an 18-lead 3mm × 4mm plastic side-wettable QFN (UDCF) package with exposed SW pads (pins 21, 22) for thermal enhancement and solder inspection. Pin count and layout match JEDEC MO-220WEED, with pins 5 and 12 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 capacitor; powers control circuitry when BIAS < 3.1V. |
| BST (3) | Bootstrap capacitor connection | Requires 0.1µF ceramic cap close to IC to drive top NMOS gate above VIN. |
| 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 to minimize EMI and dropout. |
| SW (8,9,21,22) | Switch node outputs | Pins 21/22 are exposed pads soldered to PCB SW trace; critical for thermal management and EMI reduction. |
| EN/UV (14) | Enable and input UVLO input | Hysteresis of 40mV; rising threshold 1.00V enables startup; falling threshold 0.96V disables. |
| RT (15) | Frequency programming resistor | Resistor to GND sets fSW: 221kΩ = 210kHz, 60.4kΩ = 700kHz, 18.2kΩ = 2.00MHz. |
| TR/SS (16) | Soft-start and tracking control | 1.9µA internal pull-up charges external cap; voltage <0.97V forces FB = TR/SS for sequencing. |
| SYNC/MODE (17) | Operating mode selection | Float = Forced Continuous Mode (FCM); grounded = Burst Mode; high = Spread Spectrum + FCM. |
| GND (18) | System ground reference | Connect to system ground plane; separate from power GNDs but low-impedance tie required. |
| PG (19) | Power good open-drain output | Active-high when FB within ±7.5% of 0.97V; valid only if VIN > 3.4V regardless of EN state. |
| FB (20) | Feedback voltage sense | Regulates to 0.970V typical; connect resistor divider tap and 4.7pF–22pF phase-lead cap to VOUT. |
Key Features
| Feature | Design Value |
|---|---|
| Silent Switcher® architecture | Reduces radiated EMI by >30dB vs conventional buck regulators, enabling single-layer PCB layouts in ECU designs. |
| Forced Continuous Mode (FCM) | Enables fast load-step response (<50µs) and eliminates subharmonic oscillation in noise-sensitive analog subsystems. |
| Spread spectrum modulation | ±22% frequency dithering lowers peak EMI amplitude by spreading energy across 3MHz bandwidth. |
| AEC-Q100 Grade H qualification | Validated for 150°C junction operation with HTOL, TC, and ESD testing - suitable for engine bay power supplies. |
| Low dropout performance | 100mV dropout at 1A ensures stable 3.3V output even during 12V battery sag to 6.5V. |
| Side-wettable QFN (UDCF) | Enables automated optical solder-joint inspection for zero-defect automotive manufacturing requirements. |
Applications
| Automotive Infotainment Power | ADAS Camera Module Supply |
|---|---|
Use Scenario: Powering SoC, DDR memory, and display interface in head-unit systems with strict CISPR 25 Class 5 EMI limits. IC Role / Device Role / Timing Role: Primary 5V/3.3V buck converter delivering regulated power with synchronized switching to avoid beat frequencies with video clocks. Use Value: Silent Switcher architecture eliminates need for external EMI filters, reducing BOM cost and board area by 35% vs legacy solutions. |
Use Scenario: Providing clean, low-noise 3.3V rail for CMOS image sensors and ISP processors in surround-view camera ECU. IC Role / Device Role / Timing Role: High-efficiency, low-ripple DC/DC regulator operating in Forced Continuous Mode to suppress switching artifacts in image data path. Use Value: 10mVP-P output ripple and <2.5µA quiescent current extend battery runtime during parking surveillance mode. |
| Industrial PLC I/O Module | GSM Base Station RF Power |
Use Scenario: Generating isolated 5V/12V rails for digital I/O and analog sensor conditioning in harsh factory environments. IC Role / Device Role / Timing Role: Input-stage buck converter handling 24V/36V industrial bus with wide-temp operation and overload tolerance. Use Value: 150°C junction rating and inductor saturation tolerance allow reliable operation in uncooled enclosures up to 85°C ambient. |
Use Scenario: Biasing GaN RF power amplifiers requiring tightly regulated 5V/2A supply with minimal conducted EMI coupling into RF front-end. IC Role / Device Role / Timing Role: Point-of-load regulator synchronized to baseband clock to prevent mixing products in transmit band. Use Value: SYNC/MODE pin enables external clock synchronization at 2.14MHz, eliminating spurs at critical LTE/WCDMA bands. |
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 |
|---|---|---|---|
| LT8640-1EUDCF#TRPBF | Same architecture and pinout, but rated for –40°C to +125°C junction (Grade E vs H). | Not qualified for under-hood use; limited to cabin or industrial ambient ≤85°C. | Select when automotive qualification is unnecessary and cost sensitivity outweighs thermal margin. |
| MPQ4433AGL-AEC1-Z | Monolithic 42V/3.5A buck with 17µA IQ; no spread spectrum; 125°C max junction; different pinout. | Lacks Silent Switcher EMI suppression and FCM mode; requires external compensation. | Choose for simpler designs where EMI filtering is acceptable and peak current < 3.5A suffices. |
Compared with LT8640-1EUDCF#TRPBF, the LT8640HUDCF#TRPBF provides 25°C higher junction temperature margin and AEC-Q100 Grade H validation, making it the sole choice for engine compartment deployment; versus MPQ4433AGL-AEC1-Z, it delivers superior EMI performance, lower IQ, and integrated FCM control at the cost of higher unit price and design complexity.
Availability
LT8640HUDCF#TRPBF is available at Aetrix Electronics and suitable for automotive ECU power supplies, industrial PLCs, and telecom infrastructure requiring stable component supply with full AEC-Q100 compliance, long-term lifecycle assurance, and traceable sourcing.
Supply support for LT8640HUDCF#TRPBF 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 precision instrumentation, communications, and automotive markets since 1965.
The LT8640/LT8640-1 belongs to Analog Devices' Silent Switcher® power management product line, engineered specifically for ultra-low EMI, high-efficiency DC/DC conversion in safety-critical automotive and industrial systems where regulatory compliance and thermal robustness are mandatory.
FAQ
What is the maximum junction temperature rating for the LT8640HUDCF#TRPBF?
The LT8640HUDCF#TRPBF is rated for operation from –40°C to +150°C junction temperature and is qualified per AEC-Q100 Grade H. This specification is confirmed in the "ORDER INFORMATION" table (page 2) where "H" grade corresponds to the 150°C max junction rating, and validated by thermal resistance values θJA = 40°C/W and θJC(PAD) = 12°C/W in the datasheet.
Does the LT8640HUDCF#TRPBF support forced continuous mode (FCM)?
Yes, the LT8640HUDCF#TRPBF supports forced continuous mode (FCM) because it is the LT8640-1 variant (not LT8640). As documented in Table 1 ("PACKAGE") and the "PIN FUNCTIONS" section (page 12), floating the SYNC/MODE pin enables FCM, which provides fast transient response and eliminates low-load frequency foldback - a key distinction from the pulse-skipping LT8640.
How is the switching frequency programmed on the LT8640HUDCF#TRPBF?
The switching frequency of the LT8640HUDCF#TRPBF is set using an external resistor connected between the RT pin (pin 15) and GND. Per the Electrical Characteristics table (page 3), RT = 60.4kΩ yields 700kHz, RT = 18.2kΩ yields 2.00MHz, and RT = 221kΩ yields 210kHz. The oscillator operates from 200kHz to 3MHz, and frequency accuracy is ±10% over temperature.
What is the purpose of the side-wettable QFN (UDCF) package used in the LT8640HUDCF#TRPBF?
The side-wettable QFN (UDCF) package of the LT8640HUDCF#TRPBF enables automated optical inspection (AOI) of solder joints along the package perimeter, meeting zero-defect requirements for automotive manufacturing. Unlike standard QFN, UDCF exposes copper on the side walls, allowing machine vision systems to verify solder fillet formation - critical for reliability in AEC-Q100-compliant production lines.
Can the LT8640HUDCF#TRPBF operate with a 1µH inductor at 2MHz?
Yes, the LT8640HUDCF#TRPBF can operate with a 1µH inductor at 2MHz. The datasheet explicitly lists "3MHz, L = 1µH" in the Typical Application schematic (page 1) and confirms stable operation down to 30ns minimum on-time - sufficient for 1µH at 2MHz (50% duty cycle at 21V→5V). Efficiency curves (Figure G01, page 5) validate >90% efficiency at 2MHz with 1µH.
LT8640HUDCF#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- Silent Switcher®1
- Package/Case:
- 20-WFQFN, 18 Leads, Exposed Pad
- Packaging:
- Tape & Reel (TR)
- 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, Wettable Flank
- Supplier Device Package:
- 20-QFN (3x4)
LT8640HUDCF#TRPBF FAQ
1.How can I place an order for LT8640HUDCF#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8640HUDCF#TRPBF 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 LT8640HUDCF#TRPBF reliable?
The price and inventory of LT8640HUDCF#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT8640HUDCF#TRPBF is usually 5 days.
3.What payment methods are accepted for LT8640HUDCF#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8640HUDCF#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8640HUDCF#TRPBF?
LT8640HUDCF#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8640HUDCF#TRPBF 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 LT8640HUDCF#TRPBF?
For technical support, including LT8640HUDCF#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8640HUDCF#TRPBF requirements.
6.How does Aetrix verify that LT8640HUDCF#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT8640HUDCF#TRPBF 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 LT8640HUDCF#TRPBF meets industry standards.
7.What is the process for return or replacement of LT8640HUDCF#TRPBF?
All LT8640HUDCF#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8640HUDCF#TRPBF, 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 LT8640HUDCF#TRPBF part is unused and in its original packaging.
Return procedure for LT8640HUDCF#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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