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Analog Devices Inc. LT8636HV#PBF
- Part No.:
- LT8636HV#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 20-TFQFN Exposed Pad
- Datasheet:
-
LT8636HV#PBF.pdf
- Description:
- IC REG BUCK ADJ 5A 20LQFN
- Quantity:
- Payment:
- Shipping:
Inventory:226
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Product details
Overview
LT8636HV#PBF from Analog Devices is a 42V input, 5A continuous synchronous step-down regulator with Silent Switcher architecture, 2.5µA quiescent current in regulation, 30ns minimum on-time, and AEC-Q100 qualification for automotive applications. It delivers up to 96% efficiency at 1MHz (12VIN to 5VOUT) and operates across –40°C to 150°C junction temperature.
For engineers reviewing the LT8636HV#PBF datasheet, LT8636HV#PBF pinout, LT8636HV#PBF application, or LT8636HV#PBF equivalent, key selection criteria include ultralow IQ for battery-powered systems, EMI-sensitive automotive power rails, high step-down ratio capability at 2–3MHz switching, and thermal robustness in under-hood environments.
Technical Context
The LT8636HV#PBF implements peak current mode control with internal compensation and a fixed 0.970V feedback reference. Its Silent Switcher architecture uses symmetrical layout and integrated bypass capacitors to suppress common-mode EMI without external filters.
It supports four operating modes via the SYNC/MODE pin: Burst Mode (ultralow IQ), forced continuous mode (fast transient response), spread spectrum (±20% frequency modulation), and external clock synchronization. The TR/SS pin enables soft-start and output voltage tracking with 1.9µA internal pull-up current.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.4V to 42V - supports wide automotive battery transients including cold-crank (4.5V) and load-dump (40V+) |
| Output Current | 5A continuous, 7A peak - sustains pulsed loads like radar or camera flash without dropout |
| Quiescent Current | 2.5µA at full regulation - enables >10-year battery life in always-on vehicle modules |
| Switching Frequency | 200kHz to 3MHz - programmable via RT resistor; enables compact magnetics and avoids AM band |
| Min On-Time | 30ns - allows direct 42V-to-3.3V conversion at 2MHz without intermediate stages |
| Thermal Rating | –40°C to 150°C junction - qualified per AEC-Q100 Grade H for engine compartment use |
| EMI Performance | CISPR 25 Class 5 compliant - meets automotive radiated emission limits without added shielding |
Pinout & Package
LT8636HV#PBF is housed in a thermally enhanced 20-lead 4mm × 3mm LQFN package with exposed pad (Pin 21 = GND). The package footprint matches standard QFN-20 layouts and supports θJC(pad) = 8.0°C/W for high-power dissipation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| PG (1) | Open-drain Power Good | Asserts high when FB is within ±8% of 0.970V and no fault (UVLO, thermal, INTVCC); valid only above 3.4V VIN |
| BIAS (2) | Bias Supply Input | Reduces VIN current draw by powering internal regulators from VOUT (≥3.3V); requires 1µF local bypass if externally sourced |
| INTVCC (3) | Internal 3.4V Regulator Bypass | Must be decoupled with ≥1µF low-ESR ceramic; supplies gate drivers and control logic; draws from BIAS if >3.1V, else from VIN |
| GND (4,13,21) | Ground Reference | Pins 4/13 are signal GND; Pin 21 is exposed thermal pad - must be soldered to PCB plane for thermal integrity and EMI reduction |
| VIN (6,11) | Main Input Power | Dual pins reduce trace inductance; require two 1µF ceramic caps placed adjacent to each pin plus ≥2.2µF bulk capacitance |
| BST (7) | Bootstrap Supply | Drives high-side MOSFET gate; requires 0.1µF ceramic capacitor between BST and SW with minimal loop area |
| SW (8–10) | Power Switch Node | Three paralleled pins carry high di/dt switching current; must connect directly to inductor with minimal copper area to limit EMI |
| EN/UV (14) | Enable / Input UVLO | Hysteretic threshold (1.00V rise / 0.96V fall); resistor divider from VIN sets custom undervoltage lockout point |
| SYNC/MODE (15) | Mode Control | Ground = Burst Mode; float = FCM; ~3.4V = spread spectrum + FCM; external clock = sync mode |
| CLKOUT (16) | Switch Clock Output | 200ns pulse at fSW in FCM/spread/sync modes; low during Burst Mode; high-impedance when unused |
| RT (17) | Frequency Set | Resistor to GND programs fSW: 221kΩ = 210kHz, 60.4kΩ = 700kHz, 18.2kΩ = 1.95MHz |
| TR/SS (18) | Soft-Start / Tracking | 1.9µA internal current source charges external cap for controlled VOUT ramp; also enables supply tracking with external reference |
| FB (19,20) | Feedback Input | Regulates to 0.970V; dual pins improve noise immunity; requires 4.7–22pF phase-lead capacitor from FB to VOUT |
Key Features
| Feature | Design Value |
|---|---|
| Silent Switcher Architecture | Integrated input capacitors and symmetrical layout reduce radiated EMI by >30dB vs conventional buck ICs |
| Ultralow Quiescent Current | 2.5µA IQ in regulation enables >10-year shelf life in automotive telematics and ADAS sensors |
| 30ns Minimum On-Time | Enables single-stage 42V-to-3.3V conversion at 2MHz, eliminating cascaded regulators and saving board space |
| AEC-Q100 Grade H Qualification | Validated for –40°C to 150°C operation with 100% HTOL testing - suitable for engine control units and transmission modules |
| Four-Mode Operation | Selectable Burst Mode (low IQ), FCM (fast transient), spread spectrum (EMI reduction), or sync (system timing coherence) |
Applications
| Automotive Engine Control Unit (ECU) | Industrial Motor Drive Controller |
|---|---|
Use Scenario: Powering microcontroller, CAN transceiver, and sensor interfaces in under-hood ECU with 8V–40V battery input. IC Role / Device Role / Timing Role: Primary 5V/3.3V power rail regulator with AEC-Q100 compliance and load-dump survivability. Use Value: 2.5µA IQ extends battery backup runtime during ignition-off; Silent Switcher meets CISPR 25 Class 5 without shielded inductors. | Use Scenario: Generating isolated gate drive bias and logic supply in servo amplifier with 24V–48V DC bus. IC Role / Device Role / Timing Role: High-efficiency, high-PWM-frequency auxiliary supply for FPGA, ADC, and isolated gate drivers. Use Value: 30ns min on-time supports 48V-to-5V conversion at 2MHz, enabling small 1µH inductors and fast transient response to motor current spikes. |
| Railway Signaling Module | Medical Portable Diagnostic Device |
Use Scenario: Converting 72V nominal railway supply to 5V/3.3V for microcontroller and communication ICs in trackside equipment. IC Role / Device Role / Timing Role: Wide-input, high-reliability DC-DC converter with extended temperature range and EMI robustness. Use Value: 42V max input accommodates 72V system transients; 150°C rating ensures operation in uncooled enclosures near traction motors. | Use Scenario: Battery-powered ultrasound probe requiring silent, efficient power conversion for analog front-end and FPGA. IC Role / Device Role / Timing Role: Low-noise, low-EMI power supply for sensitive RF and analog circuitry in handheld medical devices. Use Value: Spread spectrum mode reduces spectral peaks that could interfere with echo signal acquisition; 2.5µA IQ extends single-charge battery life beyond 8 hours. |
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 |
|---|---|---|---|
| LT8646S#PBF | Same 42V/5A rating but 2.8µA IQ, 20-lead 4mm×3mm LQFN, AEC-Q100 Grade H, includes integrated compensation network and improved light-load efficiency | Optimized for higher efficiency below 10mA; lacks CLKOUT and TR/SS tracking functionality | Select LT8646S#PBF when lowest possible light-load IQ and simplified design are priorities over output tracking or clock synchronization |
| MPQ4436-AEC1 | 42V/5A, 2.5µA IQ, 20-lead 4mm×3mm QFN, AEC-Q100 Grade 1 (–40°C to 125°C), no spread spectrum or Silent Switcher architecture | Lower EMI performance requires external filtering; limited to 125°C junction, not 150°C | Select MPQ4436-AEC1 for cost-sensitive automotive infotainment where 125°C rating suffices and EMI filtering is acceptable |
Compared with LT8646S#PBF and MPQ4436-AEC1, the LT8636HV#PBF uniquely combines 150°C operation, Silent Switcher EMI suppression, and full four-mode control (Burst/FCM/spread/sync) - making it optimal for high-reliability, thermally constrained, and EMI-sensitive automotive power rails.
Availability
LT8636HV#PBF is available at Aetrix Electronics and suitable for automotive engine control units, industrial motor drives, railway signaling modules, and portable medical diagnostics requiring stable component supply across extended temperature and high-reliability environments.
Supply support for LT8636HV#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.
The LT8636HV#PBF belongs to the Silent Switcher® family of high-efficiency, low-EMI synchronous step-down regulators designed specifically for demanding automotive and industrial power applications where thermal robustness and electromagnetic compatibility are critical.
FAQ
What is the maximum junction temperature rating for the LT8636HV#PBF?
The LT8636HV#PBF is rated for operation from –40°C to 150°C junction temperature and is AEC-Q100 qualified for Grade H automotive applications. This rating is verified through 100% high-temperature operating life (HTOL) testing and enables use in under-hood environments such as engine control units and transmission control modules where ambient temperatures exceed 125°C.
How does the LT8636HV#PBF achieve ultralow 2.5µA quiescent current while maintaining regulation?
The LT8636HV#PBF achieves 2.5µA IQ in regulation by combining Burst Mode operation with optimized internal biasing and low-leakage process technology. During light loads, it enters deep sleep cycles where most control circuitry is powered down, yet maintains feedback loop integrity to hold output voltage within ±8% tolerance. This enables multi-year battery life in always-on automotive modules without sacrificing regulation accuracy.
Can the LT8636HV#PBF synchronize to an external clock, and what are the requirements?
Yes, the LT8636HV#PBF can synchronize to an external clock via the SYNC/MODE pin (Pin 15). The external clock must be a clean CMOS-level signal with 200ns minimum pulse width, 0.7V to 2.9V logic thresholds, and frequency within the 200kHz–3MHz range. When synchronized, the device operates in forced continuous mode with switch transitions aligned to the external clock edge, enabling deterministic timing in multi-rail systems.
What is the purpose of the dual VIN pins (Pins 6 and 11) on the LT8636HV#PBF?
The dual VIN pins (Pins 6 and 11) on the LT8636HV#PBF reduce parasitic inductance and improve high-frequency current delivery to the internal top switch. Each pin must be independently decoupled with a 1µF ceramic capacitor placed adjacent to the pin, and both paths feed into a shared input bulk capacitor (≥2.2µF). This layout minimizes voltage spikes and EMI during high di/dt switching events, especially critical in 2–3MHz operation.
Does the LT8636HV#PBF support output voltage tracking, and how is it implemented?
Yes, the LT8636HV#PBF supports output voltage tracking via the TR/SS pin (Pin 18). An internal 1.9µA current source charges an external capacitor connected to TR/SS, generating a linear ramp that the regulator follows during startup. When used with an external reference (e.g., another regulator's output), TR/SS enables precise sequencing of multiple power rails - essential for FPGAs and processors requiring controlled power-up order.
LT8636HV#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 20-TFQFN Exposed Pad
- Packaging:
- Tray
- 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:
- 200kHz ~ 3MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-LQFN (4x3)
LT8636HV#PBF FAQ
1.How can I place an order for LT8636HV#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8636HV#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 LT8636HV#PBF reliable?
The price and inventory of LT8636HV#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT8636HV#PBF is usually 5 days.
3.What payment methods are accepted for LT8636HV#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8636HV#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8636HV#PBF?
LT8636HV#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8636HV#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 LT8636HV#PBF?
For technical support, including LT8636HV#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8636HV#PBF requirements.
6.How does Aetrix verify that LT8636HV#PBF is sourced from the original manufacturer or authorized distributors?
All LT8636HV#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 LT8636HV#PBF meets industry standards.
7.What is the process for return or replacement of LT8636HV#PBF?
All LT8636HV#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8636HV#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 LT8636HV#PBF part is unused and in its original packaging.
Return procedure for LT8636HV#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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