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Analog Devices Inc. LT8637EV#PBF
- Part No.:
- LT8637EV#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 20-TFQFN Exposed Pad
- Datasheet:
-
LT8637EV#PBF.pdf
- Description:
- IC REG BUCK ADJ 5A 20LQFN
- Quantity:
- Payment:
- Shipping:
Inventory:494
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Product details
Overview
LT8637EV#PBF from Analog Devices is a 42V, 5A continuous/7A peak synchronous step-down regulator with external compensation, Silent Switcher architecture, and 30ns minimum on-time. It delivers up to 95% efficiency at 2MHz (12VIN to 5VOUT), supports 200kHz–3MHz switching frequency, and operates from –40°C to 125°C junction temperature. It is used in automotive infotainment power supplies requiring low EMI and fast transient response.
For engineers reviewing the LT8637EV#PBF datasheet, LT8637EV#PBF pinout, LT8637EV#PBF application, or LT8637EV#PBF equivalent, key selection criteria include external loop compensation capability, CLKOUT synchronization support, spread spectrum EMI reduction, and 2.5µA quiescent current in Burst Mode operation with BIAS = 5V.
Technical Context
The LT8637EV#PBF implements peak current mode control with an externally accessible error amplifier output (VC pin) for precise loop shaping, enabling current sharing across parallel regulators and optimized transient response at high frequencies. Its Silent Switcher architecture uses dual, matched input paths and integrated bypass capacitors to suppress common-mode EMI.
It supports four operating modes via the SYNC/MODE pin: Burst Mode (ultralow IQ), forced continuous mode (FCM), spread spectrum (±20% frequency modulation), and external clock synchronization. The VC pin allows direct access to the error amplifier output (1.7mS transconductance, ±350µA sink/source), and TR/SS enables soft-start and output 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 range including cold-crank (4.5V) and load-dump (40V) conditions. |
| Output Current | 5A continuous, 7A peak - sustains short-term surge loads without thermal shutdown in properly heatsinked layouts. |
| Switching Frequency | 200kHz to 3MHz - programmable via RT resistor; enables compact magnetics and avoids AM band interference. |
| Quiescent Current | 230µA (BIAS = 0V) / 25µA (BIAS = 5V) in Burst Mode - enables >10-year battery life in always-on automotive modules. |
| Min On-Time | 30ns - permits high step-down ratios (e.g., 42V to 3.3V) at 2MHz without pulse-skipping instability. |
| Feedback Reference | 0.970V ±3mV - high-accuracy reference enables tight output regulation (<±1% over line/load/temp). |
| Thermal Range | –40°C to 125°C junction - qualified per AEC-Q100 Grade E, suitable for under-hood automotive applications. |
Pinout & Package
LT8637EV#PBF is housed in a thermally enhanced 20-lead 4mm × 3mm × 0.94mm LQFN package with exposed GND pad (Pin 21) for optimal thermal performance. The package is RoHS-compliant (e4 Au finish) and MSL Level 3.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| PG (1) | Power Good Open-Drain Output | Asserts high when FB is within ±8% of 0.97V and no fault (UVLO, thermal, INTVCC undervoltage); requires external pull-up. |
| BIAS (2) | Bias Supply Input | Accepts 3.3V–25V supply (e.g., VOUT) to reduce VIN current draw; improves efficiency at high VIN or high fSW. |
| INTVCC (3) | Internal 3.4V Regulator Bypass | Requires ≥1µF ceramic capacitor to GND; powers internal logic and drivers; sourced 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 θJC(pad) = 8.0°C/W. |
| VIN (6,11) | Main Input Power | Dual pins reduce IR drop and improve high-current routing; requires local 1µF + 1µF + ≥2.2µF ceramic bypass network. |
| BST (7) | Bootstrap Supply | Connects to 0.1µF ceramic capacitor between BST and SW; provides gate drive voltage >VIN for top MOSFET. |
| SW (8–10) | Power Switch Node | Three paralleled pins carry high di/dt switch current; must be routed as single low-inductance node to inductor. |
| EN/UV (14) | Enable / Input UVLO Control | Hysteretic threshold (1.00V rise / 0.96V fall); resistor divider from VIN sets custom input undervoltage lockout. |
| SYNC/MODE (15) | Operating Mode Select | Ground = Burst Mode; float = FCM; INTVCC = spread spectrum; external clock = sync - no external components needed. |
| CLKOUT (16) | Switch Clock Output | 200ns pulse at fSW during FCM/spread/sync modes; drives other regulators' SYNC pins; low in Burst Mode. |
| RT (17) | Frequency Set Resistor | Resistor to GND programs fSW: 221kΩ = 210kHz, 60.4kΩ = 700kHz, 18.2kΩ = 1.95MHz - enables precise EMI band placement. |
| TR/SS (18) | Soft-Start / Tracking Input | 1.9µA internal pull-up charges external capacitor for controlled VOUT ramp; <1.6V enables tracking to external rail. |
| VC (19) | Error Amplifier Output | Direct access to EA output (1.7mS, ±350µA); RC network to GND sets loop compensation for fast transient response. |
| FB (20) | Feedback Input | Regulated to 0.970V; connects to resistor divider tap; phase-lead capacitor (4.7–22pF) from FB to VOUT improves stability. |
Key Features
| Feature | Design Value |
|---|---|
| External Compensation (VC Pin) | Enables custom loop tuning for multi-phase current sharing and <10µs load-step recovery in automotive ADAS systems. |
| Silent Switcher Architecture | Reduces radiated EMI by >30dB vs conventional buck converters - meets CISPR 25 Class 5 limits without shielding. |
| Spread Spectrum Modulation | ±20% triangular frequency dither spreads EMI energy, easing compliance with stringent automotive EMC standards. |
| CLKOUT Synchronization | Allows precise timing alignment of multiple regulators - eliminates beat frequencies and simplifies system-level noise filtering. |
| AEC-Q100 Qualified | Validated for automotive Grade E (–40°C to 125°C), including HTOL, TC, and UHAST - suitable for front-end power in telematics ECUs. |
Applications
| Automotive Infotainment Power | Industrial PLC I/O Module |
|---|---|
Use Scenario: Powering SoC core rails (1.0V/1.2V) and DDR memory (1.2V/1.35V) in head-unit designs with strict CISPR 25 radiated emissions limits. IC Role / Device Role / Timing Role: Primary 12V-to-5V intermediate converter feeding downstream POLs; provides clean, low-noise 5V bias for analog audio codecs and video decoders. Use Value: Silent Switcher architecture achieves <35dBµV/m at 150MHz (Class 5 limit) with minimal filter area, reducing BOM cost by 40% vs shielded inductors. | Use Scenario: Generating isolated 5V/3.3V rails for digital I/O expansion cards in modular industrial controllers operating in electrically noisy factory environments. IC Role / Device Role / Timing Role: High-reliability main DC-DC stage converting 24V field bus to regulated 5V; synchronized via CLKOUT to avoid interference with CAN FD communication timing. Use Value: 7A peak current handles inrush from hot-plug I/O modules; AEC-Q100 qualification ensures 15-year field life under thermal cycling stress. |
| Medical Portable Monitor | Test & Measurement Equipment |
Use Scenario: Battery-powered patient monitor requiring >100-hour runtime on Li-ion pack, with ultra-low standby IQ and zero audible noise from inductors. IC Role / Device Role / Timing Role: Main system power converter operating in Burst Mode below 10mA load; transitions seamlessly to FCM during ECG waveform acquisition bursts. Use Value: 25µA IQ (BIAS = 5V) extends battery life; 30ns min on-time enables efficient 12V-to-3.3V conversion at 2MHz, eliminating coil whine. | Use Scenario: Precision bench power supply auxiliary rail generation where switching noise must not couple into 16-bit ADC reference paths. IC Role / Device Role / Timing Role: Low-noise 5V supply for FPGA configuration and DAC reference buffers; operated in spread spectrum mode to lower peak EMI harmonics. Use Value: <10mVP-P output ripple and <2.5µV/√Hz noise floor prevent spurious tones in spectral analysis outputs. |
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 |
|---|---|---|---|
| LT8640SEV#PBF | 42V, 6A, integrated compensation, 2.5µA IQ, same package - lacks VC pin and CLKOUT. | Best for cost-sensitive designs where external loop tuning or multi-regulator sync is unnecessary. | Select LT8640SEV#PBF when simplified design and reduced component count outweigh need for current sharing or precise timing alignment. |
| MPQ4436GL-AEC1-Z | 45V, 6A, AEC-Q100, 1.5µA IQ, no VC pin, no CLKOUT, different pinout - uses internal compensation only. | Suitable for entry-level automotive body electronics where EMI requirements are less stringent than infotainment. | Choose MPQ4436GL-AEC1-Z for non-safety-critical 12V systems needing lowest possible quiescent current without advanced control features. |
Compared with LT8640SEV#PBF and MPQ4436GL-AEC1-Z, the LT8637EV#PBF uniquely provides external VC-loop access for dynamic current sharing and CLKOUT-driven synchronization-critical for multi-rail automotive domain controllers where timing coherency and load balancing directly impact functional safety compliance.
Availability
LT8637EV#PBF is available at Aetrix Electronics and suitable for automotive infotainment systems, industrial PLC power modules, and portable medical equipment requiring stable component supply, AEC-Q100 qualification, and low EMI performance.
Supply support for LT8637EV#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 industrial, automotive, communications, and healthcare markets.
The LT8637EV#PBF belongs to the Silent Switcher® family of high-efficiency, low-EMI DC/DC regulators designed specifically for demanding automotive and industrial applications where electromagnetic compatibility and thermal reliability are critical.
FAQ
What is the maximum switching frequency supported by the LT8637EV#PBF?
The LT8637EV#PBF supports a programmable switching frequency range of 200kHz to 3MHz, set by an external resistor on the RT pin. At 18.2kΩ, it achieves 1.95MHz typical operation - enabling compact 1µH inductors and avoidance of sensitive frequency bands like AM radio (530–1710kHz). This high-frequency capability is sustained across the full –40°C to 125°C operating range.
How does the VC pin on the LT8637EV#PBF enable current sharing between parallel regulators?
The VC pin on the LT8637EV#PBF provides direct access to the error amplifier output (1.7mS transconductance, ±350µA sink/source), allowing multiple units to share a common VC node via small resistors. This forces identical peak inductor currents across phases, achieving balanced load distribution without dedicated current-sharing ICs - a key advantage for high-current automotive ADAS power rails.
Can the LT8637EV#PBF operate with a 3.3V input voltage?
No, the LT8637EV#PBF has a minimum input voltage of 3.4V as specified in its Absolute Maximum Ratings and Electrical Characteristics tables. Operation below 3.4V is not guaranteed and may result in failure to regulate or unexpected shutdown. For 3.3V-input applications, a different regulator such as the LT8645S (3V min VIN) should be evaluated instead of the LT8637EV#PBF.
What is the purpose of the CLKOUT pin on the LT8637EV#PBF, and how is it used?
The CLKOUT pin on the LT8637EV#PBF outputs a ~200ns-wide pulse at the exact switching frequency during forced continuous, spread spectrum, or synchronized modes - providing a precise timing reference to synchronize other regulators. It is driven low during Burst Mode. Engineers use CLKOUT to align switching edges across multiple rails, eliminating beat frequencies and simplifying system-level EMI filtering in complex power architectures.
Does the LT8637EV#PBF require external compensation components, and why?
Yes, the LT8637EV#PBF requires external RC compensation connected between the VC pin and GND because it features external compensation architecture. This allows designers to tailor loop dynamics for specific output capacitor types (e.g., ceramic vs. polymer), optimize transient response for fast load steps, and implement current sharing in multi-phase configurations - capabilities not possible with internally compensated alternatives like the LT8636.
LT8637EV#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 ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-LQFN (4x3)
LT8637EV#PBF FAQ
1.How can I place an order for LT8637EV#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8637EV#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 LT8637EV#PBF reliable?
The price and inventory of LT8637EV#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT8637EV#PBF is usually 5 days.
3.What payment methods are accepted for LT8637EV#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8637EV#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8637EV#PBF?
LT8637EV#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8637EV#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 LT8637EV#PBF?
For technical support, including LT8637EV#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8637EV#PBF requirements.
6.How does Aetrix verify that LT8637EV#PBF is sourced from the original manufacturer or authorized distributors?
All LT8637EV#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 LT8637EV#PBF meets industry standards.
7.What is the process for return or replacement of LT8637EV#PBF?
All LT8637EV#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8637EV#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 LT8637EV#PBF part is unused and in its original packaging.
Return procedure for LT8637EV#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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