LT8645SIV#PBF - 65V 8A Silent Switcher 2 Buck | Analog Devices
MPN: LT8645SIV#PBF ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $6.9098 | $6.91 |
| 10 | $0 | $0.00 |
| 100 | $0 | $0.00 |
| 500 | $0 | $0.00 |
| 1,000 | $0 | $0.00 |
LT8645SIV#PBF Overview
A synchronous buck converter is a DC-DC voltage regulator that uses high-side and low-side switching transistors to transfer energy from an input rail to a lower output rail through an inductor. The LT8645S belongs to the power-management hierarchy: DC-DC converter, synchronous buck regulator, switching regulator, and semiconductor. Its Silent Switcher 2 architecture integrates features intended to suppress switching-node energy and radiated emissions while supporting operation at high switching frequencies.
The LT8645S delivers up to 8A of continuous output current, accepts a broad input range reported by distributors as 3.4V to 65V, and provides an adjustable output beginning at 0.97V. Newark identifies the adjustable output capability and 3.4V-to-65V input range, while DigiKey describes the device as a positive, single-output, 8A synchronous buck regulator. These values make it suitable for reducing higher-voltage buses to lower rails for processors, communications equipment, sensors, and industrial control electronics.
The family is specifically engineered to minimize EMI emissions without sacrificing high-frequency operation. Distributed bypass-capacitor integration can simplify high-current layout and improve switching-node behavior compared with conventional layouts that rely entirely on external input bypass arrangements. The result is useful when the power supply must operate beside sensitive analog, RF, measurement, or communications circuitry while maintaining a compact 32-lead TQFN footprint.
Typical applications include 48V industrial power distribution, automotive and transportation power systems, GSM and communications infrastructure, and high-current embedded computing. The wide input range allows the regulator to sit directly behind a protected higher-voltage bus, while the adjustable output supports multiple point-of-load rails when paired with appropriate external components.
Designers should follow the manufacturer datasheet for the exact pinout, compensation settings, exposed-pad layout, switching-frequency selection, and recommended capacitor and inductor values. Thermal design is especially important at 8A because regulator efficiency and voltage conversion ratio determine dissipation even though the package provides an exposed pad for board-level heat spreading.
This page combines verified distributor specifications, package details, sourcing information, application guidance, and engineering design notes. It highlights the LT8645S as a high-current, low-EMI, wide-input buck regulator while avoiding unverified details that should be confirmed against the current Analog Devices datasheet before layout or production release.
Drop-in alternatives for LT8645SIV#PBF — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with LT8645SIV#PBF (same form factor and footprint) — differing in Architecture, Operating Temperature Range, Package, Maximum Output Current, Output Voltage Range.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
LT8645SEV#PBF
✅ Drop-In ⚠️ Specs Unverified✓ In Stock
$5.18 / Unit
View Datasheet →LT8645SJV-2#PBF
✅ Drop-In✓ In Stock
$6.6 / Unit
View Datasheet →LT8645S-2IV#PBF
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
LT8645SIV#PBF-TR
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
LT8645SEV#W
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
LT8645SIV#PBF Maximum Ratings & Electrical Characteristics
| Regulator Topology | Synchronous step-down buck regulator |
| Input Voltage Range | 3.4V to 65V |
| Maximum Output Current | 8A |
| Minimum Adjustable Output Voltage | 0.97V |
| Output Configuration | Single positive adjustable output |
| Switching Frequency | 1.95MHz |
| Architecture | Second-generation Silent Switcher 2 |
| Integrated Bypass Capability | Yes, integrated bypass capacitor |
| Package | 32-lead TQFN exposed pad |
| Package Footprint | 6mm x 4mm QFN-class footprint |
| Mounting Type | Surface mount |
| Operating Temperature Range | -40C to +125C |
| RoHS Compliance | Compliant for PBF-terminated versions |
| WEEE Compliance | Compliant for PBF-terminated versions |
| Automotive Controlled Manufacturing | Available in #W-suffix versions |
| Switching Node | SW |
LT8645SIV#PBF 6mm x 4mm qfn-class footprint Pin Configuration Guide
Pin configuration for LT8645SIV#PBF (6mm x 4mm qfn-class footprint package). This power device features gate, drain, and source terminals. For non-polarized packages, refer to the manufacturer datasheet for exact pin 1 orientation and footprint details. Common applications include power supply design, motor driving, and load switching.
No detailed pinout data available for LT8645SIV#PBF.
Refer to the datasheet for full pin configuration.
Typical Applications
LT8645SIV#PBF is suitable for 6 applications: 48V Industrial Power Rails, Automotive Electrical Control Units, Communications Infrastructure Equipment, High-Current Embedded Processing Rails, Precision Measurement and Test Equipment, Low-EMI Point-of-Load Conversion.
48V Industrial Power Rails
The LT8645SIV#PBF suits 48V industrial systems that need a compact, high-current rail with reduced EMI. Its verified 3.4V-to-65V input range and 8A output capability provide the required voltage and current envelope for many controller, sensor, actuator, and communications loads. Place the regulator near the protected bus with low-inductance input routing, and use the exposed pad as a controlled thermal spreader. Silent Switcher 2 architecture helps simplify adjacent analog and communications circuitry, while the adjustable output down to 0.97V supports multiple rail requirements with appropriate feedback components.
Recommended
Automotive Electrical Control Units
The LT8645SIV#PBF is appropriate for evaluating automotive ECU power conversion when the input transients remain within the verified 65V limit and the exact ordering variant meets program requirements. The 8A rating supports mixed digital loads, while Silent Switcher 2 targets electromagnetic-emission control in compact electronics. The verified Mouser datasheet notes that controlled-manufacturing versions carry a #W suffix; therefore, engineers should not assume the standard LT8645SIV#PBF is automatically automotive-qualified. Prototype with careful input protection, exposed-pad thermal management, and conducted-versus-radiated emissions testing.
Recommended
Communications Infrastructure Equipment
The LT8645SIV#PBF fits communications infrastructure that converts a higher-voltage bus into a lower current-intensive rail for line cards, radios, and signal-processing electronics. Its 8A capability provides useful load margin, while the 1.95MHz switching architecture and integrated bypass functionality support compact layouts with controlled EMI. Keep the switching loop small and provide local high-frequency and bulk capacitance to preserve control-loop performance. For RF-adjacent systems, validate radiated emissions across operating states because compliance depends on board layout, filtering, shielding, and cable configuration as well as the regulator itself.
Recommended
High-Current Embedded Processing Rails
The LT8645SIV#PBF can generate an adjustable low-voltage rail for processors, modules, and high-speed digital subsystems that require up to 8A from a higher-voltage supply. Its output begins at 0.97V, allowing configuration for low core voltages when external feedback and compensation support the target rail. The regulator's high-current switching design demands short copper paths, low-ESR input/output capacitors, and correct inductor selection. Treat the exposed pad as part of the thermal design rather than an optional copper feature, and verify startup, load transient, and dropout behavior across the complete input range.
Recommended
Precision Measurement and Test Equipment
The LT8645SIV#PBF is useful in measurement and test electronics when a subsystem requires substantial current but must avoid adding significant EMI to sensitive analog channels. Silent Switcher 2 architecture is designed to reduce switching emissions, and the integrated bypass capability can support a compact implementation. Keep analog and digital return currents separated carefully, use star-point grounding where appropriate, and maintain short high-current switching paths. Emphasize thermal verification because noise performance and stability alone do not guarantee safe junction temperature at 8A. Validate the final board with conducted-emissions measurements rather than relying only on schematic simulation.
Recommended
Low-EMI Point-of-Load Conversion
The LT8645SIV#PBF is effective as a point-of-load converter where a wide-input bus is present and the resulting rail must combine 8A capability with controlled switching emissions. Its adjustable output down to 0.97V permits programmed rails from low digital voltages to higher intermediate supplies. Designers should use the datasheet's recommended compensation, switching-frequency, and capacitor arrangements to preserve loop stability and Silent Switcher 2 behavior. The 32-lead TQFN exposed pad improves heat flow only when connected to a properly sized thermal plane, so power-loss calculations and copper area remain part of the selection process.
Recommended
Recommended Products Summary
Engineering reference data for LT8645SIV#PBF — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | LT8645SEV#PBF | LT8645SJV-2#PBF | LT8645S-2IV#PBF | LT8645SIV#PBF-TR | LT8645SEV#W |
|---|---|---|---|---|---|---|
| Package | 32-lead TQFN exposed pad | 32-lead TQFN exposed pad | 32-lead TQFN exposed pad | 32-lead TQFN exposed pad | 32-lead TQFN exposed pad | 32-lead TQFN exposed pad |
| Brand | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices |
| Regulator Topology | Synchronous step-down regulator | Synchronous step-down regulator | Synchronous step-down regulator | Synchronous step-down regulator | Synchronous step-down regulator | Synchronous step-down regulator |
| Maximum Output Current | 8A | 8A | 8A | 8A | 8A | 8A |
| Output Configuration | Adjustable, minimum 0.97V | Fixed-output variant | Fixed -2 output variant | Fixed -2 output variant | Adjustable, minimum 0.97V | Fixed-output automotive variant |
| EMI Architecture | Second-generation Silent Switcher 2 | Silent Switcher 2 family | Silent Switcher 2 family; bypass details differ | Silent Switcher 2 family | Second-generation Silent Switcher 2 | Silent Switcher 2 automotive version |
| Automotive Manufacturing | Not identified as #W automotive version | Not identified as #W | Not identified as #W | Not identified as #W | Not identified as #W | Controlled manufacturing for automotive applications |
Key Differentiators
- Higher verified switching frequency (vs Generic 8A synchronous buck regulators)
- Integrated low-EMI architecture (vs Generic 8A synchronous buck regulators)
- Wide input range with high output current (vs Low-voltage-only 8A buck regulators)
- Compact exposed-pad thermal implementation (vs Leaded high-current regulators)
Design Notes
Use the manufacturer's Silent Switcher 2 layout and follow the current LT8645S datasheet exactly; the supplied search data does not include individual pin names. Keep the high-current input loop, SW node, and exposed-pad connection exceptionally short to preserve the low-EMI behavior. The verified package uses a 6mm by 4mm QFN-class footprint, so confirm land pattern and thermal-via recommendations against the official mechanical drawing rather than relying on a generic QFN footprint.
Estimated thermal design requirement: use PD = (VIN - VOUT) × IOUT for an ideal first-order regulator-loss estimate before accounting for switching and conduction losses. For example, 12V input, 5V output, and 8A load implies approximately 56W, so an 8A rail does not necessarily mean every operating point is practical. Copper under the exposed pad, thermal vias, board area, ambient temperature, and copper weight must be evaluated using the package thermal data.
Do not assume that every LT8645S suffix is a drop-in substitute. The cross-reference discussion for LT8645SJV-2#PBF raises concerns about INTVCC and BST bypass capacitors, while IV, EV, and JV suffixes can represent adjustable or fixed-output choices. Before replacing an existing LT8645SIV#PBF, compare the exact pinout, bias-network requirements, switching frequency, output configuration, thermal limits, and PCB footprint.
Silent Switcher 2 reduces EMI but does not eliminate board-level compliance testing. Keep the converter away from sensitive analog inputs, use the smallest practical switching loop, maintain a continuous return path, and avoid routing SW copper beneath sensitive nodes. Validate radiated emissions, conducted emissions, load-transient behavior, and output ripple on final hardware because enclosure, cables, filtering, and grounding can materially change system-level results.
Compliance Information
The verified Mouser datasheet states that parts ending in PBF are RoHS and WEEE compliant. It also states that controlled-manufacturing versions are designated with a #W suffix for automotive quality and reliability requirements; LT8645SIV#PBF itself is not explicitly identified as that automotive variant. REACH, halogen-free, and conflict-minerals evidence were not supplied.
