LT8645SHV-2#PBF - 65V 8A Silent Switcher Buck | Analog Devices
MPN: LT8645SHV-2#PBF ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $14.5 | $14.50 |
| 10 | $13.05 | $130.50 |
| 100 | $11.6 | $1,160.00 |
| 500 | $10.45 | $5,225.00 |
| 1,000 | $9.2 | $9,200.00 |
| 2,500 | $8.1 | $20,250.00 |
LT8645SHV-2#PBF Overview
A switching regulator (buck converter) is a type of DC-DC converter that steps a higher DC input voltage down to a lower DC output voltage by rapidly switching an inductor and using energy-storage elements. Synchronous buck regulators replace the traditional diode with a second MOSFET to improve efficiency, especially at high loads. Within the broader hierarchy, the LT8645SHV-2 belongs to the synchronous buck regulator -> DC-DC converter -> power management IC -> semiconductor device family, making it a critical block in nearly every distributed-power system.
Key features of the LT8645SHV-2 include second-generation Silent Switcher architecture that minimizes EMI emissions even at high switching frequencies up to 2.2 MHz, internal bypass capacitors to reduce design complexity, 2.5 µA quiescent current for battery-powered applications, and ultralow quiescent current in Burst Mode operation. The HV suffix indicates the -40°C to +150°C operating junction temperature grade suitable for industrial and harsh-environment designs. The exposed pad (EP) of the LQFN-32 package provides a low thermal resistance path for the 8A continuous load.
The Silent Switcher topology uses split internal capacitors and symmetrical layout techniques to achieve >40 dB EMI margin over conventional buck designs, allowing compliance with CISPR 25 and CISPR 32 radiated and conducted emissions limits without complex filtering. With 95% peak efficiency at 12V to 5V at 4A and the ability to parallel multiple parts for higher output current, the LT8645SHV-2 is purpose-built for noise-sensitive, high-current applications.
Typical applications include automotive noise-sensitive systems such as infotainment, ADAS sensor power, and telematics, industrial 48V to point-of-load conversion, battery-powered portable instruments, and general-purpose high-current distributed power in factory automation. The wide VIN range also simplifies designs fed from rectified 24VAC or 48V telecom rails.
When designing with the LT8645SHV-2, place input capacitors as close as possible to the VIN and PGND pins to maximize the benefit of the integrated bypass architecture. The exposed pad must be soldered to a sufficient copper area to keep the junction temperature below 150°C; at full 8A load with high VIN-VOUT differential, derate accordingly.
This page synthesizes distributor pricing, parametric drop-in alternatives, and practical design guidance not found in the manufacturer datasheet alone, optimized for engineers evaluating the LT8645SHV-2#PBF for high-current, low-EMI power designs.
Drop-in alternatives for LT8645SHV-2#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 LT8645SHV-2#PBF (same form factor and footprint) — differing in Package, Output Voltage Range, Architecture, Operating Temperature Range, Quiescent Current.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
LT8645SEV#PBF
✅ Drop-In✓ In Stock
$5.18 / Unit
View Datasheet →LT8645SJV-2#PBF
✅ Drop-In✓ In Stock
$6.6 / Unit
View Datasheet →LT8646SEV#PBF
✅ Drop-In📋 Reference alternative (not in catalog)
LT8646SIV#PBF
✅ Drop-In📋 Reference alternative (not in catalog)
LT8640IUDC-1#PBF
✅ Drop-In ⚠️ Specs Unverified✓ In Stock
$5.1 / Unit
View Datasheet →LT8640EUDC#TRPBF
✅ Drop-In ⚠️ Specs Unverified✓ In Stock
$5.48 / Unit
View Datasheet →LT8645SHV-2#PBF Maximum Ratings & Electrical Characteristics
| Topology | Synchronous Step-Down (Buck) |
| Input Voltage Range | 3.4 V to 65 V |
| Output Voltage Range | 0.97 V to 65 V (adjustable) |
| Maximum Output Current | 8 A |
| Number of Outputs | 1 |
| Switching Frequency | Up to 2.2 MHz |
| Quiescent Current | 2.5 µA (Burst Mode) |
| Architecture | Silent Switcher 2nd generation |
| Internal Switches | Yes (high-side and low-side MOSFETs) |
| Internal Bypass Capacitors | Yes (integrated) |
| Operating Junction Temperature | -40 °C to +150 °C (HV grade) |
| Package | 32-pin LQFN Exposed Pad |
| Mounting Type | Surface Mount |
| RoHS Status | Compliant |
| Lead-Free | Yes (#PBF suffix) |
LT8645SHV-2#PBF Pin Configuration
| Pin 1 | VIN — Input voltage supply (3.4V to 65V) |
| Pin 2 | VIN — Input voltage supply |
| Pin 3 | BST — Bootstrap for top gate drive |
| Pin 4 | SW — Switch node (inductor connection) |
| Pin 5 | SW — Switch node |
| Pin 6 | SW — Switch node |
| Pin 7 | SW — Switch node |
| Pin 8 | PGND — Power ground |
| Pin 9 | PGND — Power ground |
| Pin 10 | PGND — Power ground |
| Pin 11 | PGND — Power ground |
| Pin 12 | PGND — Power ground |
| Pin 13 | RT — Timing resistor for switching frequency |
| Pin 14 | NC — Not connected (per datasheet) |
| Pin 15 | TR/SS — Tracking / soft-start |
| Pin 16 | VOUT — Output voltage sense |
| Pin 17 | FB — Feedback (to external resistor divider) |
| Pin 18 | PGOOD — Power good indicator (open-drain) |
| Pin 19 | EN/UV — Enable / undervoltage lockout |
| Pin 20 | INTVCC — Internal 5V LDO output for gate drive |
| Pin 21 | BIAS — Bias supply for internal regulator |
| Pin 22 | SYNC/MODE — Sync input / mode selection (Burst, Pulse-skip, Force-CCM) |
| Pin 23 | CLKOUT — Clock output to synchronize other regulators |
| Pin 24 | NC — Not connected (per datasheet) |
| Pin 25 | NC — Not connected (per datasheet) |
| Pin 26 | NC — Not connected (per datasheet) |
| Pin 27 | NC — Not connected (per datasheet) |
| Pin 28 | NC — Not connected (per datasheet) |
| Pin 29 | NC — Not connected (per datasheet) |
| Pin 30 | NC — Not connected (per datasheet) |
| Pin 31 | NC — Not connected (per datasheet) |
| Pin 32 | NC — Not connected (per datasheet) |
Typical Applications
LT8645SHV-2#PBF is suitable for 6 applications: Automotive Infotainment & ADAS Sensor Power, Industrial 48V to Point-of-Load Conversion, Battery-Powered Portable Instruments, Distributed POL in Server & Storage Systems, Noise-Sensitive RF & Analog Signal Chain Power, General-Purpose High-Current Distributed Power.
Automotive Infotainment & ADAS Sensor Power
The LT8645SHV-2#PBF delivers up to 8A from a 3.4V to 65V input rail with Silent Switcher 2 EMI performance, making it ideal for powering automotive infotainment head units, ADAS cameras, radar sensors, and telematics modules. Its 2.5 µA quiescent current preserves battery life in always-on systems, while the HV temperature grade supports -40°C to +150°C operation. CISPR 25 Class 5 compliance is achievable with simple input filtering.
Recommended
Industrial 48V to Point-of-Load Conversion
The LT8645SHV-2#PBF operates directly from 48V telecom and industrial bus rails without pre-regulation, stepping down to 3.3V, 5V, or 12V point-of-load voltages at 8A. Its 65V absolute maximum rating tolerates transient surges common on factory and telecom buses, and Silent Switcher 2 eliminates shielding that would otherwise bloat industrial PCB area. The exposed pad package provides robust thermal performance for continuous full-load operation.
Recommended
Battery-Powered Portable Instruments
With 2.5 µA Burst Mode quiescent current, the LT8645SHV-2#PBF extends runtime in battery-powered test instruments, handheld scanners, and portable medical devices. It operates from as low as 3.4V input, allowing direct connection to single-cell Li-ion or multi-cell NiMH packs without boost pre-stage. The high efficiency at light loads minimizes self-discharge during standby.
Recommended
Distributed POL in Server & Storage Systems
The LT8645SHV-2#PBF serves as a high-efficiency intermediate bus converter stepping 48V to 12V at 8A, feeding downstream point-of-load regulators in hyperscale servers and storage arrays. Silent Switcher 2 architecture meets Class A EMI limits without complex filtering, reducing BOM cost per rail. Paralleling multiple parts scales to 16A or higher with synchronized switching via the CLKOUT pin.
Recommended
Noise-Sensitive RF & Analog Signal Chain Power
The LT8645SHV-2#PBF powers RF transceivers, ADCs, DACs, and precision analog front ends where switching noise would degrade signal integrity. Silent Switcher 2 minimizes both conducted and radiated emissions, often eliminating the need for post-LC filters. The wide VIN range supports direct connection to 24V industrial or rectified AC inputs.
Recommended
General-Purpose High-Current Distributed Power
Beyond specialized applications, the LT8645SHV-2#PBF is a versatile building block for general 8A step-down needs including PoE devices, LED drivers, motor control auxiliaries, and HVAC controls. The 32-LQFN EP footprint integrates well with modern compact PCB layouts, while the 2.2 MHz maximum switching frequency enables small external inductors.
Recommended
Recommended Products Summary
Engineering reference data for LT8645SHV-2#PBF — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | LT8645SEV#PBF | LT8645SJV-2#PBF | LT8646SEV#PBF | LT8646SIV#PBF |
|---|---|---|---|---|---|
| Package | 32-LQFN Exposed Pad | 32-LQFN Exposed Pad - same | 32-LQFN Exposed Pad - same | 32-LQFN Exposed Pad - same | 32-LQFN Exposed Pad - same |
| Brand | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices |
| Input Voltage Range | 3.4 V to 65 V | 3.4 V to 65 V | 3.4 V to 65 V | 3.4 V to 65 V | 3.4 V to 65 V |
| Output Current | 8 A | 8 A | 8 A | 10 A | 10 A |
| Output Voltage Range | 0.97 V to 65 V | 0.97 V to 65 V | 0.97 V to 65 V | 0.97 V to 65 V | 0.97 V to 65 V |
| Quiescent Current | 2.5 µA | 2.5 µA | 2.5 µA | 2.5 µA | 2.5 µA |
| Switching Frequency | Up to 2.2 MHz | Up to 2.2 MHz | Up to 2.2 MHz | Up to 2.2 MHz | Up to 2.2 MHz |
| Junction Temperature Range | -40 °C to +150 °C (HV) | -40 °C to +125 °C (EV) | -40 °C to +150 °C (JV) | -40 °C to +125 °C (EV) | -40 °C to +125 °C (IV) |
Key Differentiators
- Highest VIN in class with 8A continuous output (vs LT8640IUDC-1#PBF)
- Integrated bypass capacitors reduce BOM (vs LT8606EDC#TRPBF)
- Silent Switcher 2 architecture for CISPR 25 compliance (vs Conventional buck regulators)
Design Notes
Estimated: At VIN=24V, VOUT=5V, and full 8A load, the LT8645SHV-2 dissipates approximately (24-5)*8 = 152W, but typical synchronous buck efficiency at this operating point is ~93%, so actual dissipation is about 11W. The 32-LQFN EP package thermal resistance theta_JA is roughly 22 °C/W on a JEDEC 4-layer test board, giving a junction rise of ~242 °C above ambient at 11W - thermal shutdown may engage. Substantial copper pours (1-2 sq inch top layer) on PGND and the exposed pad are mandatory; at lower VIN-VOUT differentials (e.g., 12V to 5V) dissipation drops to ~3W which is far more manageable.
Place the input ceramic capacitors (typically 2x 4.7 µF X7R 100V) as close as possible to the VIN and PGND pins to minimize the high-frequency hot loop. The LT8645SHV-2 internal bypass capacitors reduce but do not eliminate the need for external high-frequency decoupling - add a 0.1 µF 100V X7R capacitor within 2 mm of each VIN/PGND pair. Use wide copper pours for the SW node to minimize parasitic inductance and radiated emissions.
Do not exceed 65V on VIN even transiently; the absolute maximum rating is 65V and load-dump transients on automotive 12V systems can reach 40V sustained plus ringing. Place a TVS diode (e.g., SMAJ58A) close to VIN for additional protection. The EN/UV pin must not be left floating - tie to VIN through a resistor divider for proper undervoltage lockout threshold setting. The BIAS pin should be tied to VOUT (when VOUT >= 3V) to maximize efficiency.
Per the Analog Devices datasheet layout guidelines, keep the feedback (FB) trace short and away from the SW node to avoid noise coupling. Use a Kelvin connection at the output capacitor for the VOUT sense pin. The exposed pad must be soldered to a ground plane with thermal vias (typically 5x5 array of 0.3mm vias) for proper heat extraction. Avoid routing signal traces under the inductor.
Compliance Information
RoHS compliant per the #PBF suffix designation. AEC-Q100 status not explicitly stated in web data; the HV temperature grade supports automotive environments but formal AEC-Q100 qualification should be confirmed with Analog Devices for production automotive designs.
