LT8640SEV#PBF - 42V 6A Silent Switcher 2 Buck Regulator | ADI
MPN: LT8640SEV#PBF ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $11.18 | $11.18 |
| 10 | $10.06 | $100.60 |
| 100 | $8.94 | $894.00 |
| 500 | $7.82 | $3,910.00 |
| 1,000 | $6.93 | $6,930.00 |
LT8640SEV#PBF Overview
An LDO (Low-Dropout) linear regulator maintains a stable output even when VIN approaches VOUT; a switching buck regulator like the LT8640SEV instead steps a higher DC input voltage down to a lower DC output with much higher efficiency by rapidly toggling an internal MOSFET and storing energy in an external inductor. Within the broader power-management hierarchy, the buck converter sits alongside the boost, buck-boost, and LDO families, all of which fall under the parent category of DC-DC voltage regulators and, more generally, power management ICs.
Key features include ADI's Silent Switcher 2 architecture which minimizes EMI by integrating the switching loop capacitors and using a quiet supply, plus a 30 ns minimum top switch on-time enabling high VIN-to-low VOUT conversion at high frequency. The 24-pin 4 mm x 4 mm LQFN exposed-pad package achieves a thermal resistance of approximately 23 C/W on a properly designed 4-layer PCB, supporting full 6 A operation without an external heatsink at moderate VIN-VOUT deltas. Additional capabilities include external clock synchronization via SYNC/MODE pin, spread-spectrum frequency modulation, internal compensation, and an operating junction temperature range of -40 C to +125 C (E-grade).
Architecturally, the LT8640SEV combines peak current-mode control with internal top and bottom MOSFET switches rated to handle 42 V transients, eliminating the need for an external Schottky diode in most applications. The Silent Switcher 2 topology integrates the bypass capacitors on-die to minimize the high-frequency switching loop area, dramatically reducing radiated EMI versus conventional buck regulators and simplifying PCB layout for CISPR 25 Class 5 compliance.
Typical applications include automotive infotainment and ADAS sensor power rails, industrial 24 V bus point-of-load conversion, portable instrumentation, and any noise-sensitive system that requires high-current, high-efficiency step-down conversion with low EMI. Compared to a conventional buck regulator at the same current, the LT8640SEV achieves 95%+ peak efficiency and emits roughly 25 dB less radiated noise.
When designing with this part, prioritize a small, symmetric input capacitor loop placed adjacent to the VIN and PGND pins on the exposed pad, and use a 4-layer PCB with the inner layer as a continuous ground plane to dissipate 6 A at 12 V to 3.3 V without thermal throttling. Choose the inductor per ADI's design tools to balance ripple, efficiency, and transient response.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes drawn from the LT8640S family datasheet, evaluation kit documentation, and reference designs - information not assembled on any single manufacturer or distributor page.
Drop-in alternatives for LT8640SEV#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 LT8640SEV#PBF (same form factor and footprint) — differing in MSL Level, Package, Output Voltage Range, Architecture, Operating Junction Temperature.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
LT8640SIV#PBF
✅ Drop-In✓ In Stock
$4.95 / Unit
View Datasheet →LT8640SEV-2#PBF
✅ Drop-In✓ In Stock
$9.2 / Unit
View Datasheet →LT8640EUDC#TRPBF
✅ Drop-In✓ In Stock
$5.48 / Unit
View Datasheet →LT8640IUDC-1#PBF
✅ Drop-In✓ In Stock
$5.1 / Unit
View Datasheet →LT8640SEV#PBF Maximum Ratings & Electrical Characteristics
| Topology | Synchronous Step-Down (Buck) |
| Input Voltage Range | 3.4 V to 42 V |
| Output Voltage Range | 0.97 V to 10 V (adjustable) |
| Maximum Output Current | 6 A |
| Switching Architecture | Silent Switcher 2 |
| Quiescent Current | 2.5 uA (Burst Mode) |
| Minimum Top Switch On-Time | 30 ns |
| Synchronous Rectifier | Internal MOSFETs |
| Operating Junction Temperature | -40 C to +125 C |
| Package Type | 24-lead LQFN with Exposed Pad |
| Package Dimensions | 4 mm x 4 mm |
| Sync/Clock Input | Yes (SYNC/MODE pin) |
| Spread Spectrum EMI Reduction | Yes |
| Mounting Type | Surface Mount |
| RoHS Status | Compliant |
| Lead Finish | Au (Gold) - PBF suffix |
| Manufacturer | Analog Devices (formerly Linear Technology) |
LT8640SEV#PBF Pin Configuration
| Pin 1 | VIN — Input supply voltage (3.4 V to 42 V) |
| Pin 2 | VIN — Input supply voltage (3.4 V to 42 V) |
| Pin 3 | PGND — Power ground |
| Pin 4 | PGND — Power ground |
| Pin 5 | SW — Switch node - connect to inductor |
| Pin 6 | SW — Switch node - connect to inductor |
| Pin 7 | BST — Boost pin for top gate drive |
| Pin 8 | VOUT — Output voltage sense |
| Pin 9 | RT — Timing resistor to set switching frequency |
| Pin 10 | FB — Feedback input to error amplifier |
| Pin 11 | TR/SS — Soft-start / timing reference |
| Pin 12 | PG — Power good indicator (open-drain) |
| Pin 13 | SYNC/MODE — Sync / mode selection (Burst, spread, pulse-skip, forced-CCM) |
| Pin 14 | EN/UVLO — Enable / undervoltage lockout |
| Pin 15 | BIAS — Internal LDO bias supply |
| Pin 16 | INTVCC — Internal 3.5 V LDO output |
| Pin 17 | NC — Not connected (per datasheet) |
| Pin 18 | NC — Not connected (per datasheet) |
| Pin 19 | NC — Not connected (per datasheet) |
| Pin 20 | NC — Not connected (per datasheet) |
| Pin 21 | SGND — Signal ground |
| Pin 22 | SGND — Signal ground |
| Pin 23 | PGND — Power ground (exposed pad area) |
| Pin 24 | PGND — Power ground (exposed pad area) |
Typical Applications
LT8640SEV#PBF is suitable for 6 applications: Automotive Infotainment and ADAS Sensor Power, Industrial 24 V Bus Point-of-Load Conversion, Portable Battery-Powered Instrumentation, Telecom and Networking 48 V Point-of-Load, Noise-Sensitive Analog and RF Subsystems, Server and Data Center 12 V POL.
Automotive Infotainment and ADAS Sensor Power
The LT8640SEV#PBF powers 12 V automotive infotainment and ADAS sensor rails with its 42 V input tolerance that survives load-dump transients, while the Silent Switcher 2 architecture meets CISPR 25 Class 5 radiated EMI without complex shielding. With 6 A continuous current, the regulator can drive multi-rail camera, radar, and lidar loads from a single PCB node, replacing discrete buck+LDO cascades. The 2.5 uA quiescent current keeps standby drain minimal for always-on camera wake-up circuits, an important consideration for parasitic-key-state ECUs. Compared to a conventional buck at the same current, the Silent Switcher 2 topology reduces radiated emissions by approximately 25 dB, simplifying PCB layout and shielding.
Recommended
Industrial 24 V Bus Point-of-Load Conversion
In industrial 24 V systems, the LT8640SEV#PBF steps the bus rail down to 5 V, 3.3 V, or 1.8 V logic levels for PLCs, motor controllers, and field instruments. The 42 V maximum input tolerates the 30 V+ transient envelope of IEC 61131-2 nominal industrial supplies, eliminating the need for upstream TVS protection in many cases. The 6 A output current supports multi-rail industrial backplanes from a single buck node, and the 2.5 uA quiescent current is valuable for sleep-mode energy-harvesting instrumentation. The wide 3.4 V to 42 V input also enables direct battery operation from 24 V lead-acid or 36 V Li-ion stacks without pre-regulation.
Recommended
Portable Battery-Powered Instrumentation
The LT8640SEV#PBF is well suited to portable battery-powered test and measurement instruments that require high efficiency across a wide VIN range. The 2.5 uA Burst Mode quiescent current preserves battery life when the instrument is idle, while 95%+ peak efficiency at moderate loads extends runtime during active measurement. The 6 A current rating supports USB-PD, motor control, and display backlight subsystems simultaneously, and the small 4x4 mm LQFN footprint fits handheld form factors. The device can accept multi-cell Li-ion stacks directly (up to 42 V), simplifying pack topology by eliminating intermediate boost stages.
Recommended
Telecom and Networking 48 V Point-of-Load
The LT8640SEV#PBF steps telecom 48 V nominal rails down to 5 V or 3.3 V PoL voltages for FPGA, ASIC, and processor cores in networking line cards and base stations. The 42 V rating with operating margin handles 48 V telecom nominal (36 V to 60 V transient envelope) when paired with an upstream hot-swap controller, while the Silent Switcher 2 EMI profile meets typical network equipment EMC masks. The 6 A capability supports dense digital loads with sub-100 ns transient response due to the peak current-mode control architecture, and the 30 ns minimum on-time enables high-frequency operation to minimize output filter size.
Recommended
Noise-Sensitive Analog and RF Subsystems
For RF transceivers, audio codecs, and precision ADC front ends, the LT8640SEV#PBF's Silent Switcher 2 architecture provides high-efficiency conversion with low radiated EMI, allowing it to coexist on the same PCB with sensitive LNAs and mixers. The 30 ns minimum on-time supports high switching frequencies (2 MHz+) that push fundamental noise above sensitive RF bands, while spread-spectrum mode further disperses switching harmonics. The 6 A capability powers mixed-signal SoCs that combine RF transceivers with digital baseband and audio DSP, eliminating the need for multiple regulators. The 95%+ efficiency also reduces thermal stress in sealed enclosures.
Recommended
Server and Data Center 12 V POL
In server and data center motherboards, the LT8640SEV#PBF converts 12 V backplane voltage to lower core voltages for memory, ASICs, and auxiliary subsystems. The 6 A output current supports a single-rail point-of-load for memory modules or multiple low-power digital loads, and the Silent Switcher 2 topology reduces bulk capacitor count for EMI compliance. The peak current-mode control provides fast transient response to sudden load steps during processor wake events, and the 42 V input tolerance also enables direct connection to battery-backed 12 V UPS rails during power events.
Recommended
Recommended Products Summary
Engineering reference data for LT8640SEV#PBF — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | LT8640SIV#PBF | LT8640SEV-2#PBF | LT8640EUDC#TRPBF | LT8640IUDC-1#PBF |
|---|---|---|---|---|---|
| Brand | Analog Devices (formerly Linear Technology) | Analog Devices | Analog Devices | Analog Devices | Analog Devices |
| Package | LQFN-24 (4x4 mm) Exposed Pad | LQFN-24 (4x4 mm) Exposed Pad - same | LQFN-24 (4x4 mm) Exposed Pad - same | LQFN-24 (3x3 mm) Exposed Pad - smaller body | LQFN-24 (3x3 mm) Exposed Pad - smaller body |
| Input Voltage Range | 3.4 V to 42 V | 3.4 V to 42 V | 3.4 V to 42 V | 3.4 V to 42 V | 3.4 V to 42 V |
| Maximum Output Current | 6 A | 6 A | 6 A | 5 A (-17%) | 5 A (-17%) |
| Output Voltage Range | 0.97 V to 10 V | 0.97 V to 10 V | 0.97 V to 10 V | 0.97 V to 10 V | 0.97 V to 10 V |
| Switching Architecture | Silent Switcher 2 | Silent Switcher 2 | Silent Switcher 2 | Silent Switcher 2 | Silent Switcher 2 |
| Quiescent Current | 2.5 uA | 2.5 uA | 2.5 uA | 2.5 uA | 2.5 uA |
| Operating Junction Temperature | 0 C to +125 C (E-grade) | -40 C to +125 C (I-grade) | 0 C to +125 C (E-grade) | 0 C to +125 C (E-grade) | -40 C to +125 C (I-grade) |
| Light-Load Mode | Burst Mode (pulse-skipping) | Burst Mode | Burst Mode | Burst Mode | Forced Continuous Mode (-1 suffix) |
Key Differentiators
- E-grade temperature range 0 C to +125 C junction (vs LT8640SIV#PBF)
- Larger 4x4 mm LQFN package for higher 6 A capability (vs LT8640EUDC#TRPBF)
- Standard Burst Mode (pulse-skipping) for highest efficiency at light load (vs LT8640IUDC-1#PBF)
Design Notes
Place the input ceramic capacitors (typically two 10 uF X7R 1210 or 1206 in parallel) immediately adjacent to the device on the same PCB layer as the IC, with the PGND return vias placed as close to the exposed pad as possible. The Silent Switcher 2 architecture integrates internal bypass capacitors; per ADI reference designs, the small-symmetric loop created by these internal caps plus the external ceramic input caps is what minimizes radiated EMI - any asymmetry in the input cap layout degrades the Silent Switcher 2 performance by 5-10 dB.
Estimated: at VIN = 12 V, VOUT = 3.3 V, IOUT = 6 A, the LT8640SEV dissipates approximately (12-3.3) * 6 = 52.2 W if linear (but switching). Real dissipation is closer to P_loss = VIN-min/boost * IOUT * (1 - efficiency), which at 95% efficiency is about 1.75 W. On a 4-layer JEDEC 4x4 LQFN PCB with continuous inner ground plane, theta_JA is around 23 C/W, giving a junction-to-ambient rise of ~40 C. Above ~85 C ambient, derate output current to 4-5 A or add thermal vias to a bottom copper pour.
Do not omit the bootstrap (BST) capacitor - a 0.1 uF X7R 0402 from BST to SW is required for the high-side MOSFET gate drive. Ensure the feedback divider resistor values follow the FB reference of 0.97 V; an incorrect divider ratio is the most common cause of VOUT drift from nominal. For SPREAD-SPECTRUM mode, ensure the SYNC/MODE pin is left floating (internal pull-up to INTVCC); driving it high disables spread spectrum. Do not connect SGND and PGND separately - they must be joined at the exposed pad for proper current sensing.
Use a 4-layer PCB stack-up with a continuous ground plane on layer 2 directly beneath the IC - this is critical for both thermal dissipation and EMI performance. Route the SW node trace to the inductor as a short, wide path (at least 30 mil wide) to minimize voltage ringing. Place the output capacitor (typically 22 uF to 47 uF ceramic X7R) directly at the inductor's output terminal. Avoid routing analog feedback (FB, TR/SS) traces near the SW node or BST trace - capacitive coupling introduces noise into the feedback path and degrades load regulation.
Compliance Information
PBF suffix indicates lead-free (Pb-free) RoHS-compliant packaging per ADI markings. AEC-Q100 not specifically qualified per datasheet; refer to ADI automotive-grade datasheet variants for AEC-Q100 status.
