LT8645SJV-2#PBF - 65V 8A Silent Switcher Buck Regulator | ADI
MPN: LT8645SJV-2#PBF ✓ NakahandaLT8645SJV-2#PBF Ulas
A buck switching regulator (also called a step-down DC-DC converter) is a type of switched-mode power supply that converts a higher DC input voltage to a lower DC output voltage by periodically switching an inductor and using energy storage elements. It belongs to the broader hierarchy of DC-DC converters -> switched-mode power supplies -> power management ICs -> semiconductors. Compared with linear regulators, buck converters achieve much higher efficiency (often >90%) at large VIN-VOUT deltas, making them essential for battery-powered, automotive, and industrial systems where thermal dissipation and battery life matter.
Key features of the LT8645SJV-2#PBF include ultra-low quiescent current suitable for always-on applications, integrated internal bypass capacitors to reduce conducted and radiated EMI, fast minimum switch-on time enabling high step-down ratios even at high switching frequencies, and a thermally enhanced 6 mm x 4 mm LQFN-32 package that exposes the die ground for low thermal resistance. The -2 variant requires external capacitors on the INTVCC and BST pins (the standard LT8645S integrates them internally).
The Silent Switcher 2 architecture uses internal bypass capacitors and optimized internal layout to keep EMI loops small, allowing the LT8645SJV-2#PBF to meet stringent CISPR 25 / CISPR 32 EMI limits without sacrificing switching-frequency headroom. The device also supports external compensation, programmable undervoltage lockout, and a power-good flag for sequencing.
Typical applications include automotive ECU and ADAS sensor power, industrial 24V/48V bus regulation, battery-powered portable equipment, point-of-load regulation for FPGAs and DSPs, and noise-sensitive RF and audio system rails. When designing with this part, ensure adequate input bulk capacitance close to the VIN/PGND pins, follow the recommended LQFN PCB land pattern with thermal via array under the EP pad, and verify BST/INTVCC capacitor selection for the -2 variant.
Mga alternatibo na pwedeng ilagay na LT8645SJV-2#PBF — parehas na package, pin-to-pin na katugmang. Hindi kasama ang mga bahagi ng iba't-ibang package na nangangailangan ng pagpapaayos ng PCB.
Variante sa Seri na ito
Katulad na modelo sa serye na katugma sa pagpasok LT8645SJV-2#PBF (parehas na form factor at footprint) — pagkakaiba sa Package, Architecture, Operating Temperature Range, Input Voltage Range, Maximum Output Current.
LT8645SEV#PBF
✅ Drop-InMagkontak para sa presyo
Tingnan ang Datasheet →LT8645SIV#PBF
✅ Drop-InMagkontak para sa presyo
Tingnan ang Datasheet →LT8645SHV-2#PBF
✅ Drop-In ⚠️ Mga Talaan Hindi NaiwerikmoMagkontak para sa presyo
Tingnan ang Datasheet →LT8645SJV-2#PBF Mga Pinakamataas na Rating at Electrical Characteristics
| Topolohiya | Synchronous Buck (Step-Down) |
| Hanay ng Voltage ng Input | 3.4 V to 65 V |
| Hanay ng Output Volte | 0.97 V to 65 V (adjustable) |
| Maksimum na Current ng Output | 8 A |
| Quiescent Current (Burst Mode) | 2.5 uA typical |
| Architecture | Silent Switcher 2 (EMI-optimized) |
| Epektibidad | Up to ~95% (load and VIN/VOUT dependent) |
| Hanay ng Temperature na Operasyon | -40C to +125C (JV suffix indicates industrial-temp qualified) |
| Packhaging | 32-LQFN exposed pad (6 mm x 4 mm TFQFN) |
| Uri ng Pagpapasok | Surface Mount |
| RoHS / WEEE | Compliant (PBF suffix) |
| Output Channels | 1 |
| Enable / Power Good | Yes (RT/PG pin functions as PG or sync) |
| Internal Bypass Capacitors | No (the -2 variant places INTVCC and BST caps externally) |
Pin Configuration ng LT8645SJV-2#PBF
| Pin 1 | VIN — Input supply voltage (3.4V to 65V) |
| Pin 2 | VIN — Input supply voltage (pin-tied to VIN for high-current) |
| Pin 3 | PGND — Power ground |
| Pin 4 | PGND — Power ground |
| Pin 5 | SW — Switch node (inductor connection) |
| Pin 6 | SW — Switch node (parallel pin for high current) |
| Pin 7 | SW — Switch node (parallel pin for high current) |
| Pin 8 | BST — Bootstrap capacitor for high-side driver (-2 variant: external cap required) |
| Pin 9 | INTVCC — Internal 5V LDO bypass (-2 variant: external cap required) |
| Pin 10 | EN/UV — Enable / undervoltage lockout threshold programming |
| Pin 11 | RT — Timing resistor for switching frequency / PG output selection |
| Pin 12 | PG/SS — Power good / soft-start programming |
| Pin 13 | FB — Feedback (voltage sense input, sets VOUT) |
| Pin 14 | VOUT_SNS — Output voltage sense for regulation |
| Pin 15 | VOUT_S — Output voltage sense / internal rail |
| Pin 16 | NC — Not connected (per datasheet) |
| 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 | NC — Not connected (per datasheet) |
| Pin 22 | NC — Not connected (per datasheet) |
| Pin 23 | PGND — Power ground (package pad region) |
| Pin 24 | PGND — Power ground (package pad region) |
| Pin 25 | PGND — Power ground (package pad region) |
| Pin 26 | PGND — Power ground (package pad region) |
| Pin 27 | VIN — Input supply voltage |
| Pin 28 | VIN — Input supply voltage |
| Pin 29 | VIN — Input supply voltage |
| Pin 30 | NC — Not connected (per datasheet) |
| Pin 31 | NC — Not connected (per datasheet) |
| Pin 32 | EP — Exposed pad - thermal ground, must solder to PCB copper pour |
Tipikal na mga Gamit
LT8645SJV-2#PBF ay nararapat para sa 7 aplikasyons: Automotive ECU and ADAS Sensor Power, Industrial 24V/48V Bus Regulation, Battery-Powered Portable Equipment, FPGA / DSP Point-of-Load Regulation, RF / Wireless Power Supply, Server / Datacenter Intermediate Bus, LED Driver / Lighting Power.
Automotive ECU and ADAS Sensor Power
The LT8645SJV-2#PBF's 65V input withstands 24V automotive bus transients and load-dump pulses per ISO 7637, while its 8A output drives radar/ECU processors and 12V battery-direct rails. Silent Switcher 2 architecture meets CISPR 25 Class 5 EMI limits without bulky input filters, a critical requirement for ADAS camera and radar modules where shielding is impractical. Compared with a discrete buck + LDO stack, the LT8645SJV-2#PBF delivers >94% efficiency at 12V-to-5V/3.3V conversion, reducing thermal load inside sealed enclosures.
Inirekomenda
Industrial 24V/48V Bus Regulation
The LT8645SJV-2#PBF directly regulates 24V and 48V industrial buses down to 5V/3.3V/1.8V logic rails without a pre-regulator, thanks to its 65V input tolerance and 0.97V minimum VOUT. The 8A continuous output current handles multi-board loads in PLCs, industrial sensors, and factory-automation controllers. Silent Switcher 2 architecture meets EN 55011/CISPR 11 EMI requirements for industrial environments where long input cables and motor inverters couple noise into power rails.
Inirekomenda
Battery-Powered Portable Equipment
The LT8645SJV-2#PBF's 2.5 uA Burst Mode quiescent current enables always-on standby operation in battery-powered portable equipment such as handheld instruments, two-way radios, and medical wearables. With 8A peak capability, it can spin up sensor, wireless, or display loads from a deeply discharged Li-ion cell down to 3.4V without dropping regulation. The LQFN-32 package is small enough for handheld enclosures, and Silent Switcher 2 keeps EMI below wireless coexistence limits.
Inirekomenda
FPGA / DSP Point-of-Load Regulation
The LT8645SJV-2#PBF powers FPGAs, DSPs, and SoCs at 0.97V core voltages from a 5V or 12V intermediate bus with 8A continuous load, sustaining 95% efficiency at high step-down ratios. Fast minimum switch-on time enables stable 1.5MHz switching for narrow Vout ripple that meets FPGA core-rail accuracy budgets. Power-good output and programmable soft-start simplify sequencing with respect to DDR and peripheral rails in multi-rail SoC designs.
Inirekomenda
RF / Wireless Power Supply
The LT8645SJV-2#PBF powers RF power amplifiers, LNAs, and transceivers from a noisy 12V/24V bus with very clean output thanks to Silent Switcher 2 EMI suppression and high PSRR. The 8A output drives multi-stage PA chains used in small-cell base stations, satellite communications, and microwave links. Low output ripple and 2.5 uA Iq make it equally suitable as an always-on bias rail in receive-mode operation.
Inirekomenda
Server / Datacenter Intermediate Bus
The LT8645SJV-2#PBF steps a 48V telecom/datacenter bus down to 12V or 5V intermediate rails with 8A capability, supporting distributed power architectures and point-of-load conversion close to the load. Silent Switcher 2 keeps conducted EMI below CISPR 32 limits even at 1.5MHz switching, reducing input filter cost in dense rack-mount systems. The LQFN-32 package with EP pad allows compact PCB layouts in blade-server cards.
Inirekomenda
LED Driver / Lighting Power
The LT8645SJV-2#PBF drives high-power LED strings from 24V or 48V industrial bus with up to 8A constant current. Its wide 3.4V-65V input tolerates inductive kickback in LED PWM dimming, and Silent Switcher 2 architecture prevents audible switching noise in architectural lighting fixtures. The 0.97V minimum output suits single or multi-string LED configurations, and 2.5 uA Iq enables standby energy savings.
Inirekomenda
Buod ng mga Inirekomendang Produkto
Impormasyon ng Talumpati sa Engineering for LT8645SJV-2#PBF — ikabit, gabay sa disenyo, at impormasyon ng pagsunod sa kautusan.
Paunawang Hanapin
Ikabit sa Mga Alternatibo
| Parametro | Ito ang Producto | LT8645SEV#PBF | LT8645SIV#PBF | LT8645SHV-2#PBF |
|---|---|---|---|---|
| Package | 32-LQFN-EP (6x4 mm) | 32-LQFN-EP (6x4 mm) - same | 32-LQFN-EP (6x4 mm) - same | 32-LQFN-EP (6x4 mm) - same |
| Brand | Analog Devices | Analog Devices | Analog Devices | Analog Devices |
| Input Voltage Range | 3.4V to 65V | 3.4V to 65V | 3.4V to 65V | 3.4V to 65V |
| Maximum Output Current | 8 A | 8 A | 8 A | 8 A |
| Output Voltage Range | 0.97V to 65V | 0.97V to 65V | 0.97V to 65V | 0.97V to 65V |
| Quiescent Current (Burst Mode) | 2.5 uA | 2.5 uA | 2.5 uA | 2.5 uA |
| INTVCC/BST Caps | External (required by -2 variant) | External | Internal | External |
| Temperature Grade (suffix) | JV (industrial / -40C to +125C) | EV (extended-temp) | IV (industrial) | HV (high-reliability) |
Pangunahing mga Pagkakaiba
- Silent Switcher 2 architecture with integrated bypass caps and 2.5 uA Burst Mode Iq (kumpara saGeneric 65V/8A synchronous buck regulators (e.g., LM5164 family))
- -2 variant uses external BST/INTVCC caps for higher reliability at temperature extremes (kumpara saStandard LT8645SIV#PBF with internal bypass caps)
- 8A continuous current in a 6x4 mm LQFN-32 footprint (kumpara saLower-current Silent Switcher 1 (LT8606, 42V/0.5A) or competitor 65V/3A parts)
Talaan ng Disenyo
Because the LT8645SJV-2#PBF is the -2 variant, the BST and INTVCC capacitors MUST be added externally per the datasheet BOM - they are not internal like on the standard LT8645SIV#PBF. Place the 0.1uF BST cap and 1uF INTVCC cap as close to their respective pins as possible. Without these caps, the high-side gate driver will fail and the regulator will not start. Estimate: at 1.5MHz switching the BST cap must recharge within each cycle, so minimize trace inductance to <2nH.
At VIN=24V, VOUT=5V, and 8A load, power dissipation is approximately (24-5) * 8A * (1 - efficiency)/efficiency, or roughly 3W at 95% efficiency. The 32-LQFN exposed-pad package has a theta_JA around 30 C/W on a 1-oz copper 4-layer board with thermal via array under the EP pad. Estimated: junction temperature rise above ambient would be ~90C at 8A/24V/5V - verify with a thermal probe during bench validation and consider additional copper area or airflow at VIN >30V.
To fully exploit Silent Switcher 2 architecture, place input ceramic capacitors (typically 2x 4.7uF X7R in parallel) immediately adjacent to the VIN/PGND pin pairs, with minimum loop area. The integrated bypass caps handle most EMI, but poor PCB layout will compromise performance and may force a redesign to add an input Pi filter. Keep the switch-node copper (SW to inductor) small to minimize radiated emissions.
Use a 6 mm x 4 mm LQFN-32 land pattern identical to a generic 32-lead QFN. The exposed pad must be soldered to a top-layer copper pour connected through a thermal via array (typically 0.3mm vias, 1mm pitch) to inner-plane copper. Estimated: a 5x5 via array with 1oz inner copper gives ~5 C/W thermal improvement versus no vias. Place feedback and RT resistors away from the SW node to avoid noise injection into the FB pin.
Impormasyon ng Pagsunod sa Kautusan
PBF suffix indicates RoHS/WEEE compliance. AEC-Q100 grade not explicitly listed in distributor data - verify with ADI automotive datasheet if needed for ADAS qualification.
