LTC4357CMS8#PBF - 80V Ideal Diode ORing Controller | ADI
N.º de pieza: LTC4357CMS8#PBF ✓ ActivoLTC4357CMS8#PBF Descripción general
An ideal diode controller is a power management IC that actively senses the voltage across a MOSFET and controls its gate so the device conducts current in only one direction, emulating a diode with near-zero forward drop. In the power-path hierarchy, the LTC4357 sits between upstream supplies and the load in ORing controllers, hot-swap and power-mux subsystems of distributed power architectures.
Key features include the wide 9 V to 80 V operating range with 100 V absolute maximum transient tolerance, a fast 0.5 us response to input voltage reversal that protects the MOSFET during faults, an internal 12 V gate clamp for standard and logic-level FETs, and micropower shutdown. A 3 V to 80 V IN pin monitors the input supply independently, enabling wide-range protection.
Architecturally, the device regulates the MOSFET gate to maintain a 25 mV forward drop, smoothly transitioning to full enhancement at light loads. When the input falls below the output, an internal comparator pulls the gate down within microseconds, preventing reverse current. This closed-loop gate control eliminates the oscillation problems common in simpler comparator-based diode controllers.
Typical applications include N+1 redundant power supply ORing in servers and telecom rectifiers, -48 V and high-voltage DC power-path protection, solar/battery combiner boxes, and industrial backplane ORing where Schottky conduction losses would otherwise dominate thermal budgets.
For design, select a MOSFET whose RDS(on) times expected load current yields an acceptable dissipation; at currents above a few amps, the savings versus a Schottky are dramatic. Layout the SOURCE and GATE traces short and Kelvin-connect the sense elements.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet.
Alternativas directas para LTC4357CMS8#PBF — mismo encapsulado, compatible pin a pin. Se excluyen las piezas de otro encapsulado que requieren retrabajo de la PCB.
LTC4357IMS8#PBF
✅ Sustitución directa ⚠️ Especificaciones sin verificar📋 Alternativa de referencia (no en el catálogo)
LTC4357MPMS8#PBF
✅ Sustitución directa📋 Alternativa de referencia (no en el catálogo)
LTC4359IMS8#PBF
✅ Sustitución directa📋 Alternativa de referencia (no en el catálogo)
LTC4357CMS8#PBF Valores máximos y características eléctricas
| Función | Positive High Voltage Ideal Diode Controller |
| Rango de tensión de entrada | 9 V to 80 V |
| IN Pin Monitoring Range | 3 V to 80 V |
| Controlled Device | External N-channel MOSFET |
| Forward Regulation Drop | 25 mV (regulated) |
| Configuration | N+1 ORing Controller, N:1 |
| Gate Clamp | Internal 12 V gate protection |
| Encapsulado | 8-MSOP |
| Tipo de montaje | Surface Mount |
| Operating Temperature Grade | C grade (commercial) |
| Lead Free | Yes (#PBF suffix) |
| Estado RoHS | Compliant |
| Datasheet Length | 12 pages (Linear Technology datasheet) |
Configuración de pines de LTC4357CMS8#PBF
| Pin 1 | VDD — Controller supply, 9 V to 80 V operating range |
| Pin 2 | IN — Input supply monitor, 3 V to 80 V |
| Pin 3 | GND — Ground |
| Pin 4 | SOURCE — MOSFET source sense input |
| Pin 5 | GATE — Gate drive output with internal 12 V clamp |
| Pin 6 | OUT — Output voltage sense |
| Pin 7 | NC — Not connected (per datasheet) |
| Pin 8 | NC — Not connected (per datasheet) |
Aplicaciones típicas
LTC4357CMS8#PBF es adecuado para 6 aplicacións: N+1 Redundant Server Power Supply ORing, Telecom -48V Rectifier ORing, Solar and Battery Combiner Boxes, Industrial Backplane Power Muxing, High-Current Diode Rectification Replacement, Avionics and Automotive High-Voltage Power Paths.
N+1 Redundant Server Power Supply ORing
In N+1 redundant server and storage power shelves, multiple PSU outputs are diode-ORed onto a shared backplane bus so any failed unit is automatically isolated. The LTC4357CMS8#PBF fits this role because its 9 V to 80 V input range covers 12 V, 24 V, and 48 V rails, and its 25 mV regulated forward drop cuts per-supply conduction loss from several watts (Schottky) to a fraction of a watt at typical 10 A to 20 A loads. Its fast reverse-current turn-off disconnects a failing supply within microseconds, preventing bus back-feeding. Place the controller and MOSFET on the PSU output with Kelvin-sensed SOURCE/OUT traces; power loss is I squared times MOSFET RDS(on), so choose a 100 V, low-RDS(on) FET to keep the ORing element cool.
Recomendado
Telecom -48V Rectifier ORing
Telecom rectifier plants and -48 V DC plants OR multiple rectifier outputs onto the battery bus. The LTC4357CMS8#PBF is well suited because its 80 V maximum input accommodates high-voltage rails with transient headroom, and the IN pin monitors the rectifier output from 3 V to 80 V for independent supervision. Replacing the ORing Schottky with a MOSFET controlled at 25 mV drop in a 50 A plant path saves on the order of tens of watts per rectifier versus a 0.5 V Schottky drop, shrinking heatsinks and improving plant efficiency. Use the gate clamp-protected drive with a 100 V N-channel FET, and rely on the fast turn-off to isolate a failed rectifier from the battery bus without service interruption.
Recomendado
Solar and Battery Combiner Boxes
Photovoltaic string combiners and multi-battery systems need low-loss unidirectional coupling between sources and a common bus. The LTC4357CMS8#PBF drives an N-channel MOSFET as an ideal diode so each string or battery feeds the bus but cannot be back-driven by higher-voltage neighbors, with only 25 mV forward drop versus 0.4 V to 0.7 V for Schottky blocking. Its 9 V to 80 V range matches 24 V and 48 V battery stacks and string voltages, while the internal 12 V gate clamp simplifies FET drive at high bus voltages. Power savings scale with current: at 15 A the MOSFET solution can dissipate under 1 W where a Schottky would waste over 7 W, allowing sealed outdoor combiner enclosures without active cooling.
Recomendado
Industrial Backplane Power Muxing
Industrial controllers, PLC backplanes, and process instrumentation frequently combine a primary 24 V supply with a backup source. The LTC4357CMS8#PBF implements this power multiplexing with a single controller plus MOSFET per source: whichever input is higher conducts, and the other is blocked with no reverse leakage path. The 80 V rating provides generous margin on nominal 24 V industrial buses with surge conditions, and the fast fault turn-off prevents a sagging primary from dragging down the live rail. Because dissipation drops to I squared times RDS(on) (typically well under 1 W at 10 A with a modern FET), dense DIN-rail modules can omit dedicated ORing heatsinking, and the MSOP-8 footprint keeps the mux section compact.
Recomendado
High-Current Diode Rectification Replacement
Wherever a high-current rectifying diode is needed - welder output stages, plating supplies, motor braking paths, and DC UPS outputs - the LTC4357CMS8#PBF plus an N-channel MOSFET replaces the diode with a near-ideal element regulated at 25 mV. This is the controller's N:1 high-current diode mode described on the Analog Devices product page. The efficiency gain grows with current: a 30 A Schottky path dissipates 15 W to 21 W, while a 2 mOhm MOSFET dissipates under 2 W, an order-of-magnitude thermal improvement. Design the PCB with wide copper for the SOURCE-to-OUT current path, keep the GATE trace short, and verify MOSFET SOA at the intended continuous current; the controller handles only gate drive, not the load current itself.
Recomendado
Avionics and Automotive High-Voltage Power Paths
Transportation platforms - 28 V avionics buses, 48 V mild-hybrid automotive rails, and railway auxiliary supplies - need robust ORing with wide transient tolerance. The LTC4357MPMS8#PBF, the MP-grade drop-in variant of this part, brings the same 9 V to 80 V ideal diode control with higher reliability screening for these environments. The 80 V ceiling absorbs load-dump-style surges on 28 V and 48 V systems, the 25 mV regulated drop preserves scarce bus margin, and microsecond reverse blocking isolates generator or converter faults. Pair with a 100 V N-channel MOSFET sized for the continuous load, and place the controller close to the FET for a tight gate loop that preserves the fast turn-off fault response under high dV/dt transients.
Recomendado
Resumen de productos recomendados
Datos de referencia de ingeniería para LTC4357CMS8#PBF — comparación, orientación de diseño e información de cumplimiento.
Guía de selección
Comparación con alternativas
| Parámetro | Este producto | LTC4357IMS8#PBF | LTC4357MPMS8#PBF | LTC4359IMS8#PBF |
|---|---|---|---|---|
| Package | MSOP-8 | MSOP-8 - same | MSOP-8 - same | MSOP-8 - same |
| Brand | Analog Devices | Analog Devices | Analog Devices | Analog Devices |
| Temperature Grade | C (commercial) | I (industrial) | MP (automotive) | I (industrial) |
| Pin Compatibility | Reference (MSOP-8 LTC4357 pinout) | Pin-to-pin identical | Pin-to-pin identical | Different pin functions - verify schematic |
| Controlled Device | External N-channel MOSFET | External N-channel MOSFET | External N-channel MOSFET | External N-channel MOSFET |
| RoHS / Lead Free | Compliant (#PBF) | Compliant (#PBF) | Compliant (#PBF) | Compliant (#PBF) |
Diferenciadores clave
- True high-voltage ORing coverage to 80 V (frente a LTC4359IMS8#PBF)
- Automotive-grade drop-in available (frente a LTC4357MPMS8#PBF)
- 25 mV regulated forward drop vs comparator-only controllers (frente a LTC4359IMS8#PBF)
Notas de diseño
Keep the GATE trace as short as possible between the LTC4357 GATE pin and the MOSFET gate, and Kelvin-connect the SOURCE sense directly at the MOSFET source pin rather than at a shared ground node. Long gate traces add inductance that degrades the microsecond reverse-current turn-off and can cause gate ringing at the 80 V operating level. Place a local 0.1 uF decoupling capacitor from VDD to GND within 5 mm of pin 1.
Estimated: the controller dissipates only microwatts, but total path loss is I_load squared times MOSFET RDS(on). For example, at 10 A with a 5 mOhm FET, dissipation is 0.5 W; at the same current a Schottky with 0.5 V drop dissipates 5 W. Select the FET so junction rise stays within limits for your airflow; a 2 oz copper pour of at least 0.5 square inch under the FET drains typically handles 1 W to 2 W without a heatsink.
Do not substitute the LTC4359 for the LTC4357 without re-checking the pinout - pin functions differ despite the shared MSOP-8 footprint. Also verify the MOSFET VDS rating exceeds the maximum transient on the rail (use 100 V FETs on 48 V and 80 V systems), and remember the LTC4357 needs at least 9 V on VDD to operate: below that threshold the controller is unpowered and the MOSFET body diode alone conducts, so low-voltage cold-start behavior must be validated in the lab.
Información de cumplimiento
The #PBF suffix denotes Analog Devices lead-free/RoHS-compliant packaging per product labeling. REACH, halogen-free, and conflict-minerals status should be confirmed from the current ADI compliance documentation.
