LTC4357CMS8#PBF - 80V Ideal Diode ORing Controller | ADI
料号： LTC4357CMS8#PBF ✓ 量产中LTC4357CMS8#PBF 概述
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.
直接替换替代料： LTC4357CMS8#PBF ——相同封装，引脚兼容。需要 PCB 改动的不同封装料号已排除。
LTC4357IMS8#PBF
✅ 直接替换 ⚠️ 规格未核验📋 参考替代料（不在目录中）
LTC4357MPMS8#PBF
✅ 直接替换📋 参考替代料（不在目录中）
LTC4359IMS8#PBF
✅ 直接替换📋 参考替代料（不在目录中）
LTC4357CMS8#PBF 最大额定值与电气特性
| 功能 | Positive High Voltage Ideal Diode Controller |
| 输入电压范围 | 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 |
| 封装 | 8-MSOP |
| 安装类型 | Surface Mount |
| Operating Temperature Grade | C grade (commercial) |
| Lead Free | Yes (#PBF suffix) |
| RoHS 状态 | Compliant |
| Datasheet Length | 12 pages (Linear Technology datasheet) |
LTC4357CMS8#PBF 引脚配置
| 引脚 1 | VDD — Controller supply, 9 V to 80 V operating range |
| 引脚 2 | IN — Input supply monitor, 3 V to 80 V |
| 引脚 3 | GND — Ground |
| 引脚 4 | SOURCE — MOSFET source sense input |
| 引脚 5 | GATE — Gate drive output with internal 12 V clamp |
| 引脚 6 | OUT — Output voltage sense |
| 引脚 7 | NC — Not connected (per datasheet) |
| 引脚 8 | NC — Not connected (per datasheet) |
典型应用
LTC4357CMS8#PBF 适用于 6 应用s: 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.
推荐
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.
推荐
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.
推荐
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.
推荐
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.
推荐
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.
推荐
推荐产品汇总
工程参考数据： LTC4357CMS8#PBF ——对比、设计指导和合规信息。
选型指南
与替代料对比
| 参数 | 本产品 | 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) |
关键差异点
- True high-voltage ORing coverage to 80 V （对比 LTC4359IMS8#PBF)
- Automotive-grade drop-in available （对比 LTC4357MPMS8#PBF)
- 25 mV regulated forward drop vs comparator-only controllers （对比 LTC4359IMS8#PBF)
设计说明
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.
合规信息
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.
