MAX4840AEXT+T - 28V Overvoltage Protection Controller SC-70-6 | ADI
料号： MAX4840AEXT+T ✓ 量产中| 数量 | 单价 | 小计 |
|---|---|---|
| 1 | $3 | $3.00 |
| 10 | $2.7 | $27.00 |
| 100 | $2.4 | $240.00 |
| 500 | $2.1 | $1,050.00 |
| 1,000 | $1.93 | $1,930.00 |
MAX4840AEXT+T 概述
An overvoltage protection controller is a type of power management IC that monitors a supply rail and disconnects the load when the input exceeds a programmed threshold, preventing damage to downstream components such as processors, ASICs, RF transceivers, and battery chargers. OVP controllers sit hierarchically above voltage regulators and supervisors in the power-tree, serving as the first line of defense against hot-plug transients, adapter mis-wiring, charger faults, and ESD/inductive kick events on cables and connectors. The internal charge pump (which eliminates the need for an external bootstrap capacitor) drives the gate of an external N-FET, so protection is achieved with very few external components.
Key features of the MAX4840AEXT+T include a wide 1.2V to 28V operating input range, an integrated charge pump for N-FET drive, an open-drain FLAG output for fault signaling to a host microcontroller, low quiescent current to preserve battery life, and a small SC-70-6 (SOT-363) footprint ideal for space-constrained portable devices. The architecture uses a precision bandgap reference and comparator to monitor VIN against the internal trip threshold, achieving fast response to overvoltage events.
Typical applications include USB Type-C VBUS protection, smartphone and tablet charger protection, hot-plug rails in servers and storage, battery pack protection circuitry, and any system where a downstream low-voltage load must be isolated from a higher-voltage source during fault conditions. The 6-pin SC-70 package makes it suitable for designs where PCB real estate is at a premium.
When designing with this device, place the external N-FET as close as possible to the IC and follow the datasheet layout guidance for the VIN sense path to prevent nuisance tripping from ringing. Also include adequate input TVS protection upstream of the controller for surge events beyond the 28V absolute maximum.
This page synthesizes distributor pricing, drop-in alternatives within the MAX4838A/MAX4840A/MAX4842A family and across vendors, and practical design notes that complement the manufacturer datasheet for engineers evaluating OVP solutions.
直接替换替代料： MAX4840AEXT+T ——相同封装，引脚兼容。需要 PCB 改动的不同封装料号已排除。
快速对比工具——选择替代料号进行并排对比：
MAX4838AEXT+T
✅ 直接替换📋 参考替代料（不在目录中）
MAX4842AEXT+T
✅ 直接替换📋 参考替代料（不在目录中）
MAX4840AEXT-T
✅ 直接替换📋 参考替代料（不在目录中）
MAX4840AEXT+T 规格参数
| 功能 | Overvoltage Protection Controller |
| Input Voltage Range (Operating) | 1.2 V to 28 V |
| Absolute Maximum Input Voltage | +28 V |
| OVP Trip Level (MAX4840A) | 5.8 V (typical) |
| External FET Type | N-Channel MOSFET |
| Charge Pump | Internal (no external capacitor required) |
| FLAG Output | Open-drain status indicator |
| 工作温度范围 | -40 C to +85 C |
| 封装 | SC-70-6 (SOT-363) |
| 引脚数量 | 6 |
| 安装类型 | Surface Mount |
| MSL 等级 | 1 |
| RoHS 状态 | Compliant |
| Lead-Free | Yes |
| Family Members | MAX4838A, MAX4840A, MAX4842A |
MAX4840AEXT+T 引脚配置
| 引脚 1 | IN — Input voltage sense (1.2V to 28V) |
| 引脚 2 | GND — Ground |
| 引脚 3 | FLAG — Open-drain status output, asserts low on OVP |
| 引脚 4 | GATE — Gate drive output for external N-channel MOSFET |
| 引脚 5 | OUT — Output to downstream load (after external FET) |
| 引脚 6 | SHDN — Shutdown / enable input |
典型应用
MAX4840AEXT+T 适用于 6 应用s: USB Type-C VBUS Overvoltage Protection, Smartphone and Tablet Charger Protection, Hot-Plug Rail Protection in Servers and Storage, Battery Pack Protection Circuitry, Industrial 24V Bus Protection for Low-Voltage Loads, RF and Audio Front-End Protection.
USB Type-C VBUS Overvoltage Protection
Protects USB Type-C VBUS rails (5V default, up to 20V in PD mode) from faulty adapters and mis-wired sources. The MAX4840A's 5.8V trip level disconnects the downstream 5V rail via an external N-FET whenever VBUS exceeds the safe threshold, with the integrated charge pump eliminating the bootstrap capacitor. The open-drain FLAG output signals a host MCU to log the fault. Compared to a TVS diode alone, the active OVP controller avoids sustained overvoltage stress on the downstream load.
推荐
Smartphone and Tablet Charger Protection
Front-end protection between a charger IC and the Li-ion battery on portable devices. The MAX4840AEXT+T monitors the adapter voltage and isolates the battery and PMIC if a malfunctioning charger delivers more than 5.8V, preventing thermal runaway or fire. Its low quiescent current preserves standby battery life, and the SC-70-6 footprint fits in compact phone/tablet PCBAs. The integrated charge pump keeps the external BOM minimal, which matters for cost-sensitive mobile designs.
推荐
Hot-Plug Rail Protection in Servers and Storage
Protects downstream low-voltage rails (3.3V, 5V) in hot-swap bays, SSDs, and removable storage modules during board insertion events. The MAX4840AEXT+T reacts within microseconds to an overvoltage spike and turns off the external N-FET, preventing backplane voltage transients from damaging downstream controllers. The open-drain FLAG output can be tied to a hot-swap controller or BMC for fault telemetry in datacenter designs.
推荐
Battery Pack Protection Circuitry
Provides redundant OVP protection inside a 1-cell Li-ion or multi-cell battery pack, complementing the internal protection FETs of the battery management IC. The MAX4840A's wide 1.2V to 28V operating range covers 1S to 4S packs and the external FET can be sized for the pack's continuous discharge rating. Combined with a fuel gauge and protection IC, it adds a defense layer against pack-side overvoltage events that could otherwise propagate to the system.
推荐
Industrial 24V Bus Protection for Low-Voltage Loads
In industrial automation, 24V control buses can carry inductive kick and surge transients that would damage 3.3V or 5V sensors and I/O modules. The MAX4840AEXT+T sits between the 24V field rail and the downstream regulator/load, disconnecting the load if the bus exceeds the OVP trip. With its 28V absolute maximum and integrated charge pump, it eliminates the need for a separate gate-drive supply in industrial PLC and sensor designs.
推荐
RF and Audio Front-End Protection
Isolates sensitive RF transceivers, audio amplifiers, and precision ADCs from supply overvoltage events in portable and connected designs. The MAX4840A's fast OVP response and minimal quiescent current make it suitable for always-on protection of RF front-end modules in smartphones, Bluetooth/Wi-Fi audio accessories, and wearables. The SC-70-6 footprint allows placement close to the antenna or audio jack without crowding the PCB.
推荐
推荐产品汇总
工程参考数据： MAX4840AEXT+T ——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 | MAX4838AEXT+T | MAX4842AEXT+T | MAX4840AEXT-T | NCP349MNAETBG |
|---|---|---|---|---|---|
| Package | SC-70-6 | SC-70-6 - same | SC-70-6 - same | SC-70-6 - same | DFN-6 - different |
| Brand | Analog Devices | Analog Devices | Analog Devices | Analog Devices | onsemi |
| OVP Trip Voltage | 5.8 V | 4.6 V | 7.4 V | 5.8 V | Adjustable |
| Charge Pump | Internal | Internal | Internal | Internal | Internal |
| FLAG Output | Yes (open-drain) | Yes (open-drain) | Yes (open-drain) | Yes (open-drain) | Yes |
| External FET | N-Channel | N-Channel | N-Channel | N-Channel | N-Channel |
| Operating Temperature | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C |
关键差异点
- Medium-threshold 5.8V OVP trip optimized for USB 5V rails （对比 MAX4838AEXT+T (4.6V trip))
- Integrated charge pump - no external capacitor needed （对比 NCP349MNAETBG)
- Family-wide SC-70-6 footprint allows threshold adjustment without PCB redesign （对比 MAX4842AEXT+T (7.4V trip))
设计说明
Place the external N-channel MOSFET as close as possible to the MAX4840AEXT+T IN pin to minimize parasitic inductance in the VIN sense path. Keep the GATE trace short and away from switching nodes to avoid noise coupling. According to the Analog Devices datasheet, the input capacitor should be placed immediately adjacent to the IN pin, with a 1uF or larger ceramic value recommended for stable operation.
The MAX4840A's absolute maximum input voltage is +28V. Sustained transients above this level can damage the IC; add an upstream TVS diode rated above 28V working voltage and below the next-stage breakdown for surge events from inductive kick, ESD, or hot-plug arcing. Do not omit the FLAG pull-up resistor or the IC will not be able to assert a fault signal to the host MCU.
Although the MAX4840AEXT+T dissipates little power itself, the external N-FET handles the full load current and the OVP-shutdown dissipation. Select an N-FET with low R_DS(on) and adequate SOA for the application. Estimated: with VIN=5V, VOUT=5V, and a 2A continuous load through the FET, conduction loss is approximately 2A x I2R_DS(on); ensure the FET is rated for the expected junction temperature rise using its theta_JA value.
合规信息
RoHS and lead-free compliance per Analog Devices (Maxim Integrated) product page. AEC-Q100 automotive qualification not present - choose a different part for automotive applications.
