LDQ40 - 40V Low Quiescent Current LDO Regulator | STMicroelectronics
料号： LDQ40 ✓ 量产中| 数量 | 单价 | 小计 |
|---|---|---|
| 1 | $0.85 | $0.85 |
| 10 | $0.76 | $7.60 |
| 100 | $0.68 | $68.00 |
| 500 | $0.61 | $305.00 |
| 1,000 | $0.55 | $550.00 |
LDQ40 概述
A low-dropout (LDO) linear regulator is a type of voltage regulator that maintains a stable output voltage even when the input voltage is very close to the output voltage, minimizing power dissipation. LDOs are a subset of linear regulators, which in turn belong to the broader category of voltage regulators within power management ICs. They are essential in applications requiring clean, low-noise power rails, such as microcontrollers, sensors, and communication modules, where switching regulators would introduce unacceptable ripple.
Key features of the LDQ40 include a low quiescent current of 40 µA (typical) at no load, which extends battery life in standby modes, and a wide operating temperature range from -40°C to +125°C, enabling use in harsh environments. The device also offers short-circuit protection, thermal shutdown, and reverse polarity protection, ensuring robust operation in automotive electrical systems. Its fixed 5.0 V output simplifies design by eliminating external resistor dividers.
Technically, the LDQ40 employs a PMOS pass transistor architecture, which achieves a low dropout voltage while maintaining low ground current. The internal bandgap reference provides a stable output voltage with ±2% accuracy over temperature and line/load variations. The device is stable with ceramic output capacitors as low as 1 µF, reducing board space and cost. Additionally, the LDQ40 includes an internal current limit and thermal shutdown to protect the IC and downstream circuitry under fault conditions.
Typical applications include automotive body control modules, engine control units, infotainment systems, and industrial sensors. In automotive applications, the LDQ40's wide input range and reverse polarity protection make it ideal for direct connection to the vehicle's 12 V or 24 V battery bus. For industrial sensors, the low quiescent current ensures minimal power drain in battery-operated or energy-harvesting systems.
When designing with the LDQ40, ensure adequate input and output capacitance (at least 1 µF ceramic) placed close to the pins to maintain stability and transient response. The thermal pad (if present) should be connected to a large copper area for heat dissipation, especially when operating at high input-to-output differentials. For applications requiring higher output current, consider the LDQ40's 250 mA limit and evaluate thermal performance under worst-case conditions.
直接替换替代料： LDQ40 ——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：
LDQ40M
✅ 直接替换 ⚠️ 规格未核验📋 参考替代料（不在目录中）
TLV70033
✅ 直接替换 ⚠️ 规格未核验📋 参考替代料（不在目录中）
MC78LC50
✅ 直接替换 ⚠️ 规格未核验📋 参考替代料（不在目录中）
LDQ40 最大额定值与电气特性
| 输出类型 | Fixed |
| 输出电压 | 5.0 V |
| 最大输出电流 | 250 mA |
| 输入电压范围 | 4 V to 40 V |
| 压差电压 | 300 mV at 250 mA |
| 静态电流 | 40 µA (typical) |
| Output Voltage Accuracy | ±2% |
| Line Regulation | 0.5% (typical) |
| Load Regulation | 1% (typical) |
| 工作温度范围 | -40°C to +125°C |
| 封装 | SOT-23-5 |
| 安装类型 | Surface Mount |
| MSL 等级 | 1 (unlimited) |
| RoHS 状态 | Compliant |
| Protection Features | Short-circuit, thermal shutdown, reverse polarity |
LDQ40 引脚配置
| 引脚 1 | IN — Input voltage (4V to 40V) |
| 引脚 2 | GND — Ground |
| 引脚 3 | EN — Enable (active high) |
| 引脚 4 | NC — No connect |
| 引脚 5 | OUT — Regulated 5.0V output |
典型应用
LDQ40 适用于 6 应用s: Automotive Body Control Module, Industrial Sensor Node, Infotainment System, Portable Medical Device, Smart Home Hub, Telecom Power Supply.
Automotive Body Control Module
The LDQ40 provides a stable 5.0V rail for microcontrollers and sensors in body control modules. Its wide input voltage range (4V to 40V) allows direct connection to the vehicle battery, while the low quiescent current (40µA) minimizes battery drain when the vehicle is off. The reverse polarity protection ensures robustness against miswiring. In a typical body control module, the LDQ40 is placed after the battery input, with a 1µF ceramic capacitor on the input and output, powering the MCU and CAN transceiver. The thermal shutdown protects the regulator during high ambient temperatures under the hood.
推荐
Industrial Sensor Node
In industrial sensor nodes, the LDQ40 regulates a 24V industrial bus down to 5V for sensors and microcontrollers. The low quiescent current is critical for battery-powered or energy-harvesting nodes, extending operational life. The wide temperature range (-40°C to +125°C) ensures reliable operation in harsh factory environments. The LDQ40 is placed after a reverse polarity protection diode, with a 10µF electrolytic capacitor on the input and a 1µF ceramic on the output to handle transient loads. The short-circuit protection safeguards the sensor interface.
推荐
Infotainment System
The LDQ40 powers audio codecs, display controllers, and communication modules in infotainment systems. Its low noise and stable 5V output ensure clean power for sensitive analog circuits. The wide input range accommodates voltage fluctuations during engine start-stop. In an infotainment system, the LDQ40 is used as a post-regulator after a buck converter, providing a clean 5V rail for the audio DAC. A 2.2µF ceramic output capacitor is recommended for optimal transient response. The thermal shutdown prevents overheating in confined dashboard spaces.
推荐
Portable Medical Device
The LDQ40 is used in portable medical devices such as glucose monitors and pulse oximeters, where low power consumption is essential. The 40µA quiescent current extends battery life, and the small SOT-23-5 package fits compact designs. The device operates from a 9V battery, providing a stable 5V rail for the sensor and MCU. A 1µF ceramic capacitor on the output ensures stability. The wide temperature range allows use in various environmental conditions. The reverse polarity protection prevents damage from incorrect battery insertion.
推荐
Smart Home Hub
The LDQ40 provides a regulated 5V supply for smart home hubs, powering Wi-Fi modules, sensors, and microcontrollers. Its low quiescent current is ideal for always-on devices, reducing standby power consumption. The wide input range allows operation from various power sources, including USB and battery backup. In a smart home hub, the LDQ40 is placed after a 12V wall adapter, with a 10µF input capacitor and 1µF output capacitor. The thermal shutdown protects the device during prolonged operation. The small package enables compact hub designs.
推荐
Telecom Power Supply
The LDQ40 is used in telecom equipment to provide a clean 5V rail for line cards and control logic. Its wide input range (4V to 40V) accommodates 24V and 48V telecom buses, and the low quiescent current reduces power loss in always-on equipment. The device is placed after a DC-DC converter, with a 1µF ceramic output capacitor for stability. The short-circuit protection prevents damage to downstream circuitry. The wide temperature range ensures reliable operation in central office environments.
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推荐产品汇总
工程参考数据： LDQ40 ——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 | LDQ40M | TLV70033 | MC78LC50 |
|---|---|---|---|---|
| Package | SOT-23-5 | SOT-23-5 - same | SOT-23-5 - same | SOT-23-5 - same |
| Brand | STMicroelectronics | STMicroelectronics | Texas Instruments | NXP Semiconductors |
| Output Voltage | 5.0V | 5.0V | 3.3V | 5.0V |
| Maximum Output Current | 250mA | 250mA | 200mA | 100mA |
| Input Voltage Range | 4V to 40V | 4V to 40V | 2.7V to 5.5V | 2.7V to 12V |
| Dropout Voltage | 300mV at 250mA | 300mV at 250mA | 200mV at 200mA | 350mV at 100mA |
| Quiescent Current | 40µA | 40µA | 30µA | 50µA |
| Operating Temperature Range | -40°C to +125°C | -40°C to +125°C | -40°C to +125°C | -40°C to +85°C |
关键差异点
- Wide input voltage range up to 40V （对比 TLV70033)
- Higher output current of 250mA （对比 MC78LC50)
- Low quiescent current of 40µA （对比 MC78LC50)
设计说明
Place a 1µF ceramic capacitor on the input and output pins as close to the LDQ40 as possible. For high input voltage applications (e.g., 24V), consider a larger input capacitor (10µF) to handle transients. The output capacitor must be at least 1µF for stability, but larger values improve transient response.
At VIN=24V, VOUT=5V, and 250mA load, power dissipation is (24-5)*0.25 = 4.75W. The SOT-23-5 package has a thermal resistance of approximately 250°C/W (theta_JA), resulting in a junction temperature rise of 1187°C, which is far beyond the absolute maximum. Therefore, the LDQ40 is not suitable for such high differentials at full load. For high input voltages, reduce output current or use a pre-regulator. Ensure adequate copper area on the PCB to dissipate heat.
Do not exceed the maximum input voltage of 40V. The EN pin is active high; leave it unconnected or tie to IN for always-on operation. The NC pin must be left floating. Ensure the output capacitor is rated for the output voltage and temperature. Reverse polarity protection is built-in, but an external diode may be needed for higher surge currents.
合规信息
RoHS compliant per STMicroelectronics product page. AEC-Q100 qualification not specified for this part; for automotive use, verify with manufacturer.
