LD1117S25TR - 800mA Low Dropout Positive Regulator | STMicroelectronics
MPN： LD1117S25TR ✓ 啟用中LD1117S25TR 概覽
A low dropout regulator (LDO) is a type of linear voltage regulator that maintains a stable output voltage even when the input voltage is only slightly higher than the output. Unlike standard linear regulators, LDOs achieve a low dropout voltage by using a PNP pass transistor or a PMOS device, allowing them to operate efficiently in applications where the input-to-output voltage difference is small. LDOs are a subset of linear regulators, which in turn are part of the broader category of voltage regulators within power management integrated circuits (ICs).
Key features of the LD1117S25TR include a fixed 2.5V output, a maximum output current of 800mA, and a dropout voltage of 1.1V at full load. The device also offers internal current limiting and thermal shutdown protection, ensuring safe operation under fault conditions. The SOT-223 package provides a compact footprint with a thermal resistance of approximately 50°C/W, enabling moderate power dissipation without external heatsinking.
The LD1117S25TR utilizes a PNP pass transistor architecture, which allows for low dropout operation and stable output with a minimum output capacitor of 10µF. The device is designed to be stable with tantalum or aluminum electrolytic capacitors, and it includes a bandgap reference for accurate output voltage regulation. The internal current limit and thermal shutdown circuits protect the device from overcurrent and overtemperature conditions, enhancing system reliability.
Typical applications for the LD1117S25TR include post-regulation for switching power supplies, battery-powered equipment, and low-voltage logic supplies. Its fixed 2.5V output is commonly used to power microcontrollers, memory ICs, and other digital circuits that require a stable 2.5V rail. The low dropout voltage and low quiescent current make it suitable for portable devices where power efficiency is critical.
When designing with the LD1117S25TR, ensure that the input voltage is at least 1.1V above the output voltage to maintain regulation. The output capacitor should be placed close to the output pin to minimize parasitic inductance and ensure stability. Additionally, the thermal pad of the SOT-223 package should be connected to a copper area on the PCB to improve heat dissipation.
直接替換替代品，適用於 LD1117S25TR — 相同封裝，腳位對腳位相容。需重新設計 PCB 的不同封裝零件不列入。
此系列的變體
與下列產品可直接替換的同系列型號： LD1117S25TR （相同外形與佔位） — 差異在於 Output Voltage, Dropout Voltage, Input Voltage Range, Line Regulation, Load Regulation.
LD1117S25TR
✅ 直接替換聯絡詢價
查看資料表 →LD1117S33TR
✅ 直接替換 ⚠️ 規格未經驗證✗ 缺貨
$0.2 / 單位
查看資料表 →LD1117S18TR
✅ 直接替換 ⚠️ 規格未經驗證聯絡詢價
查看資料表 →AMS1117-2.5
✅ 直接替換 ⚠️ 規格未經驗證📋 參考替代品（不在目錄中）
NCP1117ST25T3G
✅ 直接替換 ⚠️ 規格未經驗證📋 參考替代品（不在目錄中）
AP1117-2.5
✅ 直接替換 ⚠️ 規格未經驗證📋 參考替代品（不在目錄中）
LD1117S25TR 最大額定值與電氣特性
| 輸出類型 | Fixed |
| 輸出電壓 | 2.5 V |
| 最大輸出電流 | 800 mA |
| 輸入電壓範圍 | Up to 15 V |
| 壓降電壓 | 1.1 V at 800 mA |
| 靜態電流 | 5 mA |
| Line Regulation | 0.2% (typical) |
| Load Regulation | 0.4% (typical) |
| Output Capacitor | 10 µF (minimum) |
| 工作溫度範圍 | 0°C to +125°C |
| 封裝 | SOT-223 |
| 安裝類型 | Surface Mount |
| Thermal Resistance (θJA) | 50 °C/W |
| RoHS 狀態 | Compliant |
| Lead-Free | Yes |
LD1117S25TR 腳位配置
| 腳位 1 | IN — Input voltage pin |
| 腳位 2 | GND — Ground pin |
| 腳位 3 | OUT — Regulated output voltage |
| 腳位 4 | TAB — Thermal pad, connected to OUT |
典型應用
LD1117S25TR 適用於 6 應用s: Post-Regulation for Switching Power Supplies, Battery-Powered Equipment, Low-Voltage Logic Supplies, Consumer Electronics, Industrial Control Systems, Telecommunication Equipment.
Post-Regulation for Switching Power Supplies
The LD1117S25TR is used as a post-regulator to provide a clean 2.5V rail from a noisy switching converter output. Its low dropout voltage of 1.1V allows it to operate with minimal headroom, and its 800mA output current is sufficient for many digital loads. The device's internal current limiting and thermal shutdown protect the downstream circuitry from faults. In a typical application, the LD1117S25TR is placed after a buck converter, with a 10µF output capacitor to ensure stability. The low output noise and good line/load regulation make it suitable for powering sensitive analog and digital circuits.
推薦
Battery-Powered Equipment
In battery-powered devices, the LD1117S25TR regulates a 2.5V rail from a battery voltage that may drop as low as 3.6V. Its low quiescent current of 5mA helps extend battery life, and the low dropout voltage ensures efficient operation even when the battery is nearly discharged. The SOT-223 package is compact, making it suitable for portable devices. The device's thermal shutdown prevents damage from excessive power dissipation, which is important in small enclosures. For a 3.7V Li-ion battery, the LD1117S25TR can provide a stable 2.5V output until the battery voltage falls below 3.6V.
推薦
Low-Voltage Logic Supplies
The LD1117S25TR provides a stable 2.5V supply for low-voltage logic ICs, such as FPGAs, CPLDs, and memory devices. Its 800mA output current can power multiple logic devices, and the fixed 2.5V output eliminates the need for external resistor dividers. The device's fast transient response ensures stable operation during rapid load changes. In a typical application, the LD1117S25TR is connected to a 3.3V rail, and the output is decoupled with a 10µF capacitor. The low dropout voltage allows the regulator to maintain regulation even if the 3.3V rail dips slightly.
推薦
Consumer Electronics
The LD1117S25TR is widely used in consumer electronics such as set-top boxes, routers, and gaming consoles to provide a clean 2.5V rail for various ICs. Its low cost and availability in the SOT-223 package make it a popular choice for high-volume production. The device's thermal shutdown and current limiting ensure reliable operation in consumer environments. In a typical application, the LD1117S25TR is powered from a 5V adapter, and the output is filtered with a 10µF capacitor. The low dropout voltage allows the regulator to operate efficiently even with a 5V input.
推薦
Industrial Control Systems
In industrial control systems, the LD1117S25TR provides a stable 2.5V reference for analog-to-digital converters (ADCs), sensors, and microcontrollers. Its wide input voltage range up to 15V allows it to be powered from industrial 24V buses with a pre-regulator. The device's low output noise and good line regulation ensure accurate measurements. In a typical application, the LD1117S25TR is used to power an ADC reference, with a 10µF output capacitor and a 0.1µF bypass capacitor for noise reduction. The device's thermal shutdown protects it from overtemperature conditions in harsh industrial environments.
推薦
Telecommunication Equipment
The LD1117S25TR is used in telecommunication equipment to provide a clean 2.5V rail for line drivers, transceivers, and digital signal processors. Its low dropout voltage and high output current make it suitable for powering multiple ICs. The device's low quiescent current is beneficial in always-on communication modules. In a typical application, the LD1117S25TR is powered from a 3.3V rail, and the output is decoupled with a 10µF capacitor. The device's thermal shutdown ensures reliable operation in equipment that may be exposed to high ambient temperatures.
推薦
推薦產品摘要
工程參考資料，適用於 LD1117S25TR — 比較、設計指引及合規資訊。
選型指南
與替代品比較
| 參數 | 本產品 | LD1117S33TR | AMS1117-2.5 | NCP1117ST25T3G |
|---|---|---|---|---|
| Package | SOT-223 | SOT-223 | SOT-223 | SOT-223 |
| Brand | STMicroelectronics | STMicroelectronics | Advanced Monolithic Systems | onsemi |
| Output Voltage | 2.5V | 3.3V | 2.5V | 2.5V |
| Maximum Output Current | 800mA | 800mA | 1A | 1A |
| Dropout Voltage | 1.1V at 800mA | 1.1V at 800mA | 1.1V at 1A | 1.1V at 1A |
| Quiescent Current | 5mA | 5mA | 5mA | 5mA |
| Input Voltage Range | Up to 15V | Up to 15V | Up to 15V | Up to 15V |
| Operating Temperature Range | 0°C to +125°C | 0°C to +125°C | 0°C to +125°C | 0°C to +125°C |
主要差異化特點
- Fixed 2.5V output with 800mA current capability (對比LD1117S33TR)
- Low dropout voltage of 1.1V at full load (對比AMS1117-2.5)
- SOT-223 package with thermal pad (對比NCP1117ST25T3G)
設計說明
The SOT-223 package has a thermal resistance of approximately 50°C/W. At maximum output current of 800mA and a dropout voltage of 1.1V, the power dissipation is 0.88W, resulting in a temperature rise of 44°C above ambient. Ensure adequate copper area on the PCB to dissipate heat, especially in high-temperature environments.
Place the input and output capacitors as close to the LD1117S25TR pins as possible. A minimum output capacitor of 10µF is required for stability, and a 0.1µF ceramic capacitor should be placed in parallel for high-frequency noise bypass. The thermal pad (tab) should be connected to a large copper area to improve heat dissipation.
Do not exceed the maximum input voltage of 15V. Ensure the input voltage is at least 1.1V above the output voltage to maintain regulation. The output capacitor must be placed close to the output pin to avoid instability. Use a capacitor with low ESR, such as a tantalum or aluminum electrolytic capacitor, as specified in the datasheet.
合規資訊
RoHS compliant per STMicroelectronics product page. Not AEC-Q100 qualified. Lead-free and conflict minerals compliant.
