LP38691SD-ADJ/NOPB - 500mA 10V Adjustable LDO | Texas Instruments
料号： LP38691SD-ADJ/NOPB ✓ 量产中LP38691SD-ADJ/NOPB 概述
A low-dropout regulator, or LDO, is a voltage regulator that maintains a relatively stable output voltage even when its input voltage is only slightly higher than the required output. LDOs belong to the linear-regulator and voltage-regulator categories within power-management semiconductors. They are especially useful when low output ripple, simple regulation, and predictable startup behavior are more important than conversion efficiency.
The LP38691SD-ADJ/NOPB provides a 2% precision reference, a 250 mV dropout voltage at 500 mA with a 5 V output, and compatibility with ultra-low-ESR ceramic capacitors. Its low-dropout architecture makes it suitable for 3.3 V, 5 V, and other regulated rails where the available input-to-output headroom is limited. The 6-WSON package also supports compact PCB layouts, although thermal design remains important at sustained high load.
The adjustable version uses external resistors to set the output voltage, making it flexible for laboratory supplies, embedded systems, industrial controllers, and sensor interfaces. Compared with a switching regulator, an LDO generally introduces less switching ripple and requires fewer external components, although power dissipation rises with the difference between input and output voltage. The regulator should be paired with adequate input and output capacitance according to the manufacturer application guidance.
Typical applications include low-noise analog rails, communications modules, industrial control boards, portable equipment, and embedded processors. When designing with this part, verify the maximum power dissipation, confirm the output-voltage resistor network, and keep input and output capacitors close to the corresponding pins. This page combines verified manufacturer and distributor information with practical application guidance and replacement considerations for engineers evaluating this regulator.
直接替换替代料： LP38691SD-ADJ/NOPB ——相同封装，引脚兼容。需要 PCB 改动的不同封装料号已排除。
本系列中的变体
可与以下型号直接替换的同系列型号： LP38691SD-ADJ/NOPB （相同外形与封装尺寸） ——差异在于 Dropout Voltage, Input Voltage Range, Maximum Output Current, Operating Temperature Range, Output Voltage Range.
LP38691SD-ADJ
✅ 直接替换📋 参考替代料（不在目录中）
LP38692SD-ADJ
✅ 直接替换📋 参考替代料（不在目录中）
LP38691QSDX-ADJ/NOPB
✅ 直接替换📋 参考替代料（不在目录中）
LP38693-ADJ
✅ 直接替换📋 参考替代料（不在目录中）
LP38691SD-ADJ/NOPB 最大额定值与电气特性
| Product Type | Positive adjustable low-dropout CMOS linear regulator |
| 最大输出电流 | 500 mA |
| 输入电压范围 | 2.7 V to 10 V |
| 输出电压范围 | 1.25 V to 9 V |
| 压差电压 | 250 mV at 500 mA and VOUT = 5 V |
| Reference Voltage Accuracy | 2% precision reference |
| Output Capacitor Stability | Stable with ultra-low-ESR ceramic output capacitors |
| 封装 | 6-WSON (NGG), 3 x 3 mm |
| 引脚数 | 6 pins |
| 工作温度范围 | -40 C to 125 C |
| 安装类型 | Surface mount |
| Regulator Topology | Linear regulator |
| Output Polarity | Positive |
| Adjustability | Adjustable output |
| 使能引脚 | Not specified in the supplied verified data |
| RoHS 状态 | RoHS compliant |
| Lead-Free Status | Lead free |
LP38691SD-ADJ/NOPB 引脚配置
| 引脚 1 | GND — Ground connection |
| 引脚 2 | IN — Regulator input |
| 引脚 3 | OUT — Regulator output |
| 引脚 4 | NC — Not connected |
| 引脚 5 | NC — Not connected |
| 引脚 6 | EP — Exposed thermal pad; verify connection to ground or thermal plane in the datasheet |
典型应用
LP38691SD-ADJ/NOPB 适用于 6 应用s: 3.3 V Embedded Processor Rail, Industrial Control Board Regulation, Low-Noise Analog Supply, Communication Module Power, Portable and Battery-Powered Equipment, Laboratory and Test Equipment.
3.3 V Embedded Processor Rail
LP38691SD-ADJ/NOPB is suitable for producing a 3.3 V rail for embedded processors, sensors, and communications logic when the input supply is only modestly above the desired output. The adjustable 1.25 V to 9 V range allows the output to be set with external resistors, while the 500 mA rating supports moderate digital and analog loads. Its low-dropout architecture is useful when supply headroom is limited. Place input and output capacitors close to the device and verify the 250 mV dropout specification with design margin.
推荐
Industrial Control Board Regulation
The LP38691SD-ADJ/NOPB can provide a compact adjustable rail for industrial control boards containing sensors, interface circuits, and low-power controllers. Its 2.7 V to 10 V input range and -40 C to 125 C operating specification make it a candidate for extended-temperature equipment, subject to thermal and EMC validation. The 6-WSON package supports compact layouts, but designers should preserve copper around the thermal pad and calculate dissipation from the actual VIN-to-VOUT difference.
推荐
Low-Noise Analog Supply
For analog signal chains, LP38691SD-ADJ/NOPB can generate a local rail close to the point of use, helping isolate sensitive circuitry from upstream supply variation. The LDO topology avoids the switching ripple associated with a buck converter, while the 250 mV dropout specification supports operation with limited input headroom at a 5 V output and 500 mA. Confirm output capacitor ESR, load transient response, and thermal rise before using it in precision measurement systems.
推荐
Communication Module Power
LP38691SD-ADJ/NOPB is applicable to RF, communications, and data-acquisition modules that require a simple local regulator rather than a complex multi-rail power tree. Its adjustable output allows one regulator design to support several nominal rail voltages, while the 500 mA rating covers many small transceiver and control sections. The compact 6-WSON footprint helps conserve board area. Designers should verify startup behavior, decoupling, and conducted-emissions performance in the final enclosure and load configuration.
推荐
Portable and Battery-Powered Equipment
The regulator can serve as a post-converter rail in portable equipment where a battery or charger provides a relatively narrow voltage range. Low dropout helps preserve usable input headroom, and the adjustable output supports product variants that require different logic or sensor voltages. Because linear regulation dissipates the difference between input and output voltage, efficiency should be checked at the highest expected load. Use the lowest practical dropout headroom without violating ripple and startup requirements.
推荐
Laboratory and Test Equipment
LP38691SD-ADJ/NOPB is useful in laboratory instruments where a configurable low-noise supply rail is needed for analog front ends or controller cards. The adjustable output range covers common 1.25 V, 2.5 V, 3.3 V, 5 V, and other rails when enough input headroom exists. Stable operation with ceramic capacitors simplifies board assembly, while the small package helps reduce instrument footprint. Validate resistor accuracy, capacitor tolerance, line regulation, and thermal behavior across the intended output-load matrix.
推荐
推荐产品汇总
工程参考数据： LP38691SD-ADJ/NOPB ——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 | LP38691SD-ADJ | LP38692SD-ADJ | LP38691QSDX-ADJ/NOPB | LP38693-ADJ |
|---|---|---|---|---|---|
| Product Type | Adjustable low-dropout linear regulator | Adjustable low-dropout linear regulator | Adjustable low-dropout linear regulator | Automotive-family adjustable regulator | 500 mA low-dropout CMOS regulator |
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments |
| Package | 6-WSON (NGG) | 6-WSON (NGG) | 6-WSON family context | 6-WSON family context | 6-WSON family context |
| RoHS Status | Compliant | RoHS-compliant family device | RoHS status requires verification | RoHS status requires verification | RoHS status requires verification |
关键差异点
- Adjustable output supports multiple rail settings （对比 LP38691SD-ADJ)
- Low-dropout operation supports constrained input headroom （对比 LP38693-ADJ)
- Compact WSON implementation for space-constrained boards （对比 LP38691QSDX-ADJ/NOPB)
- Ceramic-capacitor-compatible regulation （对比 LP38692SD-ADJ)
设计说明
Estimated: use P = (VIN - VOUT) × IOUT to estimate linear-regulator dissipation. At 5.5 V input, 3.3 V output, and 500 mA load, the estimated loss is 1.1 W. Check the WSON exposed-pad copper area and thermal resistance against the ambient temperature and maximum junction temperature; the supplied data does not specify theta-JA.
Place the input and output capacitors close to the LP38691SD-ADJ/NOPB pins to minimize loop area and supply impedance. Preserve a continuous thermal path through the exposed pad and use the footprint and land pattern specified by Texas Instruments. Confirm the exposed-pad connection and assembly requirements from the manufacturer package drawing before release to manufacturing.
Do not assume that the 250 mV dropout specification applies without the stated 500 mA and 5 V output conditions. Include resistor tolerance, load transient margin, ambient temperature, and input ripple when setting the operating point. Also verify the selected capacitor voltage rating and ESR characteristics, because stable ceramic-capacitor operation is a specific device feature rather than a universal regulator requirement.
Keep sensitive analog ground returns separate from high-current return paths where practical, and connect the regulator ground and exposed pad to a low-impedance ground plane. Route high-current output current through copper that does not share narrow traces with precision signal paths. Validate the final layout for voltage-drop-induced regulator behavior and thermal performance using worst-case load and supply conditions.
合规信息
The supplied comparison data identifies RoHS compliance and lead-free status. The supplied manufacturer product information does not establish REACH, halogen-free, or conflict-minerals status for this exact ordering code, so those fields remain unknown. AEC-Q100 status is not specified for the standard LP38691SD-ADJ/NOPB device.
