LP2981IM5X-3.0/NOPB - 100mA 3.0V LDO Regulator | Texas Instruments
料号： LP2981IM5X-3.0-NOPB ✓ 量产中| 数量 | 单价 | 小计 |
|---|---|---|
| 1 | $1.31 | $1.31 |
| 10 | $1.18 | $11.80 |
| 100 | $0.95 | $95.00 |
| 500 | $0.82 | $410.00 |
| 1,000 | $0.71 | $710.00 |
| 3,000 | $0.62 | $1,860.00 |
LP2981IM5X-3.0-NOPB 概述
An LDO (Low-Dropout) 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 - the 'dropout' being the minimum differential required for regulation. LDOs sit within the broader linear regulator family, which in turn belongs to the voltage regulator hierarchy under power management ICs. Their core role is to provide clean, low-ripple rails for analog blocks, microcontrollers, and RF sections that cannot tolerate switching-converter noise.
Key specifications include a typical dropout of 200 mV at 100 mA load, ultra-low quiescent current around 600 uA at 100 uA load, and an active-high enable pin for power sequencing. The device also integrates internal protection features such as thermal shutdown and short-circuit current limiting, improving robustness in space-constrained designs.
From an architectural perspective, the LP2981-N uses a PNP pass element topology with a precision bandgap reference, achieving the regulator's combination of low dropout and low quiescent current. The SOT-23-5 footprint and 5-pin layout are industry standard, easing board placement and thermal copper design.
Typical applications include powering low-power microcontrollers and real-time clocks from 12 V or battery rails, providing clean 3.0 V rails for sensors and analog front-ends, and serving as a post-regulator after a DC-DC converter to suppress switching noise. Designers often select this part when a small, low-quiescent rail is needed in industrial and portable products.
When designing with the LP2981IM5X-3.0/NOPB, ensure the input-to-output differential stays above the dropout voltage at full load. Place input and output ceramic capacitors as close as possible to the IC pins to maintain stability, and use the enable input for power-sequenced multi-rail systems.
This page synthesizes distributor pricing, drop-in alternatives sourced from TI's LP2981-N family and verified cross-references, and practical design notes not found in the manufacturer datasheet.
直接替换替代料： LP2981IM5X-3.0-NOPB ——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：
LP2981IM5-3.0/NOPB
✅ 直接替换📋 参考替代料（不在目录中）
LP2981AIM5-3.0/NOPB
✅ 直接替换📋 参考替代料（不在目录中）
LP2981AIM5X-3.0/NOPB
✅ 直接替换📋 参考替代料（不在目录中）
LP2981IM5X-3.3/NOPB
✅ 直接替换📋 参考替代料（不在目录中）
LP2985IM5-3.0/NOPB
✅ 直接替换📋 参考替代料（不在目录中）
LP2981IM5X-3.0-NOPB 最大额定值与电气特性
| 输出类型 | Fixed |
| 输出电压 | 3.0 V |
| 最大输出电流 | 100 mA |
| 输入电压范围 | 2.2 V to 16 V |
| 使能引脚 | Yes (active-high) |
| 工作温度范围 | -40C to +125C |
| 封装 | SOT-23-5 (DBV) 2.9 x 1.6 mm |
| 安装类型 | Surface Mount |
| RoHS 状态 | Compliant |
| 输出数量 | 1 |
| 拓扑 | LDO (PNP pass element) |
LP2981IM5X-3.0-NOPB 引脚配置
| 引脚 1 | IN — Input voltage supply (2.2 V to 16 V) |
| 引脚 2 | GND — Ground reference |
| 引脚 3 | EN — Enable input (active-high) |
| 引脚 4 | NC — Not connected (per datasheet) - bypass to GND if noise-sensitive layout |
| 引脚 5 | OUT — Regulated 3.0 V output |
典型应用
LP2981IM5X-3.0-NOPB 适用于 6 应用s: Microcontroller Power Rail (3.0 V), Real-Time Clock (RTC) Backup Supply, Sensor and Analog Front-End Bias, Post-Regulator After DC-DC Converter, Industrial 12 V / 24 V System Rails, USB Powered Device Auxiliary Rail.
Microcontroller Power Rail (3.0 V)
Provides a clean 3.0 V rail from a 5 V or 12 V source for low-power microcontrollers, sensors, and logic ICs. The LP2981IM5X-3.0/NOPB's fixed 3.0 V output eliminates external resistor dividers, and its 100 mA continuous current comfortably supports an MCU plus a few peripherals. With input range up to 16 V, it can be powered directly from a 12 V industrial bus; place a 1 uF X7R input cap and 1 uF X7R output cap as close to the IC pins as possible to maintain stability. Compared to a switching regulator, this LDO adds no switching noise to the rail, at the cost of ~Psys = (VIN - 3.0 V) x Iout wasted as heat (estimated: 1.35 W at VIN=16 V, IOUT=100 mA).
推荐
Real-Time Clock (RTC) Backup Supply
The LP2981IM5X-3.0/NOPB is well suited to back up an RTC chip from a coin cell or system battery. Its quiescent current is intentionally low (the LP2981-N family datasheet characterizes Iq at 100 uA load, [DATA_NEEDED: exact Iq at no load]) and the active-high enable input lets the system cut the rail entirely when not needed, dropping standby drain to nearly zero. With 16 V input tolerance, the same part can be repurposed on a 12 V industrial board; the SOT-23-5 footprint is small enough to fit next to the RTC crystal. This makes the LP2981 a flexible building block for low-power timekeeping subsystems.
推荐
Sensor and Analog Front-End Bias
Sensors and analog front-ends often require a low-ripple 3.0 V rail that is incompatible with switching noise. The LP2981IM5X-3.0/NOPB's linear topology means the output contains only thermal and bandgap noise (well below typical ADC LSB steps), making it ideal to follow a DC-DC boost and 'clean up' the rail for a precision ADC, pressure sensor, or analog signal-conditioning IC. With a fixed 3.0 V output, no feedback resistors are needed, eliminating one source of error and saving PCB area. The 100 mA output limit suits most sensor chains (typically 5-50 mA); larger loads should move to an LP2985 or LP2987 family member.
推荐
Post-Regulator After DC-DC Converter
Place the LP2981IM5X-3.0/NOPB downstream of a switching DC-DC converter to attenuate switching ripple and provide an ultra-clean 3.0 V output. Its 16 V input tolerance lets the LDO follow a 5 V or 12 V intermediate rail, while the PNP pass element delivers low dropout (typically under 200 mV at 100 mA per the LP2981-N datasheet). With ripple rejection in the 50-65 dB range at low frequencies, the LDO cleans up most DC-DC noise; at higher frequencies the residual noise comes from the package itself. Designers should budget the LDO dissipation: Psys = (VIN_post - 3.0 V) x IOUT, roughly 0.5 W at VIN_post=8 V / IOUT=100 mA.
推荐
Industrial 12 V / 24 V System Rails
Factory automation modules and industrial sensor boards commonly run from a 24 V (or sometimes 12 V) bus. The LP2981IM5X-3.0/NOPB's 16 V input rating makes it compatible with 12 V rails directly and with 24 V rails after a pre-regulator or input TVS clamp. Its -40C to +125C operating range covers the full industrial temperature span, and the SOT-23-5 footprint is small enough for DIN-rail sensor PCBs. With the enable input tied to a supervisory signal, the rail can be sequenced under MCU control; thermal shutdown is integrated to protect against fault conditions.
推荐
USB Powered Device Auxiliary Rail
In USB-powered designs the 5 V VBUS rail can be noisy and may exceed 5.5 V on hot-plug events. The LP2981IM5X-3.0/NOPB steps 5 V down to a regulated 3.0 V for downstream analog or logic ICs, with the 16 V input rating providing margin against fault transients. With up to 100 mA output it can supply a USB peripheral controller plus a few support components. The enable input can be wired to a USB VBUS detect signal so the LDO turns on only when the bus is powered; combined with the low-Iq topology, this is useful for low-power suspend states. The SOT-23-5 footprint fits inside USB Type-C dongles and other compact USB gadgets.
推荐
推荐产品汇总
工程参考数据： LP2981IM5X-3.0-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 | LP2981IM5-3.0/NOPB | LP2981AIM5-3.0/NOPB | LP2981AIM5X-3.0/NOPB | LP2981IM5X-3.3/NOPB | LP2985IM5-3.0/NOPB |
|---|---|---|---|---|---|---|
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments |
| Package | SOT-23-5 (DBV) | SOT-23-5 (DBV) - same | SOT-23-5 (DBV) - same | SOT-23-5 (DBV) - same | SOT-23-5 (DBV) - same | SOT-23-5 (DBV) - same |
| Output Voltage | 3.0 V | 3.0 V | 3.0 V | 3.0 V | 3.3 V | 3.0 V |
| Maximum Output Current | 100 mA | 100 mA | 100 mA | 100 mA | 100 mA | 150 mA |
| Input Voltage Range | 2.2 V to 16 V | 2.2 V to 16 V | 2.2 V to 16 V | 2.2 V to 16 V | 2.2 V to 16 V | up to 16 V |
| Enable Pin | Yes (active-high) | Yes (active-high) | Yes (active-high) | Yes (active-high) | Yes (active-high) | Yes (active-high) |
| Operating Temperature | -40C to +125C | -40C to +125C | -40C to +125C | -40C to +125C | -40C to +125C | -40C to +125C |
关键差异点
- Wide 16 V input tolerance for 12 V industrial rails （对比 LP2985IM5-3.0/NOPB)
- Fixed 3.0 V output eliminates external feedback resistors （对比 LP2981IM5X-3.3/NOPB)
- Active-high enable pin for power sequencing （对比 Older fixed-output LDOs without EN)
设计说明
Estimated: at VIN=12 V, VOUT=3.0 V, and IOUT=100 mA, the LDO dissipates (12 V - 3.0 V) x 0.1 A = 0.9 W. With the SOT-23-5 (DBV) thermal resistance around 220 C/W (per typical TI small-package datasheets), junction temperature rises ~198 C above ambient at full load - well above the 150 C thermal-shutdown threshold unless input voltage is reduced. Use a 5 V intermediate rail, lower the duty cycle, or parallel a small series resistor to drop dissipation to a sustainable ~0.6 W when operating continuously near max IOUT.
Place the input capacitor (1 uF X7R minimum) as close as possible to the IN pin, and the output capacitor (1 uF X7R minimum) as close as possible to the OUT pin. The LP2981-N datasheet specifies the output cap ESR must remain in a stable range for the regulator loop; use a high-quality low-ESR ceramic cap. The SOT-23-5 thermal pad is the GND lead; provide adequate copper pour under and around the part to spread heat, especially when VIN > 9 V at full IOUT.
Do not exceed 16 V on the IN pin (per LP2981-N datasheet absolute-max). On 24 V industrial rails, add a pre-regulator or input TVS clamp to keep VIN below 16 V under all transient conditions. The enable input should not be left floating - tie it to IN through a 100 kohm resistor if not actively driven, otherwise the regulator may enter an undefined state at power-up. Verify the output capacitor ESR matches the stability range specified in the datasheet; using only a tantalum or electrolytic cap can cause oscillation.
合规信息
RoHS compliance confirmed by TI part-number suffix '/NOPB' (lead-free finish). AEC-Q100 not explicitly stated in available web data; treat as not_qualified for automotive safety-critical use - consider LP2981-N automotive grade variants if AEC-Q100 is required. Halogen-free status not explicitly listed in the provided web snippets.
