L4931ABD50 - 5V 250mA LDO Regulator with Inhibit | STMicroelectronics
N.º da peça: L4931ABD50 ✓ Ativo| Qtd. | Preço unitário | Total |
|---|---|---|
| 1 | $1.05 | $1,05 |
| 10 | $0.94 | $9,40 |
| 100 | $0.79 | $79,00 |
| 500 | $0.62 | $310,00 |
| 1.000 | $0.51 | $510,00 |
| 3.000 | $0.42 | $1.260,00 |
L4931ABD50 Visão geral
An LDO (Low-Dropout) linear regulator is a type of voltage regulator that maintains a stable output voltage even when the input-to-output differential is small, typically a few hundred millivolts. Within the broader power-management hierarchy, LDOs belong to the linear regulator family, which itself sits under voltage regulators and the overall power management IC category. LDOs are favored over switching regulators in noise-sensitive applications because they introduce no EMI from switching action, and they typically provide high PSRR and low output noise.
Key features of the L4931ABD50 include a very low dropout of 0.4 V at 250 mA, low quiescent current in both operating and inhibit states, internal current limit with thermal shutdown protection, and a TTL-compatible inhibit (shutdown) pin on the SO-8 package. The fixed 5 V output eliminates external resistor dividers and simplifies PCB layout, while the SO-8 footprint provides compact board integration with adequate copper area for sustained 250 mA delivery.
The L4931 series uses a PNP pass transistor architecture with a precision bandgap reference, achieving tight line and load regulation across the operating range. The internal inhibit logic is TTL-compatible, allowing direct interface with microcontrollers or logic gates without level shifting. Combined with very low quiescent current, this makes the part particularly efficient in battery-powered and always-on subsystems where standby drain matters.
Typical applications include battery-powered portable devices, microcontroller and DSP supply rails, post-regulation after a switching converter to clean ripple, automotive ECUs (the L4931 is AEC-Q100 qualified for automotive markets), and any system requiring a 5 V rail with low dropout and shutdown control.
When designing with this device, ensure adequate input and output capacitance (typically 2.2 µF minimum on each) for regulator stability, and respect the 0.4 V dropout budget under all load transients. The inhibit pin should be tied high (or left open, since the SO-8 version enables by default) when shutdown is not required.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet alone.
Alternativas drop-in para L4931ABD50 — mesmo encapsulamento, compatível pino a pino. Peças de encapsulamento diferente que exigem retrabalho na PCB são excluídas.
Ferramenta de comparação rápida — selecione peças alternativas para comparação lado a lado:
L4931ABD50-TR
✅ Drop-In📋 Alternativa de referência (fora do catálogo)
L4931ABD33-TR
✅ Drop-In📋 Alternativa de referência (fora do catálogo)
L4931ABD120-TR
✅ Drop-In📋 Alternativa de referência (fora do catálogo)
L4931CD50-TR
✅ Drop-In📋 Alternativa de referência (fora do catálogo)
LP2985-50
✅ Drop-In📋 Alternativa de referência (fora do catálogo)
L4931ABD50 Classificações máximas e características elétricas
| Manufacturer | STMicroelectronics |
| Series | L4931 |
| Tipo de saída | Fixed |
| Tensão de saída | 5.0 V |
| Output Current (Maximum) | 250 mA |
| Dropout Voltage (Maximum) | 0.4 V |
| Quiescent Current (Inhibit) | Very low |
| Inhibit Pin | Yes (TTL-compatible, active-high shutdown) |
| Faixa de temperatura de operação | -40 °C to +125 °C |
| Encapsulamento | 8-SOIC (SO-8) |
| Tipo de montagem | Surface Mount |
| Automotive Qualification | AEC-Q100 (per third-party datasheet notes) |
Configuração de pinos do L4931ABD50
| Pino 1 | IN — Unregulated input voltage |
| Pino 2 | IN — Unregulated input voltage (tied to pin 1) |
| Pino 3 | INH — TTL-compatible inhibit (shutdown) input, active-low on SO-8 package |
| Pino 4 | GND — Ground reference |
| Pino 5 | GND — Ground reference (tied to pin 4) |
| Pino 6 | GND — Ground reference (tied to pin 4) |
| Pino 7 | OUT — Regulated 5.0 V output |
| Pino 8 | OUT — Regulated 5.0 V output (tied to pin 7) |
Aplicações típicas
L4931ABD50 é adequado para 6 aplicaçãos: Battery-Powered Portable Devices, Microcontroller and DSP 5 V Supply Rail, Post-Regulation After Switching Converter, Automotive ECU Body Electronics, Industrial Sensor and Instrumentation 5 V Rails, Always-On and Standby Subsystems.
Battery-Powered Portable Devices
The L4931ABD50's very low dropout of 0.4 V at 250 mA and extremely low quiescent current make it an excellent fit for battery-powered portable devices such as handheld meters, wireless sensor nodes, and remote controls. With VIN near 5.4 V and a fixed 5.0 V output, the device stays useful deep into battery discharge, squeezing extra runtime from a 1S Li-ion or 3x AA stack. Compared to a switching regulator, the L4931ABD50 adds no switching noise, so it does not corrupt ADC readings or sensitive analog front-ends in the same enclosure.
Recomendado
Microcontroller and DSP 5 V Supply Rail
Many legacy microcontrollers, display controllers, and DSPs require a clean 5 V rail at modest current. The L4931ABD50's fixed 5.0 V output eliminates external resistor dividers and the tolerance stack-up they introduce, and its 250 mA rating comfortably supports a small SoC plus supporting logic. The TTL-compatible inhibit pin also enables direct GPIO control of the rail, simplifying power-state sequencing in mixed-voltage designs without an extra level shifter.
Recomendado
Post-Regulation After Switching Converter
In systems where a switching converter provides bulk power but downstream analog or RF circuitry needs a low-ripple-output noise rail, the L4931ABD50 placed downstream as a post-regulator cleans residual switching ripple. The 0.4 V dropout supports a 5.5 V intermediate rail while delivering 5.0 V at the load, and the PNP architecture provides high PSRR at low frequencies. This two-stage 'switcher then LDO' topology is common in mixed-signal designs where cost and efficiency favor a switcher upstream but noise favors an LDO at the load.
Recomendado
Automotive ECU Body Electronics
The L4931 family is AEC-Q100 qualified in the -40 °C to +125 °C range, making the L4931ABD50 a fit for automotive ECU body-electronics modules such as door-zone controllers, HVAC panels, and lighting controllers that run from a 12 V bus and need a local 5 V rail at sub-250 mA. The TTL-compatible inhibit pin permits the ECU to shut the regulator down in low-power states, reducing standby drain on the battery during key-off. Designers should size upstream input capacitance for automotive load-dump transients.
Recomendado
Industrial Sensor and Instrumentation 5 V Rails
Industrial 4-20 mA loop transmitters, RTD/thermocondition signal chains, and process-control I/O cards often require a low-noise 5 V rail at modest current. The L4931ABD50's fixed 5 V output and PNP-architecture low noise support stable excitation of bridge sensors and reference voltages for 16/24-bit ADCs. The SO-8 footprint is convenient for retrofits into existing 8-pin LDO footprints, and the wide -40 to +125 °C range covers industrial cabinet environments.
Recomendado
Always-On and Standby Subsystems
In always-on subsystems that maintain a low-current housekeeping rail during system sleep, the L4931ABD50's low quiescent current and TTL-compatible inhibit pin allow the rail to be duty-cycled or held continuously without excessive battery drain. Use cases include RTC backup, wake-on-LAN controllers, and tamper-detection circuits. The PNP architecture provides clean turn-on and turn-off transients, avoiding glitches that could couple into nearby analog or RF signal paths during state transitions.
Recomendado
Resumo dos produtos recomendados
Dados de referência de engenharia para L4931ABD50 — comparação, orientação de projeto e informações de conformidade.
Guia de seleção
Comparação com alternativas
| Parâmetro | Este produto | L4931ABD50-TR | L4931ABD33-TR | L4931ABD120-TR | L4931CD50-TR | LP2985-50 |
|---|---|---|---|---|---|---|
| Brand | STMicroelectronics | STMicroelectronics | STMicroelectronics | STMicroelectronics | STMicroelectronics | Texas Instruments |
| Package | 8-SOIC (SO-8) | 8-SOIC (SO-8) - same | 8-SOIC (SO-8) - same | 8-SOIC (SO-8) - same | 8-SOIC (SO-8) - same | 8-SOIC (SO-8) - same |
| Output Voltage | 5.0 V | 5.0 V | 3.3 V | 12 V | 5.0 V | 5.0 V |
| Maximum Output Current | 250 mA | 250 mA | 250 mA | 250 mA | 250 mA | 150 mA |
| Dropout (max) | 0.4 V | 0.4 V | 0.4 V | 0.4 V | 0.4 V | 0.28 V (typ) |
| Inhibit Pin | Yes (TTL-compatible) | Yes | Yes | Yes | Yes | Yes (Shutdown) |
| Automotive Grade | AEC-Q100 | AEC-Q100 | AEC-Q100 | AEC-Q100 | AEC-Q100 | Check variant |
| Operating Temperature | -40 °C to +125 °C | -40 °C to +125 °C | -40 °C to +125 °C | -40 °C to +125 °C | -40 °C to +125 °C | -40 °C to +125 °C |
Principais diferenciais
- Tighter 'AB' grade output accuracy versus 'CD' grade siblings (vs L4931CD50-TR)
- Includes TTL-compatible inhibit pin on SO-8 package (vs L4931 PPAK package variants)
- Wide -40 °C to +125 °C automotive temperature range with AEC-Q100 qualification (vs LP2985-50)
Notas de projeto
Place a low-ESR ceramic input capacitor of at least 2.2 µF as close as possible to the VIN pin, and the same on the output. The L4931 requires this minimum ESR for stable regulation across the 0-250 mA output range. Adding a 0.1 µF X7R bypass in parallel further suppresses high-frequency noise and improves transient response.
At VIN = 12 V, VOUT = 5 V, and 250 mA load, dissipation is (12 - 5) × 0.250 = 1.75 W. The SO-8 package has a theta_JA around 150 °C/W on a 1 oz 2-layer board; expect roughly 130 °C/W on the JEDEC EIA/JESD51 4-layer board. Provide adequate copper pour under the GND pins to dissipate this power and avoid thermal shutdown, especially in enclosed automotive environments.
Keep the input capacitor and output capacitor traces short and wide to minimize parasitic inductance. The GND pins (4, 5, 6) should all be tied together on the PCB with a low-impedance pour. The inhibit pin trace should be kept away from switching nodes; if not used, leave it open per the L4931 datasheet (the SO-8 version enables by default).
Do not reverse VIN and VOUT - the L4931 is not designed for reverse-voltage operation. Ensure VIN never exceeds the absolute-maximum rating from the datasheet, and add reverse-polarity protection at the connector if your system is exposed to user-replaceable batteries. Verify that downstream loads do not pull more than 250 mA during cold-crank transients.
Informações de conformidade
AEC-Q100 qualification noted in the L4931 datasheet excerpt and in third-party distributor listings. RoHS and REACH compliance per STMicroelectronics product family standard practice for SO-8 lead-free packages. Halogen-free status not explicitly verified from the cited sources.
