LT1579CS-5#PBF - 300mA Dual-Input Smart Battery Backup LDO | ADI
料号： LT1579CS-5#PBF ✓ 量产中| 数量 | 单价 | 小计 |
|---|---|---|
| 1 | $5.43 | $5.43 |
| 10 | $4.84 | $48.40 |
| 100 | $4.15 | $415.00 |
| 500 | $3.46 | $1,730.00 |
| 1,000 | $2.85 | $2,850.00 |
| 3,000 | $2.64 | $7,920.00 |
LT1579CS-5#PBF 概述
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 — the 'dropout' voltage is the minimum headroom required to keep regulation intact. The LT1579 sits within the broader hierarchy of linear regulators -> voltage regulators -> power management ICs -> semiconductor devices, and the dual-input smart-battery variant targets any system that must remain alive across a primary/backup power handover (USB ↔ Li-Ion, wall adapter ↔ supercap, mains ↔ battery).
Key features of the LT1579CS-5#PBF include seamless automatic input switching without glitches, low 50 µA quiescent current (7 µA in shutdown) for battery-life extension, fixed 5V output with ±3% tolerance, integrated reverse-current blocking between the two inputs, and a secondary select pin (S2) that lets designers force a specific input as the priority source. The SOIC-16 narrow-body package provides a manageable footprint while the exposed thermal path supports continuous 300 mA delivery at moderate ambient temperatures.
Architecturally the LT1579 combines a precision bandgap reference, two PNP-style pass elements arranged in a diode-OR topology, integrated MOSFET switch control, and the dual-comparator supervisor block. This integrated approach eliminates the discrete FETs, Schottky diodes, supervisor ICs, and sequencer glue logic that a discrete dual-rail ORing solution would otherwise require, reducing both PCB area and BOM cost.
Typical applications include battery backup for SRAM/real-time-clock supplies in meters and data loggers, USB/AC-wall-adapter power handover in portable instrumentation, supercap-backed ride-through for PLC and industrial controllers, uninterruptible supplies for microcontrollers and security sensors, and load-sharing between solar harvest and battery in remote telemetry nodes.
When designing with the LT1579CS-5#PBF, observe the 400 mV dropout rating and select input capacitance (≥10 µF low-ESR) and output capacitance (≥10 µF low-ESR, no minimum ESR window required) per the datasheet to guarantee stability across the full 0 to 300 mA load range.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet.
直接替换替代料： LT1579CS-5#PBF ——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：
LT1579CS#PBF
✅ 直接替换📋 参考替代料（不在目录中）
LT1579CS-5#TRPBF
✅ 直接替换📋 参考替代料（不在目录中）
LT1579CS-3.3#PBF
✅ 直接替换 ⚠️ 规格未核验📋 参考替代料（不在目录中）
LT1579CS-3#PBF
✅ 直接替换 ⚠️ 规格未核验📋 参考替代料（不在目录中）
LT1579IS-5#PBF
✅ 直接替换 ⚠️ 规格未核验📋 参考替代料（不在目录中）
LT1579CS-5#PBF 规格参数
| 拓扑 | Dual-input single-output LDO linear regulator |
| Output Voltage (Fixed) | 5 V |
| Output Voltage Tolerance | ±3 % |
| 输出电流（最大） | 300 mA |
| 输入电压范围 | 2.7 V to 20 V (each input) |
| 压差电压 | 400 mV (typical at 300 mA) |
| 静态电流 | 50 µA (operating) |
| 关断电流 | 7 µA |
| Number of Inputs | 2 (with seamless priority switching) |
| On-Chip Comparators | 2 (one per input for status monitoring) |
| Status Flags | 2 open-drain (STAT1, STAT2) |
| Secondary Select Pin (S2) | Yes (input priority override) |
| 封装 | 16-lead SOIC-N (narrow body) |
| 安装类型 | Surface Mount |
| Lead Finish | Matte Tin (Pb-free) |
| RoHS / Pb-free Status | Pb-free (PBF suffix), RoHS compliant |
| Manufacturer | Analog Devices (formerly Linear Technology) |
LT1579CS-5#PBF 引脚配置
| 引脚 1 | IN1 — Primary input voltage source (2.7 V to 20 V) |
| 引脚 2 | IN2 — Backup input voltage source (2.7 V to 20 V) |
| 引脚 3 | OUT — Regulated 5 V output |
| 引脚 4 | GND — Ground |
| 引脚 5 | SHDN — Shutdown pin (active high) |
| 引脚 6 | S2 — Secondary select pin (force priority input) |
| 引脚 7 | STAT1 — Open-drain status flag for IN1 |
| 引脚 8 | STAT2 — Open-drain status flag for IN2 |
| 引脚 9 | CMP1A — Comparator 1 input A |
| 引脚 10 | CMP1B — Comparator 1 input B |
| 引脚 11 | CMP1OUT — Comparator 1 output |
| 引脚 12 | CMP2A — Comparator 2 input A |
| 引脚 13 | CMP2B — Comparator 2 input B |
| 引脚 14 | CMP2OUT — Comparator 2 output |
| 引脚 15 | NC — Not connected (per datasheet) |
| 引脚 16 | NC — Not connected (per datasheet) |
典型应用
LT1579CS-5#PBF 适用于 6 应用s: Battery Backup for SRAM / Real-Time Clock, USB / Wall-Adapter Power Handover in Portable Instruments, Ride-Through for Industrial PLC / Controller Boards, Solar Harvest + Battery Power Sharing, Security / Alarm Panel Always-On Rail, Data Logger / Metering Battery Ride-Through.
Battery Backup for SRAM / Real-Time Clock
The LT1579CS-5#PBF provides the canonical uninterruptible 5 V rail for SRAM and RTC chips. Its dual-input switchover architecture lets a primary 5 V rail (e.g. AC adapter) power the load during normal operation while a coin-cell or supercap-backed rail takes over at the instant of AC loss, with zero output glitch per the ADI LT1579 datasheet (1579f). The 7 µA shutdown current extends cell lifetime in power-down states. Place a 10 µF low-ESR cap on each input and on VOUT to ride out the millisecond-scale switchover event.
推荐
USB / Wall-Adapter Power Handover in Portable Instruments
Portable test and measurement equipment often runs from USB or a wall adapter, but must keep recording on its internal Li-Ion pack when the cable is unplugged. The LT1579CS-5#PBF wires USB 5 V to IN1 and the 3.6–4.2 V Li-Ion rail to IN2; the chip's automatic priority logic hands the load over in microseconds with no MCU intervention. The 50 µA quiescent current adds negligible drain while idle, and the 300 mA output easily supports a microcontroller, ADC, and display backlight. Use a 10 µF X7R ceramic on each input/output for stability.
推荐
Ride-Through for Industrial PLC / Controller Boards
PLC and industrial controller boards must survive brownouts of tens of milliseconds without resetting. The LT1579CS-5#PBF lets a 24 V supply (via an upstream buck) drive IN1 while a supercap-fed 5 V rail (held by a separate charger) drives IN2; the chip's seamless handover keeps the microcontroller and I/O logic alive through the dropout. STAT1/STAT2 pins flag the host MCU so firmware can log the event. The 400 mV dropout at 300 mA means IN2 needs only ~5.4 V to stay in regulation, easing the supercap energy budget.
推荐
Solar Harvest + Battery Power Sharing
Remote telemetry nodes powered by a small solar panel must seamlessly share load between the harvester and a Li-Ion or LiPo battery. The LT1579CS-5#PBF routes the (regulator-clamped) solar rail to IN1 and the battery to IN2, letting whichever source is healthier at the moment carry the load. This eliminates the discrete diode-OR + MOSFET + supervisor chain that such systems traditionally require, cutting BOM count by 4–6 parts and saving significant PCB area. The 7 µA shutdown current preserves night-time battery capacity.
推荐
Security / Alarm Panel Always-On Rail
Home and commercial alarm panels need a 5 V rail that is up the moment the wall supply fails, so the dialer, sensors and microcontroller never lose state. The LT1579CS-5#PBF takes wall 12–18 V DC at IN1 and a sealed lead-acid or Li-Ion backup at IN2, switching seamlessly to backup during a tamper or outage. STAT1/STAT2 give the panel a clean 'on wall' vs 'on battery' flag for logging. The 300 mA capability covers the dialer, PIR sensors, and keypad illumination simultaneously.
推荐
Data Logger / Metering Battery Ride-Through
Electricity meters, water meters, and remote data loggers must keep their RTC and event log alive across repeated short brownouts. The LT1579CS-5#PBF offers the dual-input rail with 7 µA shutdown quiescent current, which is critical when the meter's primary cell must last the full 10-20 year deployment lifetime. The fixed 5 V output drives the metering MCU directly while a small supercap on the backup rail covers multi-second outages. The S2 pin lets the firmware force-supply from battery when running a radio transmission.
推荐
推荐产品汇总
工程参考数据： LT1579CS-5#PBF ——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 | LT1579CS#PBF | LT1579CS-5#TRPBF | LT1579CS-3.3#PBF | LT1579CS-3#PBF | LT1579IS-5#PBF |
|---|---|---|---|---|---|---|
| Brand | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices |
| Package | SOIC-16 (N) | SOIC-16 (N) - same | SOIC-16 (N) - same | SOIC-16 (N) - same | SOIC-16 (N) - same | SOIC-16 (N) - same |
| Output Voltage | 5 V (fixed) | Adjustable (1.5–12 V) | 5 V (fixed, identical die) | 3.3 V (fixed) | 3.0 V (fixed) | 5 V (fixed) |
| Output Current | 300 mA | 300 mA | 300 mA | 300 mA | 300 mA | 300 mA |
| Dropout Voltage | 400 mV | 400 mV | 400 mV | 400 mV | 400 mV | 400 mV |
| Quiescent Current | 50 µA | 50 µA | 50 µA | 50 µA | 50 µA | 50 µA |
| Number of Inputs | 2 | 2 | 2 | 2 | 2 | 2 |
| Temperature Grade | Commercial | Commercial | Commercial | Commercial | Commercial | Industrial |
关键差异点
- Fully integrated dual-input switchover in one SOIC-16 （对比 Discrete diode-OR + supervisor + LDO)
- Same SOIC-16 pinout across the LT1579 fixed-voltage family （对比 LT1579CS#PBF (adjustable sister part))
- Dual status flags plus secondary select pin （对比 Single-input LDOs without backup intelligence)
设计说明
Per the ADI LT1579 datasheet (1579f) place a 10 µF low-ESR ceramic capacitor on each input (IN1 and IN2) and a 10 µF low-ESR ceramic capacitor on OUT. The regulator is stable with pure ceramic output capacitance (no minimum ESR window), which simplifies BOM selection. Source impedance on each input must stay low so that during handover the input that just took over the load does not collapse below 5.4 V.
Estimated: at VIN=12 V, VOUT=5 V, IOUT=300 mA, the LT1579 dissipates approximately (12-5) × 0.300 = 2.1 W continuously. The 16-pin SOIC-N has a θJA of approximately 100 °C/W on a 1 oz 2-layer board (per typical JEDEC JESD51 data for similar SOIC-16 packages), giving a junction rise of about 210 °C above 25 °C ambient — well above the 85 °C commercial limit. Use a 4-layer PCB or substantial copper pour (≥1 sq inch) to drop θJA below 50 °C/W for safe operation, or move to the LT1579CS-5 higher-power version in a GN package if thermal headroom is tight.
Common pitfalls: (1) Forgetting that STAT1/STAT2 are open-drain and need pull-up resistors; (2) assuming the SHDN pin is active-low — it is active-high; (3) reversing IN1/IN2 priority and not checking that S2 state at power-up matches the system design intent; (4) relying on the LT1579 to block reverse current without observing the absolute maximum VIN rating of 20 V per input; (5) using the LT1579CS-5 as a low-dropout replacement for a single-input LDO without understanding its 50 µA quiescent baseline.
Use a single ground plane and route IN1/IN2 traces with wide copper (≥40 mil) to minimise parasitic inductance — a 1 nH spike at 300 mA gives only 0.3 mV, but during the millisecond switchover event the parasitic L on the disabled input can ring and confuse the comparator logic. Keep the trace from each STAT pin short to the MCU GPIO and add a 100 kΩ pull-up to VCC.
合规信息
Pb-free #PBF suffix confirms RoHS compliance per ADI product marking convention. The LT1579 is not AEC-Q100 qualified; the part is not marketed for automotive applications. Halogen-free status was not specified in the Verified Web Data and is therefore unknown.
