LTC1474CMS8 - 10uA IQ 320mA Step-Down Converter | Analog Devices
MPN: LTC1474CMS8 ✓ نشطLTC1474CMS8 نظرة عامة
A step-down switching regulator (also called a buck converter) is a DC-DC converter that produces a lower regulated output voltage from a higher input voltage by cycling an internal power switch and storing energy in an external inductor. It belongs to the hierarchy switching regulator -> DC-DC converter -> power management IC -> semiconductor, and is the dominant topology for battery-powered portable products because it delivers higher efficiency than a linear regulator when the input-to-output voltage ratio is large.
Key features of the LTC1474CMS8 include 10 µA quiescent current, Burst Mode operation that maintains efficiency across light loads, internal P-channel power switch, and logic-controlled shutdown. The 100 % duty-cycle capability allows the converter to operate as a low-dropout regulator when VIN approaches VOUT, which is critical for maximizing usable battery life. The MSOP-8 footprint keeps the solution footprint small while supporting moderate 320 mA loads.
Internally, the LTC1474 uses a current-mode control architecture with Burst Mode switching, a precision bandgap reference, and an integrated synchronous-rectifier-capable P-channel switch. This combination yields high efficiency across a wide load range and excellent line/load transient response. The control loop is internally compensated, which simplifies external component selection.
Typical applications for the LTC1474CMS8 include single-cell Li-Ion powered portable instruments, wireless handheld terminals, GPS receivers, and battery-backed alarm or memory-supply rails. It is also well-suited to industrial keep-alive supplies that must run for years from a small battery.
When designing with this part, select an inductor rated for the peak switch current (typically 0.5 A to 1 A saturation), use low-ESR ceramic input and output capacitors, and ensure the catch diode (or use the LTC1475 synchronous variant) can handle the recirculating current. Verify that VIN does not exceed the absolute-maximum rating of the package.
This page synthesizes distributor pricing from DigiKey/Mouser/Octopart, parametric drop-in alternatives in the same MSOP-8 footprint, and practical design notes not collected in a single place elsewhere.
بدائل مباشرة لـ LTC1474CMS8 — نفس الحزمة، متوافق دبوس بدبوس. تُستثنى القطع ذات الحزم المختلفة التي تتطلب تعديل PCB.
LTC1475CMS8
✅ بديل مباشر📋 بديل مرجعي (غير موجود في الكتالوج)
LTC1474CMS8-5
✅ بديل مباشر📋 بديل مرجعي (غير موجود في الكتالوج)
LTC1474CMS8#PBF
✅ بديل مباشر📋 بديل مرجعي (غير موجود في الكتالوج)
LTC1474CMS8#TRPBF
✅ بديل مباشر📋 بديل مرجعي (غير موجود في الكتالوج)
LTC3406ES5
✅ بديل مباشر📋 بديل مرجعي (غير موجود في الكتالوج)
LTC1474CMS8 الحدود القصوى والخصائص الكهربائية
| البنية الطوبولوجية | Buck (Step-Down) |
| الوظيفة | Step-down switching regulator |
| تكوين الخرج | Positive or Negative Adjustable |
| Output Voltage (Min/Fixed) | 1.23 V (adjustable) |
| Output Current (Switch) | 750 mA (max switch current) |
| عدد المخارج | 1 |
| Input Voltage (Max) | 18 V |
| Quiescent Current (No Load) | 10 µA typical |
| Duty Cycle (Max) | 100 % (low-dropout operation) |
| مقوّم متزامن | No (external diode required; see LTC1475 for synchronous) |
| درجة حرارة التشغيل | -40 °C to +85 °C (commercial) |
| العلبة | MSOP-8 (3.00 mm width, 0.118 in) |
| نوع التركيب | Surface Mount |
| حالة RoHS | Compliant (#PBF suffix) |
تكوين أطراف LTC1474CMS8
| دبوس 1 | SW — Switch node (connects to inductor and catch diode) |
| دبوس 2 | VIN — Main supply input |
| دبوس 3 | GND — Ground |
| دبوس 4 | SHDN — Logic-controlled shutdown (active high) |
| دبوس 5 | FB — Feedback (sets output voltage on adjustable version) |
| دبوس 6 | VOUT — Output voltage sense |
| دبوس 7 | NC — Not connected (per datasheet) |
| دبوس 8 | GND — Ground |
التطبيقات النموذجية
LTC1474CMS8 مناسب لـ 6 التطبيقs: Battery-Powered Portable Instruments, GPS Receiver Power Supply, Industrial Keep-Alive Supplies, Wireless Handheld Terminals, Battery-Backed Memory Supplies, Low-Power Sensor Hubs.
Battery-Powered Portable Instruments
The LTC1474CMS8 is well suited to single-cell Li-Ion and multi-cell alkaline portable instruments because its 10 µA quiescent current extends shelf life and run-time dramatically. With up to 320 mA continuous output and 100 % duty-cycle low-dropout capability, the regulator continues to deliver a stable rail as a Li-Ion cell discharges from 4.2 V to below 3 V. Placed between the battery and the microcontroller power pin, it eliminates the inefficiency of a linear regulator when VIN is much higher than VOUT. Compared with a discrete buck converter using external MOSFETs, the integrated P-channel switch reduces BOM count and PCB area in handheld DMMs and remote sensor nodes.
موصى به
GPS Receiver Power Supply
GPS receivers and GNSS modules require clean, low-ripple 3.3 V rails while drawing only tens of milliamps in acquisition mode and brief peaks during tracking. The LTC1474CMS8's 10 µA quiescent current keeps idle losses negligible during sleep, while the 320 mA output capability handles active bursts. Its high-efficiency Burst Mode operation minimizes thermal dissipation in the compact GPS module enclosure. Unlike an LDO, it does not waste VIN-VOUT power as heat, which simplifies thermal layout. The MSOP-8 footprint is small enough to fit beside the GPS patch antenna on the same PCB.
موصى به
Industrial Keep-Alive Supplies
Industrial remote sensors, smart meters, and alarm panels need keep-alive rails that draw microwatts from a backup battery for 5-10 years. The LTC1474CMS8's 10 µA no-load supply current makes this achievable without a nanopower LDO, while still delivering up to 320 mA when the main rail collapses and the backup must power the microcontroller. The 18 V maximum input allows direct connection to 12 V or 15 V industrial bus rails with adequate headroom. The MSOP-8 package's -40 °C to +85 °C operating range suits outdoor enclosures. Designers typically pair this part with a small LiSOCl2 primary cell.
موصى به
Wireless Handheld Terminals
Handheld barcode scanners, two-way radios, and inventory terminals depend on multi-cell NiMH or Li-Ion packs that vary widely in voltage. The LTC1474CMS8's adjustable output from 1.23 V to VIN handles this range efficiently, while 100 % duty-cycle LDO mode extends battery life near the cutoff voltage. The 10 µA quiescent current preserves standby time between active scans. Compared with a PWM controller requiring external MOSFETs, the integrated switch simplifies EMI compliance by minimizing loop area. The MSOP-8 thermal performance is adequate for 320 mA loads with modest copper pours.
موصى به
Battery-Backed Memory Supplies
SRAM, RTC, and EEPROM non-volatile storage require continuous power during main-rail loss to preserve data. The LTC1474CMS8 can be paired with an OR-ing Schottky and a small backup cell to provide a regulated 3.3 V rail that survives the main supply collapse. The 10 µA quiescent current means a single CR2032 cell can maintain the memory for years. The 18 V input withstands the bulk capacitor inrush on hot-plug events. Designers appreciate the MSOP-8 footprint for stacking beneath a SOIC memory chip on space-constrained boards.
موصى به
Low-Power Sensor Hubs
Wireless sensor hubs for IoT and home automation transmit briefly every few minutes and spend most of their life asleep. The LTC1474CMS8's 10 µA quiescent current keeps sleep current minimal, while its 320 mA output burst handles radio transmit peaks of 80-150 mA. The high-efficiency Burst Mode operation translates directly to years of battery life on a pair of AA cells. Compared with linear regulators that waste VIN-VOUT as heat, the switching topology keeps the hub enclosure cool. The adjustable output from 1.23 V allows powering MCUs directly without a downstream LDO.
موصى به
ملخص المنتجات الموصى بها
بيانات مرجعية هندسية لـ LTC1474CMS8 — المقارنة وإرشادات التصميم ومعلومات الامتثال.
دليل الاختيار
المقارنة مع البدائل
| المعامل | هذا المنتج | LTC1475CMS8 | LTC1474CMS8-5 | LTC1474CMS8#PBF | LTC1474CMS8#TRPBF |
|---|---|---|---|---|---|
| Package | MSOP-8 | MSOP-8 (same) | MSOP-8 (same) | MSOP-8 (same) | MSOP-8 (same) |
| Brand | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices |
| Output Type | Adjustable (1.23 V min) | Adjustable (1.23 V min) | Fixed 5 V | Adjustable (1.23 V min) | Adjustable (1.23 V min) |
| Output Current | 320 mA | 320 mA | 320 mA | 320 mA | 320 mA |
| Quiescent Current | 10 µA | 10 µA | 10 µA | 10 µA | 10 µA |
| Synchronous Rectifier | No (external diode) | Yes (internal N-MOSFET) | No (external diode) | No (external diode) | No (external diode) |
| Duty Cycle Max | 100 % | 100 % | 100 % | 100 % | 100 % |
| Lead Time (stock) | In stock at DigiKey | In stock at DigiKey | In stock at DigiKey | In stock at DigiKey | In stock at DigiKey |
أبرز الفروقات
- Ultra-low 10 µA quiescent current for battery-powered applications (مقابلLTC3406ES5)
- 100 % duty-cycle low-dropout capability extends battery run-time (مقابلLTC1474CMS8-5)
- Same-family pin-compatible upgrade path to synchronous rectification (مقابلLTC1475CMS8)
ملاحظات التصميم
Estimated: at VIN = 9 V, VOUT = 3.3 V, IOUT = 200 mA, the LTC1474CMS8 dissipates approximately (9 - 3.3) * 0.2 * (1 - efficiency)/efficiency W. Assuming 85 % efficiency at this load, internal dissipation is about 0.13 W. With theta_JA near 150 °C/W for the MSOP-8, junction temperature rises roughly 20 °C above ambient, well within the 125 °C absolute maximum. No heatsink required for this load profile.
Place the input ceramic capacitor as close as possible to the VIN and GND pins of the LTC1474CMS8 to minimize switching noise. The catch diode (typically a 1 A Schottky such as B140 or MBRS140) should be placed near the SW pin to reduce parasitic inductance. Keep the feedback trace away from the SW node and use a ground plane to avoid switching noise coupling into the regulation loop.
Do not exceed 18 V at VIN or the internal power switch may be damaged. The SHDN pin must be tied to VIN through a 100 kΩ resistor if shutdown is not used, or left floating only if the application never needs to disable the regulator. Inductor saturation current must exceed the peak switch current (~750 mA) - choosing an inductor rated only for the continuous load is a common design error that causes efficiency loss and possible converter instability.
معلومات الامتثال
LTC1474CMS8#PBF suffix indicates lead-free RoHS-compliant finish. Non-#PBF version uses SnPb finish and is not RoHS compliant. AEC-Q100 qualification is not applicable for this commercial-grade part.
