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Analog Devices Inc. LTC1771EMS8#PBF
- Part No.:
- LTC1771EMS8#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
- Datasheet:
-
LTC1771EMS8#PBF.pdf
- Description:
- IC REG CTRLR BUCK 8MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:238
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Product details
Overview
LTC1771EMS8#PBF from Analog Devices (formerly Linear Technology) is a high-efficiency, current-mode step-down DC/DC controller driving an external P-channel MOSFET. It delivers up to 5A output current with 10µA no-load quiescent current, ±2% output voltage accuracy over 1.23V–18V range, and supports 2.8V–20V input operation - ideal for battery-powered portable instrumentation requiring ultra-low standby power.
For engineers reviewing the LTC1771EMS8#PBF datasheet, LTC1771EMS8#PBF pinout, LTC1771EMS8#PBF application, or LTC1771EMS8#PBF equivalent, key selection criteria include its constant off-time architecture, 3.5µs minimum off-time, Burst Mode enable/disable via MODE pin, 1.23V internal reference, and MSOP-8 package compatibility with space-constrained PCB layouts.
Technical Context
The LTC1771EMS8#PBF implements a constant off-time, current-mode control architecture with a 3.5µs nominal off-time that extends to 70µs under low-VFB conditions - enabling robust short-circuit protection and stable operation down to 100% duty cycle. Its error amplifier output (ITH pin) directly programs peak inductor current, while the 1.23V reference (VFB pin) sets output voltage via external resistor divider.
Burst Mode operation - enabled by pulling MODE ≥2V - reduces no-load supply current to 9µA by entering sleep mode when load falls below ~25% of full scale; disabling Burst Mode (MODE = GND) eliminates switching noise at light loads but degrades light-load efficiency. The RUN/SS pin provides both soft-start ramping (via external capacitor) and shutdown control (≤0.5V).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VIN Range | 2.8V to 20V - supports single-to-4-cell Li-ion batteries and wide industrial input rails without external regulators. |
| VOUT Range | 1.23V to 18V - programmable via resistive divider; 1.23V internal reference enables precise regulation across full range. |
| IOUT Max | Up to 5A - determined by external P-MOSFET and RSENSE; peak current sensing allows scalable current capability. |
| IQ (No Load) | 10µA - enables multi-week battery life in always-on portable devices; drops to 2µA in shutdown mode. |
| Efficiency | Over 93% - achievable at mid-load (e.g., 1A @ VIN=10V, VOUT=3.3V); Burst Mode maintains >80% efficiency down to 1mA. |
| Accuracy | ±2% output voltage - includes line, load, and temperature variation; ensures stable system-level voltage margins. |
| Off-Time | 3.5µs (typ), up to 70µs - dynamically lengthens during overload/short-circuit to prevent MOSFET saturation and ensure safe current decay. |
Pinout & Package
Package: 8-Lead MSOP (MS8), 3mm × 3mm, 0.65mm pitch, exposed pad (thermal enhancement). RoHS-compliant, lead-free (Pb-free) finish.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| RUN/SS (1) | Run Enable / Soft-Start Input | Pull ≤0.5V to shut down (IQ = 2µA); connect capacitor for controlled IOUT ramp-up; internal 1µA current source charges CSS. |
| ITH (2) | Error Amplifier Output / Current Limit Control | Voltage sets peak inductor current; clamped at ~40% max during soft-start; used for foldback limiting with external diodes. |
| VFB (3) | Feedback Input | Compares divided VOUT against 1.23V reference; 1nA input bias enables high-resistor-divider networks to minimize IQ. |
| GND (4) | Analog & Power Ground | Common return for feedback, error amp, and internal logic; requires low-impedance connection to minimize noise coupling. |
| PGATE (5) | P-Channel MOSFET Gate Driver | High-current (1A peak) driver swinging from GND to VIN; optimized for fast turn-on/turn-off (70ns tr/tf) to reduce switching losses. |
| VIN (6) | Main Input Supply | Power source for internal circuitry and PGATE driver; accepts 2.8V–20V; absolute max 20V. |
| SENSE (7) | Current Sense Input | Monitors voltage drop across external RSENSE; threshold adjustable from 110mV to 180mV; sets maximum switch current and Burst Mode entry point. |
| MODE (8) | Burst Mode Control | ≥2V enables Burst Mode (low IQ, higher ripple); GND disables it (continuous switching, lower noise, reduced light-load efficiency). |
Key Features
| Feature | Design Value |
|---|---|
| Constant Off-Time Architecture | 3.5µs fixed off-time ensures predictable frequency scaling with input/output ratio; simplifies EMI filtering and loop compensation. |
| Defeatable Burst Mode | Reduces no-load IQ to 9µA while maintaining regulation; disable via MODE pin for noise-sensitive applications like audio or RF subsystems. |
| 100% Duty Cycle Operation | Enables ultra-low dropout - VOUT can approach VIN - critical for Li-ion end-of-discharge support (e.g., 3.0V → 2.8V output). |
| Short-Circuit Protection | Automatic current limiting via SENSE pin; off-time extension to 70µs prevents MOSFET thermal runaway during sustained faults. |
| Programmable Soft-Start | RUN/SS pin accepts external capacitor (e.g., 0.01µF) to linearly ramp ITH from 40% to 100% of max current over ~10ms - eliminating inrush surge. |
Applications
| Portable Medical Monitors | Handheld Test Equipment |
|---|---|
|
Use Scenario: Battery-powered ECG or pulse oximeter operating continuously on 2-cell Li-ion (6.4V–8.4V), requiring stable 3.3V rail for MCU and analog front-end with <10µA standby drain. IC Role / Device Role / Timing Role: Step-down controller managing power conversion from battery to regulated 3.3V; operates in Burst Mode during sensor sleep cycles to extend runtime. Use Value: 10µA no-load IQ and 2µA shutdown enable >3-month battery life in standby; 1.23V reference ensures ±2% VOUT stability across temperature for accurate ADC readings. |
Use Scenario: Portable oscilloscope or multimeter powered by 3-cell Li-ion (9V–12.6V), needing clean 5V and 3.3V rails for FPGA, display, and precision references. IC Role / Device Role / Timing Role: Primary buck controller for main 5V rail; configured with disabled Burst Mode to avoid audible switching noise near sensitive analog inputs. Use Value: Continuous-mode operation eliminates low-frequency ripple; ±2% output accuracy and 93% peak efficiency maintain tight voltage margins under dynamic load changes. |
| Wireless Modem Modules | Lithium-Ion Battery Chargers |
|
Use Scenario: Cellular or LoRaWAN modem module in asset tracker, drawing bursty 500mA peaks but averaging <10mA; powered by 3.7V Li-ion cell. IC Role / Device Role / Timing Role: High-efficiency buck controller supplying 3.3V to modem IC; leverages Burst Mode to sustain >2-year battery life in low-duty-cycle deployments. Use Value: >80% efficiency at 1mA load (Burst Mode active) and 100% duty cycle capability allow operation down to 3.0V battery voltage without brownout. |
Use Scenario: Standalone Li-ion charger IC (e.g., LTC4054) powered from USB 5V or wall adapter; requires regulated 3.3V for charger management logic and status LEDs. IC Role / Device Role / Timing Role: Secondary buck regulator providing isolated, low-noise 3.3V supply independent of main charging path; uses MODE = GND for quiet operation. Use Value: 2.8V–20V input range accommodates both 5V USB and 12V adapters; 10µA IQ minimizes parasitic drain when charger is idle but powered. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT8610EMS8E#PBF | Integrated synchronous buck regulator (no external MOSFET required); 2.5µA IQ; 3.4V–42V input; fixed 3.3V/5V options only. | Eliminates external MOSFET and sense resistor; better for compact designs where 3.3V/5V fixed outputs suffice. | Choose LT8610EMS8E#PBF if board space is critical and fixed output voltage is acceptable; LTC1771EMS8#PBF retains flexibility for custom VOUT and higher current scaling. |
| TPS54202DRCT | Integrated 2A synchronous buck converter; 26µA IQ; 4.5V–28V input; adjustable VOUT via resistor divider; no Burst Mode. | Lower max current (2A vs 5A); lacks Burst Mode - less suitable for ultra-low-power battery apps. | Select TPS54202DRCT for cost-sensitive, medium-current applications where 26µA IQ is sufficient and continuous-mode noise is not prohibitive. |
Compared with LT8610EMS8E#PBF and TPS54202DRCT, the LTC1771EMS8#PBF uniquely combines external MOSFET scalability (up to 5A), 10µA no-load current, programmable Burst Mode, and 2.8V–20V input - making it optimal for high-flexibility, ultra-low-power portable systems requiring custom output voltages and extended battery life.
Availability
LTC1771EMS8#PBF is available at Aetrix Electronics and suitable for portable instrumentation, wireless modems, battery-powered medical devices, and handheld test equipment requiring stable component supply with long-term lifecycle assurance.
Supply support for LTC1771EMS8#PBF includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Analog Devices acquired Linear Technology in 2017 and maintains full product support, documentation, and manufacturing continuity for all Linear parts including the LTC1771 series.
The LTC1771 belongs to Linear's high-efficiency DC/DC controller family designed specifically for battery-powered portable applications demanding ultralow quiescent current, wide input range, and flexible external component integration.
FAQ
What is the minimum input voltage supported by the LTC1771EMS8#PBF?
The LTC1771EMS8#PBF supports a minimum input voltage of 2.8V, enabling reliable operation down to the end-of-discharge voltage of a single Li-ion cell. This 2.8V minimum - combined with 100% duty cycle capability - ensures uninterrupted regulation even as battery voltage declines, making the LTC1771EMS8#PBF well-suited for deep-discharge portable applications.
How does the MODE pin affect efficiency and noise performance of the LTC1771EMS8#PBF?
The MODE pin on the LTC1771EMS8#PBF directly controls Burst Mode operation: pulling it ≥2V enables Burst Mode (reducing no-load IQ to 9µA but introducing low-frequency ripple), while grounding it disables Burst Mode for continuous switching (lower noise, higher light-load ripple, and reduced efficiency below ~100mA). This dual-mode capability lets designers optimize the LTC1771EMS8#PBF for either battery life or EMI-sensitive environments.
Can the LTC1771EMS8#PBF be used with a P-channel MOSFET having VGS(th) > 2.5V?
No - the LTC1771EMS8#PBF requires a sublogic-level P-channel MOSFET with guaranteed RDS(ON) at VGS = 2.5V or lower, because it must operate reliably down to VIN = 2.8V. A MOSFET with VGS(th) > 2.5V may fail to fully enhance at low input voltages, causing excessive conduction loss or startup failure. The LTC1771EMS8#PBF datasheet explicitly recommends sublogic-level devices for this reason.
What is the purpose of the SENSE pin on the LTC1771EMS8#PBF, and how is it configured?
The SENSE pin on the LTC1771EMS8#PBF monitors voltage across an external current-sense resistor (RSENSE) connected between VIN and the MOSFET source. It sets both peak switch current (for overcurrent protection) and the Burst Mode entry threshold. RSENSE is calculated as ≈100mV/IMAX; typical values range from 0.02Ω to 0.1Ω. The LTC1771EMS8#PBF senses thresholds from 110mV to 180mV, allowing precise, scalable current limiting.
Does the LTC1771EMS8#PBF require an external compensation network, and where is it connected?
Yes - the LTC1771EMS8#PBF uses OPTI-LOOP™ compensation connected to the ITH pin (Pin 2). A series RC network (e.g., 10kΩ + 1nF) from ITH to GND stabilizes the current-mode loop and optimizes transient response. Unlike voltage-mode controllers, this network directly shapes the error amplifier output driving the current comparator, and its values depend on selected inductor, output capacitor, and load characteristics per the LTC1771EMS8#PBF datasheet guidelines.
LTC1771EMS8#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- Output Type:
- Transistor Driver
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Number of Outputs:
- 1
- Output Phases:
- 1
- Voltage - Supply (Vcc/Vdd):
- 2.8V ~ 18V
- Frequency - Switching:
- -
- Duty Cycle (Max):
- 100%
- Synchronous Rectifier:
- No
- Clock Sync:
- No
- Serial Interfaces:
- -
- Control Features:
- Enable, Soft Start
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-MSOP
LTC1771EMS8#PBF FAQ
1.How can I place an order for LTC1771EMS8#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1771EMS8#PBF on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for LTC1771EMS8#PBF reliable?
The price and inventory of LTC1771EMS8#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1771EMS8#PBF is usually 5 days.
3.What payment methods are accepted for LTC1771EMS8#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1771EMS8#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1771EMS8#PBF?
LTC1771EMS8#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1771EMS8#PBF order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for LTC1771EMS8#PBF?
For technical support, including LTC1771EMS8#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1771EMS8#PBF requirements.
6.How does Aetrix verify that LTC1771EMS8#PBF is sourced from the original manufacturer or authorized distributors?
All LTC1771EMS8#PBF products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that LTC1771EMS8#PBF meets industry standards.
7.What is the process for return or replacement of LTC1771EMS8#PBF?
All LTC1771EMS8#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1771EMS8#PBF, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The LTC1771EMS8#PBF part is unused and in its original packaging.
Return procedure for LTC1771EMS8#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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