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Analog Devices Inc. LTC1773EMS#PBF
- Part No.:
- LTC1773EMS#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width)
- Datasheet:
-
LTC1773EMS#PBF.pdf
- Description:
- IC REG CTRLR BUCK 10MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:485
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Product details
Overview
LTC1773EMS#PBF from Analog Devices (formerly Linear Technology) is a current-mode synchronous buck DC/DC controller IC that drives external complementary P- and N-channel MOSFETs in fixed-frequency step-down converters. It operates from 2.65V to 8.5V input, delivers output voltages from 0.8V to VIN, features 550kHz internal switching frequency, ±1.5% reference accuracy, and supports Burst Mode operation for high light-load efficiency - ideal for single/dual-cell Li-ion portable power systems.
For engineers reviewing the LTC1773EMS#PBF datasheet, LTC1773EMS#PBF pinout, LTC1773EMS#PBF application, or LTC1773EMS#PBF equivalent, key selection considerations include its 10-lead MSOP package, OPTI-LOOP® compensation architecture, SYNC/FCB multifunction pin for secondary winding regulation or synchronization up to 750kHz, and confirmed 100% duty-cycle low-dropout capability in battery-depletion scenarios.
Technical Context
The LTC1773EMS#PBF implements a constant-frequency current-mode control loop with an internal 550kHz oscillator, peak-current sensing via external RSENSE, and error amplifier output at the ITH pin to modulate switch conduction. Its architecture includes slope compensation above 30% duty cycle and anti-shoot-through logic to prevent cross-conduction between top and bottom MOSFETs.
It integrates precision undervoltage lockout (2.5V threshold), soft-start via RUN/SS pin with 1.5µA current source, and dual-mode operation: forced continuous mode (SYNC/FCB grounded) or Burst Mode (SYNC/FCB floating or high). The SYNC/FCB pin also serves as auxiliary feedback input for flyback secondary winding regulation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.65V to 8.5V - enables direct use with 1–2 cell Li-ion batteries without pre-regulation. |
| Output Voltage Range | 0.8V to VIN - supports wide VOUT programmability via resistive divider on VFB pin. |
| Switching Frequency | 550kHz (typical), synchronizable to 585–750kHz - allows small inductor sizing and EMI control. |
| Reference Voltage Accuracy | ±1.5% at VFB = 0.8V - ensures tight output voltage regulation across line/load/temperature. |
| Quiescent Current (Burst Mode) | 80µA - extends battery runtime in standby or ultra-light-load conditions. |
| Shutdown Current | 10µA max - prevents deep discharge of Li-ion cells during system sleep. |
| Duty Cycle Capability | 100% - maintains regulation down to VIN ≈ VOUT + ILOAD × RDS(ON)_P + ILOAD × RSENSE. |
| UVLO Threshold | 2.5V (typical), 150mV hysteresis - provides clean startup/shutdown for lithium battery protection. |
Pinout & Package
Package: 10-lead MSOP (3mm × 3mm, 0.5mm pitch), RoHS-compliant, moisture-sensitive level 1.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| ITH (1) | Error amplifier output / current limit control | Voltage sets peak inductor current threshold; clamped during soft-start; range 0–1.2V (up to 2.4V near current limit). |
| RUN/SS (2) | Soft-start timing & enable/disable control | Internal 1.5µA current source charges external capacitor; <0.4V forces shutdown; 0.7V enables operation. |
| SYNC/FCB (3) | Multifunction: sync input / FCB feedback / Burst Mode select | 0.8V threshold determines Burst vs continuous mode; also accepts secondary winding feedback for isolated outputs. |
| VFB (4) | Feedback input for output voltage regulation | Compares resistive-divider voltage against 0.8V reference; max 0.01µF feedforward capacitance allowed. |
| GND (5) | Analog and power ground reference | Common return for internal circuitry, gate drivers, and current sense; must be low-impedance connection. |
| BG (6) | Bottom gate driver output | Drives N-channel MOSFET source-to-drain; swings 0V to VIN; designed for fast rise/fall (80/45ns typ). |
| TG (7) | Top gate driver output | Drives P-channel MOSFET source-to-drain; swings 0V to VIN; optimized for 45/48ns rise/fall times. |
| VIN (8) | Main supply input | Powers internal circuitry and gate drivers; requires local low-ESR decoupling to GND (Pin 5). |
| SENSE– (9) | Negative current sense input | Connects to source of external P-MOSFET; senses voltage drop across RSENSE to set peak current limit (max 100mV). |
| SW (10) | Switch node connection | Connects to inductor and drains of both external MOSFETs; carries high dv/dt; requires careful layout for EMI control. |
Key Features
| Feature | Design Value |
|---|---|
| OPTI-LOOP® Compensation | Minimizes required output capacitance by optimizing phase margin across wide COUT ESR ranges - reduces BOM count and board area. |
| Burst Mode® Operation | Reduces quiescent current to 80µA at light loads while maintaining regulation - extends battery life without sacrificing transient response. |
| Synchronization Capability | Accepts external TTL/CMOS clock (585–750kHz) to align switching frequency - eliminates beat frequencies and eases EMI filtering. |
| Secondary Winding Regulation | SYNC/FCB pin functions as auxiliary feedback input - enables precise regulation of isolated flyback secondaries without optocoupler. |
| 100% Duty Cycle Low-Dropout | Continues regulation as VIN approaches VOUT - maximizes usable battery capacity in portable systems. |
| Integrated UVLO with Hysteresis | 2.5V turn-on threshold with 150mV hysteresis - prevents oscillatory startup/shutdown during battery voltage sag. |
Applications
| Cellular Telephones | RF PA Supplies |
|---|---|
Use Scenario: Powering baseband processor and RF transceiver subsystems in 3G/4G smartphones operating from single Li-ion cell. IC Role / Device Role / Timing Role: Synchronous buck controller regulating 1.2V core and 2.8V RF bias rails with fast load transient response. Use Value: Burst Mode extends talk time by >25% at standby; 100% duty cycle sustains operation until battery reaches 2.8V. | Use Scenario: Generating stable, low-noise 3.3V or 5V supply for high-efficiency RF power amplifiers in wireless infrastructure and handset front-ends. IC Role / Device Role / Timing Role: Fixed-frequency current-mode controller driving discrete MOSFETs with synchronized switching to avoid interference with RF bands. Use Value: 550kHz operation enables compact LC filter design; SYNC input allows alignment with system clock to suppress conducted EMI. |
| Notebook Computers | Distributed Power Systems |
Use Scenario: Providing 1.5V CPU core voltage and 1.8V memory rail in ultraportable notebooks powered by dual-cell Li-ion packs. IC Role / Device Role / Timing Role: Primary buck controller managing high-current, dynamically scaled outputs with precise remote sensing. Use Value: ±1.5% reference accuracy ensures compliance with Intel VR12/VR13 specifications; OPTI-LOOP accommodates polymer capacitor aging. | Use Scenario: Regulating intermediate bus voltages (e.g., 5V or 3.3V) in modular telecom or industrial systems with multiple point-of-load converters. IC Role / Device Role / Timing Role: Centralized synchronous buck controller enabling coordinated power sequencing and fault reporting via RUN/SS and SYNC/FCB pins. Use Value: Soft-start ramping prevents inrush into downstream POLs; SYNC input allows system-wide clock domain alignment. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous buck controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3850EMS#PBF | Higher VIN range (4–36V), adjustable frequency (50kHz–900kHz), no integrated UVLO hysteresis - requires external components for Li-ion compatibility. | Targeted at industrial/high-VIN applications; lacks native 2.65V start-up and Burst Mode optimization for sub-3V battery operation. | Select only if input exceeds 4V and higher voltage tolerance is required; not drop-in for Li-ion battery systems. |
| TPS40210DGQ | Current-mode controller with 500kHz fixed frequency, but no Burst Mode, no 100% duty cycle, and no SYNC/FCB multifunction pin - limited light-load efficiency and secondary regulation capability. | Designed for general-purpose DC/DC conversion where cost is prioritized over battery runtime or isolated auxiliary outputs. | Choose when secondary winding regulation is unnecessary and quiescent current <100µA is not critical. |
Compared with LTC1773EMS#PBF, LTC3850EMS#PBF supports wider input ranges but sacrifices Li-ion-specific features like low-VIN start-up and Burst Mode efficiency; TPS40210DGQ offers lower cost but lacks the multifunction SYNC/FCB pin and 100% dropout capability essential for portable battery systems.
Availability
LTC1773EMS#PBF is available at Aetrix Electronics and suitable for cellular telephones, notebook computers, and distributed power systems requiring stable component supply, long-term lifecycle support, and guaranteed RoHS-compliant sourcing.
Supply support for LTC1773EMS#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 technical and manufacturing continuity for all Linear power products.
The LTC1773EMS#PBF belongs to Linear's high-efficiency synchronous buck controller product line, engineered specifically for battery-powered portable electronics requiring extended runtime, precise regulation, and robust transient performance under dynamic load conditions.
FAQ
What is the minimum input voltage required for LTC1773EMS#PBF to start switching?
The LTC1773EMS#PBF features a precision undervoltage lockout with a typical turn-on threshold of 2.65V when ramping up from 0V. Below this voltage, the device remains in shutdown with <30µA current draw. Stable operation begins once VIN exceeds 2.65V, and the RUN/SS pin voltage reaches 0.7V to initiate soft-start. This makes LTC1773EMS#PBF suitable for single-cell Li-ion batteries down to end-of-discharge voltage.
How does the SYNC/FCB pin function in secondary winding regulation for flyback topologies?
In flyback configurations, the SYNC/FCB pin serves as an auxiliary feedback input referenced to ground. When the secondary winding voltage, divided down to match the 0.8V internal reference, falls below the 0.76–0.84V threshold, the LTC1773EMS#PBF forces continuous conduction mode to maintain regulation - eliminating the need for optocouplers or TL431-based feedback networks. This functionality is unique to LTC1773EMS#PBF among its class and directly supported in the datasheet's Applications Information section.
Can LTC1773EMS#PBF operate with 100% duty cycle, and what limits its dropout performance?
Yes, LTC1773EMS#PBF supports true 100% duty cycle operation, allowing VOUT regulation even when VIN drops to within ~100mV of VOUT. Dropout performance is limited by the sum of IR drops across the external P-channel MOSFET's RDS(ON), the current-sense resistor RSENSE, and the inductor DCR. For example, with RSENSE = 0.025Ω and 2A load, dropout adds ~50mV; total dropout is typically <200mV in well-designed layouts using low-RDS(ON) MOSFETs.
What is the purpose of the ITH pin, and how does it interact with OPTI-LOOP® compensation?
ITH is the error amplifier output and primary current limit control node. In OPTI-LOOP® configuration, external RC networks on ITH shape the loop gain to maintain stability across varying output capacitor ESR and capacitance - unlike conventional Type-II/III compensation. This allows designers to use low-ESR ceramic or polymer capacitors without risking oscillation. The LTC1773EMS#PBF's ITH pin directly controls peak inductor current and is clamped during soft-start to ensure controlled current ramp-up.
Does LTC1773EMS#PBF require external Schottky diodes when used with synchronous rectification?
No, LTC1773EMS#PBF is designed for fully synchronous operation using external N-channel and P-channel MOSFETs - eliminating the need for a Schottky diode. However, a 1A Schottky diode may be placed in parallel with the bottom N-MOSFET to conduct during dead-time and prevent body diode conduction, recovering ~1% efficiency in high-frequency, high-current designs. This is optional and not required for basic operation of LTC1773EMS#PBF.
LTC1773EMS#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 10-TFSOP, 10-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):
- 2.65V ~ 8.5V
- Frequency - Switching:
- 550kHz
- Duty Cycle (Max):
- 100%
- Synchronous Rectifier:
- Yes
- Clock Sync:
- Yes
- Serial Interfaces:
- -
- Control Features:
- Enable, Soft Start
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 10-MSOP
LTC1773EMS#PBF FAQ
1.How can I place an order for LTC1773EMS#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1773EMS#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 LTC1773EMS#PBF reliable?
The price and inventory of LTC1773EMS#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1773EMS#PBF is usually 5 days.
3.What payment methods are accepted for LTC1773EMS#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1773EMS#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1773EMS#PBF?
LTC1773EMS#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1773EMS#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 LTC1773EMS#PBF?
For technical support, including LTC1773EMS#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1773EMS#PBF requirements.
6.How does Aetrix verify that LTC1773EMS#PBF is sourced from the original manufacturer or authorized distributors?
All LTC1773EMS#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 LTC1773EMS#PBF meets industry standards.
7.What is the process for return or replacement of LTC1773EMS#PBF?
All LTC1773EMS#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1773EMS#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 LTC1773EMS#PBF part is unused and in its original packaging.
Return procedure for LTC1773EMS#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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