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Analog Devices Inc. LTC1627CS8#PBF
- Part No.:
- LTC1627CS8#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LTC1627CS8#PBF.pdf
- Description:
- IC REG BUCK ADJ 500MA 8SO
- Quantity:
- Payment:
- Shipping:
Inventory:651
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Product details
Overview
LTC1627CS8#PBF from Analog Devices (formerly Linear Technology) is a monolithic synchronous step-down DC/DC regulator IC with fixed-frequency current-mode control. It operates from 2.65V to 8.5V input, delivers up to 500mA output at adjustable voltage (0.8V–VIN), and achieves up to 96% efficiency in Burst Mode for lithium-ion battery-powered portable instruments and wireless modems.
For engineers reviewing the LTC1627CS8#PBF datasheet, LTC1627CS8#PBF pinout, LTC1627CS8#PBF application, or LTC1627CS8#PBF equivalent, key selection criteria include its 350kHz internal oscillator, 100% duty-cycle dropout capability, ±1.5% reference accuracy, SYNC/FCB multifunction pin for secondary winding regulation or external synchronization up to 525kHz, and SO-8 package compatibility with space-constrained PCB layouts.
Technical Context
The LTC1627CS8#PBF implements a constant-frequency current-mode buck architecture with integrated P-channel high-side and N-channel low-side MOSFETs. Its error amplifier drives the ITH pin to regulate peak inductor current, while slope compensation prevents subharmonic oscillation above 40% duty cycle.
Control logic includes undervoltage lockout (2.5V threshold), soft-start via RUN/SS pin (2.25µA current source), burst mode activation via floating or high-biased SYNC/FCB, and forced continuous operation when SYNC/FCB is grounded - enabling precise auxiliary winding regulation independent of main output load.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.65V to 8.5V - supports single/dual Li-ion battery operation without external LDO pre-regulation. |
| Output Voltage Range | 0.8V to VIN - programmable via external resistor divider; enables 3.3V, 2.5V, or 1.8V rails from common input. |
| Max Output Current | 500mA - sustained under thermal limits with SO-8 package and typical PCB copper area. |
| Switching Frequency | 350kHz (internal) or 385–525kHz (externally synchronized) - balances inductor size, EMI, and efficiency trade-offs. |
| Reference Voltage | 0.800V ±1.5% - sets output accuracy; used directly by VFB feedback loop for tight regulation. |
| Quiescent Current | 200µA (Burst Mode), 15µA (shutdown) - extends battery runtime in standby and sleep states. |
| Duty Cycle Limit | 100% - maintains regulation during input voltage sag near VOUT, critical for battery end-of-discharge. |
| UVLO Threshold | 2.50V ±0.15V - precision undervoltage lockout prevents deep discharge of Li-ion cells. |
Pinout & Package
Package: 8-lead plastic SO (SO-8), surface-mount, JEDEC MS-012AC compliant, θJA = 110°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SYNC/FCB (Pin 8) | Multifunction analog input | Enables secondary winding regulation (0.8V threshold), external clock sync (385–525kHz), or Burst/continuous mode select (float/high = Burst, GND = forced continuous). |
| VDR (Pin 7) | Top driver return | Allows bootstrapping below GND to reduce RDS(ON) of P-FET at low VIN (<4.5V); improves efficiency in single-cell Li-ion applications. |
| VIN (Pin 6) | Main power supply input | Accepts 2.65–8.5V; requires local 22µF/16V ceramic or low-ESR capacitor for high-frequency decoupling. |
| SW (Pin 5) | Switch node | Connects to inductor; carries high di/dt square-wave current; must be routed with minimal loop area to reduce EMI. |
| ITH (Pin 1) | Error amplifier output | Controls peak inductor current; voltage range 0–1.2V; used for compensation and current limiting. |
| RUN/SS (Pin 2) | Soft-start and shutdown control | 2.25µA current source charges external capacitor; <0.4V forces shutdown (15µA IQ); 0.7V triggers startup. |
| VFB (Pin 3) | Feedback input | Monitors resistive divider output; regulates VOUT to 0.800V reference; ±1.5% accuracy over temperature. |
| GND (Pin 4) | Power and signal ground | Common return for all internal circuits; must be connected to low-impedance PCB ground plane. |
Key Features
| Feature | Design Value |
|---|---|
| Synchronous rectification | Eliminates external Schottky diode - reduces component count, board space, and conduction losses by replacing diode drop with low-RDS(ON) FETs. |
| Burst Mode operation | Reduces quiescent current to 200µA at light loads - extends battery life in portable devices with intermittent active periods. |
| 100% duty-cycle dropout | Maintains regulation as VIN approaches VOUT - avoids system reset during battery voltage decay in handheld equipment. |
| Secondary winding regulation | Uses SYNC/FCB pin to force continuous conduction - enables stable auxiliary outputs (e.g., bias rails) without loading main output. |
| Internal current-mode control | Provides inherent line/load transient immunity - eliminates need for external compensation components in most designs. |
| Low-noise synchronization | Accepts external TTL/CMOS clock up to 525kHz - allows EMI reduction by aligning switching frequency with system noise margins. |
Applications
| Cellular Telephones | Portable Instruments |
|---|---|
Use Scenario: Power management in GSM/UMTS handsets requiring dual regulated rails (e.g., 3.3V core, 2.8V RF) from single Li-ion cell. IC Role / Device Role / Timing Role: Primary step-down regulator delivering 500mA at 3.3V with Burst Mode for standby efficiency and 100% duty cycle for end-of-life battery support. Use Value: Enables >96% peak efficiency and 200µA quiescent current - directly extends talk time and standby duration per charge cycle. | Use Scenario: Battery-powered handheld multimeters and oscilloscopes needing clean, stable 2.5V analog reference and 3.3V digital rail. IC Role / Device Role / Timing Role: Synchronous buck converter supplying precision analog subsystems with low ripple and minimal load-transient deviation. Use Value: ±1.5% reference accuracy and current-mode control ensure <20mV load-step deviation - preserves measurement fidelity across operating conditions. |
| Wireless Modems | RF Communications |
Use Scenario: Compact LTE/Wi-Fi modules where PCB area is constrained and thermal dissipation must be minimized. IC Role / Device Role / Timing Role: High-efficiency DC/DC converter operating at 350kHz to allow use of 15µH shielded inductors and compact 100µF output capacitors. Use Value: SO-8 footprint and integrated FETs reduce BOM count by ≥3 components - accelerates layout and lowers assembly cost. | Use Scenario: Low-power transceivers requiring isolated auxiliary supplies (e.g., 5V PA bias) derived from main 3.3V rail. IC Role / Device Role / Timing Role: Regulator using SYNC/FCB pin to enforce continuous conduction - ensures stable auxiliary output regardless of main load variation. Use Value: Eliminates need for separate flyback controller or optocoupler feedback - simplifies design and improves reliability in RF front-end power chains. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3652EMSE#PBF | Integrated Li-ion charger + buck regulator; 2MHz switching; no Burst Mode; different pinout and control scheme. | Designed for battery charging systems, not standalone regulation; lacks SYNC/FCB auxiliary regulation capability. | Select only if battery charging functionality is required alongside regulation - not a functional replacement for LTC1627CS8#PBF's pure buck + secondary winding features. |
| TPS62231DRYR | 3MHz fixed-frequency buck; 300mA max output; 2.05V–6.5V input; no 100% duty cycle; different enable/soft-start behavior. | Optimized for ultra-small footprint and high-frequency filtering; unsuitable for low-VIN dropout or multi-output regulation. | Consider only for space-critical, low-current applications where 350kHz operation and auxiliary winding control are unnecessary. |
Compared with LT3652EMSE#PBF and TPS62231DRYR, the LTC1627CS8#PBF uniquely combines 100% duty-cycle operation, SYNC/FCB-based secondary winding regulation, and Burst Mode efficiency down to 200µA - making it irreplaceable for dual-rail, battery-sensitive portable systems requiring both primary and auxiliary output stability.
Availability
LTC1627CS8#PBF is available at Aetrix Electronics and suitable for cellular telephones, portable instruments, and wireless modems requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.
Supply support for LTC1627CS8#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, datasheets, and application notes for legacy Linear parts including the LTC1627 series.
The LTC1627 belongs to Linear's precision monolithic DC/DC regulator family, designed specifically for high-efficiency, low-noise power conversion in portable and battery-operated systems with demanding thermal and space constraints.
FAQ
What is the maximum output current capability of the LTC1627CS8#PBF?
The LTC1627CS8#PBF delivers up to 500mA of continuous output current under typical thermal conditions (SO-8 package, 2-layer PCB with 1 in² copper). This rating assumes proper layout, adequate input/output capacitance, and inductor selection per the datasheet guidelines. Peak currents may exceed 500mA briefly during transients, but sustained operation above this level risks thermal shutdown or reduced reliability. The LTC1627CS8#PBF's internal MOSFET RDS(ON) values (0.5Ω P-FET, 0.6Ω N-FET) define its conduction loss ceiling.
How does the SYNC/FCB pin enable secondary winding regulation in the LTC1627CS8#PBF?
The SYNC/FCB pin on the LTC1627CS8#PBF serves as an auxiliary feedback input with a 0.8V threshold. When the voltage at this pin drops below 0.8V - typically from a resistive divider across a transformer secondary winding - the LTC1627CS8#PBF forces continuous conduction mode, ensuring synchronous switching regardless of main output load. This guarantees stable regulation of the auxiliary output without cross-regulation issues. The LTC1627CS8#PBF does not require optocouplers or external controllers for this function.
Can the LTC1627CS8#PBF operate with a single 3.3V lithium-ion cell as input?
Yes, the LTC1627CS8#PBF supports input voltages as low as 2.65V, making it fully compatible with single-cell Li-ion batteries (2.7V–4.2V). Its 100% duty-cycle capability maintains regulation even when VIN sags near VOUT (e.g., 3.3V out from 3.4V in), and optional VDR bootstrapping further improves efficiency below 4.5V. The LTC1627CS8#PBF's 2.5V UVLO threshold also prevents deep discharge, protecting battery health. Operation at minimum VIN requires attention to RDS(ON) derating and thermal management.
What is the purpose of the VDR pin on the LTC1627CS8#PBF, and how is it used?
The VDR (top driver return) pin on the LTC1627CS8#PBF provides a floating reference for the internal P-channel MOSFET gate driver. By connecting VDR below ground (e.g., via a charge pump tied to SW), the gate-source voltage of the high-side FET increases, reducing its RDS(ON) and improving efficiency at low input voltages (<4.5V). The LTC1627CS8#PBF datasheet Figure 2 shows a standard charge pump implementation. Grounding VDR disables bootstrapping but allows 100% duty cycle; incorrect VDR biasing risks exceeding absolute maximum ratings.
Does the LTC1627CS8#PBF require external compensation components?
No, the LTC1627CS8#PBF uses internal compensation for its current-mode control loop and does not require external compensation components on the ITH pin. Stability is ensured across the full operating range with standard external components (inductor, input/output capacitors, feedback resistors). The ITH pin is solely for current limit programming and error amplifier output access - not for loop compensation. Designers should follow the recommended layout practices and component selection guidelines in the LTC1627CS8#PBF datasheet to maintain stability without added parts.
LTC1627CS8#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 2.65V
- Voltage - Input (Max):
- 8.5V
- Voltage - Output (Min/Fixed):
- 0.8V
- Voltage - Output (Max):
- 8.5V
- Current - Output:
- 500mA
- Frequency - Switching:
- 35kHz ~ 350kHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SO
LTC1627CS8#PBF FAQ
1.How can I place an order for LTC1627CS8#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1627CS8#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 LTC1627CS8#PBF reliable?
The price and inventory of LTC1627CS8#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1627CS8#PBF is usually 5 days.
3.What payment methods are accepted for LTC1627CS8#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1627CS8#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1627CS8#PBF?
LTC1627CS8#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1627CS8#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 LTC1627CS8#PBF?
For technical support, including LTC1627CS8#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1627CS8#PBF requirements.
6.How does Aetrix verify that LTC1627CS8#PBF is sourced from the original manufacturer or authorized distributors?
All LTC1627CS8#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 LTC1627CS8#PBF meets industry standards.
7.What is the process for return or replacement of LTC1627CS8#PBF?
All LTC1627CS8#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1627CS8#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 LTC1627CS8#PBF part is unused and in its original packaging.
Return procedure for LTC1627CS8#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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