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Analog Devices Inc. LTC3639IMSE#PBF
- Part No.:
- LTC3639IMSE#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 16-TFSOP (0.118", 3.00mm Width), 12 Leads, Exposed Pad
- Datasheet:
-
LTC3639IMSE#PBF.pdf
- Description:
- IC REG BUCK ADJ 100MA 16MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:281
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Product details
Overview
LTC3639IMSE#PBF from Analog Devices (formerly Linear Technology) is a high-efficiency, 150V input synchronous step-down DC/DC regulator with integrated high-side P-channel and low-side N-channel MOSFETs. It delivers up to 100mA output current, operates from 4V to 150V input, maintains regulation at 100% duty cycle, and draws only 12µA quiescent current in Burst Mode® sleep. It is used in industrial control supplies and avionics power rails where wide-input, low-quiescent, high-voltage regulation is required.
For engineers reviewing the LTC3639IMSE#PBF datasheet, LTC3639IMSE#PBF pinout, LTC3639IMSE#PBF application, or LTC3639IMSE#PBF equivalent, key selection criteria include its 150V absolute max input rating, programmable 10–100mA peak current limit via ISET, 0.8V ±1% feedback reference, precise RUN/OVLO thresholds, and thermally enhanced 16-lead MSE package with exposed GND pad.
Technical Context
The LTC3639IMSE#PBF implements Burst Mode® control with hysteretic feedback, enabling ultra-low quiescent current (12µA) while maintaining regulation across load currents from µA to 100mA. Its internal P-channel high-side and N-channel low-side MOSFETs eliminate external switch drivers and reduce component count.
It features dual programmable comparators: RUN pin (1.21V rising threshold, 110mV hysteresis) for precise undervoltage lockout, and OVLO pin (1.21V rising threshold) for overvoltage protection - both triggering soft-start reset on fault recovery. The ISET pin sources 5µA (1µA in sleep) to set peak current from 17mA to 230mA, directly determining maximum average output current (half the peak value).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4V to 150V - supports direct regulation from unregulated HV rails like PoE++, battery stacks, or industrial 48V/72V/110V systems. |
| Output Current Capability | Up to 100mA average - determined by peak current limit (programmable 17–230mA); max output = ½ × IPEAK. |
| Quiescent Current | 12µA typical in Burst Mode® sleep - enables multi-year battery life in always-on remote sensors. |
| Feedback Reference | 0.800V ±1% - sets output voltage accuracy in adjustable mode; enables stable 1.8V/3.3V/5V fixed outputs via VPRG pins. |
| Duty Cycle Limit | 100% - ensures dropout operation down to VOUT + ~0.5V; critical for brownout resilience in wide-input systems. |
| Switch On-Resistance | Top: 4.2Ω, Bottom: 2.2Ω - defines conduction loss at full load; optimized for efficiency at 100mA with 470µH inductor. |
| Soft-Start Time | 1ms internal default - prevents input supply droop during startup; externally adjustable via SS pin capacitor (6.25nF = 1ms ramp). |
Pinout & Package
The LTC3639IMSE#PBF is housed in a thermally enhanced 16-lead plastic MSOP (MSE) package with four missing pins (pins 2, 4, 13, 15), exposing a GND pad (pin 17) that must be soldered to PCB ground for thermal performance (θJA = 40°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SW (1) | Switch node | Connects to inductor; carries pulsed current through internal high-side and low-side MOSFETs. |
| VIN (3) | Main input supply | Accepts 4V–150V; requires local ceramic bypass capacitor to GND for stability and EMI reduction. |
| FBO (5) | Feedback comparator output | Open-drain status flag (20µA pull-up, 70Ω pull-down); indicates regulation status for system monitoring. |
| VPRG1/VPRG2 (6,7) | Output voltage selection | Configure fixed 1.8V/3.3V/5V or adjustable output by grounding or tying to SS pin per datasheet table. |
| GND (8,16,17) | Ground reference & thermal path | Pins 8/16 are signal GND; exposed pad (17) is mandatory thermal GND connection for rated power dissipation. |
| VFB (9) | Feedback input | Compares divided output to 0.8V reference; connects to resistor divider (adjustable) or directly to VOUT (fixed). |
| SS (10) | Soft-start control | Sources 5µA (1µA sleep) to external capacitor; sets output ramp time (1ms per 6.25nF to GND). |
| ISET (11) | Peak current programming | Sources 5µA to resistor-to-GND; sets peak inductor current from 17mA (shorted) to 230mA (open). |
| OVLO (12) | Overvoltage lockout input | Disables switching when >1.21V; resets with soft-start after transient - protects against input surges. |
| RUN (14) | Enable/disable control | Enables regulation above 1.21V; shuts down to 1.4µA when <0.7V - provides precise UVLO with 110mV hysteresis. |
Key Features
| Feature | Design Value |
|---|---|
| Burst Mode® operation | Reduces quiescent current to 12µA at no load while maintaining regulation - extends battery life without sacrificing transient response. |
| Integrated synchronous MOSFETs | Eliminates need for external switches and gate drivers; reduces BOM count and layout complexity for HV buck conversion. |
| Programmable peak current limit | Adjusts IPEAK from 17mA to 230mA via single resistor on ISET - optimizes efficiency, ripple, and inductor size per application load. |
| Precision RUN and OVLO comparators | 1.21V thresholds with 110mV hysteresis - enables robust, repeatable start-up and fault recovery across temperature and supply variations. |
| 100% duty cycle dropout operation | Uses P-channel high-side switch to sustain regulation as VIN approaches VOUT - essential for brownout tolerance in wide-input systems. |
Applications
| Industrial Control Supplies | Avionics Power Rails |
|---|---|
Use Scenario: Regulating 110VDC aircraft bus to 5V for flight data recorders and sensor interfaces. IC Role / Device Role / Timing Role: Primary HV buck regulator providing isolated, low-noise 5V rail with fault-tolerant start-up and surge immunity. Use Value: Withstands 150V transients, maintains regulation during engine cranking dips, and draws <15µA in standby - meets DO-160 Section 22 surge requirements. | Use Scenario: Powering FPGA configuration circuitry from 28V aircraft supply with strict quiescent current limits. IC Role / Device Role / Timing Role: Always-on auxiliary regulator delivering 3.3V at <100mA with minimal self-heating in sealed avionics enclosures. Use Value: 12µA sleep current and 40°C/W thermal resistance enable reliable operation at 125°C ambient without forced air cooling. |
| Medical Imaging Sensors | Portable Test Equipment |
Use Scenario: Supplying bias voltage to X-ray detector ASICs from rechargeable Li-ion battery packs (12–48V). IC Role / Device Role / Timing Role: High-efficiency step-down converter enabling multi-hour battery runtime while maintaining tight output regulation. Use Value: Burst Mode® efficiency >85% at 1mA load and 0.8V reference accuracy ensure stable analog front-end performance across battery discharge. | Use Scenario: Generating 1.8V core voltage for microcontrollers in handheld multimeters powered by AA batteries. IC Role / Device Role / Timing Role: Low-IQ buck regulator supporting deep-sleep modes and fast wake-up without output overshoot. Use Value: Internal 1ms soft-start and 100% duty cycle operation prevent brownout during battery voltage sag under load - improves measurement reliability. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar high-voltage synchronous buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3631EMSE#PBF | Lower max input (60V), no OVLO pin, fixed 3.3V/5V only, 150mA max output. | Suitable for 24–48V industrial systems but lacks 150V capability and programmable OVLO for aerospace use. | Select when input ≤60V and fixed-output simplicity outweighs HV flexibility. |
| MAX5033BASA+T | Asynchronous (external diode), 76V max input, 125mA output, no programmable peak current or Burst Mode®. | Higher quiescent current (100µA), less efficient at light loads, requires external flyback diode and compensation. | Choose for cost-sensitive 48V applications where 12µA IQ and synchronous efficiency are non-critical. |
Compared with LTC3639IMSE#PBF, LTC3631EMSE#PBF trades 150V operation and OVLO programmability for higher output current and simpler fixed-VOUT setup, while MAX5033BASA+T sacrifices efficiency and integration for lower unit cost in non-battery-critical 48V designs.
Availability
LTC3639IMSE#PBF is available at Aetrix Electronics and suitable for industrial control supplies, avionics power rails, medical imaging sensors, and portable test equipment requiring stable component supply with guaranteed long-term availability.
Supply support for LTC3639IMSE#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 its high-performance power management portfolio with rigorous automotive and industrial qualification standards.
The LTC3639IMSE#PBF belongs to Linear's high-voltage monolithic buck regulator product line, designed specifically for ruggedized power conversion in aerospace, medical, and industrial environments where input voltages exceed 60V and reliability under transient stress is critical.
FAQ
What is the maximum input voltage rating for the LTC3639IMSE#PBF?
The LTC3639IMSE#PBF has an absolute maximum input voltage rating of 150V, with a functional operating range from 4V to 150V. This allows direct regulation from high-voltage sources such as 110VDC aircraft buses, PoE++ injectors, or industrial 72V/96V battery systems without external pre-regulation. Exceeding 150V risks permanent damage per Absolute Maximum Ratings.
How does the ISET pin on the LTC3639IMSE#PBF control output current?
The ISET pin on the LTC3639IMSE#PBF sources a 5µA (1µA in sleep) current to ground through an external resistor, setting the peak inductor current threshold between 17mA and 230mA. Since the LTC3639IMSE#PBF's maximum average output current equals half the peak current, a 200mA ISET setting yields ~100mA max output. Shorting ISET to GND sets minimum peak current (25mA typ), while leaving it open sets maximum (230mA typ).
Can the LTC3639IMSE#PBF operate in 100% duty cycle dropout mode?
Yes, the LTC3639IMSE#PBF supports true 100% duty cycle operation using its integrated P-channel high-side MOSFET. When input voltage drops near the output voltage, the high-side switch remains continuously on, sustaining regulation without dropout. This feature is critical for brownout resilience in wide-input applications like avionics and industrial controls where input sags below nominal levels are common.
What is the purpose of the FBO pin on the LTC3639IMSE#PBF?
The FBO (Feedback Comparator Output) pin on the LTC3639IMSE#PBF is an open-drain status indicator that pulls low when the output is in regulation and goes high-impedance during sleep or fault conditions. With a typical 20µA pull-up and 70Ω pull-down impedance, it provides real-time system-level monitoring of regulator health - useful for host microcontrollers to detect undervoltage or startup completion without additional sensing circuitry.
Does the LTC3639IMSE#PBF require external compensation components?
No, the LTC3639IMSE#PBF uses a hysteretic Burst Mode® control architecture with internal compensation, eliminating the need for external Type-II or Type-III compensation networks. This simplifies design, reduces BOM count, and improves stability across input/output combinations - a key advantage over voltage-mode or current-mode controllers that require careful loop compensation tuning.
LTC3639IMSE#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-TFSOP (0.118", 3.00mm Width), 12 Leads, Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 4V
- Voltage - Input (Max):
- 150V
- Voltage - Output (Min/Fixed):
- 0.8V
- Voltage - Output (Max):
- 150V
- Current - Output:
- 100mA
- Frequency - Switching:
- -
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-MSOP-EP
LTC3639IMSE#PBF FAQ
1.How can I place an order for LTC3639IMSE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3639IMSE#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 LTC3639IMSE#PBF reliable?
The price and inventory of LTC3639IMSE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3639IMSE#PBF is usually 5 days.
3.What payment methods are accepted for LTC3639IMSE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3639IMSE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3639IMSE#PBF?
LTC3639IMSE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3639IMSE#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 LTC3639IMSE#PBF?
For technical support, including LTC3639IMSE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3639IMSE#PBF requirements.
6.How does Aetrix verify that LTC3639IMSE#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3639IMSE#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 LTC3639IMSE#PBF meets industry standards.
7.What is the process for return or replacement of LTC3639IMSE#PBF?
All LTC3639IMSE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3639IMSE#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 LTC3639IMSE#PBF part is unused and in its original packaging.
Return procedure for LTC3639IMSE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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