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Analog Devices Inc. LTC3638EMSE#PBF
- Part No.:
- LTC3638EMSE#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 16-TFSOP (0.118", 3.00mm Width), 12 Leads, Exposed Pad
- Datasheet:
-
LTC3638EMSE#PBF.pdf
- Description:
- IC REG BUCK ADJ 250MA 16MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,987
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Product details
Overview
LTC3638EMSE#PBF from Analog Devices (formerly Linear Technology) is a high-efficiency, wide-input 140V step-down DC/DC regulator with integrated P-channel MOSFET, delivering up to 250mA output current, operating from 4V to 140V input, featuring 12µA no-load quiescent current and programmable peak current limit for optimized light-load efficiency in industrial power supplies.
For engineers reviewing the LTC3638EMSE#PBF datasheet, LTC3638EMSE#PBF pinout, LTC3638EMSE#PBF application, or LTC3638EMSE#PBF equivalent, key selection considerations include its 140V absolute max input rating, Burst Mode® operation enabling ultra-low IQ, programmable 40–575mA peak current via ISET, precise RUN/OVLO thresholds, and parallelability via FBO pin for higher-current systems.
Technical Context
The LTC3638EMSE#PBF implements a hysteretic Burst Mode® control architecture with internal P-channel MOSFET switch, where regulation is maintained by alternating short burst cycles (with inductor current ramp-up) and extended sleep cycles (drawing only 12µA). Its feedback comparator monitors VFB against a 0.800V ±1% reference and triggers bursts when VFB falls 5mV below threshold.
Peak current is set by an external resistor on ISET (40–575mA range), directly determining maximum average output current (½ × IPEAK); output voltage is selected via VPRG1/VPRG2 pin strapping for 1.8V/3.3V/5V fixed or adjustable mode; RUN and OVLO pins provide independent, precision-programmable undervoltage and overvoltage lockout with 110mV hysteresis each.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4V to 140V - supports direct regulation from unregulated HV rails including 48V telecom, 120V AC-derived supplies, and automotive transients. |
| Max Output Current | 250mA - achievable only when peak current is set ≥500mA; actual continuous load limited by thermal design and inductor saturation. |
| No-Load Quiescent Current | 12µA typical - enables multi-year battery life in always-on remote sensors and low-power IoT nodes. |
| Feedback Reference Voltage | 0.800V ±1% - sets accuracy of adjustable output; enables stable 0.8V–VIN regulation with external resistor divider. |
| Peak Current Range | 40mA to 575mA - programmed via ISET-to-GND resistor; determines tradeoff between light-load ripple, efficiency, and component size. |
| Switch On-Resistance | 1.8Ω typical - limits conduction loss at full load; impacts thermal rise in high-VIN, high-duty-cycle dropout operation. |
| Soft-Start Time | 1ms default (SS floating) - prevents input supply droop during startup; externally adjustable via SS-to-GND capacitor (1ms per 6.25nF). |
Pinout & Package
The LTC3638EMSE#PBF is housed in a thermally enhanced 16-lead plastic MSOP package (MSE) with four missing pins (pins 2, 4, 13, 15), exposing pad (pin 17) soldered to PCB ground for optimal thermal performance (θJC = 10°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SW (1) | Switch Node | Drain of internal P-MOSFET; connects to inductor and catch diode cathode; carries high dv/dt switching waveform. |
| VIN (3) | Main Input Supply | Accepts 4V–140V input; requires local 1µF/250V ceramic bypass to GND for stability and transient suppression. |
| FBO (5) | Feedback Comparator Output | Open-drain output (20µA pull-up, 70Ω pull-down) used to synchronize multiple LTC3638s in parallel for >250mA total output. |
| VPRG2 (6), VPRG1 (7) | Output Voltage Selection | Strap combinations select 1.8V/3.3V/5V fixed outputs or enable adjustable mode (both grounded). |
| GND (8, 16, 17) | Ground Reference | Pins 8/16 are signal GND; exposed pad (17) is power GND - must be soldered to PCB ground plane for thermal and EMI performance. |
| VFB (9) | Feedback Input | Compares divided output voltage to 0.800V reference; in fixed-output mode, tied directly to VOUT. |
| SS (10) | Soft-Start Control | Sourced 5µA (normal) or 50µA (startup) current; external capacitor sets controlled output voltage ramp time. |
| ISET (11) | Peak Current Programming | Resistor-to-GND sets peak inductor current (40–575mA); floating = max, shorted = min; current reduced to 1µA in sleep mode. |
| OVLO (12) | Overvoltage Lockout Input | Resistive divider from VIN sets disable threshold (1.21V rising); triggers soft-start reset on overvoltage transients. |
| RUN (14) | Enable/Undervoltage Control | Resistive divider enables operation above 1.21V rising threshold; shuts down to 1.4µA when <0.7V. |
Key Features
| Feature | Design Value |
|---|---|
| Burst Mode® Operation | Maintains regulation at ultra-light loads by alternating active burst cycles and 12µA sleep periods - eliminates switching losses while preserving output accuracy. |
| Programmable Peak Current Limit | Enables optimization of inductor size, output ripple, and efficiency across 40–575mA range using single ISET resistor - avoids overdesign for low-current applications. |
| Parallelable Architecture | FBO pin allows master-slave configuration of multiple LTC3638EMSE#PBF units - scales output current linearly without external current-sharing circuitry. |
| Precision RUN and OVLO Thresholds | 1.21V rising / 1.10V falling thresholds with 110mV hysteresis - enables robust, noise-immune input voltage monitoring for reliable brown-in/brown-out protection. |
| 100% Duty Cycle Dropout | P-channel MOSFET enables seamless transition into dropout - maintains regulation down to VOUT + (IOUT × RON), critical for high-VIN, low-VOUT applications. |
Applications
| Industrial Control Supplies | Avionics Power Management |
|---|---|
Use Scenario: Regulating 24V–72V aircraft bus or 115VAC-derived DC to 3.3V/5V for flight control sensors and data acquisition modules. IC Role / Device Role / Timing Role: Primary non-isolated step-down regulator providing clean, low-noise bias for analog front-ends and microcontrollers. Use Value: 140V absolute max rating withstands lightning-induced transients; 12µA IQ extends backup battery runtime during emergency power modes. | Use Scenario: Powering mission-critical cockpit displays and communication interfaces from variable aircraft electrical systems (28V nominal, up to 32V surge). IC Role / Device Role / Timing Role: High-reliability point-of-load converter with programmable OVLO to reject input spikes beyond safe operating envelope. Use Value: Precise RUN threshold ensures controlled startup after cold cranking; parallel FBO capability supports redundant dual-rail designs. |
| Medical Diagnostic Equipment | Distributed Power Systems |
Use Scenario: Generating isolated 5V/3.3V rails for portable ultrasound probes and patient monitoring sensors powered by Li-ion batteries or wall adapters. IC Role / Device Role / Timing Role: Efficient primary DC/DC stage converting wide-range input (e.g., 9–36V adapter or 3S–4S battery) to stable logic supply. Use Value: Adjustable peak current minimizes inductor size and EMI in compact handheld enclosures; low IQ preserves battery charge during standby. | Use Scenario: Providing auxiliary 5V/12V rails in telecom base stations or industrial gateways fed from 48V backplane with high-voltage transients. IC Role / Device Role / Timing Role: Robust secondary regulator handling input surges up to 140V while maintaining tight output regulation under dynamic load steps. Use Value: Thermal-enhanced MSE package sustains 250mA at elevated ambient temperatures; programmable ISET reduces ripple in sensitive RF subsystems. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar high-voltage step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3637EMSE#PBF | Lower 80V max input, same 250mA output and Burst Mode® architecture; lacks OVLO pin and FBO paralleling capability. | Suitable for 48V systems but not 100V+ industrial or avionics inputs; no input overvoltage protection or multi-chip scaling. | Select LTC3637EMSE#PBF only if input stays ≤80V and parallel operation is unnecessary - saves cost but sacrifices HV robustness. |
| MAX5033BASA+ | 85V max input, 250mA output, no programmable peak current or FBO; uses PWM (not Burst Mode®), resulting in higher 100µA IQ at no load. | Less suitable for battery-powered or energy-harvesting applications due to higher quiescent current; no precision RUN/OVLO thresholds. | Choose MAX5033BASA+ only for cost-sensitive 48V–72V applications where 100µA IQ is acceptable and parallel operation is not required. |
Compared with LTC3637EMSE#PBF and MAX5033BASA+, the LTC3638EMSE#PBF uniquely combines 140V input tolerance, 12µA IQ, programmable peak current, and FBO-based paralleling - making it the only option for scalable, ultra-low-power, high-voltage step-down in harsh environments.
Availability
LTC3638EMSE#PBF is available at Aetrix Electronics and suitable for industrial control supplies, avionics power management, and distributed power systems requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LTC3638EMSE#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 reliability testing and long-term product commitments.
The LTC3638EMSE#PBF belongs to Linear's high-voltage monolithic DC/DC regulator family, designed specifically for ruggedized point-of-load conversion in aerospace, industrial, and medical systems where input transients, wide voltage ranges, and ultra-low standby power are critical.
FAQ
What is the maximum input voltage the LTC3638EMSE#PBF can safely handle?
The LTC3638EMSE#PBF has an absolute maximum input voltage rating of 140V, with guaranteed operation from 4V to 140V. It remains functional and undamaged at 140V even when disabled (e.g., during RUN pin shutdown or OVLO lockout), provided thermal limits are observed. This makes LTC3638EMSE#PBF suitable for direct connection to 120VAC-derived supplies and high-voltage industrial buses.
How does the LTC3638EMSE#PBF achieve 12µA quiescent current?
The LTC3638EMSE#PBF achieves 12µA typical quiescent current through Burst Mode® operation: during light loads, it enters extended sleep cycles where the internal power switch, current comparators, and most bias circuits are disabled. Only essential monitoring circuitry remains active, drawing minimal current from VIN. This behavior is intrinsic to the LTC3638EMSE#PBF's architecture and requires no external enable control.
Can multiple LTC3638EMSE#PBF ICs be connected in parallel to increase output current?
Yes - the LTC3638EMSE#PBF includes a dedicated FBO (Feedback Comparator Output) pin that enables master-slave parallel operation. Connecting the FBO pin of a master LTC3638EMSE#PBF to the VFB pins of one or more slave LTC3638EMSE#PBF units synchronizes regulation and shares load current proportionally, delivering up to N × 250mA total output with N devices.
What output voltage options does the LTC3638EMSE#PBF support, and how are they configured?
The LTC3638EMSE#PBF supports 1.8V, 3.3V, and 5V fixed outputs, plus adjustable mode (0.8V to VIN), selected via VPRG1 and VPRG2 pin strapping. For 1.8V: both pins tied to SS; for 3.3V: VPRG1 to GND, VPRG2 to SS; for 5V: VPRG1 to SS, VPRG2 to GND; for adjustable: both pins grounded. No external resistors needed for fixed outputs - simplifying layout and improving noise immunity.
Does the LTC3638EMSE#PBF require external compensation components?
No - the LTC3638EMSE#PBF uses a hysteretic current-mode control architecture with internal compensation, eliminating the need for external Type-II or Type-III compensation networks. This reduces BOM count, board area, and design complexity while ensuring stable operation across all valid input/output combinations and load conditions specified in the datasheet.
LTC3638EMSE#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):
- 140V
- Voltage - Output (Min/Fixed):
- 0.8V
- Voltage - Output (Max):
- 140V
- Current - Output:
- 250mA
- Frequency - Switching:
- -
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-MSOP-EP
LTC3638EMSE#PBF FAQ
1.How can I place an order for LTC3638EMSE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3638EMSE#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 LTC3638EMSE#PBF reliable?
The price and inventory of LTC3638EMSE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3638EMSE#PBF is usually 5 days.
3.What payment methods are accepted for LTC3638EMSE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3638EMSE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3638EMSE#PBF?
LTC3638EMSE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3638EMSE#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 LTC3638EMSE#PBF?
For technical support, including LTC3638EMSE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3638EMSE#PBF requirements.
6.How does Aetrix verify that LTC3638EMSE#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3638EMSE#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 LTC3638EMSE#PBF meets industry standards.
7.What is the process for return or replacement of LTC3638EMSE#PBF?
All LTC3638EMSE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3638EMSE#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 LTC3638EMSE#PBF part is unused and in its original packaging.
Return procedure for LTC3638EMSE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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