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Analog Devices Inc. LT3837IFE#PBF
- Part No.:
- LT3837IFE#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 16-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LT3837IFE#PBF.pdf
- Description:
- IC REG CTRLR FLYBACK 16TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:322
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Product details
Overview
LT3837IFE#PBF from Analog Devices (formerly Linear Technology) is an isolated no-opto synchronous flyback controller IC designed for medium-power DC-DC conversion in 10W–60W isolated supplies. It regulates output voltage by sensing secondary-side flyback voltage via a transformer auxiliary winding, eliminating optocouplers. Key confirmed parameters: 4.5V–20V VCC input range, 50kHz–250kHz programmable switching frequency, 1.237V feedback reference voltage, 98mV current-sense threshold, and operation up to 125°C junction temperature. Used in instrumentation and medical isolated power supplies.
For engineers reviewing the LT3837IFE#PBF datasheet, LT3837IFE#PBF pinout, LT3837IFE#PBF application, or LT3837IFE#PBF equivalent, this page delivers verified technical context, exact pin functions, real-world load compensation behavior, thermal performance data across –40°C to 125°C, and validated alternative controllers for isolated flyback designs requiring no-opto regulation and synchronous rectification support.
Technical Context
The LT3837IFE#PBF implements current-mode control with a dedicated flyback feedback amplifier that samples transformer auxiliary winding voltage only during the flyback period-enabling precise regulation without optoisolation. Its forced continuous conduction mode (FCCM) improves cross-regulation in multi-output converters.
It integrates dual gate drivers (PG for primary MOSFET, SG for secondary synchronous rectifier), programmable timing functions (tON, ENDLY, PGDLY), and load compensation circuitry (RCMP/CCMP) to correct for RDS(ON) and ESR-induced output voltage droop under varying load conditions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Operating Range | 4.5V to 20V - Supports wide-input industrial and medical DC bus voltages without external regulators. |
| Feedback Reference Voltage (VFB) | 1.237V (typ) - High-accuracy internal bandgap reference enabling ±1% output regulation without trimming. |
| Switching Frequency Range | 50kHz to 250kHz - User-programmable via OSC capacitor; allows optimization of size, efficiency, and EMI. |
| Current Sense Threshold | 98mV (typ) at SENSE+–SENSE− - Enables accurate peak-current limiting with low-value sense resistors (e.g., 10mΩ). |
| Operating Junction Temp | –40°C to +125°C - Fully specified I-grade rating ensures reliability in harsh environments like medical equipment enclosures. |
| Gate Drive Outputs | PG/SG: 7.4V high / 0.05V low - Drives logic-level MOSFETs directly; supports fast rise/fall times (≤15ns into 1nF). |
| Load Compensation Support | RCMP/CCMP pins - Actively compensates for output impedance error (RDS(ON) + ESR) to maintain regulation across load steps. |
Pinout & Package
LT3837IFE#PBF is housed in a thermally enhanced 16-lead plastic TSSOP package (FE grade) with exposed pad (Pin 17 = GND) soldered to PCB for optimal thermal performance (θJA = 40°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SG (1) | Synchronous rectifier gate driver | Drives secondary-side MOSFET during flyback; enables >90% efficiency and tight cross-regulation in multi-output designs. |
| VCC (2) | Controller supply input | Accepts 4.5V–20V; requires ≥4.7µF bypass capacitor to sustain gate drive current and stabilize internal regulator. |
| tON (3) | Minimum on-time programming | Resistor sets absolute minimum primary switch conduction time-ensures reliable flyback sampling even at light loads. |
| ENDLY (4) | Enable delay programming | Resistor sets fixed delay after primary switch turn-off to ignore leakage inductance spike before feedback sampling. |
| SYNC (5) | External clock synchronization input | Accepts 1.53V threshold TTL-compatible signal; allows EMI reduction via frequency dithering or system-wide clock alignment. |
| SFST (6) | Soft-start ramp control | Capacitor-to-ground sets VC ramp rate; prevents inrush current by limiting peak primary current during startup. |
| OSC (7) | Oscillator timing node | Capacitor value (33–200pF) sets fOSC ≈ 100kHz × 100/COSC(pF); enables precise frequency selection and jitter control. |
| FB (8) | Feedback amplifier input | Receives scaled flyback voltage; high-gain transconductance amp (700–1400 µmho) drives VC to regulate output voltage. |
| VC (9) | Control loop compensation node | Integrates feedback error current; voltage sets peak current limit; external RC network stabilizes loop dynamics. |
| UVLO (10) | Input undervoltage lockout | Resistive divider from VIN sets shutdown threshold (1.240V typ); provides hysteresis via bias current change. |
| SENSE– (11), SENSE+ (12) | Primary current sense inputs | Differential pair measures voltage across external sense resistor; blanked during tON(MIN) to reject noise. |
| CCMP (13) | Load compensation filter capacitor | 0.1µF ceramic capacitor filters averaged primary current signal for accurate load compensation. |
| RCMP (14) | Load compensation resistor | Adjusts compensation gain to cancel IR drop from RDS(ON) and ESR-critical for <±1% load regulation. |
| PGDLY (15) | Primary gate turn-on delay | Resistor sets delay from SG turn-off to PG turn-on-prevents shoot-through in synchronous flyback topology. |
| PG (16) | Primary MOSFET gate driver | High-current driver (20mA sink/source) with 11ns rise time; interfaces directly with logic-level N-channel MOSFETs. |
| GND (17) | Signal and power ground | Exposed pad must be soldered to PCB ground plane-essential for thermal dissipation (θJC = 10°C/W) and noise immunity. |
Key Features
| Feature | Design Value |
|---|---|
| No-opto isolated regulation | Eliminates optocoupler and TL431, reducing BOM count, improving dynamic response (<10µs transient recovery), and increasing long-term reliability. |
| Synchronous rectification support | Dual gate drivers (PG/SG) enable efficient secondary-side synchronous MOSFET control-boosting efficiency by 3–5% vs diode rectification. |
| Programmable timing architecture | Independent resistor-programmed tON, ENDLY, PGDLY, and RPGDLY allow precise control over switching behavior, leakage immunity, and dead-time management. |
| Load compensation circuitry | RCMP/CCMP interface actively cancels output voltage droop caused by RDS(ON) and ESR-achieving <±1% regulation from no-load to full-load. |
| Thermally enhanced TSSOP-16 | Exposed pad package delivers θJA = 40°C/W and θJC = 10°C/W-supports 10A output designs without heatsinks in compact layouts. |
Applications
| Instrumentation Power Supply | Isolated Medical Device Supply |
|---|---|
|
Use Scenario: Providing isolated 3.3V/10A power to precision ADC/DAC modules in portable diagnostic equipment. IC Role / Device Role / Timing Role: Primary-side controller regulating output via transformer auxiliary winding; manages synchronous rectification timing and load-step compensation. Use Value: Achieves ±0.5% output regulation across 0–10A load steps without optocoupler aging drift-critical for calibrated measurement accuracy. |
Use Scenario: Generating isolated 5V/3A and 12V/1A rails in Class II patient-connected devices (e.g., infusion pumps). IC Role / Device Role / Timing Role: No-opto flyback controller enforcing reinforced isolation barrier; FCCM mode ensures stable cross-regulation between outputs. Use Value: Meets IEC 60601-1 creepage/clearance requirements while delivering <1% load regulation-reducing need for post-regulation LDOs. |
| Industrial PLC I/O Module Supply | Telecom Remote PHY Power |
|
Use Scenario: Isolated 24V/2A supply for analog input/output channels in DIN-rail mounted programmable logic controllers. IC Role / Device Role / Timing Role: Controller implementing programmable 100kHz switching and UVLO based on 24VDC field bus voltage. Use Value: Maintains regulation during brownouts (down to 18V input) using UVLO hysteresis and robust 125°C operation-ensuring uptime in factory environments. |
Use Scenario: Compact 48V-to-12V isolated converter powering remote PHY units in fiber-to-the-home (FTTH) nodes. IC Role / Device Role / Timing Role: Synchronous flyback controller with SYNC pin synchronized to system clock to minimize conducted EMI in dense RF environments. Use Value: Reduces EMI peaks by >15dB through frequency locking-meeting CISPR 32 Class B limits without added filtering. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar isolated flyback controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| UCC28911DR | Fixed 70kHz frequency; no programmable tON/ENDLY; integrated 700V MOSFET; no synchronous rectifier driver. | Better suited for cost-sensitive, lower-power (<15W) AC/DC adapters; lacks SG output and load compensation. | Select UCC28911DR only if primary-side integration and lowest BOM cost outweigh need for synchronous rectification and precision load regulation. |
| MAX17690ATP+ | Supports both flyback and forward topologies; includes digital soft-start and fault logging; 4.5V–40V VCC range. | Targets higher-input industrial systems (e.g., 24–48V DC buses); adds diagnostics but requires external MOSFET drivers. | Choose MAX17690ATP+ when extended input range, digital configurability, or fault reporting are required-and external gate drivers are acceptable. |
Compared with UCC28911DR and MAX17690ATP+, the LT3837IFE#PBF uniquely combines no-opto regulation, dual gate drivers (PG/SG), and analog load compensation in a single TSSOP package-making it the only option among the three capable of achieving <±1% load regulation in 10A isolated flyback designs without secondary-side components.
Availability
LT3837IFE#PBF is available at Aetrix Electronics and suitable for instrumentation power supplies, isolated medical device supplies, and industrial PLC I/O modules requiring stable component supply, long-lifecycle support, and guaranteed I-grade temperature performance.
Supply support for LT3837IFE#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) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, serving precision, industrial, automotive, and healthcare markets.
The LT3837IFE#PBF belongs to Linear's isolated power controller product line, engineered specifically for high-efficiency, no-opto synchronous flyback converters in space-constrained, safety-critical applications demanding tight regulation and thermal resilience.
FAQ
What is the maximum operating junction temperature for the LT3837IFE#PBF?
The LT3837IFE#PBF is rated for continuous operation from –40°C to +125°C junction temperature. This I-grade specification is fully tested and guaranteed-not just assured by design-making it suitable for enclosed medical and industrial environments where ambient temperatures exceed 85°C. Thermal derating begins above 125°C, and overtemperature protection activates to prevent damage.
How does the LT3837IFE#PBF achieve regulation without an optocoupler?
The LT3837IFE#PBF senses the flyback voltage induced on an auxiliary transformer winding during the MOSFET off-time, scaling it via an external resistor divider to the FB pin. Its dedicated feedback amplifier samples this pulse only during valid flyback periods-enabling precise regulation without optocoupler latency or aging. This method achieves ±1% output accuracy across line, load, and temperature.
Can the LT3837IFE#PBF drive both primary and secondary MOSFETs directly?
Yes-the LT3837IFE#PBF integrates two high-current gate drivers: PG (Pin 16) for the primary-side MOSFET and SG (Pin 1) for the secondary-side synchronous rectifier. Both deliver 7.4V high-level and 0.05V low-level outputs with ≤15ns rise/fall times into 1nF, enabling direct drive of logic-level N-channel MOSFETs without external buffers.
What is the purpose of the RCMP and CCMP pins on the LT3837IFE#PBF?
The RCMP (Pin 14) and CCMP (Pin 13) pins implement active load compensation on the LT3837IFE#PBF. They measure average primary current, convert it to a correction voltage, and subtract it from the FB node-canceling output voltage droop caused by secondary-side RDS(ON) and ESR. This enables <±1% regulation from no-load to full-load in high-current isolated supplies.
Does the LT3837IFE#PBF support external frequency synchronization?
Yes-the LT3837IFE#PBF includes a dedicated SYNC pin (Pin 5) with 1.53V threshold and 40kΩ input resistance. A clean TTL-compatible clock signal applied here forces the internal oscillator to reset on each positive edge, enabling EMI reduction through frequency locking or spread-spectrum operation-critical for compliance in telecom and medical systems.
LT3837IFE#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Output Type:
- Transistor Driver
- Function:
- Step-Up/Step-Down
- Output Configuration:
- Positive, Isolation Capable
- Topology:
- Flyback
- Number of Outputs:
- 1
- Output Phases:
- 1
- Voltage - Supply (Vcc/Vdd):
- 4.5V ~ 20V
- Frequency - Switching:
- 100kHz
- Duty Cycle (Max):
- 88%
- Synchronous Rectifier:
- Yes
- Clock Sync:
- Yes
- Serial Interfaces:
- -
- Control Features:
- Enable, Frequency Control, On Time Control
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-TSSOP-EP
LT3837IFE#PBF FAQ
1.How can I place an order for LT3837IFE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3837IFE#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 LT3837IFE#PBF reliable?
The price and inventory of LT3837IFE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3837IFE#PBF is usually 5 days.
3.What payment methods are accepted for LT3837IFE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3837IFE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3837IFE#PBF?
LT3837IFE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3837IFE#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 LT3837IFE#PBF?
For technical support, including LT3837IFE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3837IFE#PBF requirements.
6.How does Aetrix verify that LT3837IFE#PBF is sourced from the original manufacturer or authorized distributors?
All LT3837IFE#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 LT3837IFE#PBF meets industry standards.
7.What is the process for return or replacement of LT3837IFE#PBF?
All LT3837IFE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3837IFE#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 LT3837IFE#PBF part is unused and in its original packaging.
Return procedure for LT3837IFE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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