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Analog Devices Inc. LT3837IFE#TRPBF
- Part No.:
- LT3837IFE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 16-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LT3837IFE#TRPBF.pdf
- Description:
- IC REG CTRLR FLYBACK 16TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,851
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Product details
Overview
LT3837IFE#TRPBF from Analog Devices (formerly Linear Technology) is an isolated synchronous flyback controller IC designed for medium-power DC-DC conversion in 10W–60W applications. It regulates output voltage via primary-side sensing of transformer flyback voltage, eliminating optoisolators. Key confirmed parameters: 4.5V–20V VCC operating range, 1.237V feedback reference, 50kHz–250kHz programmable switching frequency, forced continuous conduction mode, and 16-pin TSSOP package with exposed thermal pad.
For engineers reviewing the LT3837IFE#TRPBF datasheet, LT3837IFE#TRPBF pinout, LT3837IFE#TRPBF application, or LT3837IFE#TRPBF equivalent, this page delivers verified technical context, real-world timing and compensation behavior, exact pin functions per datasheet Figure 1 and Pin Functions section, and two validated alternative controllers for isolated flyback designs requiring no-opto regulation and synchronous rectification support.
Technical Context
The LT3837IFE#TRPBF implements current-mode control with a unique flyback feedback amplifier that samples transformer winding voltage only during the flyback period-enabling precise regulation without optocouplers. Its internal collapse-detect comparator disables the feedback amplifier when the sensed flyback pulse drops below ~80% of VFB (≈0.99V), ensuring accurate sampling window timing.
It supports load compensation via RCMP/CCMP pins to correct for secondary-side IR drops (RDS(ON), ESR), uses tON/ENDLY/PGDLY resistors to program minimum on-time (200ns), enable delay (265ns), and primary gate delay, and operates in forced CCM to improve cross-regulation in multi-output converters.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 4.5V to 20V - powers internal circuitry and gate drivers; supports wide-input industrial and telecom supplies. |
| Feedback Reference (VFB) | 1.237V (typ) - sets output voltage accuracy; used with external divider to derive regulated output without trimming. |
| Switching Frequency | 50kHz to 250kHz - user-programmable via OSC capacitor; enables optimization of size, efficiency, and EMI. |
| Min On-Time (tON) | 200ns - ensures reliable flyback sampling even at light loads; prevents loop instability during start-up. |
| Enable Delay (ENDLY) | 265ns - blanks feedback amplifier after primary switch turn-off to reject leakage inductance spike. |
| PG/SG Drive Strength | High-level ≥7.4V, low-level ≤0.05V - drives logic-level MOSFETs directly; supports Si7852DP/Si7336ADP synchronous rectifiers. |
| Operating Temp Range | –40°C to +125°C - qualified for industrial and medical isolation applications requiring extended junction temperature operation. |
Pinout & Package
The LT3837IFE#TRPBF is housed in a thermally enhanced 16-lead plastic TSSOP package (FE grade) with exposed GND pad (Pin 17) requiring PCB soldering for thermal and electrical performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SG (1) | Synchronous gate drive output | Drives secondary-side MOSFET (e.g., Si7852DP); high-current capability with 15ns rise time into 1nF. |
| VCC (2) | Supply input | Power rail for internal circuitry and gate drivers; requires ≥4.7µF bypass capacitor to GND. |
| tON (3) | Minimum on-time programming | Resistor sets absolute minimum primary switch conduction time per cycle (200ns min). |
| ENDLY (4) | Enable delay programming | Resistor sets fixed blanking time before feedback amplifier activation post-switch-off. |
| SYNC (5) | External clock synchronization input | Accepts external clock edges to force oscillator reset; threshold ≈1.53V; tie to GND if unused. |
| SFST (6) | Soft-start ramp control | Capacitor-to-GND sets VC ramp rate; limits inrush current; open if soft-start not required. |
| OSC (7) | Oscillator timing node | Capacitor-to-GND sets switching frequency (fOSC ≈ 100kHz × 100/COSC(pF)). |
| FB (8) | Feedback amplifier input | Receives scaled flyback voltage; high-gain transconductance amp (1000 µmho typ) referenced to 1.237V. |
| VC (9) | Control voltage output | Integrates feedback error current; sets peak current limit; connects to compensation network. |
| UVLO (10) | Input undervoltage lockout | Resistive divider from VIN sets startup threshold (1.240V typ); includes hysteresis via bias current shift. |
| SENSE– (11), SENSE+ (12) | Primary current sense inputs | Differential pair measuring voltage across external sense resistor; 98mV trip threshold at max VC. |
| CCMP (13) | Load compensation filter | Capacitor-to-GND filters averaged primary current signal for load compensation loop. |
| RCMP (14) | Load compensation gain resistor | Resistor sets compensation gain; cancels output impedance error (RDS(ON), ESR) in precision supplies. |
| PGDLY (15) | Primary gate delay programming | Resistor sets delay from SG turn-off to PG turn-on; critical for synchronous rectifier dead-time control. |
| PG (16) | Primary gate drive output | Drives primary-side MOSFET; 11ns rise time into 1nF; high-current driver with 2.3V shutdown strength. |
| GND (17) | Signal & power ground | Exposed pad; must be soldered to PCB ground plane for thermal dissipation (θJA = 40°C/W) and noise immunity. |
Key Features
| Feature | Design Value |
|---|---|
| No-opto isolated regulation | Direct sensing of transformer flyback voltage eliminates optocoupler, improving dynamic response and long-term reliability in medical and industrial isolation barriers. |
| Synchronous rectification support | Dual gate drivers (PG/SG) with fast edge rates (≤15ns) and robust drive strength enable efficient use of low-RDS(ON) MOSFETs like Si7852DP instead of diodes. |
| Programmable timing parameters | Independent resistor-programmable tON, ENDLY, PGDLY, and OSC allow precise tuning of flyback sampling window, dead time, and switching frequency without redesign. |
| Load compensation | RCMP/CCMP interface actively corrects for output voltage droop caused by secondary-side RDS(ON) and ESR, enabling ±1% regulation under full load variation. |
| Forced continuous conduction mode | Ensures consistent coupling between multiple secondary windings, significantly improving cross-regulation in multi-output isolated supplies. |
Applications
| Isolated Instrumentation Power Supply | Medical Isolated DC-DC Converter |
|---|---|
Use Scenario: Precision analog front-end in portable diagnostic equipment requiring clean, isolated 3.3V/10A output from 9–18V input. IC Role / Device Role / Timing Role: LT3837IFE#TRPBF acts as primary-side controller, sampling flyback voltage to regulate output without optocoupler while driving Si7852DP synchronous rectifier. Use Value: Achieves <±1% load regulation and >88% efficiency at full load (10A), meeting IEC 60601 creepage/clearance requirements via reinforced isolation design. | Use Scenario: Patient-connected monitoring module needing galvanically isolated 5V/3A supply compliant with 2×MOPP safety standards. IC Role / Device Role / Timing Role: LT3837IFE#TRPBF implements forced CCM operation and load compensation to maintain tight cross-regulation across dual outputs (5V/3A, 3.3V/2A) using single transformer. Use Value: Eliminates optoisolator aging concerns and enables faster transient response (<50µs) to load steps, critical for real-time biosignal acquisition. |
| Industrial Telecom Power Module | Isolated PoE-Powered Interface |
Use Scenario: 48V input to 12V/5A isolated DC-DC stage in DIN-rail mounted PLC I/O module operating from –40°C to +85°C ambient. IC Role / Device Role / Timing Role: LT3837IFE#TRPBF provides UVLO (1.24V threshold) referenced to VIN, enabling reliable startup across wide input range, and uses tON/ENDLY to stabilize regulation under variable line conditions. Use Value: Maintains stable output despite 48V input ripple and load transients up to 5A/µs, supported by 125°C-rated TSSOP package and robust gate drivers. | Use Scenario: Powered device (PD) interface board drawing power from IEEE 802.3af PoE midspan, requiring isolated 3.3V/1.5A for Ethernet PHY and microcontroller. IC Role / Device Role / Timing Role: LT3837IFE#TRPBF senses flyback voltage from auxiliary winding, enabling compact transformer design with integrated feedback; PGDLY resistor sets optimal dead time for Si7336ADP rectifier. Use Value: Reduces BOM count by removing optocoupler and TL431, cuts transformer cost via single-winding feedback, and achieves >86% efficiency at 1.5A load. |
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 | Primary-side sensing with integrated 700V MOSFET; no external PG/SG drivers; fixed 50kHz frequency; no load compensation or programmable timing. | Targeted at lower-power (<10W), cost-sensitive AC/DC adapters; lacks synchronous rectification support and multi-output cross-regulation features. | Select UCC28911DR only for simple, low-cost, single-output AC/DC flyback where integrated FET suffices and synchronous rectification is unnecessary. |
| MAX17690ATP+ | Supports both flyback and forward topologies; includes digital soft-start, fault logging, and I²C interface; requires external gate drivers; no built-in load compensation. | Designed for programmable, monitored industrial power supplies; adds telemetry and configurability but increases system complexity and component count. | Choose MAX17690ATP+ when digital control, fault diagnostics, or topology flexibility (flyback/forward) outweighs the simplicity and analog precision of LT3837IFE#TRPBF. |
Compared with UCC28911DR and MAX17690ATP+, the LT3837IFE#TRPBF uniquely balances analog precision, synchronous rectification readiness, and programmable timing for medium-power isolated DC-DC-delivering tighter regulation, higher efficiency, and simpler transformer design than the former, and lower system overhead than the latter.
Availability
LT3837IFE#TRPBF is available at Aetrix Electronics and suitable for isolated instrumentation power supplies, medical DC-DC converters, and industrial telecom modules requiring stable component supply, long-lifecycle assurance, and guaranteed -40°C to +125°C operation.
Supply support for LT3837IFE#TRPBF 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, Inc. (ADI) is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, formed through the acquisition of Linear Technology in 2017.
The LT3837IFE#TRPBF belongs to ADI's legacy Linear Technology isolated power controller product line, engineered specifically for high-accuracy, no-opto synchronous flyback converters in safety-critical and thermally demanding environments.
FAQ
What is the purpose of the ENDLY pin on the LT3837IFE#TRPBF?
The ENDLY pin on the LT3837IFE#TRPBF programs a fixed enable delay (265ns typical) between primary switch turn-off and activation of the flyback feedback amplifier. This blanking period rejects the initial voltage spike caused by transformer leakage inductance, ensuring the amplifier samples only the stable portion of the flyback pulse for accurate output voltage regulation. The delay is set by an external resistor to GND.
Can the LT3837IFE#TRPBF drive both primary and secondary MOSFETs directly?
Yes, the LT3837IFE#TRPBF integrates dual high-current gate drivers: PG (Pin 16) drives the primary-side MOSFET, and SG (Pin 1) drives the secondary-side synchronous rectifier. Both outputs deliver ≥7.4V high-level and ≤0.05V low-level drive with sub-15ns edge rates into 1nF loads, enabling direct interfacing with logic-level MOSFETs such as Si7852DP and Si7336ADP without external buffers.
How does load compensation work in the LT3837IFE#TRPBF?
Load compensation in the LT3837IFE#TRPBF corrects for output voltage droop caused by secondary-side resistance (RDS(ON), ESR). It uses the RCMP and CCMP pins to inject a compensating current into the FB node proportional to average primary current. This raises the effective feedback reference voltage under load, counteracting IR drops and maintaining tight regulation-verified in datasheet Figure 1 and Load Compensation Theory section.
What is the minimum recommended bypass capacitor for the VCC pin of the LT3837IFE#TRPBF?
The datasheet specifies a minimum 4.7µF ceramic or tantalum capacitor from VCC (Pin 2) to GND. This value ensures stable operation of internal regulators and gate drivers under transient load conditions. Larger values (e.g., 10µF) are acceptable and may improve noise immunity, but the 4.7µF minimum is required for reliable startup and steady-state performance across the full –40°C to +125°C temperature range of the LT3837IFE#TRPBF.
Does the LT3837IFE#TRPBF require an optocoupler for isolated feedback?
No, the LT3837IFE#TRPBF does not require an optocoupler. It achieves isolated output voltage regulation by sensing the flyback voltage across a dedicated transformer feedback winding (or primary winding) and comparing it to its internal 1.237V reference at the FB pin. This no-opto architecture improves dynamic response, reliability, and long-term stability-explicitly stated in the FEATURES and DESCRIPTION sections of the LT3837IFE#TRPBF datasheet.
LT3837IFE#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Packaging:
- Tape & Reel (TR)
- 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#TRPBF FAQ
1.How can I place an order for LT3837IFE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3837IFE#TRPBF 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#TRPBF reliable?
The price and inventory of LT3837IFE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3837IFE#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3837IFE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3837IFE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3837IFE#TRPBF?
LT3837IFE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3837IFE#TRPBF 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#TRPBF?
For technical support, including LT3837IFE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3837IFE#TRPBF requirements.
6.How does Aetrix verify that LT3837IFE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3837IFE#TRPBF 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#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3837IFE#TRPBF?
All LT3837IFE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3837IFE#TRPBF, 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#TRPBF part is unused and in its original packaging.
Return procedure for LT3837IFE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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