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Analog Devices Inc. LT1737IGN#TRPBF
- Part No.:
- LT1737IGN#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 16-SSOP (0.154", 3.90mm Width)
- Datasheet:
-
LT1737IGN#TRPBF.pdf
- Description:
- IC REG CTRLR FLYBACK 16SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:8,441
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Product details
Overview
LT1737IGN#TRPBF from Analog Devices (formerly Linear Technology) is a current-mode isolated flyback controller IC designed to drive an external N-channel MOSFET in primary-side regulated, transformer-isolated DC/DC converters. It operates from 4.5V to 20V supply, supports 50kHz–250kHz switching frequency via external OSCAP capacitor, delivers up to tens of watts output power, and achieves ±1.2% feedback reference accuracy (1.245 V typ) without user trimming - enabling compact, low-cost medical and instrumentation power supplies.
For engineers reviewing the LT1737IGN#TRPBF datasheet, LT1737IGN#TRPBF pinout, LT1737IGN#TRPBF application, or LT1737IGN#TRPBF equivalent, key selection considerations include primary-side sensing capability (no optoisolator required), discontinuous-mode regulation stability, programmable soft-start (SFST pin), load compensation (ROCMP/RCMPC), and undervoltage lockout (UVLO pin) with hysteresis control - all critical for reliable isolated supply design under variable line/load conditions.
Technical Context
The LT1737IGN#TRPBF implements a specialized flyback error amplifier that samples the reflected flyback pulse from a third winding (or primary) to derive output voltage information - eliminating optocouplers. Its internal 1.245 V bandgap reference (VBG) sets FB pin threshold, and VC pin serves as integrator node for loop compensation.
Control timing includes three user-programmable delays: tON (minimum switch on time), ENDLY (enable delay to reject leakage spikes), and MINENAB (minimum enable time to prevent latch-up during start-up). Collapse detection disables the error amplifier when the flyback pulse falls below 80% of VBG, supporting both continuous and discontinuous conduction modes.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage Range | 4.5 V to 20 V - powers internal bias regulator and gate driver; UVLO ensures operation only above 1.25 V on UVLO pin. |
| Feedback Reference Voltage | 1.245 V (typ) - precise internal bandgap sets output voltage via R1/R2 divider; enables ±1.2% regulation without trimming. |
| Switching Frequency Range | 50 kHz to 250 kHz - set by external OSCAP capacitor (33 pF to 200 pF); allows optimization of size, efficiency, and EMI. |
| Current Sense Threshold | 250 mV (typ) at ISENSE - limits peak switch current; supports high-power designs with external MOSFET and sense resistor. |
| Gate Drive Output | 12.1 V high / 0.45 V low (at 100 mA) - drives N-MOSFET gates directly; rise/fall times ≤30 ns support fast switching. |
| Operating Temperature | –40°C to +125°C - industrial-grade rating (I-grade) suitable for medical instruments and embedded systems with thermal stress. |
| Shutdown Current | 50 µA (typ) - achieved by pulling UVLO pin low; reduces system standby power significantly. |
Pinout & Package
LT1737IGN#TRPBF is housed in a 16-lead plastic SSOP (GN) package with exposed pad for thermal performance. Pin layout follows standard SSOP top view: pins 1–8 on bottom row (left to right), pins 9–16 on top row (right to left).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| PGND (1) | Power ground return | Carries high-current GATE discharge spikes; must connect directly to low-inductance ground plane. |
| ISENSE (2) | Current sense input | Monitors external sense resistor voltage; triggers switch turn-off at 250 mV threshold. |
| SFST (3) | Soft-start capacitor | Controls startup ramp rate; external capacitor sets soft-start duration and prevents inrush overshoot. |
| ROCMP (4) | Load compensation resistor | Enables correction for secondary impedance (diode ESR, winding resistance) to improve load regulation. |
| RCMPC (5) | Load compensation filter | Filters average switch current signal; 0.1 µF ceramic typical for stable compensation loop. |
| OSCAP (6) | Oscillator timing capacitor | Sets switching frequency; value (33–200 pF) directly determines fSW per datasheet curve. |
| VC (7) | Control voltage integrator | Output of feedback amplifier and input to current comparator; external RC network sets loop compensation. |
| FB (8) | Feedback input | Compares scaled flyback pulse to 1.245 V reference; Thevenin impedance ~3 kΩ recommended. |
| 3VOUT (9) | 3 V reference output | Stable 3.0 V (±0.2 V) source for auxiliary circuits; internally current-limited to 15 mA. |
| UVLO (10) | Undervoltage lockout/shutdown | Pulling low disables controller and reduces IQ to 50 µA; resistor divider enables programmable input UVLO threshold. |
| SGND (11) | Signal ground | Reference for FB, OSCAP, VC; must be isolated from PGND to avoid noise coupling into feedback path. |
| MINENAB (12) | Minimum enable time resistor | Prevents feedback amplifier disable too early during light-load or start-up; avoids VC pump-down failure. |
| ENDLY (13) | Enable delay resistor | Delays feedback amplifier activation after switch turn-off to reject transformer leakage spikes. |
| tON (14) | Minimum on-time resistor | Ensures minimum conduction per cycle; maintains regulation at very light loads and prevents erratic behavior. |
| VCC (15) | Supply input | Accepts 4.5–20 V; requires ≥1 µF local bypass capacitor to suppress switching noise. |
| GATE (16) | MOSFET gate driver | High-current push-pull output; trace must be short and low-inductance to minimize ringing and EMI. |
Key Features
| Feature | Design Value |
|---|---|
| Primary-side regulation | Eliminates optoisolator and secondary-side feedback components - reduces BOM cost and improves reliability in medical/isolated systems. |
| Discontinuous mode stability | Maintains tight output regulation even at light loads where flyback energy transfer becomes intermittent - critical for variable-output applications. |
| Programmable timing functions | tON, ENDLY, and MINENAB pins allow independent adjustment of minimum on-time, enable delay, and minimum enable time - enabling robust design across wide input/output ranges. |
| Load compensation interface | ROCMP/RCMPC pins support active correction of output impedance errors from diode forward drop, winding resistance, and capacitor ESR - improves load regulation to <±2% over full load range. |
| Integrated 3 V reference | Provides stable, low-noise 3.0 V output (±0.2 V) for biasing sensors or logic - eliminates need for external LDO in auxiliary rail generation. |
Applications
| Medical Power Supplies | Industrial Instrumentation |
|---|---|
Use Scenario: Isolated 15 V @ 300 mA output from 12–18 V input in portable diagnostic equipment requiring reinforced isolation and low EMI. IC Role / Device Role / Timing Role: Primary-side flyback controller managing MOSFET switching, flyback pulse sampling, and dynamic loop compensation without optocoupler. Use Value: Enables compact, CE/IEC 60601-compliant design with <1% load regulation drift and no secondary-side feedback components. | Use Scenario: Dual-rail ±12 V isolated supply for precision analog front-ends in data acquisition modules operating in noisy factory environments. IC Role / Device Role / Timing Role: Isolated flyback controller implementing programmable enable delay (ENDLY) and minimum on-time (tON) to reject transformer leakage spikes and maintain regulation under transient loads. Use Value: Delivers stable output despite 10–90% load steps and input ripple up to 2 Vpp, with <±1.5% total output variation. |
| Laboratory Test Equipment | Point-of-Care Diagnostics |
Use Scenario: 5 V/2 A isolated output from 24 V bus in benchtop oscilloscope power stage requiring low standby power and fast transient response. IC Role / Device Role / Timing Role: Flyback controller using UVLO pin for brown-out protection and SFST pin for controlled soft-start to limit inrush current during hot-plug events. Use Value: Achieves <50 µA shutdown current and <100 ms startup time with no output overshoot or oscillation. | Use Scenario: Compact 3.3 V @ 500 mA isolated supply for battery-powered blood glucose meters needing long shelf life and IEC 60601 creepage/clearance compliance. IC Role / Device Role / Timing Role: Primary-side regulated controller leveraging integrated 3VOUT pin to power microcontroller and sensor bias rails - reducing component count. Use Value: Reduces bill-of-materials by two regulators and simplifies PCB layout while meeting 2× MOPP isolation requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar isolated flyback controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| UCC28740DR | Fixed-frequency quasi-resonant controller with integrated HV start-up; lacks primary-side sensing flexibility and programmable timing (ENDLY/tON). | Better suited for high-efficiency AC/DC adapters; less flexible for custom DC/DC flyback designs with variable input or tight regulation needs. | Select UCC28740DR only if HV start-up and QR operation are mandatory; LT1737IGN#TRPBF offers superior primary-side control granularity for DC-input isolated supplies. |
| MAX17595ATP+ | Current-mode flyback controller with integrated MOSFET driver but no 3VOUT pin or load compensation interface; fixed 100 kHz default frequency. | Targeted at cost-sensitive industrial PSUs; lacks ROCMP/RCMPC and SFST pins, limiting load regulation and soft-start customization. | Choose MAX17595ATP+ for simpler, lower-cost implementations where ±3% load regulation suffices; LT1737IGN#TRPBF preferred when <±1.5% regulation and programmable dynamics are required. |
Compared with UCC28740DR and MAX17595ATP+, the LT1737IGN#TRPBF provides unique primary-side timing programmability (tON/ENDLY/MINENAB), dedicated load compensation (ROCMP/RCMPC), and an integrated 3 V reference - making it the only option among the three capable of achieving sub-1% load regulation in medical-grade DC/DC flyback designs without secondary feedback.
Availability
LT1737IGN#TRPBF is available at Aetrix Electronics and suitable for medical power supplies, industrial instrumentation, laboratory test equipment, and point-of-care diagnostics requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.
Supply support for LT1737IGN#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 (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 LT1737IGN#TRPBF belongs to Linear's legacy isolated power controller family, engineered specifically for primary-side regulated flyback converters in safety-critical applications where optocoupler elimination, tight regulation, and robust transient response are essential.
FAQ
What is the maximum switching frequency supported by the LT1737IGN#TRPBF?
The LT1737IGN#TRPBF supports a switching frequency range of 50 kHz to 250 kHz, set by the external OSCAP capacitor value (33 pF to 200 pF). At 100 pF, the typical frequency is 100 kHz. Operation beyond 250 kHz is not specified and may compromise regulation stability or increase gate drive losses in the external MOSFET driven by the LT1737IGN#TRPBF.
Does the LT1737IGN#TRPBF require an optocoupler for feedback?
No, the LT1737IGN#TRPBF does not require an optocoupler. It implements primary-side regulation by sensing the reflected flyback voltage from a third winding or the primary winding itself, comparing it to its internal 1.245 V reference at the FB pin. This architecture eliminates optocouplers and secondary-side error amplifiers, reducing cost and improving reliability in the LT1737IGN#TRPBF-based design.
How does the LT1737IGN#TRPBF handle discontinuous conduction mode (DCM)?
Unlike many flyback controllers, the LT1737IGN#TRPBF maintains stable regulation well into discontinuous conduction mode due to its specialized flyback error amplifier and collapse-detect circuitry. The amplifier activates only during the flyback pulse window, and the collapse comparator disables it when the pulse drops below 80% of VBG - ensuring consistent loop behavior across continuous and DCM operation in the LT1737IGN#TRPBF.
Can the LT1737IGN#TRPBF generate a 3 V auxiliary supply?
Yes, the LT1737IGN#TRPBF features a dedicated 3VOUT pin delivering a stable 3.0 V (±0.2 V) reference output with up to 15 mA drive capability. This pin is internally current-limited and optimized for driving small capacitive loads (≤100 pF) or large ones (≥0.1 µF), enabling direct biasing of microcontrollers or sensors without adding an external LDO - a key integration advantage of the LT1737IGN#TRPBF.
What is the purpose of the ROCMP and RCMPC pins on the LT1737IGN#TRPBF?
The ROCMP and RCMPC pins implement active load compensation to correct for output voltage droop caused by secondary-side impedance (diode VF, winding resistance, capacitor ESR). ROCMP sets compensation gain via an external resistor, while RCMPC filters the average switch current signal. Together, they inject corrective current into the FB node, improving load regulation from >±5% to <±2% - a critical capability in precision applications using the LT1737IGN#TRPBF.
LT1737IGN#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-SSOP (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Output Type:
- Transistor Driver
- Function:
- Step-Up/Step-Down
- Output Configuration:
- Positive or Negative, Isolation Capable
- Topology:
- Flyback
- Number of Outputs:
- 1
- Output Phases:
- 1
- Voltage - Supply (Vcc/Vdd):
- 4.1V ~ 20V
- Frequency - Switching:
- 90kHz ~ 115kHz
- Duty Cycle (Max):
- 90%
- Synchronous Rectifier:
- No
- Clock Sync:
- No
- Serial Interfaces:
- -
- Control Features:
- Enable, Soft Start
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SSOP
LT1737IGN#TRPBF FAQ
1.How can I place an order for LT1737IGN#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1737IGN#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 LT1737IGN#TRPBF reliable?
The price and inventory of LT1737IGN#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1737IGN#TRPBF is usually 5 days.
3.What payment methods are accepted for LT1737IGN#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1737IGN#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1737IGN#TRPBF?
LT1737IGN#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1737IGN#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 LT1737IGN#TRPBF?
For technical support, including LT1737IGN#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1737IGN#TRPBF requirements.
6.How does Aetrix verify that LT1737IGN#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT1737IGN#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 LT1737IGN#TRPBF meets industry standards.
7.What is the process for return or replacement of LT1737IGN#TRPBF?
All LT1737IGN#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1737IGN#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 LT1737IGN#TRPBF part is unused and in its original packaging.
Return procedure for LT1737IGN#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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