My Inquiry
My Account
Analog Devices Inc. LT1737CGN#TRPBF
- Part No.:
- LT1737CGN#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 16-SSOP (0.154", 3.90mm Width)
- Datasheet:
-
LT1737CGN#TRPBF.pdf
- Description:
- IC REG CTRLR FLYBACK 16SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,122
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
LT1737CGN#TRPBF from Analog Devices (acquired Linear Technology) is a current-mode isolated flyback controller IC designed to drive external N-channel MOSFETs in primary-side regulated, transformer-isolated DC/DC converters. It operates from 4.5V to 20V supply, supports 50kHz–250kHz switching via external OSCAP capacitor, senses output voltage directly from the primary winding without optocoupler, and delivers up to tens of watts with discontinuous-mode regulation maintained. It is used in medical instrument power supplies requiring reinforced isolation and low EMI.
For engineers reviewing the LT1737CGN#TRPBF datasheet, LT1737CGN#TRPBF pinout, LT1737CGN#TRPBF application, or LT1737CGN#TRPBF equivalent, key selection considerations include primary-side feedback accuracy (±1.2% VFB), UVLO threshold (1.25V typ), gate drive capability (500mA sink/source), soft-start control via SFST pin, and load compensation support via ROCMP/RCMPC pins for improved line/load regulation in high-precision isolated supplies.
Technical Context
The LT1737CGN#TRPBF implements a proprietary flyback error amplifier that samples the reflected flyback pulse during a precisely timed window-enabled after programmable ENDLY delay and disabled by collapse detection-ensuring accurate output voltage sensing independent of secondary-side components. Its current-mode architecture uses ISENSE pin voltage (250mV typ limit) and VC control node for cycle-by-cycle peak current limiting and loop stability.
It integrates a 3V reference (3.0V ±0.2V at 1mA), shutdown logic reducing IQ to 50µA typ, and timing functions set by external resistors on tON, MINENAB, and ENDLY pins. The internal oscillator frequency is determined solely by OSCAP capacitance (e.g., 100pF → 100kHz), with no internal RC dependency.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage Range | 4.5V to 20V - Enables direct operation from 5V, 12V, or 15V intermediate rails without LDO pre-regulation. |
| Feedback Reference Voltage | 1.245V (typ) - Sets output voltage accuracy; combined with R1/R2 divider and transformer turns ratio, enables precise primary-side regulation without optocoupler. |
| Switching Frequency Range | 50kHz to 250kHz - Adjustable via OSCAP capacitor; higher frequencies reduce transformer size but increase MOSFET switching loss. |
| Gate Drive Output | 11.8V high / 0.45V low (at 500mA) - Sufficient to fully enhance standard logic-level N-MOSFETs with minimal external buffering. |
| UVLO Threshold | 1.25V (typ) - Provides clean startup and brownout protection; hysteresis configurable via external resistor divider on UVLO pin. |
| Shutdown Current | 50µA (typ) - Enables ultra-low-power standby mode; critical for battery-backed or energy-sensitive medical systems. |
| Operating Temperature | 0°C to 100°C (C-grade) - Qualified for commercial/industrial environments; junction max 125°C with θJA = 110°C/W in GN package. |
Pinout & Package
LT1737CGN#TRPBF is housed in a 16-lead plastic SSOP (GN) package with exposed pad for thermal enhancement. Pin pitch is 0.65mm; body dimensions are 5.0mm × 6.0mm × 1.1mm. Recommended PCB layout isolates PGND (high di/dt) from SGND (signal reference) and routes GATE trace short and wide.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| PGND (1) | Power ground return for GATE discharge current | Carries high-frequency, high-amplitude current spikes (hundreds of mA); must connect directly to solid ground plane to avoid noise coupling into signal paths. |
| ISENSE (2) | Current sense input for MOSFET peak current limit | Monitors voltage across external shunt resistor; internal 250mV threshold ensures accurate cycle-by-cycle current limiting and overcurrent protection. |
| SFST (3) | Soft-start capacitor connection | Charges linearly via 40µA internal current source; controls ramp rate of VC voltage to prevent inrush current and overshoot during startup. |
| ROCMP (4) | Load compensation resistor input | Accepts current proportional to average switch current; compensates for output impedance errors (diode ESR, winding resistance) to improve load regulation. |
| RCMPC (5) | Load compensation filter capacitor | Filters ROCMP current signal; 0.1µF ceramic typical; stabilizes compensation loop and prevents instability under dynamic load steps. |
| OSCAP (6) | Oscillator timing capacitor | Sets switching frequency (e.g., 100pF → 100kHz); value directly determines fSW with no trimming required. |
| VC (7) | Control voltage output of feedback amplifier | Integrates net current from FB amplifier and fixed current source; sets current comparator trip point and defines loop compensation node. |
| FB (8) | Feedback voltage input | Receives scaled flyback pulse from third winding; referenced to internal 1.245V bandgap; Thevenin impedance ~3kΩ for optimal bias cancellation. |
| 3VOUT (9) | Internal 3V reference output | Stable 3.0V ±0.2V source; current-limited to 15mA; drives small logic loads or provides bias for auxiliary circuitry without external regulator. |
| UVLO (10) | Undervoltage lockout and shutdown control | Pulling below 0.95V disables controller and reduces IQ to 50µA; resistor divider from VIN enables programmable brownout threshold with hysteresis. |
| SGND (11) | Signal ground reference | Reference for FB, OSCAP, VC, and internal references; must be isolated from PGND to prevent switching noise from corrupting feedback accuracy. |
| MINENAB (12) | Minimum enable time programming | Resistor sets minimum duration the flyback amplifier remains active; prevents lockup during low-load or start-up conditions. |
| ENDLY (13) | Enable delay time programming | Resistor sets delay between MOSFET turn-off and flyback amplifier activation; avoids leakage spike corruption of feedback sampling. |
| tON (14) | Minimum switch on-time programming | Resistor enforces absolute minimum conduction time per cycle; ensures flyback pulse generation even at light loads to maintain regulation. |
| VCC (15) | Controller supply input | Requires ≥1µF local ceramic bypass to PGND; powers internal bias, oscillator, and gate driver; not internally regulated. |
| GATE (16) | MOSFET gate driver output | High-current push-pull stage; capable of 500mA sink/source; requires short, low-inductance trace to MOSFET gate to minimize ringing and EMI. |
Key Features
| Feature | Design Value |
|---|---|
| Primary-side regulation without optocoupler | Eliminates optocoupler aging, CTR drift, and bandwidth limitations-enabling long-term stability and reduced BOM count in medical and industrial isolation barriers. |
| Programmable flyback sampling window | ENDLY, MINENAB, and tON pins allow precise timing control of feedback acquisition, enabling robust operation despite transformer leakage inductance and variable duty cycles. |
| Integrated 3V reference with current limiting | Provides stable, low-noise bias for auxiliary circuits (e.g., sensor bias, ADC reference) without external LDO-reducing board space and improving system efficiency. |
| Load compensation via ROCMP/RCMPC | Corrects for output impedance effects (diode VF, winding resistance, capacitor ESR), achieving <±2% load regulation across 10–100% load range in well-designed implementations. |
| Discontinuous-mode regulation maintenance | Unique control architecture sustains tight output regulation even as converter transitions into DCM-critical for wide-input-range supplies powering variable loads. |
Applications
| Medical Isolated Power Supplies | Industrial Sensor Interface Power |
|---|---|
Use Scenario: Providing reinforced-isolation 15V/300mA output from 12–18V input in portable ultrasound or patient-monitoring equipment. IC Role / Device Role / Timing Role: Primary-side flyback controller executing gated flyback pulse sampling and current-mode PWM to regulate output without secondary-side feedback components. Use Value: Meets IEC 60601-1 creepage/clearance requirements while eliminating optocoupler reliability concerns and simplifying certification documentation. | Use Scenario: Generating isolated ±12V rails for precision analog front-ends in factory automation IO modules operating from 24V DC bus. IC Role / Device Role / Timing Role: Isolated flyback controller managing dual-output transformer with cross-regulation via primary-sampled feedback and load compensation. Use Value: Achieves <±3% cross-regulation across load steps without post-regulators, reducing component count and thermal stress in compact enclosures. |
| Test Equipment Auxiliary Supplies | Energy Metering Isolation Barriers |
Use Scenario: Delivering 5V/1A isolated bias for digital isolators and ADC drivers in benchtop multimeters with 100-year MTBF target. IC Role / Device Role / Timing Role: High-accuracy flyback controller using VC node compensation and soft-start to ensure monotonic startup and zero output overshoot. Use Value: Guarantees no voltage glitch during power-on reset of sensitive metrology ICs-preventing calibration faults and field returns. | Use Scenario: Supplying isolated 3.3V for microcontroller and communication ICs in DIN-rail mounted smart electricity meters with 15-year service life. IC Role / Device Role / Timing Role: Low-quiescent flyback controller leveraging 50µA shutdown current and temperature-stable VFB to maintain accuracy over –25°C to +70°C ambient. Use Value: Extends battery backup runtime during mains failure and ensures meter data integrity across full industrial temperature range. |
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 65kHz frequency; integrated high-voltage start-up; no 3VOUT pin; lower gate drive (200mA) | Optimized for cost-sensitive consumer adapters; lacks programmable timing and load compensation | Select UCC28740DR only if fixed frequency, HV start-up, and lower gate drive suffice-and optocoupler-based designs are acceptable. |
| MAX17690ATP+T | Higher VCC range (up to 36V); integrated 5V LDO; no primary-side sampling-requires optocoupler feedback | Targets industrial 24V/48V input systems; adds complexity and cost with optocoupler and secondary-side circuitry | Choose MAX17690ATP+T when input exceeds 20V or when secondary-side regulation with tighter tolerance (<±1%) is mandatory. |
Compared with UCC28740DR and MAX17690ATP+T, the LT1737CGN#TRPBF uniquely combines primary-side regulation, programmable timing, load compensation, and a 3V reference-making it the only choice for high-reliability, optocoupler-free isolated supplies where transformer parasitics and load variation must be actively managed without secondary feedback.
Availability
LT1737CGN#TRPBF is available at Aetrix Electronics and suitable for medical instrumentation power supplies, industrial sensor interface modules, test equipment auxiliary rails, and energy metering isolation barriers requiring stable component supply, long-term lifecycle assurance, and guaranteed traceable sourcing.
Supply support for LT1737CGN#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 technologies, serving industrial, automotive, communications, and healthcare markets.
The LT1737CGN#TRPBF belongs to ADI's legacy Linear Technology isolated power controller family, engineered specifically for primary-side regulated flyback converters where safety certification, long-term reliability, and transformer parasitic immunity are critical design constraints.
FAQ
What is the maximum recommended switching frequency for LT1737CGN#TRPBF?
The LT1737CGN#TRPBF supports a switching frequency range of 50kHz to 250kHz, set by the external OSCAP capacitor. At 250kHz, the minimum OSCAP value is 33pF. Higher frequencies increase MOSFET switching losses and require careful attention to transformer leakage inductance and snubber design. For most medical and industrial applications, 100kHz–150kHz offers optimal balance of size, efficiency, and EMI performance in the LT1737CGN#TRPBF.
Does LT1737CGN#TRPBF require an optocoupler for feedback?
No, the LT1737CGN#TRPBF does not require an optocoupler. It implements primary-side regulation by sampling the reflected flyback pulse from a third transformer winding (or primary winding) and comparing it to its internal 1.245V reference. This eliminates optocoupler CTR drift, aging, and bandwidth limitations-making the LT1737CGN#TRPBF ideal for long-life, high-reliability isolated supplies.
How is load regulation improved using the ROCMP pin on LT1737CGN#TRPBF?
The ROCMP pin on LT1737CGN#TRPBF accepts a current proportional to average MOSFET switch current, which is used to offset the FB pin voltage. This compensates for voltage drops caused by secondary-side impedances-including Schottky diode forward voltage, transformer winding resistance, and output capacitor ESR-thereby improving load regulation to typically <±2% across full load range when properly configured.
What is the purpose of the ENDLY and MINENAB pins on LT1737CGN#TRPBF?
The ENDLY pin programs the delay between MOSFET turn-off and activation of the flyback error amplifier, preventing contamination by transformer leakage spikes. The MINENAB pin sets the minimum duration the amplifier remains enabled, ensuring sufficient integration time for VC node settling-especially during startup or low-load conditions. Both are essential for stable, accurate regulation in the LT1737CGN#TRPBF across varying transformer designs and load profiles.
Can LT1737CGN#TRPBF operate with input voltages below 4.5V?
No, the LT1737CGN#TRPBF has a specified minimum VCC supply voltage of 4.5V (4.1V min over temperature). Operation below this risks improper gate drive, unstable oscillator behavior, and failure of the feedback amplifier. For sub-4.5V inputs, a pre-regulator or charge-pump booster is required before the VCC pin. The UVLO function will hold the LT1737CGN#TRPBF in shutdown until VCC exceeds the 4.5V threshold.
LT1737CGN#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:
- 0°C ~ 100°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SSOP
LT1737CGN#TRPBF FAQ
1.How can I place an order for LT1737CGN#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1737CGN#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 LT1737CGN#TRPBF reliable?
The price and inventory of LT1737CGN#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1737CGN#TRPBF is usually 5 days.
3.What payment methods are accepted for LT1737CGN#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1737CGN#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1737CGN#TRPBF?
LT1737CGN#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1737CGN#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 LT1737CGN#TRPBF?
For technical support, including LT1737CGN#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1737CGN#TRPBF requirements.
6.How does Aetrix verify that LT1737CGN#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT1737CGN#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 LT1737CGN#TRPBF meets industry standards.
7.What is the process for return or replacement of LT1737CGN#TRPBF?
All LT1737CGN#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1737CGN#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 LT1737CGN#TRPBF part is unused and in its original packaging.
Return procedure for LT1737CGN#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LT1737CGN#TRPBF Tags
-
UCC28C45DR
Texas Instruments
-
UCC28C40DR
Texas Instruments
-
UCC28C43DR
Texas Instruments
-
ZXSC410E6TA
Diodes Incorporated
-
LM3524DMX/NOPB
Texas Instruments
-
LM3489MMX/NOPB
Texas Instruments
-
MIC2102YML-TR
Microchip Technology
-
LM5148RGYR
Texas Instruments
-
TL598CDR
Texas Instruments
-
LM5155DSSR
Texas Instruments
-
LM25085MYX/NOPB
Texas Instruments
-
UCC2813DTR-0
Texas Instruments
Tech Hub
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…
