My Inquiry
My Account
Analog Devices Inc. LT1737CGN#PBF
- Part No.:
- LT1737CGN#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 16-SSOP (0.154", 3.90mm Width)
- Datasheet:
-
LT1737CGN#PBF.pdf
- Description:
- IC REG CTRLR FLYBACK 16SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:289
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
LT1737CGN#PBF from Analog Devices (formerly Linear Technology) is a current-mode isolated flyback controller IC designed to drive an external N-channel MOSFET in high-efficiency, galvanically 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 enables primary-side regulation without optocoupler-used in medical instrument power supplies and industrial isolated bias rails.
For engineers reviewing the LT1737CGN#PBF datasheet, LT1737CGN#PBF pinout, LT1737CGN#PBF application, or LT1737CGN#PBF equivalent, key selection considerations include its 16-pin SSOP (GN) package, UVLO and shutdown control via UVLO pin, soft-start via SFST, load compensation via ROCMP/RCMPC, and primary-side feedback architecture eliminating optoisolator dependency.
Technical Context
The LT1737CGN#PBF implements a specialized flyback error amplifier that samples the reflected flyback pulse from a third transformer winding (or primary), comparing it to a 1.245V internal bandgap reference. Its timing logic enforces minimum on-time (tON), enable delay (ENDLY), and minimum enable time (MINENAB) to ensure stable operation across continuous and discontinuous conduction modes.
It integrates a 3V reference output (3VOUT), programmable load compensation using ROCMP/RCMPC, and current-sense amplification with 250mV threshold at ISENSE. Gate drive delivers >11V high-level output with 100mA sink/source capability and <30ns rise/fall times into 1000pF load-optimized for fast-switching MOSFETs in compact flyback topologies.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage Range | 4.5V to 20V - powers internal bias circuitry and gate driver; absolute max 22V limits input rail design margin. |
| Switching Frequency | 50kHz to 250kHz - set by external OSCAP capacitor (33pF–200pF); enables trade-off between size, efficiency, and EMI. |
| Feedback Reference Voltage | 1.245V ±15mV - precise internal bandgap reference used to regulate output voltage via FB pin divider ratio. |
| Current Sense Threshold | 250mV nominal at ISENSE - sets peak switch current limit; tolerance ±30mV ensures consistent overcurrent protection. |
| GATE Drive Output | 11.8V min high level @500mA sink - drives standard logic-level MOSFETs directly; low-level <0.45V @100mA ensures clean turn-off. |
| UVLO Threshold | 1.25V ±0.04V - halts operation when VUVLO falls below threshold; hysteresis enabled via external resistor divider. |
| Shutdown Current | 50µA typical - reduces quiescent draw during disable; enables low-power standby in battery-backed systems. |
Pinout & Package
LT1737CGN#PBF is housed in a 16-lead plastic SSOP (GN) package with exposed pad thermal enhancement. Pin pitch is 0.025", body dimensions 5.0mm × 6.2mm × 1.0mm. Thermal resistance θJA = 110°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| PGND (1) | Power ground return for GATE discharge current | Carries high di/dt spikes (hundreds of mA, ns duration); must connect directly to low-impedance ground plane. |
| ISENSE (2) | Primary-side current sense input | Monitors external sense resistor voltage; internal comparator trips at ~250mV to limit peak MOSFET current. |
| SFST (3) | Soft-start capacitor connection | Charges linearly to ramp VC voltage; controls startup dV/dt and prevents output overshoot. |
| ROCMP (4) | Load compensation resistor input | Accepts current proportional to average switch current; compensates for secondary impedance-induced output droop. |
| RCMPC (5) | Load compensation filter capacitor | Filters ROCMP current signal; 0.1µF ceramic typical; stabilizes compensation loop against noise. |
| OSCAP (6) | Oscillator timing capacitor | Sets switching frequency; value 33pF–200pF determines fSW = 50–250kHz per datasheet curve. |
| VC (7) | Control voltage node / loop compensation point | Integrator output of feedback amplifier; connects to external RC network for stability tuning. |
| FB (8) | Feedback voltage input | Compares divided flyback pulse to 1.245V reference; Thevenin impedance ~3kΩ recommended. |
| 3VOUT (9) | Internal 3V reference output | Provides stable 3.0V ±0.2V reference; current-limited to 15mA; drives small capacitive loads or logic inputs. |
| UVLO (10) | Undervoltage lockout and shutdown control | Pulling to GND disables IC and reduces IQ to 50µA; resistor divider enables programmable input UVLO threshold. |
| SGND (11) | Signal ground reference | Reference for FB, OSCAP, VC; must be isolated from PGND currents to avoid noise coupling into feedback path. |
| MINENAB (12) | Minimum enable time programming | Resistor sets minimum duration FB amplifier is active; prevents latch-up during low-load or start-up conditions. |
| ENDLY (13) | Enable delay programming | Resistor sets delay between MOSFET turn-off and FB amplifier activation; rejects leakage spike artifacts. |
| tON (14) | Minimum switch on-time programming | Resistor sets absolute minimum MOSFET conduction time per cycle; maintains regulation at light loads. |
| VCC (15) | IC supply input | Requires ≥1µF local bypass capacitor; powers internal regulators, gate driver, and analog blocks. |
| GATE (16) | MOSFET gate driver output | High-current push-pull output; layout requires short trace + series damping resistor (≥5Ω) to suppress ringing. |
Key Features
| Feature | Design Value |
|---|---|
| Primary-side regulation without optocoupler | Uses third-winding or primary-referred flyback pulse sampling-eliminates opto latency, aging, and CMTI constraints in medical/industrial isolation. |
| Discontinuous mode regulation maintenance | Specialized timing logic (ENDLY, MINENAB, tON) sustains stable control down to zero load in DCM-critical for variable-output or standby applications. |
| Programmable load compensation | ROCMP/RCMPC interface corrects for secondary winding resistance, diode VF, and capacitor ESR-improves load regulation from ±5% to ±1% typical. |
| Integrated 3V reference output | Stable 3.0V ±0.2V source with 15mA drive-enables local bias for auxiliary circuits (e.g., sensing, monitoring) without extra LDO. |
| UVLO with user-adjustable hysteresis | VUVLO threshold 1.25V ±40mV; hysteresis set by Thevenin impedance of external divider-prevents oscillation near brownout thresholds. |
Applications
| Medical Isolated Bias Supply | Industrial Sensor Interface Power |
|---|---|
Use Scenario: Providing isolated ±15V and +5V rails for EEG amplifiers and patient-connected front-end circuitry in diagnostic equipment. IC Role / Device Role / Timing Role: LT1737CGN#PBF acts as primary-side flyback controller, regulating output via third-winding feedback while maintaining 4kV reinforced isolation and low leakage current. Use Value: Eliminates optocoupler and secondary-side TL431, reducing BOM count and long-term drift; meets IEC 60601-1 creepage/clearance requirements with simplified transformer design. | Use Scenario: Generating isolated 12V/5V outputs for 4–20mA transmitter modules mounted in hazardous area field enclosures. IC Role / Device Role / Timing Role: LT1737CGN#PBF controls external MOSFET to deliver regulated output under wide input (12–18V) and load (10–100mA) variation, with UVLO preventing operation below safe input range. Use Value: Programmable load compensation maintains ±1% output accuracy across temperature and load-ensuring precise sensor excitation and ADC reference stability. |
| Lab Equipment Auxiliary Supply | Test & Measurement Isolated DUT Power |
Use Scenario: On-board isolated 15V@300mA converter for oscilloscope channel front-ends requiring low-noise, low-ripple bias. IC Role / Device Role / Timing Role: LT1737CGN#PBF implements fixed-frequency current-mode control with soft-start (SFST) and minimum on-time (tON) to prevent startup instability and output overshoot. Use Value: 100kHz–200kHz operation balances transformer size and EMI filtering; integrated 3VOUT powers local DACs and comparators-reducing component count. | Use Scenario: Programmable isolated DC source (5–24V) for powering devices-under-test in automated test systems with floating grounds. IC Role / Device Role / Timing Role: LT1737CGN#PBF serves as digitally adjustable flyback controller-feedback divider and ROCMP tuned via microcontroller GPIO to change output voltage/load compensation dynamically. Use Value: Primary-side sensing enables rapid voltage reconfiguration without secondary-side communication; shutdown via UVLO pin allows remote power cycling. |
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; requires optocoupler for tight regulation. | Better suited for cost-sensitive consumer adapters; lacks primary-side precision and load compensation. | Select UCC28740DR only if start-up simplicity and lower BOM cost outweigh need for opto-free design and tight load regulation. |
| MAX17690ATP+T | Higher VCC range (up to 36V); includes synchronous rectifier control; no built-in 3V reference; different pinout and compensation scheme. | Targeted at higher-input industrial supplies; requires redesign of feedback and gate drive paths. | Choose MAX17690ATP+T when input exceeds 20V or synchronous rectification is required-but expect full schematic and layout revision. |
Compared with UCC28740DR and MAX17690ATP+T, the LT1737CGN#PBF uniquely combines optocoupler-free primary-side regulation, programmable load compensation, and an integrated 3V reference-making it optimal for medical and precision industrial flyback designs where isolation integrity, load accuracy, and auxiliary bias integration are critical.
Availability
LT1737CGN#PBF is available at Aetrix Electronics and suitable for medical instrumentation power supplies, industrial sensor interface rails, and lab-grade isolated auxiliary converters requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.
Supply support for LT1737CGN#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, Inc. (ADI) is a global semiconductor leader specializing in high-performance analog, mixed-signal, and digital signal processing technologies for precision, power, and connectivity applications.
The LT1737CGN#PBF belongs to ADI's legacy Linear Technology isolated power controller product line, engineered specifically for high-reliability, optocoupler-free flyback converters in medical, test equipment, and industrial environments demanding tight regulation and robust isolation.
FAQ
What is the maximum switching frequency supported by the LT1737CGN#PBF?
The LT1737CGN#PBF supports a switching frequency range of 50kHz to 250kHz, set by the external OSCAP capacitor value (33pF to 200pF). At 100pF, typical frequency is 100kHz. Operation beyond 250kHz is not characterized or guaranteed-exceeding this may compromise regulation stability and gate drive timing margins in the LT1737CGN#PBF.
Does the LT1737CGN#PBF require an optocoupler for isolated output regulation?
No, the LT1737CGN#PBF does not require an optocoupler. It achieves isolated output regulation by sensing the reflected flyback voltage from a third transformer winding or the primary winding, comparing it to its internal 1.245V reference at the FB pin. This primary-side sensing architecture eliminates optocoupler dependency, reducing cost, size, and long-term drift in the LT1737CGN#PBF-based design.
How is load regulation improved using the ROCMP and RCMPC pins on the LT1737CGN#PBF?
The ROCMP and RCMPC pins implement active load compensation in the LT1737CGN#PBF by injecting a current into the FB node proportional to average switch current-counteracting voltage drop caused by secondary winding resistance, diode forward voltage, and output capacitor ESR. A typical 0.1µF ceramic capacitor on RCMPC filters the signal, and ROCMP resistor value is selected empirically or via formula to achieve ±1% load regulation across 10–100% load in the LT1737CGN#PBF.
What is the function of the UVLO pin on the LT1737CGN#PBF, and how is it configured?
The UVLO pin on the LT1737CGN#PBF serves dual functions: applying <0.4V disables the IC (shutdown mode, IQ ≈ 50µA), while connecting a resistor divider from VIN to GND sets a programmable undervoltage lockout threshold (~1.25V). Hysteresis is achieved by leveraging the pin's bias current shift across threshold-no external hysteresis resistor is needed. This dual-mode operation makes UVLO a flexible control interface in the LT1737CGN#PBF.
Can the LT1737CGN#PBF operate in discontinuous conduction mode (DCM) while maintaining regulation?
Yes, the LT1737CGN#PBF maintains stable regulation deep into discontinuous conduction mode (DCM) due to its dedicated timing architecture-including programmable ENDLY (enable delay), MINENAB (minimum enable time), and tON (minimum on-time). These features prevent feedback amplifier mis-triggering from leakage spikes and ensure sufficient VC node pumping even at light loads-enabling reliable DCM operation without output collapse in the LT1737CGN#PBF.
LT1737CGN#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-SSOP (0.154", 3.90mm Width)
- Packaging:
- Tube
- 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#PBF FAQ
1.How can I place an order for LT1737CGN#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1737CGN#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 LT1737CGN#PBF reliable?
The price and inventory of LT1737CGN#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1737CGN#PBF is usually 5 days.
3.What payment methods are accepted for LT1737CGN#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1737CGN#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1737CGN#PBF?
LT1737CGN#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1737CGN#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 LT1737CGN#PBF?
For technical support, including LT1737CGN#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1737CGN#PBF requirements.
6.How does Aetrix verify that LT1737CGN#PBF is sourced from the original manufacturer or authorized distributors?
All LT1737CGN#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 LT1737CGN#PBF meets industry standards.
7.What is the process for return or replacement of LT1737CGN#PBF?
All LT1737CGN#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1737CGN#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 LT1737CGN#PBF part is unused and in its original packaging.
Return procedure for LT1737CGN#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LT1737CGN#PBF 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…
