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Analog Devices Inc. LT1952IGN#PBF
- Part No.:
- LT1952IGN#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 16-SSOP (0.154", 3.90mm Width)
- Datasheet:
-
LT1952IGN#PBF.pdf
- Description:
- IC REG CTRLR FWRD CONV 16SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:100
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Product details
Overview
LT1952IGN#PBF from Analog Devices (formerly Linear Technology) is a current-mode PWM controller optimized for single-switch synchronous forward converters. It delivers synchronous rectifier control, programmable volt-second clamp (preventing transformer saturation), 107mV precision overcurrent threshold, and 100kHz–500kHz programmable switching frequency. It enables high-efficiency 25W–500W telecom and industrial DC/DC supplies with >50% duty cycle operation.
For engineers reviewing the LT1952IGN#PBF datasheet, LT1952IGN#PBF pinout, LT1952IGN#PBF application, or LT1952IGN#PBF equivalent, key selection considerations include its adaptive maximum duty cycle clamp, low 460µA start-up current at 14.25V VIN turn-on, true op-amp error amplifier for flexible compensation, synchronous timing delay (via DELAY pin), and SSOP-16 package compatibility with space-constrained isolated power designs.
Technical Context
The LT1952IGN#PBF implements current-mode control using ISENSE for peak-current sensing and OC for cycle-by-cycle 107mV overcurrent protection. Its adaptive volt-second clamp uses SD_VSEC and SS_MAXDC pins to dynamically limit maximum duty cycle based on input voltage-enabling reliable >50% duty cycle operation without external capacitors or oscillator drift dependency.
It features dual gate drivers: OUT (±1A, 13V-clamped) for primary-side N-MOSFET and SOUT (±50mA, 12V-clamped) for secondary-side synchronous rectifiers, with programmable tDELAY between their rising edges. Soft-start is implemented via SS_MAXDC ramping, and shutdown is triggered by VIN undervoltage (8.75V off), SD_VSEC <1.32V, or OC trip.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Topology Support | Single-switch synchronous forward converter with adaptive volt-second clamp for transformer reset safety |
| Switching Frequency Range | 100kHz–500kHz, programmable via ROSC resistor; supports external synchronization up to 1.5×fOSC |
| Overcurrent Threshold | Precision 107mV (±9mV), independent of duty cycle-enables hiccup-mode short-circuit protection |
| VIN Start-up Current | 460µA typical at 14.25V turn-on-allows micropower bootstrap start from high-input-voltage rails |
| Output Drivers | OUT: ±1A peak, 13V-clamped; SOUT: ±50mA peak, 12V-clamped; tDELAY programmable via DELAY pin resistor |
| Error Amplifier | True op-amp architecture (65–85dB gain, 3MHz GBW)-supports wide-range RC compensation networks |
| Reference Voltages | Internal 1.23V FB reference (±25mV); 2.5V VREF output (2.5mA capable) for external bias and divider programming |
Pinout & Package
LT1952IGN#PBF is housed in a 16-pin plastic SSOP (Shrink Small Outline Package) with exposed pad thermal enhancement, rated for –40°C to +125°C junction temperature.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| COMP (1) | Error amplifier output | Drives compensation network; 0.8V–2.5V range maps to 0–220mV ISENSE threshold; disableable via FB = VREF |
| FB (2) | Feedback input | Compares output voltage (via resistor divider) to 1.23V internal reference; FB = VREF disables COMP output |
| ROSC (3) | Oscillator frequency set | Resistor-to-ground programs fOSC from 100kHz to 500kHz; nominal pin voltage = 1.0V |
| SYNC (4) | External clock sync input | Logic-compatible input (10–90% duty cycle); enables master-slave operation up to 1.5×fOSC |
| SS_MAXDC (5) | Soft-start & max duty cycle clamp | Capacitor/resistor network sets soft-start time; voltage defines adaptive duty cycle guardrail (e.g., 1.84V → 72% at SD_VSEC=1.32V) |
| VREF (6) | 2.5V reference output | Supplies internal circuitry and external bias; 0.1µF ceramic bypass required; 2.5mA source capability |
| SD_VSEC (7) | UVLO & volt-second clamp control | 1.32V accurate threshold; 10µA hysteresis enables programmable UVLO; directly scales max duty cycle clamp |
| GND (8) | Analog ground | Reference for FB, COMP, ROSC, SYNC, SS_MAXDC, VREF, SD_VSEC, BLANK, OC, DELAY |
| BLANK (9) | Leading edge blanking adjust | Resistor-to-ground sets blanking duration (180–540ns) to suppress MOSFET switching noise false trips |
| ISENSE (10) | Primary current sense input | Connects to MOSFET source sense resistor; slope compensation programmed via series resistor |
| OC (11) | Dedicated overcurrent comparator | 107mV threshold triggers immediate soft-start latch; independent of duty cycle and slope compensation |
| DELAY (12) | Synchronous rectifier timing delay | Resistor-to-ground programs tDELAY (40–120ns) between SOUT and OUT rising edges for optimal FET timing |
| PGND (13) | Power ground | Return path for OUT and SOUT drivers; separate from analog GND to minimize noise coupling |
| OUT (14) | Primary MOSFET gate driver | ±1A peak drive, 13V clamped; active pull-off during shutdown; rise/fall times ≤50/30ns (1nF load) |
| VIN (15) | Main supply input | Operates from 25V max; 14.25V ON / 8.75V OFF thresholds; 5.2–6.5mA quiescent current |
| SOUT (16) | Synchronous rectifier sync output | ±50mA peak, 12V clamped; phase-aligned with OUT; active pull-off in shutdown |
Key Features
| Feature | Design Value |
|---|---|
| Adaptive volt-second clamp | Eliminates need for external timing capacitor; reduces MOSFET voltage rating requirement and improves transformer utilization |
| True op-amp error amplifier | Enables standard Type II/III compensation networks-no special design constraints for loop stability |
| Programmable synchronous timing delay | Adjustable tDELAY ensures optimal dead-time between primary switch and secondary rectifier for ZVS/ZCS operation |
| Hiccup-mode short-circuit protection | Combines 107mV OC threshold with soft-start latch to limit fault energy and thermal stress during overload |
| Low-power bootstrap start-up | 460µA start-up current at 14.25V enables RC-based high-voltage start without auxiliary winding dependency |
Applications
| Telecom Bus Converter | Industrial Isolated DC/DC |
|---|---|
Use Scenario: 36V–72V telecom input converted to semi-regulated 12V/20A bus for line cards and baseband units. IC Role / Device Role / Timing Role: Primary-side PWM controller managing single MOSFET forward topology with synchronous rectification on secondary side. Use Value: Enables >90% efficiency at full load via synchronous rectifier control and adaptive duty cycle clamp-reducing heat sink size and improving power density. | Use Scenario: 48V industrial input powering isolated 5V/3.3V logic rails in PLCs and motor drives. IC Role / Device Role / Timing Role: Forward controller providing precise current-mode regulation and programmable UVLO hysteresis for robust brown-out recovery. Use Value: SD_VSEC pin allows direct resistive scaling of system input UVLO threshold with 10µA hysteresis-eliminating external comparators and saving BOM cost. |
| High-Power LED Driver | Medical Power Supply |
Use Scenario: Constant-current 48V LED string driver delivering up to 500W with tight output regulation. IC Role / Device Role / Timing Role: Current-mode controller implementing ISENSE-based peak-current limiting and OC-triggered soft-start for LED open/short protection. Use Value: Precision 107mV OC threshold ensures repeatable short-circuit response across temperature-critical for LED reliability and safety compliance. | Use Scenario: 24V–48V input powering isolated 12V/5V medical subsystems requiring low EMI and high reliability. IC Role / Device Role / Timing Role: Forward controller with programmable slope compensation and leading edge blanking to suppress switching noise in sensitive analog environments. Use Value: Adjustable BLANK resistor (40k–120k) provides noise immunity against radiated EMI-meeting IEC 60601-1 conducted emission limits without added filtering. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar forward converter controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3748IMS#PBF | Integrated transformer-isolation feedback via optocoupler interface; no VREF output; requires external slope compensation resistor | Designed for isolated flyback and forward topologies with primary-side sensing; lacks SD_VSEC-based volt-second clamp | Choose LT3748 when optocoupler-based isolation feedback is preferred and adaptive volt-second clamp is not required |
| UCC2891DR | Fixed 500kHz frequency; no programmable fOSC or external sync; lower start-up current (200µA); no SOUT pin or synchronous timing delay | Optimized for cost-sensitive telecom forward converters; lacks dual-output timing control for advanced synchronous rectification | Choose UCC2891 when fixed-frequency operation suffices and secondary-side timing flexibility is unnecessary |
Compared with LT3748IMS#PBF and UCC2891DR, the LT1952IGN#PBF uniquely combines adaptive volt-second clamp, dual synchronized outputs (SOUT/OUT), and true op-amp error amplifier-making it optimal for high-efficiency, high-reliability forward converters where transformer reset margin and layout simplicity are critical.
Availability
LT1952IGN#PBF is available at Aetrix Electronics and suitable for telecommunications power supplies, industrial distributed power systems, and isolated DC/DC converters requiring stable component supply, extended temperature operation (–40°C to +125°C), and long-term lifecycle support.
Supply support for LT1952IGN#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 and maintains its legacy of high-performance analog ICs for power management, signal conditioning, and precision timing.
The LT1952IGN#PBF belongs to Linear's synchronous forward controller product line, designed specifically for high-efficiency, single-MOSFET isolated DC/DC conversion in space-constrained telecom and industrial applications.
FAQ
What is the operating temperature range for the LT1952IGN#PBF?
The LT1952IGN#PBF is specified for operation from –40°C to +125°C junction temperature. This I-grade rating makes it suitable for industrial and telecom environments where ambient temperatures exceed commercial-grade limits. The SSOP-16 package includes thermal enhancements to sustain continuous operation at maximum junction temperature under proper PCB copper pour and airflow conditions. Derating curves for VIN quiescent current and switching frequency stability versus temperature are provided in the official datasheet graphs G03–G05.
How does the LT1952IGN#PBF implement adaptive maximum duty cycle clamping?
The LT1952IGN#PBF implements adaptive maximum duty cycle clamping using two dedicated pins: SD_VSEC and SS_MAXDC. SD_VSEC is resistively divided from the primary input voltage to generate a voltage proportional to input rail; as VIN rises, SD_VSEC increases and reduces the allowable duty cycle. SS_MAXDC is programmed via a resistor divider from VREF to set the baseline clamp level (e.g., 1.84V yields 72% at SD_VSEC = 1.32V). This resistor-only method avoids capacitor drift and oscillator inaccuracies-delivering tighter duty cycle control than capacitor-based clamps.
Can the LT1952IGN#PBF be used in non-isolated forward converter designs?
Yes, the LT1952IGN#PBF supports both isolated and non-isolated forward converter topologies. In non-isolated configurations, the FB pin connects directly to the output voltage divider, and the error amplifier operates as a standard op-amp. The ISENSE pin senses primary-side current, while OC provides cycle-by-cycle overcurrent protection. SOUT remains functional for driving synchronous rectifiers on the output side-even without transformer isolation-enabling high-efficiency buck-derived topologies with active secondary-side conduction.
What is the purpose of the DELAY pin on the LT1952IGN#PBF?
The DELAY pin on the LT1952IGN#PBF programs the time delay (tDELAY) between the rising edge of SOUT and the rising edge of OUT. This delay optimizes synchronous rectifier timing in forward converters by aligning secondary-side FET turn-on with the correct point in the transformer reset cycle-minimizing reverse recovery losses and improving efficiency. A resistor from DELAY to ground sets tDELAY from 40ns to 120ns (typical), allowing fine-tuning for specific MOSFET gate charge and transformer leakage characteristics.
Does the LT1952IGN#PBF require an external reference voltage?
No, the LT1952IGN#PBF does not require an external reference voltage. It integrates a precision 1.23V internal reference for the FB pin and a buffered 2.5V VREF output (pin 6) capable of sourcing up to 2.5mA. The VREF pin is used to bias resistor dividers for SS_MAXDC and SD_VSEC programming, eliminating the need for external references. For higher accuracy applications, the 2.5V VREF can also serve as a stable bias for external circuits such as precision current monitors or ADC references.
LT1952IGN#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, Isolation Capable
- Topology:
- Forward Converter
- Number of Outputs:
- 1
- Output Phases:
- 1
- Voltage - Supply (Vcc/Vdd):
- 9.25V ~ 25V
- Frequency - Switching:
- 100kHz ~ 500kHz
- Duty Cycle (Max):
- 90%
- Synchronous Rectifier:
- Yes
- Clock Sync:
- Yes
- Serial Interfaces:
- -
- Control Features:
- Enable, Frequency Control
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SSOP
LT1952IGN#PBF FAQ
1.How can I place an order for LT1952IGN#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1952IGN#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 LT1952IGN#PBF reliable?
The price and inventory of LT1952IGN#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1952IGN#PBF is usually 5 days.
3.What payment methods are accepted for LT1952IGN#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1952IGN#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1952IGN#PBF?
LT1952IGN#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1952IGN#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 LT1952IGN#PBF?
For technical support, including LT1952IGN#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1952IGN#PBF requirements.
6.How does Aetrix verify that LT1952IGN#PBF is sourced from the original manufacturer or authorized distributors?
All LT1952IGN#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 LT1952IGN#PBF meets industry standards.
7.What is the process for return or replacement of LT1952IGN#PBF?
All LT1952IGN#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1952IGN#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 LT1952IGN#PBF part is unused and in its original packaging.
Return procedure for LT1952IGN#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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