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Analog Devices Inc. LT1950EGN#PBF
- Part No.:
- LT1950EGN#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 16-SSOP (0.154", 3.90mm Width)
- Datasheet:
-
LT1950EGN#PBF.pdf
- Description:
- IC REG CTRLR MULT TOP 16SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:160
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Product details
Overview
LT1950EGN#PBF from Analog Devices (formerly Linear Technology) is a wide-input, current-mode PWM controller with integrated auxiliary boost converter for forward, flyback, boost, and SEPIC DC/DC topologies. It supports 3V–25V input, delivers up to 500W output power, features programmable 100kHz–500kHz switching frequency, 60ns current-sense delay, and provides 10V gate drive from as low as 3V VIN via its internal boost switcher. It is used in telecom and automotive isolated power supplies requiring robust volt-second clamping.
For engineers reviewing the LT1950EGN#PBF datasheet, LT1950EGN#PBF pinout, LT1950EGN#PBF application, or LT1950EGN#PBF equivalent, this page delivers verified functional identity, validated SSOP-16 pin mapping, confirmed 1.23V ±2% FB reference and 2.5V VREF output, real-world duty-cycle clamp behavior via VSEC, and authoritative alternative part guidance grounded in manufacturer documentation.
Technical Context
The LT1950EGN#PBF implements true current-mode control with externally adjustable slope compensation (via SLOPE pin), programmable leading-edge blanking (via BLANK pin), and a fast 60ns current-sense comparator path. Its oscillator uses a single external resistor (ROSC) to set frequency from 100kHz to 500kHz, and the SYNC pin enables synchronization to an external clock up to 1.5× fOSC without loss of slope compensation integrity.
It integrates an auxiliary NPN-based boost switcher (fixed 0.5µs off-time, 125mA current limit) that generates a regulated ~11V supply at VIN2 from VIN ≥3V - enabling full 10V+ gate drive for standard N-channel MOSFETs even under ultra-low input conditions. The VSEC pin implements a precise volt-second clamp by setting maximum duty cycle as (105/VSEC)% over 1.4V–2.8V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3V to 25V - supports battery-backed, automotive, and telecom inputs without external pre-regulation. |
| Switching Frequency | 100kHz to 500kHz - set by single ROSC resistor; enables optimization of magnetics size vs. efficiency trade-off. |
| FB Reference Voltage | 1.23V ±2% - high-accuracy internal reference for stable output voltage regulation across temperature. |
| VREF Output | 2.5V ±3% (2.425V–2.575V), 2.5mA max - usable as precision bias for external circuitry or feedback divider. |
| Current Sense Delay | 60ns - enables accurate peak-current sensing in high-speed switching applications. |
| Gate Drive Capability | 10V min at GATE pin with VIN as low as 3V - achieved via internal boost converter driving VIN2 to ~11V. |
| Max Duty Cycle Clamp | (105/VSEC)% for VSEC = 1.4V–2.8V - implements hardware-enforced volt-second limit critical in forward converters. |
Pinout & Package
LT1950EGN#PBF is housed in a 16-lead narrow plastic SSOP (GN) package with 0.65mm lead pitch, JEDEC MO-153 compliant, θJA = 110°C/W, θJC (Pin 8) = 30°C/W, and rated for TJ = –40°C to +125°C operation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| COMP (1) | Error amplifier output | Drives external RC compensation network; sets ISENSE threshold; typical operating range 1V–2.5V. |
| FB (2) | Inverting input of error amplifier | Compares output-derived voltage against 1.23V internal reference to regulate output. |
| ROSC (3) | Oscillator frequency programming | Resistor to ground sets fOSC from 100kHz to 500kHz; nominal pin voltage = 1V. |
| SYNC (4) | External clock synchronization input | Logic-compatible input; accepts 10%–90% duty cycle clocks up to 1.5× fOSC. |
| SLOPE (5) | Slope compensation adjustment | Open = default compensation; resistor to VREF increases compensation for >50% duty cycles. |
| VREF (6) | 2.5V precision reference output | Supplies internal circuitry and external loads up to 2.5mA; requires 0.1µF ceramic bypass. |
| SHDN (7) | Shutdown enable with hysteresis | 1.32V threshold; external resistor network programs UVLO turn-on/off hysteresis. |
| GND (8) | Analog ground reference | Reference point for FB divider, ROSC, VREF bypass, and sensitive analog circuitry. |
| BLANK (9) | Leading-edge blanking control | Ground = 110ns blanking; resistor to ground extends blanking up to 290ns. |
| ISENSE (10) | Current sense comparator input | Connects to MOSFET source sense resistor; 100mV threshold limits peak switch current. |
| VIN2 (11) | Gate driver supply input | Accepts external supply or boosted voltage (~11V); must exceed 8V to enable GATE output. |
| GATE (12) | High-current MOSFET gate driver | Active pull-up/pull-down; clamped to 13V max; drives N-channel MOSFETs directly. |
| PGND (13) | Power ground for gate driver | Separate return path for high di/dt gate current; minimizes noise coupling into analog ground. |
| BOOST (14) | Internal boost switch collector | Drives external inductor/diode/capacitor to generate VIN2 from low VIN (≥3V). |
| VIN (15) | Main IC supply input | Bypassed locally; powers internal logic and references; UVLO at 2.6V ensures safe start-up. |
| VSEC (16) | Volt-second clamp programming | Programs max duty cycle as (105/VSEC)% - essential for forward converter reset timing control. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated auxiliary boost converter | Generates ~11V at VIN2 from VIN ≥3V, enabling full gate drive for standard N-MOSFETs without external bias rails. |
| Programmable volt-second clamp | VSEC pin sets max duty cycle as (105/VSEC)%, providing hardware-level protection against transformer saturation in forward converters. |
| 60ns current-sense propagation delay | Enables accurate peak-current-mode control at high frequencies and fast transient response without added latency. |
| Externally adjustable slope compensation | SLOPE pin allows tuning of compensation ramp amplitude - avoids subharmonic oscillation across all inductor/frequency combinations. |
| Accurate shutdown with programmable hysteresis | 1.32V SHDN threshold with µA-level input current enables precise, noise-immune UVLO with user-defined turn-on/turn-off windows. |
| True op-amp error amplifier | Allows flexible Type II/III compensation networks between COMP and FB, supporting wide bandwidth and stability margins. |
Applications
| Telecom Power Supplies | Automotive Power Supplies |
|---|---|
Use Scenario: 36V–72V DC input telecom rectifier powering 26V/5A isolated forward converter. IC Role / Device Role / Timing Role: Primary-side PWM controller managing synchronous rectification timing, volt-second clamp, and gate drive sequencing. Use Value: Enables 95% peak efficiency across wide input range while maintaining strict duty-cycle limits to prevent transformer core saturation. |
Use Scenario: 12V battery-powered ADAS ECU requiring isolated 5V/3A supply with cold-crank immunity down to 3.5V. IC Role / Device Role / Timing Role: Current-mode controller with VIN2 boost ensuring reliable 10V gate drive during cranking events. Use Value: Maintains regulation and MOSFET RDS(on) performance below 6V input - eliminating need for external charge pump or LDO bias rail. |
| Isolated DC/DC Converters | Portable Electronic Equipment |
Use Scenario: Medical-grade isolated 48V-to-12V flyback supply with reinforced insulation and <100mW no-load consumption. IC Role / Device Role / Timing Role: Primary-side controller implementing primary-sensed regulation, programmable blanking, and burst-mode synchronization. Use Value: Achieves <100mW no-load power via VIN shutdown and programmable hysteresis, meeting IEC 60601 standby requirements. |
Use Scenario: High-density 5V-to-12V boost converter in portable test equipment with 3.3V–5.5V battery input. IC Role / Device Role / Timing Role: Boost controller with integrated slope compensation and fast current sensing for compact inductor selection. Use Value: Supports 500kHz operation with minimal external components, reducing solution footprint by >30% vs. legacy controllers. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar PWM controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3748EMS#PBF | No integrated boost converter; requires external 10V bias for gate drive; fixed 100kHz–1MHz fOSC range; includes primary-side sensing for flyback only. | Optimized for isolated flyback with no secondary feedback; lacks VSEC clamp and VIN2 boost capability. | Select when flyback topology dominates and external bias is acceptable; avoid for forward or low-VIN boost applications. |
| UCC2897APWR | Fixed 100kHz–1MHz fOSC; no VSEC-based duty-cycle clamp; no integrated boost; requires external 12V gate drive; supports active clamp forward. | Targets high-efficiency active-clamp forward converters; lacks low-VIN gate drive and volt-second clamp functionality. | Select for active-clamp forward designs where external gate bias is available; not suitable for 3V–8V input operation. |
Compared with LT3748EMS#PBF and UCC2897APWR, the LT1950EGN#PBF uniquely combines integrated VIN2 boost, programmable VSEC clamp, and 3V start-up - making it the only option among the three capable of self-sustaining 10V gate drive and hardware-enforced volt-second limiting in forward converters with ultra-low input voltage.
Availability
LT1950EGN#PBF is available at Aetrix Electronics and suitable for telecom rectifiers, automotive ADAS power modules, and isolated medical DC/DC converters requiring stable component supply, long-term lifecycle support, and guaranteed parametric compliance over –40°C to +125°C.
Supply support for LT1950EGN#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. (including former Linear Technology assets) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, serving industrial, automotive, communications, and healthcare markets.
The LT1950EGN#PBF belongs to Linear Technology's legacy high-voltage current-mode controller family, designed specifically for isolated and non-isolated DC/DC converters requiring robust low-VIN operation, precise volt-second control, and integrated gate-drive bias generation.
FAQ
What is the minimum input voltage required for LT1950EGN#PBF to start switching?
The LT1950EGN#PBF has a guaranteed minimum start-up voltage of 2.6V on the VIN pin. However, full functionality-including activation of the VREF output and enabling of the GATE driver-requires VIN2 ≥6.8V and ≥8V respectively. When using the internal BOOST converter, stable switching begins once VIN exceeds ~3V and VIN2 reaches ~8V, as confirmed in the Electrical Characteristics table and Figure 2 of the datasheet.
How does the VSEC pin function in LT1950EGN#PBF, and what voltage range should be applied?
The VSEC pin on the LT1950EGN#PBF programs the maximum duty cycle as (105/VSEC)%, providing hardware-enforced volt-second clamping critical in forward converters. It operates linearly over 1.4V to 2.8V - e.g., 1.75V on VSEC sets max duty cycle to 60%. If unused, VSEC must be tied to GND to retain the natural ~95% max duty cycle. This behavior is explicitly defined in the Electrical Characteristics table and Applications Information section.
Can LT1950EGN#PBF synchronize to an external clock, and what are the frequency limits?
Yes, the LT1950EGN#PBF supports synchronization via its SYNC pin, which accepts logic-level signals with 10%–90% duty cycle. The maximum allowable SYNC frequency is 1.5× the programmed fOSC, with an absolute upper limit of 500kHz per Note 7 in the datasheet. For example, if fOSC is set to 200kHz via ROSC, SYNC can run up to 300kHz. Synchronization preserves slope compensation integrity only if the free-running fOSC is set to ~80% of the external clock frequency.
What is the purpose of the BOOST pin on LT1950EGN#PBF, and how is it implemented?
The BOOST pin on LT1950EGN#PBF is the collector output of an internal NPN switch that forms an auxiliary boost converter. When connected to an external inductor, diode, and capacitor, it generates ~11V at VIN2 from VIN as low as 3V. It operates in burst mode (fixed 0.5µs off-time, 125mA current limit), enabling full 10V+ gate drive for standard N-MOSFETs without external bias supplies - a key differentiator confirmed in the Functional Description and Typical Application schematics.
Does LT1950EGN#PBF include slope compensation, and how is it adjusted?
Yes, the LT1950EGN#PBF includes externally adjustable slope compensation via the SLOPE pin. With SLOPE open, default compensation is applied. Connecting a resistor from SLOPE to VREF increases compensation amplitude - e.g., 8kΩ yields 2× default, 3.3kΩ yields 3× default - preventing subharmonic oscillation at duty cycles above 50%. This adjustment method and scaling factors are specified in the Electrical Characteristics table under "Slope Compensation".
LT1950EGN#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-Up/Step-Down
- Output Configuration:
- Positive, Isolation Capable
- Topology:
- Boost, Flyback, Forward Converter, SEPIC
- Number of Outputs:
- 1
- Output Phases:
- 1
- Voltage - Supply (Vcc/Vdd):
- 3V ~ 25V
- Frequency - Switching:
- 100kHz ~ 500kHz
- Duty Cycle (Max):
- 95%
- Synchronous Rectifier:
- No
- 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
LT1950EGN#PBF FAQ
1.How can I place an order for LT1950EGN#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1950EGN#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 LT1950EGN#PBF reliable?
The price and inventory of LT1950EGN#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1950EGN#PBF is usually 5 days.
3.What payment methods are accepted for LT1950EGN#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1950EGN#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1950EGN#PBF?
LT1950EGN#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1950EGN#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 LT1950EGN#PBF?
For technical support, including LT1950EGN#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1950EGN#PBF requirements.
6.How does Aetrix verify that LT1950EGN#PBF is sourced from the original manufacturer or authorized distributors?
All LT1950EGN#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 LT1950EGN#PBF meets industry standards.
7.What is the process for return or replacement of LT1950EGN#PBF?
All LT1950EGN#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1950EGN#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 LT1950EGN#PBF part is unused and in its original packaging.
Return procedure for LT1950EGN#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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