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Analog Devices Inc. LT3999HMSE#PBF
- Part No.:
- LT3999HMSE#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LT3999HMSE#PBF.pdf
- Description:
- IC REG PUSH-PULL ADJ 1A 10MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:573
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Product details
Overview
LT3999HMSE#PBF from Analog Devices (formerly Linear Technology) is a monolithic, high-voltage, high-frequency push-pull DC/DC transformer driver IC designed for isolated power generation in compact, low-noise applications. It integrates dual 1A current-limited switches operating out-of-phase, supports programmable switching frequency up to 1MHz, features duty cycle control for line regulation, and operates across a 2.7V–36V input range with <1µA shutdown current.
For engineers reviewing the LT3999HMSE#PBF datasheet, LT3999HMSE#PBF pinout, LT3999HMSE#PBF application, or LT3999HMSE#PBF equivalent, key selection considerations include its 10-lead MSOP package with exposed GND pad, –40°C to 150°C guaranteed junction temperature rating, dual-switch cross-conduction prevention, and programmable soft-start via ILIM/SS pin.
Technical Context
The LT3999HMSE#PBF implements a synchronous push-pull topology with two NPN power switches driven out-of-phase to generate square-wave excitation on the primary of a center-tapped transformer. Its oscillator supports internal frequency programming (50kHz–1MHz) via RT resistor or external synchronization up to 1MHz using the SYNC pin.
Duty cycle is actively controlled via the OVLO/DC and RDC pins to compensate for input voltage variation-enabling pseudo-regulation before post-LDO stages. Protection functions include precision UVLO (1.25V threshold, 125mV hysteresis), OVLO (1.25V threshold), thermal shutdown, and non-overlap timing (70ns) to prevent shoot-through.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.7V to 36V - supports wide industrial and automotive supply rails without external pre-regulation. |
| Switch Current Limit | 1.0A to 1.7A (typical 1.4A) - sets maximum per-switch conduction current to protect internal transistors and transformer. |
| Switching Frequency | 50kHz to 1MHz - adjustable via RT resistor; higher frequencies reduce magnetic component size but increase switching losses. |
| Duty Cycle Range | 20% to 48% - programmable via RDC and OVLO/DC voltage to maintain stable output under varying VIN. |
| Shutdown Current | <1µA - enables ultra-low-power standby in battery-backed or energy-sensitive systems. |
| Junction Temperature Range | –40°C to +150°C - H-grade qualification ensures reliability in high-ambient environments like motor drives or under-hood electronics. |
| Package Thermal Resistance | θJA = 40°C/W (MSOP) - requires exposed pad soldering to PCB ground plane for effective heat dissipation. |
Pinout & Package
LT3999HMSE#PBF is housed in a 10-lead MSOP package (MSE) with exposed GND pad (Pin 11), requiring soldering to PCB ground for thermal and electrical integrity. Pin pitch is 0.5mm; package dimensions are 3.00mm × 3.00mm × 1.10mm max height.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SWA (Pin 1) | Power switch collector node A | Drives outer terminal of center-tapped transformer primary; carries high pulsed current - requires short, wide PCB trace. |
| RBIAS (Pin 2) | Bias current setting input | Connects to 49.9kΩ resistor to GND to set optimal base drive for SWA/SWB transistors. |
| VIN (Pin 3) | Main supply input | Supplies internal regulator and switch drivers; requires ≥4.7µF low-ESR ceramic capacitor placed near pin. |
| UVLO (Pin 4) | Undervoltage lockout enable | Disables switching when VIN drops below 1.25V threshold; hysteresis prevents chatter during brownout recovery. |
| OVLO/DC (Pin 5) | Overvoltage lockout / duty cycle control | Double-function pin: sets OVLO threshold or provides feedback voltage for duty cycle adjustment based on VIN. |
| RDC (Pin 6) | Duty cycle programming resistor | Resistor to GND sets duty cycle percentage; floating disables duty control, defaulting to ~50%. |
| RT (Pin 7) | Oscillator frequency setting | Resistor value determines switching frequency (e.g., 49.9kΩ = 300kHz); enables precise harmonic placement. |
| SYNC (Pin 8) | External clock synchronization input | Accepts >2V square wave to align switching edges; internal oscillator must be set 10–50% lower than sync frequency. |
| ILIM/SS (Pin 9) | Current limit / soft-start control | Resistor sets cycle-by-cycle current limit; capacitor adds soft-start ramp to limit inrush current at startup. |
| SWB (Pin 10) | Power switch collector node B | Complementary switch to SWA; driven 180° out-of-phase to enable push-pull transformer operation. |
| GND (Pin 11) | Ground reference / exposed pad | Thermal and electrical ground; exposed pad must be soldered to PCB ground plane with multiple vias. |
Key Features
| Feature | Design Value |
|---|---|
| Low-noise push-pull topology | Minimizes EMI and output ripple without requiring complex filtering - ideal for medical and data acquisition systems. |
| Programmable duty cycle control | Compensates for input voltage variation by dynamically adjusting switch on-time, reducing post-regulator power loss. |
| Cross-conduction prevention | 70ns non-overlap timing ensures SWA and SWB never conduct simultaneously - eliminates shoot-through current and device stress. |
| Adjustable soft-start | Capacitor on ILIM/SS pin ramps peak switch current over time, limiting inrush and preventing transformer saturation at startup. |
| Wide input voltage range | 2.7V–36V operation supports direct connection to 3.3V, 5V, 12V, 24V, and 32V rails - reduces need for upstream regulators. |
Applications
| Medical Isolated Supplies | Noise-Sensitive Data Acquisition |
|---|---|
|
Use Scenario: Powering isolated analog front-ends in portable ECG or EEG monitors where galvanic isolation meets IEC 60601-1 creepage/clearance requirements. IC Role / Device Role / Timing Role: LT3999HMSE#PBF acts as the primary-side push-pull driver generating clean, low-noise isolated DC for ADC reference and op-amp supplies. Use Value: Achieves <100mVP-P output noise without LC filtering - preserves signal integrity in sub-µV biomedical measurements. |
Use Scenario: Providing isolated ±12V rails for RS485 transceivers and precision instrumentation amplifiers in factory automation PLCs. IC Role / Device Role / Timing Role: LT3999HMSE#PBF delivers tightly regulated, low-EMI isolated power synchronized to system clock via SYNC pin. Use Value: Synchronization enables predictable harmonic placement - simplifies EMI filter design and passes CISPR 11 Class A emissions limits. |
| Industrial Distributed Power | Positive-to-Negative Conversion |
|
Use Scenario: Generating local 5V or 12V isolated supplies for remote I/O modules in 24V-powered distributed control systems. IC Role / Device Role / Timing Role: LT3999HMSE#PBF serves as compact, thermally robust DC/DC driver driving custom center-tapped transformers. Use Value: H-grade (–40°C to +150°C) operation ensures reliability in uncooled enclosures near motors or power converters. |
Use Scenario: Creating dual-rail ±15V supplies for op-amp biasing in analog signal conditioning circuits requiring bipolar operation. IC Role / Device Role / Timing Role: LT3999HMSE#PBF drives center-tapped transformer with symmetrical push-pull waveform to generate balanced positive/negative outputs. Use Value: Programmable duty cycle maintains rail symmetry across wide input voltage swings - improves PSRR and common-mode rejection. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar isolated push-pull DC/DC driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3439EFE#PBF | SO-16 package; slew-rate controlled switches; fixed 1A current limit; no duty cycle control; 2.7V–17.5V input. | Better suited for ultra-low-noise (<100mVP-P) applications where transformer size is secondary to EMI performance. | Select LT3439EFE#PBF when lowest possible output noise is critical and input range is limited to ≤17.5V. |
| LT3999EMSE#PBF | Same functionality and pinout; rated for –40°C to +125°C junction temperature instead of +150°C. | Appropriate for commercial/industrial ambient conditions where extended temperature margin is not required. | Choose LT3999EMSE#PBF for cost-sensitive designs operating below 125°C ambient with identical circuit layout. |
Compared with LT3439EFE#PBF, LT3999HMSE#PBF offers wider input range and active duty cycle control for line regulation but lacks slew-rate control; compared with LT3999EMSE#PBF, it provides guaranteed operation up to +150°C junction temperature - critical for high-reliability thermal environments.
Availability
LT3999HMSE#PBF is available at Aetrix Electronics and suitable for medical isolation, industrial distributed power, and noise-sensitive data acquisition applications requiring stable component supply and long-term manufacturability.
Supply support for LT3999HMSE#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. (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and power management semiconductors.
The LT3999 product line was designed specifically for compact, low-noise isolated DC/DC conversion in safety-critical and EMI-sensitive applications - emphasizing thermal robustness, programmable protection, and transformer-driven efficiency.
FAQ
What is the maximum operating junction temperature for LT3999HMSE#PBF?
The LT3999HMSE#PBF is guaranteed to operate continuously over a junction temperature range of –40°C to +150°C. This H-grade qualification is verified per manufacturer specifications and enables use in high-ambient environments such as motor control enclosures or under-hood automotive modules where thermal derating beyond 125°C is required. The LT3999HMSE#PBF achieves this via enhanced process and packaging design validated across temperature extremes.
How does duty cycle control work on LT3999HMSE#PBF?
Duty cycle control on LT3999HMSE#PBF uses the OVLO/DC and RDC pins to adjust switch on-time in response to input voltage changes. By connecting OVLO/DC to a resistor divider from VIN and setting RDC to ground, the IC dynamically modifies duty cycle to maintain constant output voltage - reducing post-regulator dissipation. The LT3999HMSE#PBF supports 20%–48% duty cycle range depending on resistor values, with formulas provided in the datasheet for precise calculation.
Can LT3999HMSE#PBF synchronize to an external clock?
Yes, LT3999HMSE#PBF supports external synchronization via the SYNC pin. It accepts a >2V square wave input and locks its internal oscillator to the external frequency - with the switching frequency equal to half the sync frequency. To ensure reliable locking, the internal oscillator (set by RT) must be configured 10–50% lower than the external sync frequency. This capability allows precise harmonic placement for EMI compliance in sensitive systems.
What is the purpose of the RBIAS pin on LT3999HMSE#PBF?
The RBIAS pin on LT3999HMSE#PBF sets the base drive current for the internal NPN power switches (SWA and SWB). A 49.9kΩ resistor to GND establishes optimal bias for efficient switching across the full input voltage and load range. Incorrect RBIAS values may cause excessive switch saturation voltage or reduced current capability. The LT3999HMSE#PBF datasheet specifies this value as standard for nominal operation and thermal stability.
Is the exposed pad on LT3999HMSE#PBF electrically connected?
Yes, the exposed pad on LT3999HMSE#PBF is internally connected to GND (Pin 11) and must be soldered directly to the PCB ground plane. It serves both thermal and electrical functions: lowering θJA to 40°C/W and providing low-inductance return path for high-frequency switch currents. Manufacturer guidelines require at least four 0.3mm vias under the pad connected to an inner-layer ground plane - failure to do so risks thermal overload and EMI degradation in the LT3999HMSE#PBF.
LT3999HMSE#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width) Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Function:
- Step-Up/Step-Down
- Output Configuration:
- Positive, Isolation Capable
- Topology:
- Push-Pull
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 2.7V
- Voltage - Input (Max):
- 36V
- Voltage - Output (Min/Fixed):
- -
- Voltage - Output (Max):
- -
- Current - Output:
- 1A
- Frequency - Switching:
- 50kHz ~ 1MHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 10-MSOP-EP
LT3999HMSE#PBF FAQ
1.How can I place an order for LT3999HMSE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3999HMSE#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 LT3999HMSE#PBF reliable?
The price and inventory of LT3999HMSE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3999HMSE#PBF is usually 5 days.
3.What payment methods are accepted for LT3999HMSE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3999HMSE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3999HMSE#PBF?
LT3999HMSE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3999HMSE#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 LT3999HMSE#PBF?
For technical support, including LT3999HMSE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3999HMSE#PBF requirements.
6.How does Aetrix verify that LT3999HMSE#PBF is sourced from the original manufacturer or authorized distributors?
All LT3999HMSE#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 LT3999HMSE#PBF meets industry standards.
7.What is the process for return or replacement of LT3999HMSE#PBF?
All LT3999HMSE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3999HMSE#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 LT3999HMSE#PBF part is unused and in its original packaging.
Return procedure for LT3999HMSE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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