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Analog Devices Inc. LT3999IMSE#TRPBF
- Part No.:
- LT3999IMSE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LT3999IMSE#TRPBF.pdf
- Description:
- IC REG PUSH-PULL ADJ 1A 10MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,885
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Product details
Overview
LT3999IMSE#TRPBF from Analog Devices (formerly Linear Technology) is a monolithic high-voltage push-pull DC/DC transformer driver IC designed for isolated power generation in compact, low-noise applications. It integrates two 1A current-limited out-of-phase power switches, supports programmable switching frequency up to 1MHz, features duty cycle control for line regulation, and operates across a 2.7V–36V input range - enabling use in medical isolation, distributed power, and RS485 data acquisition supplies.
For engineers reviewing the LT3999IMSE#TRPBF datasheet, LT3999IMSE#TRPBF pinout, LT3999IMSE#TRPBF application, or LT3999IMSE#TRPBF equivalent, key selection criteria include its dual-switch topology with cross-conduction prevention, programmable soft-start via ILIM/SS, precision UVLO/OVLO thresholds (1.25V ±0.1V), <1µA shutdown current, and MSOP-10 package with exposed GND pad for thermal management.
Technical Context
The LT3999IMSE#TRPBF implements a fixed-frequency, non-overlapping push-pull driver architecture with independent oscillator control via RT and external synchronization capability on SYNC. Its dual NPN-based switches (SWA/SWB) operate with 70ns non-overlap time and 350mV typical saturation voltage at 1A, enabling efficient drive of center-tapped transformers.
Duty cycle is actively controlled through the OVLO/DC and RDC pins to compensate for input voltage variation, supporting pseudo-regulation before post-LDO stages. Protection functions include programmable undervoltage lockout (UVLO), overvoltage lockout (OVLO), and cycle-by-cycle current limiting set via resistor on ILIM/SS - all implemented with precision 1.25V reference thresholds and 125mV hysteresis.
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) - internal default limit ensures safe operation into transformer primary impedance |
| Switching Frequency | 50kHz to 1MHz - set by RT resistor; enables trade-off between efficiency and magnetics size |
| Duty Cycle Range | 20% to 48% - programmable via RDC and OVLO/DC voltage to maintain stable output under VIN variation |
| Shutdown Current | <1µA - enables ultra-low-power standby in battery-backed or safety-critical systems |
| UVLO/OVLO Threshold | 1.25V ±0.1V with 125mV hysteresis - provides precise, noise-immune enable/disable control referenced to VIN divider |
| Package Thermal Resistance | θJA = 40°C/W (MSOP-10 with exposed pad) - requires PCB thermal vias to GND plane for >1W continuous operation |
Pinout & Package
LT3999IMSE#TRPBF is housed in a 10-lead MSOP package (MSE) with exposed GND pad (Pin 11), requiring soldering to PCB ground plane for thermal and electrical integrity. Package dimensions: 3.00mm × 3.00mm × 1.10mm, pitch 0.5mm.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SWA (Pin 1) | Power switch collector node | Drives outer terminal of center-tapped transformer primary; handles pulsed 1A currents - requires short, wide PCB trace |
| RBIAS (Pin 2) | Bias current setting | Connects to 49.9kΩ resistor to GND to set optimal base drive for SWA/SWB transistors |
| VIN (Pin 3) | Main supply input | Accepts 2.7V–36V; must be bypassed with ≥4.7µF low-ESR ceramic capacitor near pin |
| UVLO (Pin 4) | Undervoltage lockout input | 1.25V threshold with hysteresis; disables switching and reduces supply current to <1µA when VIN drops below programmed level |
| OVLO/DC (Pin 5) | Overvoltage lockout / duty cycle control | 1.25V threshold with hysteresis; when used as OVLO, disables switching above VIN limit; when used with RDC, enables VIN-compensated duty cycle adjustment |
| RDC (Pin 6) | Duty cycle programming | Resistor-to-GND sets duty cycle percentage (20–48%); floating or tied to OVLO/DC disables function for ~50% fixed operation |
| RT (Pin 7) | Oscillator frequency setting | Resistor-to-GND programs switching frequency from 50kHz to 1MHz per datasheet table |
| SYNC (Pin 8) | External clock synchronization | Accepts 2V+ square wave; locks internal oscillator to external source for harmonic placement control |
| ILIM/SS (Pin 9) | Current limit / soft-start control | Resistor sets cycle-by-cycle current limit (0.4–0.6A typical); capacitor adds soft-start ramp to limit inrush current |
| SWB (Pin 10) | Second power switch collector node | Complementary to SWA; drives opposite outer terminal of center-tapped transformer - must mirror SWA layout symmetry |
| GND (Pin 11) | Ground / exposed pad | Thermal and electrical reference; exposed pad must be soldered to solid GND plane with multiple thermal vias |
Key Features
| Feature | Design Value |
|---|---|
| Low-noise push-pull topology | Minimizes EMI and output ripple without requiring complex filtering - validated in 12V→12V, 10W isolated converter |
| Programmable duty cycle control | Enables line regulation across 2.7V–36V input range by dynamically adjusting switch on-time, reducing post-regulator power dissipation |
| Cross-conduction prevention | 70ns guaranteed non-overlap between SWA and SWB ensures zero shoot-through current and transformer core reset safety |
| Adjustable soft-start | Capacitor on ILIM/SS pin ramps peak switch current over user-defined time (e.g., 0.01µF → ~0.8ms), eliminating input inrush stress |
| High-temperature grade | Rated for –40°C to +125°C junction operation (I-grade), suitable for industrial and medical environments without derating |
Applications
| Medical Isolation Supplies | Distributed Power Architectures |
|---|---|
Use Scenario: Isolated 5V/12V bias rails for patient-connected ECG front-end amplifiers and ADCs. IC Role / Device Role / Timing Role: Push-pull transformer driver generating galvanically isolated DC output with <100mVP-P noise. Use Value: Meets IEC 60601 creepage/clearance requirements while maintaining signal integrity in low-noise analog paths. |
Use Scenario: Local 12V→±12V isolated rails for RS485 transceivers in factory automation nodes. IC Role / Device Role / Timing Role: Dual-output isolated DC/DC driver powering differential bus drivers with common-mode noise immunity. Use Value: Eliminates ground loops and prevents bus latch-up during ESD events via reinforced isolation barrier. |
| Positive-to-Negative Conversion | Noise-Sensitive Data Acquisition |
Use Scenario: Generating –12V rail from 12V input for op-amp bias in precision instrumentation. IC Role / Device Role / Timing Role: Center-tapped transformer driver configured for bipolar output with synchronous rectification. Use Value: Delivers tightly regulated negative voltage without discrete charge pumps or inefficient inverting topologies. |
Use Scenario: Low-noise 3.3V isolated supply for 24-bit sigma-delta ADC reference and analog front-end. IC Role / Device Role / Timing Role: Ultra-low-EMI push-pull driver feeding LDO post-regulator to achieve sub-10µV RMS noise floor. Use Value: Reduces switching artifacts in digitized sensor data, enabling true 22+ ENOB performance. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar isolated DC/DC driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3439EDD#PBF | SO-16 package; slew-rate controlled switches; lower max VIN (17.5V); higher quiescent current (12mA) | Better suited for ultra-low-noise (<100mVP-P) applications where EMI filtering is critical and input voltage is ≤17.5V | Select LT3439EDD#PBF when sub-100mVP-P noise and independent slew control outweigh size and input range constraints. |
| LT1533CS#PBF | SO-16 package; integrated LDO post-regulator; no duty cycle control; fixed 50% duty cycle; 2.7V–23V input | Designed for single-rail isolated outputs requiring tight regulation without external LDO; lacks VIN compensation | Choose LT1533CS#PBF for simplified design where output regulation is prioritized over input range flexibility and transformer efficiency. |
Compared with LT3439EDD#PBF and LT1533CS#PBF, the LT3999IMSE#TRPBF offers wider input range (2.7V–36V), programmable duty cycle for line regulation, and smaller MSOP-10 footprint - making it optimal for space-constrained, wide-input industrial and medical isolated supplies requiring design flexibility.
Availability
LT3999IMSE#TRPBF is available at Aetrix Electronics and suitable for medical isolation supplies, distributed power architectures, and noise-sensitive data acquisition systems requiring stable component supply and long-term lifecycle support.
Supply support for LT3999IMSE#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 (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, serving industrial, automotive, communications, and healthcare markets.
The LT3999 belongs to Linear's isolated power driver product line, engineered specifically for compact, low-noise, transformer-coupled DC/DC conversion in safety-critical and EMI-sensitive applications - emphasizing robust protection, precise control, and thermal reliability.
FAQ
What is the maximum operating temperature for the LT3999IMSE#TRPBF?
The LT3999IMSE#TRPBF is rated for an operating junction temperature range of –40°C to +125°C, with guaranteed performance across this full range. Its MSOP-10 package features an exposed GND pad that must be soldered to a PCB thermal plane with multiple vias to maintain safe junction temperatures under continuous 1A switching loads.
Can the LT3999IMSE#TRPBF drive a transformer without external current sensing?
Yes - the LT3999IMSE#TRPBF uses internal cycle-by-cycle current limiting based on switch saturation voltage, eliminating the need for external sense resistors. The ILIM/SS pin allows optional resistor programming of the current threshold (0.4–0.6A), but leaving it unconnected defaults to the internal 1.4A limit, enabling direct transformer drive with only RBIAS, RT, and UVLO/OVLO/DC configuration.
How does duty cycle control improve regulation in the LT3999IMSE#TRPBF?
Duty cycle control in the LT3999IMSE#TRPBF adjusts the on-time of SWA/SWB switches in response to input voltage changes - implemented by connecting OVLO/DC to a VIN divider and setting RDC to ground. This pseudo-regulation maintains stable output voltage across the 2.7V–36V input range, reducing power dissipation in downstream LDOs and improving overall system efficiency.
Is the LT3999IMSE#TRPBF pin-compatible with other LT3999 variants like LT3999EMSE#TRPBF?
Yes - all LT3999 MSOP-10 variants (E, I, H, M grades) share identical pinout, package dimensions, and electrical functionality. The LT3999IMSE#TRPBF differs only in temperature grading (–40°C to +125°C), while retaining full compatibility with existing layouts, bill-of-materials, and test firmware developed for the E-grade version.
What is the purpose of the RBIAS pin on the LT3999IMSE#TRPBF?
The RBIAS pin on the LT3999IMSE#TRPBF sets the base drive current for the internal NPN power switches (SWA/SWB). A 49.9kΩ resistor to GND establishes optimal bias for reliable 1A switching at up to 1MHz, ensuring fast turn-on/turn-off while minimizing crossover distortion and transformer core saturation - critical for maintaining efficiency and low EMI in push-pull operation.
LT3999IMSE#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width) Exposed Pad
- Packaging:
- Tape & Reel (TR)
- 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 ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 10-MSOP-EP
LT3999IMSE#TRPBF FAQ
1.How can I place an order for LT3999IMSE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3999IMSE#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 LT3999IMSE#TRPBF reliable?
The price and inventory of LT3999IMSE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3999IMSE#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3999IMSE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3999IMSE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3999IMSE#TRPBF?
LT3999IMSE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3999IMSE#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 LT3999IMSE#TRPBF?
For technical support, including LT3999IMSE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3999IMSE#TRPBF requirements.
6.How does Aetrix verify that LT3999IMSE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3999IMSE#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 LT3999IMSE#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3999IMSE#TRPBF?
All LT3999IMSE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3999IMSE#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 LT3999IMSE#TRPBF part is unused and in its original packaging.
Return procedure for LT3999IMSE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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