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Analog Devices Inc. LT3999HMSE#TRPBF
- Part No.:
- LT3999HMSE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LT3999HMSE#TRPBF.pdf
- Description:
- IC REG PUSH-PULL ADJ 1A 10MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,349
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Product details
Overview
LT3999HMSE#TRPBF 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, programmable 50kHz–1MHz switching frequency, duty cycle control via RDC pin, precision UVLO/OVLO thresholds (1.25V ±100mV), and <1µA shutdown current. It enables 12V-to-12V, 10W isolated supplies in medical instrumentation and RS485 data acquisition systems.
For engineers reviewing the LT3999HMSE#TRPBF datasheet, LT3999HMSE#TRPBF pinout, LT3999HMSE#TRPBF application, or LT3999HMSE#TRPBF equivalent, key selection criteria include its –40°C to 150°C guaranteed junction temperature rating, MSOP-10 exposed-pad thermal performance (θJA = 40°C/W), dual-switch cross-conduction prevention, and ∆VIN compensation capability via duty cycle control.
Technical Context
The LT3999HMSE#TRPBF implements a synchronous push-pull topology with two out-of-phase 1A NPN power switches driving a center-tapped transformer primary. Its oscillator operates at twice the effective switch frequency (e.g., RT = 28kΩ sets fSW = 500kHz per switch), and supports external synchronization up to 1MHz with rising-edge-triggered clock alignment.
Duty cycle is actively adjusted via OVLO/DC pin voltage and RDC resistor to compensate input line variations-enabling pseudo-regulation before post-LDO stages. Protection includes programmable UVLO (1.25V threshold, 125mV hysteresis), OVLO (same threshold), non-overlap timing (70ns), and thermal shutdown above 150°C junction temperature.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switch Current Limit | 1.0A typical (internal default); programmable down to 0.5A via ILIM/SS resistor |
| Switching Frequency Range | 50kHz to 1MHz; set by RT resistor (e.g., 28kΩ → 500kHz) and synchronizable externally |
| Input Voltage Range | 2.7V to 36V operating; UVLO/OVLO thresholds programmable via resistive dividers |
| Duty Cycle Control | Adjustable 20%–48% via RDC resistor and OVLO/DC pin voltage; enables line regulation |
| Shutdown Current | <1µA at VUVLO = 0.3V; enables ultra-low-power system standby |
| Operating Junction Temp | –40°C to +150°C (H-grade); validated across full range with derating above 125°C |
| Package Thermal Resistance | θJA = 40°C/W (MSOP-10 with exposed pad soldered to PCB ground plane) |
Pinout & Package
LT3999HMSE#TRPBF is housed in a 10-lead MSOP package (MSE) with exposed thermal pad (Pin 11) that must be soldered to PCB ground for thermal and electrical integrity. Package dimensions: 3.00mm × 3.00mm × 1.10mm, pitch 0.50mm.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SWA (Pin 1) | Switch A collector output | Drives one outer terminal of center-tapped transformer; handles 1A pulsed current; requires short/wide PCB trace |
| RBIAS (Pin 2) | Bias current reference | Sets internal switch bias via 49.9kΩ-to-GND resistor; determines drive strength and saturation voltage |
| VIN (Pin 3) | Main supply input | Accepts 2.7V–36V; powers internal regulator and gate drivers; requires ≥4.7µF low-ESR ceramic bypass |
| UVLO (Pin 4) | Undervoltage lockout input | Disables switching below 1.25V threshold (125mV hysteresis); also enables shutdown mode when pulled low |
| OVLO/DC (Pin 5) | Overvoltage lockout / Duty cycle control | Double-function pin: OVLO disables switching above 1.25V; voltage level here directly modulates duty cycle |
| RDC (Pin 6) | Duty cycle programming | Resistor-to-GND sets duty cycle range (20%–48%); floating or tied to OVLO/DC disables control (≈50% default) |
| RT (Pin 7) | Oscillator timing | Resistor-to-GND sets switching frequency (50kHz–1MHz); accuracy depends on RT tolerance and tempco |
| SYNC (Pin 8) | External clock input | Accepts >2V square wave; forces oscillator sync; internal frequency must be 10%–50% lower than sync signal |
| ILIM/SS (Pin 9) | Current limit / Soft-start | Resistor sets cycle-by-cycle current limit (0.5A–1.4A); capacitor adds soft-start ramp (tSS = CSS × 80ms) |
| GND (Pin 11) | Power and thermal ground | Exposed pad; mandatory connection to solid PCB ground plane with multiple thermal vias for θJA = 40°C/W |
Key Features
| Feature | Design Value |
|---|---|
| Low-noise push-pull topology | Minimizes EMI and output ripple without requiring complex filtering; enables <100mVP-P noise in optimized layouts |
| Programmable duty cycle control | Compensates input voltage variation to stabilize transformer output prior to LDO post-regulation, reducing LDO power dissipation |
| Cross-conduction prevention | 70ns non-overlap timing ensures SWA and SWB never conduct simultaneously-preventing shoot-through and transformer saturation |
| Adjustable soft-start | Capacitor-based ramp on ILIM/SS limits inrush current during startup; prevents input rail sag and transformer core reset issues |
| High-temperature H-grade rating | Guaranteed operation from –40°C to +150°C junction temperature-suitable for under-hood automotive, industrial, and medical environments |
Applications
| Medical Isolated Power | Noise-Sensitive Data Acquisition |
|---|---|
Use Scenario: Powering isolated analog front-ends in patient-connected ECG or EEG monitors where galvanic isolation and ultra-low noise are mandated by IEC 60601. IC Role / Device Role / Timing Role: Push-pull transformer driver generating clean ±12V isolated rails; duty cycle control maintains stable output across battery voltage decay (e.g., 10V–15V input). Use Value: Enables compliance with stringent EMC and leakage current requirements while eliminating need for bulky linear regulators or complex feedback loops. |
Use Scenario: Supplying isolated power to RS485 transceivers and ADC reference circuits in factory automation PLCs subject to high common-mode noise. IC Role / Device Role / Timing Role: Low-noise DC/DC driver powering isolated data interface ICs; synchronized switching avoids interference with 1Mbps+ serial timing windows. Use Value: Reduces conducted emissions into signal grounds, improving SNR by >20dB versus standard flyback solutions-critical for 16-bit+ precision measurements. |
| Distributed Power Architecture | Positive-to-Negative Conversion |
Use Scenario: Generating local 5V or 12V isolated rails from a shared 24V or 36V backplane in telecom or server management modules. IC Role / Device Role / Timing Role: High-efficiency (≥85%) transformer driver supporting wide VIN range (2.7V–36V); programmable frequency avoids sensitive RF bands. Use Value: Delivers 10W in <100mm² footprint with minimal external components-reducing BOM count and layout complexity vs. discrete MOSFET solutions. |
Use Scenario: Creating tightly regulated ±12V supplies for op-amp biasing in audio preamplifiers or instrumentation amplifiers requiring symmetrical rails. IC Role / Device Role / Timing Role: Dual-switch push-pull driver feeding center-tapped transformer with full-wave rectification; duty cycle control stabilizes both polarities against input drift. Use Value: Achieves <±1% cross-regulation between positive and negative outputs without secondary-side feedback-simplifying design and improving reliability. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar isolated push-pull driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3439EFE#TRPBF | SO-16 package; slew-rate controlled switches; lower max VIN (17.5V); fixed 500kHz fSW | Better suited for sub-18V systems requiring <100mVP-P noise; lacks duty cycle control and wide-frequency programming | Select LT3439EFE#TRPBF only if input voltage stays ≤17.5V and ultra-low EMI is prioritized over line regulation flexibility. |
| LT3748EMSE#TRPBF | MSOP-10; no integrated switches; requires external MOSFETs; supports up to 100V VIN; no duty cycle control | Enables higher-power (>20W) or higher-VIN designs but increases component count, layout sensitivity, and gate-drive complexity | Choose LT3748EMSE#TRPBF when output power exceeds 10W or input voltage exceeds 36V-accepting added design effort for scalability. |
Compared with LT3439EFE#TRPBF and LT3748EMSE#TRPBF, the LT3999HMSE#TRPBF uniquely combines integrated 1A switches, programmable duty cycle for line regulation, and H-grade 150°C operation in a compact MSOP-10-making it optimal for space-constrained, wide-input, thermally demanding isolated supplies where post-regulator efficiency matters.
Availability
LT3999HMSE#TRPBF is available at Aetrix Electronics and suitable for medical instrumentation, industrial data acquisition, and distributed power systems requiring stable component supply, long-term lifecycle support, and guaranteed high-temperature performance.
Supply support for LT3999HMSE#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, Inc. (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 product line was designed specifically for compact, low-noise isolated DC/DC conversion in safety-critical and EMI-sensitive applications-emphasizing integrated protection, thermal robustness, and programmable regulation without secondary-side feedback.
FAQ
What is the maximum guaranteed junction temperature for LT3999HMSE#TRPBF?
The LT3999HMSE#TRPBF is fully specified and guaranteed to operate from –40°C to +150°C junction temperature. This H-grade rating is validated across the full range, with lifetime derating applied above 125°C per manufacturer guidelines. The exposed pad (Pin 11) must be soldered to a thermal ground plane to achieve θJA = 40°C/W and sustain continuous 150°C operation.
How does duty cycle control work on the LT3999HMSE#TRPBF?
Duty cycle control on the LT3999HMSE#TRPBF uses the OVLO/DC pin voltage and RDC resistor to adjust individual switch duty cycle between 20% and 48%. By referencing OVLO/DC to VIN via a resistor divider, the LT3999HMSE#TRPBF dynamically modifies duty cycle to compensate for input voltage changes-stabilizing transformer output before post-regulation. Leaving RDC floating defaults to ≈50%.
Can LT3999HMSE#TRPBF synchronize to an external clock, and what are the requirements?
Yes, the LT3999HMSE#TRPBF supports external synchronization via the SYNC pin (Pin 8). The internal oscillator frequency must be set 10%–50% lower than the external clock frequency. The SYNC signal must be a >2V square wave; its rising edge triggers clock discharge. If unused, SYNC must be tied to GND-floating is not permitted.
What is the purpose of the RBIAS pin on LT3999HMSE#TRPBF, and how is it configured?
The RBIAS pin (Pin 2) on the LT3999HMSE#TRPBF sets the internal bias current for the power switches, directly influencing saturation voltage (VCE(SAT)) and switching speed. It is configured with a single 49.9kΩ resistor connected from Pin 2 to GND. Deviating from this value alters switch conduction losses and thermal behavior-49.9kΩ is the manufacturer-optimized value for 1A operation.
Does LT3999HMSE#TRPBF require external MOSFETs, or are switches integrated?
The LT3999HMSE#TRPBF integrates two matched 1A NPN power switches (SWA and SWB) on-die-no external MOSFETs or transistors are required. These switches drive the center-tapped transformer primary directly. The IC handles gate drive, current limiting, non-overlap timing, and thermal protection internally, enabling complete isolated DC/DC solutions with minimal external components.
LT3999HMSE#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 ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 10-MSOP-EP
LT3999HMSE#TRPBF FAQ
1.How can I place an order for LT3999HMSE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3999HMSE#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 LT3999HMSE#TRPBF reliable?
The price and inventory of LT3999HMSE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3999HMSE#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3999HMSE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3999HMSE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3999HMSE#TRPBF?
LT3999HMSE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3999HMSE#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 LT3999HMSE#TRPBF?
For technical support, including LT3999HMSE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3999HMSE#TRPBF requirements.
6.How does Aetrix verify that LT3999HMSE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3999HMSE#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 LT3999HMSE#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3999HMSE#TRPBF?
All LT3999HMSE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3999HMSE#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 LT3999HMSE#TRPBF part is unused and in its original packaging.
Return procedure for LT3999HMSE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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