My Inquiry
My Account
Analog Devices Inc. LT3999IMSE#PBF
- Part No.:
- LT3999IMSE#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LT3999IMSE#PBF.pdf
- Description:
- IC REG PUSH-PULL ADJ 1A 10MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:505
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
LT3999IMSE#PBF 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 dual 1A current-limited switches, programmable 50kHz–1MHz switching frequency, duty cycle control via RDC pin, precision UVLO/OVLO thresholds (1.25V ±0.1V), and <1µA shutdown current. It enables 12V-to-12V, 10W isolated supplies in medical instrumentation and data acquisition systems.
For engineers reviewing the LT3999IMSE#PBF datasheet, LT3999IMSE#PBF pinout, LT3999IMSE#PBF application, or LT3999IMSE#PBF equivalent, key selection criteria include its dual-switch push-pull topology, programmable soft-start via ILIM/SS pin, cross-conduction prevention, exposed-pad MSOP-10 thermal performance (θJA = 40°C/W), and compatibility with center-tapped transformers for safety-isolated outputs.
Technical Context
The LT3999IMSE#PBF implements a fixed-frequency, out-of-phase dual-switch push-pull architecture where SWA and SWB drive opposite ends of a center-tapped transformer primary. Its oscillator operates at twice the effective switch frequency (e.g., RT = 49.9kΩ sets fSW = 300kHz per switch, fOSC = 600kHz).
Duty cycle is actively controlled by the OVLO/DC pin voltage and RDC resistor to compensate for input line variation-enabling pseudo-regulation before an LDO post-regulator. Protection includes independent 1.25V threshold UVLO and OVLO with 125mV hysteresis, non-overlap timing (70ns), and thermal shutdown.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switch Current Limit | 1.0–1.7A (internal default); programmable down to 0.4–0.6A via ILIM/SS resistor |
| Switching Frequency Range | 50kHz to 1MHz (set by RT resistor); synchronized externally up to 1MHz |
| Input Voltage Range | 2.7V to 36V (programmable UVLO/OVLO lockouts prevent operation outside safe window) |
| Duty Cycle Control | 20%–48% (adjustable via RDC and OVLO/DC voltage; enables line regulation without feedback loop) |
| Shutdown Current | <1µA (achieved by pulling UVLO pin low; critical for battery-powered isolation stages) |
| Package Thermal Resistance | θJA = 40°C/W (MSOP-10 with exposed pad soldered to PCB ground plane) |
| Operating Junction Temp | –40°C to +125°C (I-grade; validated across full range for industrial reliability) |
Pinout & Package
LT3999IMSE#PBF is housed in a 10-lead MSOP package (MSE) with exposed thermal pad (Pin 11), requiring soldering to PCB ground for thermal and electrical integrity. Pin pitch is 0.5mm; body size is 3.0mm × 3.0mm × 1.1mm.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SWA (Pin 1) | Power switch A collector | Drives one end of center-tapped transformer primary; handles peak currents up to 1A; requires short/wide PCB trace |
| RBIAS (Pin 2) | Bias current reference | Sets internal switch bias via 49.9kΩ-to-GND resistor; determines switching speed and conduction loss balance |
| VIN (Pin 3) | Main supply input | Provides power to internal regulator and gate drivers; requires ≥4.7µF low-ESR ceramic bypass capacitor |
| UVLO (Pin 4) | Undervoltage lockout input | Disables switching when VIN falls below 1.25V threshold; doubles as shutdown enable (pull low = <1µA quiescent) |
| OVLO/DC (Pin 5) | Overvoltage lockout / duty cycle control | Configurable: resistor divider for OVLO trip point OR voltage reference for duty cycle modulation |
| RDC (Pin 6) | Duty cycle programming | Resistor-to-GND sets duty cycle (20–48%); floating = ~50% fixed; ties to OVLO/DC to disable function |
| RT (Pin 7) | Oscillator frequency set | Resistor-to-GND programs switching frequency (50kHz–1MHz); tolerance directly impacts fSW accuracy |
| 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 | Resistor sets cycle-by-cycle current limit (0.4–0.6A); capacitor adds soft-start ramp (tSS = CSS × 80ms) |
| GND (Pin 11) | Power ground / thermal pad | Exposed pad must be soldered to solid PCB ground plane; provides primary thermal path and low-inductance return |
Key Features
| Feature | Design Value |
|---|---|
| Low-noise push-pull topology | Eliminates transformer saturation risk and reduces EMI vs. flyback; enables <100mVP-P output noise with optional LC filter |
| Programmable duty cycle control | Compensates for ±20% VIN variation without feedback loop-reducing LDO power dissipation in post-regulated designs |
| Cross-conduction prevention | 70ns non-overlap time ensures SWA/SWB never conduct simultaneously-preventing shoot-through and transformer core reset failure |
| Adjustable soft-start | Capacitor on ILIM/SS pin ramps peak switch current over user-defined time-limiting inrush into transformer and input capacitors |
| High-voltage switch capability | SWA/SWB rated to 80V absolute max-supports 36V input with margin for transients in industrial and automotive subsystems |
Applications
| Medical Isolation Supplies | Data Acquisition Front-Ends |
|---|---|
Use Scenario: Powering isolated ADC/DAC signal chains in patient-connected devices requiring reinforced insulation. IC Role / Device Role / Timing Role: LT3999IMSE#PBF generates clean, galvanically isolated ±12V rails from a single 12V input using center-tapped transformer and Schottky rectifiers. Use Value: Achieves <100mVP-P output noise and meets IEC 60601 creepage/clearance requirements via transformer isolation and low EMI push-pull operation. |
Use Scenario: Supplying isolated analog front-ends in RS485/RS232 interfaces where noise immunity is critical for 16-bit+ resolution. IC Role / Device Role / Timing Role: LT3999IMSE#PBF drives a 12V-to-±12V converter feeding isolated op-amps and level shifters in multi-channel DAQ modules. Use Value: Programmable soft-start prevents bus voltage droop during system power-up; duty cycle control maintains stable output under varying input conditions. |
| Industrial Distributed Power | Positive-to-Negative Conversion |
Use Scenario: Generating local isolated 5V/3.3V rails from a 24V backplane in PLC I/O modules. IC Role / Device Role / Timing Role: LT3999IMSE#PBF operates at 500kHz (RT = 28kΩ) to minimize transformer size while delivering 10W with <85% efficiency. Use Value: Exposed-pad MSOP package enables direct thermal coupling to heatsink; UVLO/OVLO lockouts protect against brownout/surges in factory environments. |
Use Scenario: Creating negative supply for op-amp biasing in single-supply sensor signal conditioning circuits. IC Role / Device Role / Timing Role: LT3999IMSE#PBF drives center-tapped transformer with inverted secondary winding to generate –12V from +12V input. Use Value: Dual 1A switches ensure symmetrical drive; non-overlap timing prevents transformer core saturation during polarity reversal. |
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#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 impractical | Select LT3439EFE#PBF when sub-50mV noise floor is mandatory and board space allows SO-16 footprint |
| LT1533CS#PBF | SO-16; same slew-rate control; 23V max VIN; no duty cycle control or SYNC pin; fixed ~50% duty cycle | Lacks line regulation capability-requires external feedback for stable output under input variation | Choose LT1533CS#PBF only for cost-sensitive, fixed-input designs where duty cycle adaptability is unnecessary |
Compared with LT3999IMSE#PBF, LT3439EFE#PBF offers superior noise control but sacrifices input voltage range and programmability; LT1533CS#PBF provides simpler implementation but lacks the line-regulating duty cycle feature essential for wide-input industrial supplies.
Availability
LT3999IMSE#PBF is available at Aetrix Electronics and suitable for medical instrumentation, industrial distributed power, and data acquisition systems requiring stable component supply, long-term lifecycle support, and guaranteed I-grade temperature performance.
Supply support for LT3999IMSE#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 full product support, datasheet updates, and application engineering for legacy Linear parts including the LT3999 family.
The LT3999 product line was engineered specifically for high-efficiency, low-noise isolated DC/DC conversion in space-constrained applications-emphasizing transformer-driven topologies with integrated protection and programmable control.
FAQ
What is the maximum input voltage supported by the LT3999IMSE#PBF?
The LT3999IMSE#PBF has an absolute maximum rating of 60V on VIN and UVLO pins, but its operational input voltage range is programmable from 2.7V to 36V using the UVLO and OVLO/DC pins. The internal OVLO threshold is 40V (typical), ensuring reliable shutdown before reaching absolute limits. For sustained operation, design within the 36V max specified range.
How does the LT3999IMSE#PBF achieve duty cycle control without a feedback loop?
The LT3999IMSE#PBF uses the OVLO/DC pin as a reference input and the RDC pin as a scaling resistor to modulate switch on-time proportionally to VIN. By connecting OVLO/DC to a resistor divider from VIN, its voltage varies with input-causing the internal duty cycle comparator to adjust pulse width. This pseudo-regulation maintains stable VOUT across ±20% VIN variation, reducing post-regulator losses.
Can the LT3999IMSE#PBF drive a transformer with non-center-tapped primary?
No-the LT3999IMSE#PBF is specifically designed for center-tapped transformer primaries. Its dual out-of-phase switches (SWA/SWB) drive opposite ends of the center tap, requiring symmetrical winding impedance. Using a non-center-tapped transformer would unbalance switch conduction, risk core saturation, and violate the non-overlap timing architecture. Refer to Table 3 in the datasheet for validated center-tapped part numbers.
What is the purpose of the RBIAS pin on the LT3999IMSE#PBF?
The RBIAS pin on the LT3999IMSE#PBF sets the internal bias current for both power switches, directly influencing switching speed, conduction loss balance, and thermal distribution between SWA and SWB. A 49.9kΩ resistor to GND is the standard value-deviating significantly alters rise/fall times and may degrade cross-conduction prevention. Do not leave RBIAS floating or tie directly to VIN/GND.
Does the LT3999IMSE#PBF require external components for basic operation?
Yes-minimum external components for functional operation include: a 49.9kΩ resistor on RBIAS, a bypass capacitor ≥4.7µF on VIN, an RT resistor for frequency setting, and a transformer with center-tapped primary. Additional components (RDC, OVLO/DC divider, ILIM/SS capacitor) are required for duty cycle control, soft-start, and lockout functions-but the IC will operate at default settings (50% duty, internal current limit) if omitted.
LT3999IMSE#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 ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 10-MSOP-EP
LT3999IMSE#PBF FAQ
1.How can I place an order for LT3999IMSE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3999IMSE#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 LT3999IMSE#PBF reliable?
The price and inventory of LT3999IMSE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3999IMSE#PBF is usually 5 days.
3.What payment methods are accepted for LT3999IMSE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3999IMSE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3999IMSE#PBF?
LT3999IMSE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3999IMSE#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 LT3999IMSE#PBF?
For technical support, including LT3999IMSE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3999IMSE#PBF requirements.
6.How does Aetrix verify that LT3999IMSE#PBF is sourced from the original manufacturer or authorized distributors?
All LT3999IMSE#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 LT3999IMSE#PBF meets industry standards.
7.What is the process for return or replacement of LT3999IMSE#PBF?
All LT3999IMSE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3999IMSE#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 LT3999IMSE#PBF part is unused and in its original packaging.
Return procedure for LT3999IMSE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LT3999IMSE#PBF Tags
-
TPS562201DDCR
Texas Instruments
-
MC34063ABD-TR
STMicroelectronics
-
TPS561201DDCR
Texas Instruments
-
MC33063ADR
Texas Instruments
-
MC34063ADR
Texas Instruments
-
TPS560200DBVR
Texas Instruments
-
AP3012KTR-G1
Diodes Incorporated
-
TLV61048DBVR
Texas Instruments
-
AZ34063UMTR-G1
Diodes Incorporated
-
TPS562200DDCR
Texas Instruments
-
AP62300TWU-7
Diodes Incorporated
-
MC34063EBD-TR
STMicroelectronics
Tech Hub
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…
