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Analog Devices Inc. LT1941EFE#TRPBF
- Part No.:
- LT1941EFE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 28-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LT1941EFE#TRPBF.pdf
- Description:
- IC REG BUCK BST ADJ TRPL 28TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,192
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Product details
Overview
LT1941EFE#TRPBF from Analog Devices (formerly Linear Technology) is a triple monolithic current-mode DC/DC switching regulator IC with integrated 3A step-down, 2A step-down, and 1.5A inverting/boost power switches. It operates from 3.5V to 25V input, delivers synchronized 1.1MHz switching across all channels, uses antiphase control between the two buck regulators to reduce input ripple, and provides independent shutdown, soft-start, and power-good signals for each output - enabling precise sequencing in multi-rail DSP, disk drive, and DSL modem power systems.
For engineers reviewing the LT1941EFE#TRPBF datasheet, LT1941EFE#TRPBF pinout, LT1941EFE#TRPBF application, or LT1941EFE#TRPBF equivalent, this page delivers verified technical context, exact pin functions, real-world design meanings of key specs, and validated alternative options - all grounded in the official Linear Technology LTC1941 datasheet (Rev. G) and product documentation.
Technical Context
The LT1941EFE#TRPBF implements three independent current-mode switching regulators sharing a single 1.1MHz master oscillator: two antiphase buck converters (SW1/SW2) and one configurable inverting/boost/SEPIC channel (SW3). Each regulator features dedicated VC error amplifier outputs, FB/NFB feedback inputs, RUN/SS control pins, and open-collector PGOOD indicators - enabling per-rail enablement, soft-start ramping, and regulation monitoring without external logic.
Its bipolar NPN internal switches require BOOST pin drive voltages exceeding VIN (≥1.8V above SW), supplied via external diode-capacitor networks; BIAS1 and BIAS2 pins allow partial biasing from lower-voltage rails to reduce dissipation. Input power-good comparators (5GOOD, 12GOOD) and per-output PGOOD signals support robust supply sequencing in distributed-power and wall-adapter-fed systems.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.5V to 25V - supports 4-cell Li-ion, 5V/12V logic rails, unregulated wall transformers, and lead-acid batteries without external pre-regulation. |
| Switching Frequency | 1.1MHz (typical), ±20% over temperature - enables use of ≤3.3μH inductors and ceramic output capacitors for compact triple-output designs. |
| Buck Regulator 1 | 3A integrated switch with 628mV FB reference - delivers up to 2.4A at 1.8V with typical efficiency >85% at 5V input. |
| Buck Regulator 2 | 2A integrated switch with 628mV FB reference - delivers up to 1.4A at 3.3V with typical efficiency >87% at 5V input. |
| Inverting/Boost Regulator | 1.5A integrated switch with 1.25V FB reference and NFB input - supports –12V @ 350mA or +12V boost configurations using standard external components. |
| Power-Good Monitoring | Three independent open-collector PGOOD outputs (PGOOD1/2/3) plus 5GOOD and 12GOOD input monitors - enables hardware-based rail sequencing and fault isolation without microcontroller intervention. |
| Thermal Package | 28-lead thermally enhanced TSSOP with exposed pad (Pin 29 = GND) - achieves θJA = 25°C/W, supporting ≥2.5W continuous dissipation in standard PCB layouts. |
Pinout & Package
LT1941EFE#TRPBF is housed in a 28-lead plastic TSSOP package (FE grade) with an exposed thermal pad (Pin 29) that must be soldered to PCB ground for electrical integrity and thermal performance. The package measures 4.4mm × 9.7mm × 1.1mm and is RoHS-compliant with lead-free finish (#TRPBF).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (Pins 1,2,22,25) | Primary power input | Supplies internal circuitry and power switches; multiple pins reduce IR drop and improve high-current routing - must be tied together and locally bypassed with ≥10μF ceramic. |
| SW1/SW2/SW3 (Pins 3,4,23,27) | Switch node outputs | Direct connections to external inductors and Schottky catch diodes; SW1/SW2 are antiphase buck outputs; SW3 supports inverting/boost topologies. |
| BOOST1/BOOST2 (Pins 5,24) | Bootstrap gate drive supply | Must be ≥1.8V above respective SW pin to saturate internal NPN switches; driven via external diode+capacitor from VIN or VOUT. |
| PGOOD1/2/3 (Pins 6,9,21) | Output regulation status | Open-collector outputs pulled low until FB voltage reaches 91% of target (e.g., 0.571V for 0.628V ref); used for sequencing and fault signaling. |
| RUN/SS1/2/3 (Pins 12,13,14) | Enable & soft-start control | Pull low to disable regulator; capacitor to ground sets soft-start ramp time - prevents inrush current and enables staggered turn-on. |
| FB1/FB2/FB3 (Pins 8,11,20) | Feedback voltage sense | Regulated to 0.628V (buck) or 1.25V (inverting/boost); connects to resistor divider tap - determines output voltage with ±1% accuracy over temp. |
| NFB (Pin 19) | Inverting op-amp input | Used only in negative-output configurations; forms virtual ground node with FB3 to enable precision inverting regulation (e.g., –12V) with two resistors. |
| 5GOOD/12GOOD (Pins 17,16) | Input supply monitoring | Open-collector comparators asserting low when VIN is within 10% of 5V or 12V - supports system-level brownout detection independent of regulator operation. |
| BIAS1/BIAS2 (Pins 15,28) | Internal bias supply inputs | Allow sourcing of internal regulator (BIAS1) and SW3 driver (BIAS2) from lower-voltage rails (≥2.35V/≥2.5V) to reduce quiescent dissipation. |
| VC1/VC2/VC3 (Pins 7,10,18) | Error amplifier output | Control peak switch current per cycle; clamped at 1.7V; pulled low to shut down regulator; used for loop compensation with Type II/III networks. |
Key Features
| Feature | Design Value |
|---|---|
| Triple integrated power switches | Eliminates need for six external MOSFETs/diodes - reduces BOM count, layout area, and EMI sources in space-constrained DSL/cable modem designs. |
| Antiphase buck switching | Cancels fundamental input ripple current between SW1 and SW2 - cuts input capacitor RMS current by ~30%, allowing smaller bulk capacitance. |
| Independent PGOOD and RUN/SS | Enables deterministic power-up/down sequencing across three rails without external timers or CPLDs - critical for FPGA, DSP, and mixed-signal SoC applications. |
| Configurable third channel | Supports inverting (–12V), boost (+12V), or SEPIC topologies with same IC - avoids redesign when system voltage requirements change mid-development. |
| 1.1MHz constant-frequency operation | Permits use of small, low-DCR ceramic inductors (e.g., 2.2μH) and X5R/X7R MLCCs - achieves full triple-output solution in <1.5 cm² PCB area. |
| Input supply monitoring | 5GOOD and 12GOOD pins provide hardware-level detection of upstream supply faults - improves system reliability in wall-adapter or battery-backed systems. |
Applications
| Cable Modems | DSL Modems |
|---|---|
|
Use Scenario: Powering triple-rail PHY, MAC, and analog front-end from single 12V wall adapter. IC Role / Device Role / Timing Role: Primary triple-output DC/DC controller delivering 3.3V (PHY), 1.8V (MAC), and –12V (line driver) with synchronized 1.1MHz switching. Use Value: Antiphase buck operation reduces 12V input ripple, enabling smaller input bulk cap; PGOOD sequencing ensures PHY powers before MAC to prevent initialization lockup. |
Use Scenario: Generating 3.3V, 1.2V, and –5V rails for ADSL transceiver, controller, and line interface ICs. IC Role / Device Role / Timing Role: Configured as two bucks (3.3V/1.2V) and inverting regulator (–5V); RUN/SS pins enable staggered startup per ITU-T G.992.1 timing requirements. Use Value: Independent soft-start on each rail meets strict DSL modem power-up timing windows; 1.1MHz frequency allows compact 1206-size inductors. |
| Disk Drives | DSP Power |
|
Use Scenario: Supplying 5V spindle motor, 3.3V logic, and –5V analog bias in 2.5" HDDs with tight thermal constraints. IC Role / Device Role / Timing Role: Buck1 (5V@2A), Buck2 ([email protected]), Inverter (–5V@200mA); exposed pad soldered to inner ground plane for thermal management. Use Value: Thermal TSSOP package sustains >2W dissipation at 85°C ambient; 5GOOD monitor detects adapter failure before spindle spin-up begins. |
Use Scenario: Providing isolated 1.2V core, 3.3V I/O, and –3.3V analog supply for TI C6000 or ADI SHARC DSPs in industrial control. IC Role / Device Role / Timing Role: Triple regulator with independent PGOOD outputs interfaces directly to DSP's power-enable pins for controlled boot sequence. Use Value: Per-rail shutdown via RUN/SS allows dynamic power gating during low-power modes; VC pins enable external loop compensation for wide-load transient response. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar triple-output switching regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3776EUF#PBF | Triple synchronous buck controller (no internal switches); requires external MOSFETs; supports 4.5V–38V input; 300kHz–1MHz programmable frequency. | Better suited for high-current (>5A/rail), high-efficiency (>92%) applications where thermal headroom is limited and board space allows discrete FETs. | Select LTC3776 when higher efficiency, wider input range, or greater current scalability are required - but expect +8 BOM items and +25% layout area vs. LT1941EFE#TRPBF. |
| TPS546D24RQFT | Single 6A buck converter with PMBus interface; no inverting/boost capability; 4.5V–18V input; supports AVS and telemetry. | Targeted at digital power systems requiring closed-loop margining, real-time telemetry, and multi-phase synchronization - not a functional replacement for triple-output topology. | Choose TPS546D24 only if system architecture shifts to distributed single-rail supplies with digital control - not for direct LT1941EFE#TRPBF replacement. |
Compared with LTC3776EUF#PBF and TPS546D24RQFT, LT1941EFE#TRPBF uniquely integrates three switching regulators - including a configurable inverting/boost channel - in a single TSSOP package with hardware sequencing, making it optimal for cost-sensitive, space-constrained triple-rail applications where discrete controllers add complexity and footprint.
Availability
LT1941EFE#TRPBF is available at Aetrix Electronics and suitable for cable modems, DSL modems, and disk drive power systems requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant packaging.
Supply support for LT1941EFE#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. (ADI) acquired Linear Technology in 2017 and maintains full technical and manufacturing continuity for the LT® product family, including rigorous qualification, long-term obsolescence management, and global distribution.
The LT1941EFE#TRPBF belongs to Linear Technology's monolithic switching regulator product line, designed specifically for compact, high-density multi-rail power conversion in broadband communications, storage, and signal processing equipment where integration, sequencing, and thermal performance are critical.
FAQ
What is the maximum output current capability of each regulator in LT1941EFE#TRPBF?
The LT1941EFE#TRPBF supports up to 3A on Buck1 (SW1), 2A on Buck2 (SW2), and 1.5A on the inverting/boost channel (SW3) under typical conditions. Actual deliverable current depends on input voltage, output voltage, inductor value, and thermal environment - e.g., Buck1 delivers ~2.4A at 1.8V with 5V input and proper layout. Current limits decrease linearly with duty cycle above 78% due to slope compensation.
Can LT1941EFE#TRPBF generate negative output voltages?
Yes - the third regulator (SW3) in LT1941EFE#TRPBF is explicitly designed for inverting operation. When configured with external components per Figure 2 in the datasheet, it delivers regulated negative outputs such as –12V at 350mA. The NFB pin provides the inverting op-amp's virtual ground node, enabling precise negative regulation using only two external resistors.
How does the antiphase switching between SW1 and SW2 benefit system design?
Antiphase switching in LT1941EFE#TRPBF means SW1 and SW2 operate 180° out of phase, causing their input ripple currents to cancel at the fundamental switching frequency. This reduces RMS input capacitor current by ~30%, lowers required bulk capacitance, decreases input EMI, and eases thermal design - especially valuable in compact, fanless DSL/cable modem enclosures.
What is the role of the BIAS1 and BIAS2 pins on LT1941EFE#TRPBF?
BIAS1 supplies current to the LT1941EFE#TRPBF's internal regulator and reference circuits; BIAS2 supplies current to the SW3 driver. Both can be tied to a lower-voltage rail (≥2.35V for BIAS1, ≥2.5V for BIAS2) instead of VIN to reduce internal power dissipation and improve overall efficiency - particularly beneficial when VIN is significantly higher than required output voltages.
Does LT1941EFE#TRPBF support power supply sequencing, and how is it implemented?
Yes - LT1941EFE#TRPBF supports hardware-based sequencing via three independent RUN/SS pins (for enable/soft-start) and three open-collector PGOOD outputs (indicating regulation status). By cascading PGOOD outputs to downstream RUN/SS pins using pull-up resistors, designers implement deterministic, self-contained power-up order - e.g., 3.3V rail enables before 1.8V rail - without external controllers.
LT1941EFE#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 28-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Function:
- Step-Up, Step-Down, Step-Up/Step-Down
- Output Configuration:
- Positive or Negative
- Topology:
- Buck, Boost, SEPIC
- Output Type:
- Adjustable
- Number of Outputs:
- 3
- Voltage - Input (Min):
- 3.5V
- Voltage - Input (Max):
- 25V
- Voltage - Output (Min/Fixed):
- 0.628V
- Voltage - Output (Max):
- 25V, 40V (Switch)
- Current - Output:
- 1.5A (Switch), 2A (Switch), 3A (Switch)
- Frequency - Switching:
- 1.1MHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-TSSOP-EP
LT1941EFE#TRPBF FAQ
1.How can I place an order for LT1941EFE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1941EFE#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 LT1941EFE#TRPBF reliable?
The price and inventory of LT1941EFE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1941EFE#TRPBF is usually 5 days.
3.What payment methods are accepted for LT1941EFE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1941EFE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1941EFE#TRPBF?
LT1941EFE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1941EFE#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 LT1941EFE#TRPBF?
For technical support, including LT1941EFE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1941EFE#TRPBF requirements.
6.How does Aetrix verify that LT1941EFE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT1941EFE#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 LT1941EFE#TRPBF meets industry standards.
7.What is the process for return or replacement of LT1941EFE#TRPBF?
All LT1941EFE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1941EFE#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 LT1941EFE#TRPBF part is unused and in its original packaging.
Return procedure for LT1941EFE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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