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Analog Devices Inc. LT3958IUHE#TRPBF
- Part No.:
- LT3958IUHE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 36-WFQFN, 28 Leads, Exposed Pad
- Datasheet:
-
LT3958IUHE#TRPBF.pdf
- Description:
- IC REG BOOST CUK ADJ 3.3A 36QFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,333
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Product details
Overview
LT3958IUHE#TRPBF from Analog Devices is a wide-input, current-mode DC/DC controller IC capable of configuring as boost, flyback, SEPIC, or inverting converter to generate positive or negative output voltages. It integrates an 84V/3.3A internal N-channel MOSFET, supports 5V–80V input, delivers programmable 100kHz–1MHz switching frequency via RT pin, and features soft-start, frequency foldback, and <1µA shutdown current - ideal for high-voltage automotive LED drivers and industrial power supplies.
For engineers reviewing the LT3958IUHE#TRPBF datasheet, LT3958IUHE#TRPBF pinout, LT3958IUHE#TRPBF application, or LT3958IUHE#TRPBF equivalent, this page provides verified technical context, validated pin functions, confirmed operating parameters across temperature, real-world converter configurations (SEPIC/flyback), and alternative selection guidance grounded in published electrical characteristics and package mapping.
Technical Context
The LT3958IUHE#TRPBF implements fixed-frequency current-mode control with dual feedback regulation: +1.6V reference for positive-output topologies and –0.8V reference for inverting configurations, both with ±0.031V line regulation over 5V–80V VIN. Its internal 7.2V LDO powers gate drive and logic, with UVLO at 3.75V and OVP at 12.8V, enabling robust operation in fluctuating input environments.
It uses a Kelvin-sense architecture with separate SGND and GND pins to isolate current-sense paths; SENSE1 and SENSE2 form a differential current-sense interface referenced to SGND, while SW pins (8, 9, 20, 21, and exposed pad 38) carry up to 4.6A peak switch current with 120mΩ typical RDS(on) at 25°C. Frequency synchronization via SYNC pin requires RT biasing 20% below external clock frequency.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 5V to 80V - supports direct connection to 48V telecom, 24V industrial, and 12V automotive battery rails without pre-regulation. |
| Internal Power Switch | 84V/3.3A N-channel MOSFET - eliminates external high-voltage switch in boost/flyback designs up to ~40W output. |
| Switching Frequency | 100kHz to 1MHz (RT-programmable) - enables trade-off between efficiency (lower fSW) and magnetics size (higher fSW). |
| Feedback Reference | +1.6V (positive VOUT) or –0.8V (negative VOUT) - single FBX pin supports both polarities without external op-amps. |
| Shutdown Current | <1µA - preserves battery life in always-on vehicle systems during ignition-off states. |
| Operating Temperature | –40°C to +125°C junction - qualified for under-hood automotive and industrial ambient conditions. |
| Package | 36-lead 5mm × 6mm QFN with dual exposed pads (SGND and SW) - enables low-inductance thermal and power routing. |
Pinout & Package
LT3958IUHE#TRPBF is housed in a thermally enhanced 36-lead plastic QFN (5mm × 6mm) with two exposed pads: Pin 37 (SGND) and Pin 38 (SW). Both exposed pads must be soldered to dedicated PCB planes - SGND plane for signal ground integrity and SW plane for low-inductance high-current return path.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SENSE2 (Pin 3) | Current sense input | Receives filtered voltage from SENSE1; sets current limit threshold (48mV typical) for cycle-by-cycle protection. |
| SGND (Pins 4, 23, 24, 37) | Signal ground reference | Provides Kelvin return for internal current sensing; must not be externally shorted to GND to preserve accuracy. |
| SENSE1 (Pin 6) | Current sense output | Drives SENSE2 through RC filter; connects directly to source-side shunt or transformer sense winding. |
| SW (Pins 8, 9, 20, 21, 38) | Power switch drain | High-current node tied to inductor/diode/flyback primary; exposed pad (38) must connect to SW copper pour. |
| GND (Pins 12–17) | Power ground return | Source terminal of internal MOSFET; internally connected to SGND but kept separate on PCB for noise isolation. |
| EN/UVLO (Pin 25) | Enable & input UVLO input | 1.22V falling threshold with 20mV hysteresis; enables programmable turn-on/off via resistor divider. |
| VIN (Pin 27) | Main input supply | Accepts 5V–80V; bypassed locally to GND (not SGND) with ≥4.7µF ceramic capacitor. |
| INTVCC (Pin 28) | Internal LDO output | 7.2V regulated supply for gate driver; requires ≥4.7µF ceramic cap to SGND; can be bypassed to VIN if ≤12.8V. |
| FBX (Pin 31) | Feedback input | Single pin accepts either +1.6V (boost/SEPIC/flyback) or –0.8V (inverting) reference; triggers frequency foldback when near 0V. |
| SS (Pin 32) | Soft-start control | 10µA pull-up to 2.5V rail; external capacitor sets ramp time; reset by INTVCC fault or EN/UVLO undervoltage. |
| RT (Pin 33) | Frequency programming | Resistor to SGND sets fSW: 41.2kΩ = 300kHz, 10.5kΩ = 1MHz - must not be left floating. |
| SYNC (Pin 34) | External clock sync | Accepts digital clock; disables frequency foldback; requires RT set 20% below sync frequency. |
Key Features
| Feature | Design Value |
|---|---|
| Dual-polarity feedback architecture | Single FBX pin supports +1.6V (positive VOUT) and –0.8V (negative VOUT) regulation - eliminates topology-specific IC variants. |
| Kelvin current sensing | Separate SGND and GND pins with internal connection ensure accurate RSENSE-based current limiting independent of PCB trace IR drop. |
| Programmable frequency foldback | Automatically reduces fSW when FBX approaches 0V during start-up or overload - prevents inductor saturation and switch overcurrent. |
| Thermally optimized QFN | Two exposed pads (SGND and SW) enable independent thermal management: SGND pad dissipates logic heat, SW pad handles switch losses. |
| Low-quiescent integrated LDO | 7.2V/50mA internal regulator powers gate driver; UVLO (3.75V) and OVP (12.8V) protect against supply faults without external supervision. |
Applications
| Automotive LED Headlamp Driver | Industrial 48V-to-±15V Isolated Bias Supply |
|---|---|
|
Use Scenario: Driving high-brightness LEDs from variable 9V–16V automotive battery with EMI-constrained layout. IC Role / Device Role / Timing Role: Configured as boost converter with synchronous rectification; FBX regulates LED current via sense resistor; RT sets 400kHz to minimize EMI. Use Value: Internal 84V switch withstands load-dump transients; <1µA shutdown current extends battery standby time; soft-start prevents inrush into cold LED strings. |
Use Scenario: Generating isolated ±15V rails for op-amp and ADC circuitry in factory automation PLC modules powered from 48V DC bus. IC Role / Device Role / Timing Role: Configured as flyback converter with center-tapped secondary; FBX referenced to –0.8V regulates negative rail; SYNC pin synchronized to system clock for noise reduction. Use Value: Dual feedback references eliminate need for post-regulation; 125°C rating ensures reliability in sealed enclosures; frequency foldback protects during output short-circuit events. |
| Telecom 48V Boost for PoE++ Midspan | Medical Imaging High-Voltage Bias Generator |
|
Use Scenario: Stepping up telecom 48V supply to 57V for IEEE 802.3bt Type 4 Power over Ethernet midspan injectors. IC Role / Device Role / Timing Role: Operated as boost converter; EN/UVLO programmed for 44V turn-on to avoid brownout; INTVCC tied to VIN to reduce LDO losses at high fSW. Use Value: 80V input rating accommodates 48V + 30% ripple; 3.3A switch supports >25W output; programmable UVLO prevents unstable operation during line sag. |
Use Scenario: Generating stable ±100V bias for photomultiplier tube (PMT) anodes in portable X-ray detectors with strict leakage current limits. IC Role / Device Role / Timing Role: Configured as inverting converter; FBX referenced to –0.8V; SS capacitor set for 10ms ramp to limit PMT dark current surge. Use Value: <1µA shutdown current minimizes battery drain in handheld units; 125°C rating allows compact heatsinkless design; low FBX input bias (<100nA) prevents voltage error from high-impedance dividers. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar DC/DC controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3789EFE#PBF | 4-switch synchronous buck-boost controller; no integrated switch; requires external MOSFETs; supports 4V–36V input. | Better suited for bidirectional power flow and higher-efficiency (>95%) applications where board space allows discrete FETs. | Select LTC3789EFE#PBF when efficiency >94% and input range <36V are critical; avoid for 80V input or cost-sensitive designs requiring integrated switch. |
| LM5122MH/NOPB | Wide-input (3V–65V) boost/flyback controller; no integrated switch; 1.5A gate driver; supports 50kHz–1MHz. | Requires external high-voltage MOSFET; lacks dual-polarity feedback; uses standard 0.8V reference instead of ±0.8V/1.6V. | Choose LM5122MH/NOPB for lower-cost discrete solutions where ±VOUT capability is unnecessary and 65V max input suffices. |
Compared with LTC3789EFE#PBF and LM5122MH/NOPB, the LT3958IUHE#TRPBF uniquely integrates an 84V/3.3A switch and supports both positive and negative output regulation from one FBX pin - reducing BOM count and layout complexity in high-input-voltage, polarity-flexible applications.
Availability
LT3958IUHE#TRPBF is available at Aetrix Electronics and suitable for automotive LED drivers, industrial 48V power conversion, telecom PoE midspans, and medical high-voltage bias supplies requiring stable component supply across extended temperature and long production lifecycles.
Supply support for LT3958IUHE#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 precision instrumentation, industrial automation, and automotive safety markets.
The LT3958IUHE#TRPBF belongs to Linear's high-voltage DC/DC controller product line, designed specifically for ruggedized power conversion in automotive, industrial, and telecom infrastructure where input transients, wide VIN ranges, and polarity flexibility are critical.
FAQ
What is the maximum input voltage supported by the LT3958IUHE#TRPBF?
The LT3958IUHE#TRPBF supports an absolute maximum input voltage of 80V on the VIN pin, with guaranteed operation from 5V to 80V. This makes it suitable for direct connection to 48V telecom systems, 24V industrial buses, and automotive battery rails including load-dump transients. The internal 84V-rated power switch ensures margin for transient overvoltage events without external clamping.
How does the LT3958IUHE#TRPBF support both positive and negative output voltages?
The LT3958IUHE#TRPBF uses a dual-reference feedback architecture: it regulates to +1.6V at the FBX pin for boost, flyback, and SEPIC topologies generating positive outputs, and to –0.8V for inverting configurations producing negative outputs. No external components are needed to switch modes - only the external resistor divider connected to FBX determines polarity and output level.
Can the LT3958IUHE#TRPBF be synchronized to an external clock?
Yes, the LT3958IUHE#TRPBF supports external clock synchronization via the SYNC pin. When driven with a clean digital clock signal, the device locks to the rising edge of that clock. To ensure stable locking, the RT resistor must be selected to program a free-running frequency approximately 20% slower than the SYNC frequency, and the SYNC pulse width must exceed 200ns.
What is the purpose of the separate SGND and GND pins on the LT3958IUHE#TRPBF?
The LT3958IUHE#TRPBF uses separate SGND (signal ground) and GND (power ground) pins to implement Kelvin current sensing. SGND serves as the reference for SENSE1/SENSE2 and internal error amplifiers, while GND carries high-current return paths for the internal MOSFET. Internally connected but kept separate on the PCB, this arrangement eliminates IR drop errors in current measurement and improves regulation accuracy under high load.
Does the LT3958IUHE#TRPBF include built-in protection features?
Yes, the LT3958IUHE#TRPBF integrates multiple protection functions: cycle-by-cycle current limiting (48mV SENSE2 threshold), input undervoltage lockout (programmable via EN/UVLO), INTVCC UVLO (3.75V) and overvoltage lockout (12.8V), thermal shutdown at 165°C, and FBX-based overvoltage protection (±8–11% tolerance). All protections trigger soft-start reset to prevent output overshoot during recovery.
LT3958IUHE#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 36-WFQFN, 28 Leads, Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Function:
- Step-Up, Step-Up/Step-Down
- Output Configuration:
- Positive or Negative
- Topology:
- Boost, Cuk, Flyback, SEPIC
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 5V
- Voltage - Input (Max):
- 80V
- Voltage - Output (Min/Fixed):
- 1.6V
- Voltage - Output (Max):
- 84V (Switch)
- Current - Output:
- 3.3A (Switch)
- Frequency - Switching:
- 100kHz ~ 1MHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 36-QFN (5x6)
LT3958IUHE#TRPBF FAQ
1.How can I place an order for LT3958IUHE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3958IUHE#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 LT3958IUHE#TRPBF reliable?
The price and inventory of LT3958IUHE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3958IUHE#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3958IUHE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3958IUHE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3958IUHE#TRPBF?
LT3958IUHE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3958IUHE#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 LT3958IUHE#TRPBF?
For technical support, including LT3958IUHE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3958IUHE#TRPBF requirements.
6.How does Aetrix verify that LT3958IUHE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3958IUHE#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 LT3958IUHE#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3958IUHE#TRPBF?
All LT3958IUHE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3958IUHE#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 LT3958IUHE#TRPBF part is unused and in its original packaging.
Return procedure for LT3958IUHE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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