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Analog Devices Inc. LT3957EUHE#TRPBF
- Part No.:
- LT3957EUHE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 36-WFQFN, 28 Leads, Exposed Pad
- Datasheet:
-
LT3957EUHE#TRPBF.pdf
- Description:
- IC REG BOOST CUK ADJ 5A 36QFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,650
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Product details
Overview
LT3957EUHE#TRPBF from Analog Devices (formerly Linear Technology) is a wide-input, current-mode DC/DC controller IC with an integrated 5A/40V N-channel power MOSFET. It supports boost, flyback, SEPIC, and inverting topologies; features programmable 100kHz–1MHz switching frequency via RT pin; delivers ±1.6V/±0.8V feedback regulation; and operates from 3V to 40V input for battery-powered industrial power supplies.
For engineers reviewing the LT3957EUHE#TRPBF datasheet, LT3957EUHE#TRPBF pinout, LT3957EUHE#TRPBF application, or LT3957EUHE#TRPBF equivalent, this page provides verified pin functions, topology-specific design meaning of key specs (e.g., FBX dual-polarity regulation, SW current limit, INTVCC LDO bypassing), and real-world soft-start/frequency foldback behavior under start-up and fault conditions.
Technical Context
The LT3957EUHE#TRPBF implements fixed-frequency current-mode control with internal slope compensation, enabling stable operation across wide VIN (3V–40V) and VOUT ranges. Its dual-regulation FBX pin accepts either positive (1.6V reference) or negative (–0.8V reference) feedback configurations-enabling single-pin selection between boost/SEPIC/flyback and inverting modes without external logic.
It integrates a 5.2V low-dropout regulator (INTVCC) powering gate drive and internal circuitry, with programmable UVLO on EN/UVLO (1.22V falling threshold, 20mV hysteresis) and thermal lockout at 165°C. Frequency synchronization via SYNC pin requires RT biasing 20% below external clock frequency, and frequency foldback activates when FBX voltage drops near SGND to prevent current runaway during short-circuit or low-VOUT start-up.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VIN Range | 3V to 40V - supports 12V automotive, 24V industrial, and multi-cell Li-ion battery inputs without pre-regulation. |
| Internal Switch | 5A/40V N-MOSFET - enables high-current boost/SEPIC designs up to ~24W output with minimal external components. |
| FBX Regulation | +1.6V or –0.8V reference - allows single-feedback-pin configuration of both positive and negative output topologies. |
| Switching Frequency | 100kHz–1MHz (RT-programmable) - balances efficiency (lower fSW reduces switching loss) vs. size (higher fSW permits smaller magnetics). |
| Shutdown IQ | <1μA - extends battery life in always-on systems requiring ultra-low quiescent current. |
| INTVCC LDO | 5.2V ±2.5%, 95mA max - powers internal gate driver; can be bypassed by external supply ≥5.5V to reduce on-chip dissipation. |
| Soft-Start | Capacitor-programmable via SS pin - limits inrush current and prevents inductor saturation during power-up or fault recovery. |
Pinout & Package
LT3957EUHE#TRPBF uses a thermally enhanced 36-lead QFN package (5mm × 6mm), with exposed pads soldered to SGND (Pin 37) and SW (Pin 38) planes for optimal thermal and electrical performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SENSE2 (3) | Current sense input | Connects to SENSE1 through RC filter; sets peak current limit threshold (48mV typical) for cycle-by-cycle protection. |
| SGND (4,23,24,37) | Signal ground | Kelvin return for current sensing; must remain isolated from power GND to avoid noise coupling into control loop. |
| SENSE1 (6) | Current sense output | Outputs amplified switch current signal; forms closed-loop current sensing path with SENSE2 and internal RSENSE. |
| SW (8,9,20,21,38) | Switch drain | High-current output node tied to external inductor/diode; exposed pad (38) must be soldered to SW copper for thermal relief. |
| GND (12–17) | Power ground | Source connection of internal MOSFET; internally connected to SGND but must not be externally shorted to preserve sensing accuracy. |
| EN/UVLO (25) | Enable/undervoltage detect | 1.22V falling threshold with programmable hysteresis; resets soft-start during brownout or startup undervoltage. |
| VIN (27) | Main input supply | Accepts 3V–40V; local bypass capacitor required to GND (not SGND) for transient current handling. |
| INTVCC (28) | Internal LDO output | 5.2V regulated supply for gate driver; requires ≥4.7μF ceramic cap to SGND; can be externally powered above 5.5V to reduce die heating. |
| VC (30) | Error amplifier output | Compensation node for voltage loop; connects to SGND via RC network to stabilize feedback response across load/input variations. |
| FBX (31) | Feedback input | Dual-polarity input: regulates +VOUT at 1.6V or –VOUT at –0.8V; also triggers frequency foldback and overvoltage lockout. |
| SS (32) | Soft-start control | 10μA pull-up to 2.5V rail; clamps VC during start-up; discharged by faults (thermal, INTVCC UV, EN/UVLO UV) to reinitiate soft-start. |
| RT (33) | Frequency set | Resistor-to-SGND sets switching frequency (100kHz–1MHz); open-circuit disables operation. |
| SYNC (34) | External clock sync | Accepts digital clock input; forces switching at external frequency if RT is biased 20% lower; tie to SGND if unused. |
Key Features
| Feature | Design Value |
|---|---|
| Topology Flexibility | Single IC supports boost, flyback, SEPIC, and inverting converters - eliminates need for multiple controller variants in multi-rail designs. |
| Dual-Polarity Feedback | FBX pin accepts +1.6V or –0.8V reference - enables seamless transition between positive and negative output configurations using same layout. |
| Programmable UVLO with Hysteresis | EN/UVLO pin allows precise turn-on/off thresholds (e.g., 12V nominal with 0.5V hysteresis) - prevents oscillation during input voltage sag. |
| Frequency Foldback | Reduces switching frequency when FBX approaches SGND - maintains current limit compliance during output short-circuit or low-VOUT start-up. |
| Thermal Protection | Internal thermal lockout at 165°C shuts down switching and discharges SS pin - prevents permanent damage during overload or poor heatsinking. |
| Low Shutdown IQ | <1μA shutdown current - critical for long-life battery applications such as remote sensors or backup power modules. |
Applications
| Automotive LED Driver | Industrial 24V-to-48V Boost Supply |
|---|---|
|
Use Scenario: Driving high-brightness LEDs from 12V vehicle battery with dimming control and short-circuit protection. IC Role / Device Role / Timing Role: Configured as boost converter with FBX regulating LED current via sense resistor; INTVCC powers gate driver; SYNC enables EMI reduction via spread-spectrum clock. Use Value: Integrated 5A/40V switch eliminates external FET; programmable UVLO ensures operation only above safe battery voltage; <1μA shutdown extends parking mode runtime. |
Use Scenario: Generating stable 48V rail from 24V industrial bus for PoE++ or motor control interfaces. IC Role / Device Role / Timing Role: Operates as SEPIC converter to provide non-inverting, isolated-capable boost with input/output common ground; RT sets 300kHz for optimal efficiency/size trade-off. Use Value: Dual-regulation FBX simplifies feedback design; soft-start prevents inrush into large output capacitors; thermal lockout protects against sustained overload in enclosed enclosures. |
| Telecom Negative Bias Supply | Portable Medical Instrument Power |
|
Use Scenario: Providing –15V bias for RF amplifiers or op-amp rails in telecom base station modules. IC Role / Device Role / Timing Role: Configured as inverting converter; FBX referenced to –0.8V enables precise negative output regulation; EN/UVLO disables supply during standby. Use Value: Single feedback pin eliminates polarity-select logic; 3V minimum VIN supports partial battery discharge; frequency foldback prevents current runaway during cold-start. |
Use Scenario: Powering analog front-end and ADC in handheld diagnostic devices using two-cell Li-ion (6V–8.4V). IC Role / Device Role / Timing Role: Used in flyback configuration for isolated 3.3V/5V outputs; SS capacitor sets 10ms soft-start to avoid sensor reset; INTVCC bypassed to external 5V rail to minimize self-heating. Use Value: 125°C junction rating ensures reliability in sealed enclosures; low shutdown IQ preserves battery charge during sleep; compact QFN eases layout in space-constrained PCBs. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar DC/DC controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT8330EDD#TRPBF | Lower 3.3A/60V switch, no internal LDO, requires external VCC bias; supports wider 3V–40V input but lacks FBX dual-polarity regulation. | Suitable for simpler boost-only designs where negative output or SEPIC is unnecessary; less suited for inverting or fault-tolerant applications requiring foldback. | Select LT8330EDD#TRPBF when cost and board area are prioritized over topology flexibility and integrated protection features. |
| TPS40210DRCT | External MOSFET controller (no integrated switch), 1.25V FB reference only, no dual-polarity support; higher 2.5A gate drive but requires more external components. | Better for high-efficiency, high-power (>30W) boost designs where discrete FET selection is needed; lacks integrated current sensing and soft-start simplicity. | Choose TPS40210DRCT when thermal management demands external FETs or when custom current sensing architecture is required. |
Compared with LT3957EUHE#TRPBF, LT8330EDD#TRPBF offers lower integration but better efficiency at light loads, while TPS40210DRCT provides greater power scalability at the cost of increased BOM count and layout complexity - making LT3957EUHE#TRPBF optimal for mid-power, multi-topology, space-constrained designs requiring robust fault handling.
Availability
LT3957EUHE#TRPBF is available at Aetrix Electronics and suitable for automotive LED drivers, industrial 24V-to-48V boost supplies, telecom negative bias generation, and portable medical instrument power requiring stable component supply, full temperature range support (–40°C to 125°C), and long-term production continuity.
Supply support for LT3957EUHE#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. (including legacy Linear Technology products) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, serving precision instrumentation, industrial automation, communications, and automotive markets.
The LT3957EUHE#TRPBF belongs to the LT® high-voltage DC/DC controller family, designed specifically for flexible, high-reliability power conversion in harsh environments where wide input range, topology adaptability, and integrated protection are essential.
FAQ
What topologies does the LT3957EUHE#TRPBF support?
The LT3957EUHE#TRPBF supports boost, flyback, SEPIC, and inverting converter topologies. Its dual-reference FBX pin (1.6V for positive outputs, –0.8V for negative outputs) enables configuration without external logic or component changes. Each topology leverages the same internal 5A/40V N-MOSFET and current-mode control architecture, allowing designers to reuse layout elements across product variants.
How is the switching frequency set on the LT3957EUHE#TRPBF?
The LT3957EUHE#TRPBF switching frequency is set using a single resistor (RT) connected from Pin 33 to SGND, supporting 100kHz to 1MHz. For example, a 41.2kΩ resistor yields ~300kHz. The device also supports synchronization to an external clock via the SYNC pin (Pin 34), provided the RT resistor is selected to program a frequency 20% slower than the external clock.
Can the LT3957EUHE#TRPBF generate negative output voltages?
Yes, the LT3957EUHE#TRPBF can generate negative output voltages when configured as an inverting converter. In this mode, the FBX pin regulates to –0.8V, and the output voltage is calculated as VOUT = –0.8V × (1 + R2/R1). This capability is intrinsic to the IC's dual-reference error amplifier and requires no additional components beyond the standard feedback divider.
What is the purpose of the frequency foldback function in the LT3957EUHE#TRPBF?
The frequency foldback function in the LT3957EUHE#TRPBF reduces switching frequency when the FBX pin voltage drops near SGND - such as during output short-circuit or low-VOUT start-up. This prevents peak switch current from exceeding the 5A limit when minimum on-time constraints would otherwise force excessive duty cycle, thereby avoiding inductor saturation and MOSFET overstress.
How does the LT3957EUHE#TRPBF handle thermal overload?
The LT3957EUHE#TRPBF includes internal thermal lockout that triggers at 165°C junction temperature. When activated, it immediately halts switching, discharges the SS pin via internal transistor Q3, and holds the device in shutdown until temperature falls and SS voltage drops below 0.2V - initiating a new soft-start sequence. This protects both the IC and external components during sustained overload or inadequate heatsinking.
LT3957EUHE#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):
- 3V
- Voltage - Input (Max):
- 40V
- Voltage - Output (Min/Fixed):
- 1.6V
- Voltage - Output (Max):
- 40V (Switch)
- Current - Output:
- 5A (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)
LT3957EUHE#TRPBF FAQ
1.How can I place an order for LT3957EUHE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3957EUHE#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 LT3957EUHE#TRPBF reliable?
The price and inventory of LT3957EUHE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3957EUHE#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3957EUHE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3957EUHE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3957EUHE#TRPBF?
LT3957EUHE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3957EUHE#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 LT3957EUHE#TRPBF?
For technical support, including LT3957EUHE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3957EUHE#TRPBF requirements.
6.How does Aetrix verify that LT3957EUHE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3957EUHE#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 LT3957EUHE#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3957EUHE#TRPBF?
All LT3957EUHE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3957EUHE#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 LT3957EUHE#TRPBF part is unused and in its original packaging.
Return procedure for LT3957EUHE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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