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Analog Devices Inc. LT3957AIUHE#TRPBF
- Part No.:
- LT3957AIUHE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 36-WFQFN, 28 Leads, Exposed Pad
- Datasheet:
-
LT3957AIUHE#TRPBF.pdf
- Description:
- IC REG BOOST CUK ADJ 5A 36QFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,969
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Product details
Overview
LT3957AIUHE#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, supporting boost, flyback, SEPIC, and inverting topologies. It delivers ±1.6V/–0.8V feedback regulation, programmable 100kHz–1MHz switching frequency, and operates from 3V to 40V input. It is used in automotive infotainment power supplies requiring high efficiency and negative rail generation.
For engineers reviewing the LT3957AIUHE#TRPBF datasheet, LT3957AIUHE#TRPBF pinout, LT3957AIUHE#TRPBF application, or LT3957AIUHE#TRPBF equivalent, key selection criteria include its dual-polarity feedback capability, internal 5.2V LDO for gate drive, 1μA shutdown current, thermal shutdown at 165°C, and QFN-36 (5mm × 6mm) package with exposed SW and SGND pads.
Technical Context
The LT3957AIUHE#TRPBF implements fixed-frequency current-mode control with slope compensation, enabling stable operation across wide VIN (3V–40V) and VOUT ranges. Its dual-reference error amplifier supports both positive (1.6V) and negative (–0.8V) FBX regulation, allowing single-pin configuration of boost/flyback/SEPIC (positive output) or inverting (negative output) converters.
It integrates a 5A/40V low-side N-MOSFET with 27.6mΩ typical RDS(ON) at 25°C, driven by an internal 5.2V LDO regulator. Frequency is set via RT-to-SGND resistor or synchronized externally via SYNC pin, with foldback protection active when FBX approaches SGND during startup or overload.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3V to 40V - supports 12V automotive battery systems with cold-crank margin and industrial 24V rails. |
| Switch Rating | 5A continuous, 40V drain-source - enables single-stage 24V→48V boost or 12V→–15V inverting conversion without external FET. |
| Feedback Reference | +1.6V (positive mode) / –0.8V (inverting mode) - allows precise output voltage setting using standard resistor dividers; no external reference needed. |
| Switching Frequency | 100kHz to 1MHz (programmable via RT) - balances efficiency (lower fSW) vs. size (higher fSW); supports EMI reduction via synchronization. |
| Shutdown Current | <1μA - extends battery life in always-on automotive modules such as telematics or ADAS sensors. |
| Operating Junction Temp | –40°C to +125°C - qualified for under-hood automotive applications per AEC-Q100 stress test conditions. |
| Package | 36-lead QFN (5mm × 6mm), exposed SW and SGND pads - provides low thermal resistance (θJC = 3°C/W) for high-power density layouts. |
Pinout & Package
LT3957AIUHE#TRPBF is housed in a thermally enhanced 36-lead plastic QFN package (5mm × 6mm) with two exposed pads: Pin 37 (SGND) and Pin 38 (SW), both requiring solder connection to respective PCB planes for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SENSE2 (Pin 3) | Current sense input | Receives filtered current sense signal from SENSE1; sets peak current limit threshold (48mV typical) for cycle-by-cycle protection. |
| SGND (Pins 4, 23, 24, 37) | Signal ground | Kelvin-sense return for internal current sensing; must be isolated from power GND to avoid noise coupling into control loop. |
| SENSE1 (Pin 6) | Current sense output | Source of internal MOSFET current sense voltage; connects directly or via RC filter to SENSE2 for noise immunity. |
| SW (Pins 8, 9, 20, 21, 38) | Internal MOSFET drain | High-current switching node; exposed pad (Pin 38) must be soldered to SW copper pour for thermal management and low-inductance routing. |
| GND (Pins 12–17) | Power ground | Source terminal of internal MOSFET; connects internally to SGND but must remain externally separate to preserve Kelvin sensing accuracy. |
| EN/UVLO (Pin 25) | Enable & input UVLO | 1.22V falling threshold with programmable hysteresis; resets soft-start on undervoltage - critical for reliable cold-crank startup in automotive. |
| VIN (Pin 27) | Main input supply | Accepts 3V–40V; powers internal circuitry and charges INTVCC LDO; requires local ceramic bypass to GND (not SGND). |
| INTVCC (Pin 28) | Internal LDO output | 5.2V regulated supply for gate driver and logic; requires ≥4.7μF ceramic cap to SGND; can be bypassed to external VOUT or VIN if needed. |
| VC (Pin 30) | Error amplifier output | Compensation node for voltage loop; connects to SGND via RC network to stabilize transient response and prevent oscillation. |
| FBX (Pin 31) | Positive/negative feedback | Single pin accepts either >0V (for +VOUT) or <0V (for –VOUT) divider output; also triggers frequency foldback during startup faults. |
| SS (Pin 32) | Soft-start control | 10μA pull-up current charges external capacitor; clamps VC during startup to limit inrush current and prevent inductor saturation. |
| RT (Pin 33) | Frequency programming | Resistor to SGND sets switching frequency (e.g., 41.2kΩ = 300kHz); open-circuit disables oscillator - must not float. |
| SYNC (Pin 34) | External clock sync | Accepts TTL/CMOS clock; forces switching at external frequency if RT is set 20% lower - enables multi-phase or EMI spread-spectrum operation. |
Key Features
| Feature | Design Value |
|---|---|
| Dual-polarity feedback architecture | Single FBX pin supports both +1.6V (boost/flyback/SEPIC) and –0.8V (inverting) regulation - eliminates need for external level-shifting or dual-reference circuits. |
| Integrated 5A/40V power switch | On-resistance 27.6mΩ @ 25°C reduces conduction loss in high-current 12V→24V boost stages - avoids discrete FET layout complexity and parasitics. |
| Programmable frequency with sync | 100kHz–1MHz range via RT resistor; SYNC pin enables deterministic timing alignment across multiple converters - essential for noise-sensitive ADAS camera modules. |
| Thermal shutdown with auto-recovery | 165°C junction limit with hysteresis; halts switching and discharges SS capacitor - prevents permanent damage during sustained overload or poor heatsinking. |
| Low IQ shutdown & UVLO hysteresis | <1μA shutdown current plus user-programmable EN/UVLO hysteresis (via resistor divider) ensures robust start-up under fluctuating 12V battery conditions. |
Applications
| Automotive Infotainment Power | Industrial Sensor Bias Supply |
|---|---|
|
Use Scenario: Generating isolated ±15V rails for analog audio codecs and ADCs in head-unit systems powered from unstable 12V battery. IC Role / Device Role / Timing Role: LT3957AIUHE#TRPBF acts as a flyback controller with integrated switch, regulating negative output via FBX feedback while providing synchronous timing for downstream LDOs. Use Value: Eliminates external gate driver and sense resistor; achieves >90% efficiency at 500mA load with minimal BOM count and board space. |
Use Scenario: Providing –5V bias for precision op-amps and transimpedance amplifiers in factory-floor vibration sensors operating from 24V DC supply. IC Role / Device Role / Timing Role: LT3957AIUHE#TRPBF configured as inverting converter, using FBX to regulate –5V output with tight line/load regulation over temperature. Use Value: Delivers ±0.5% output accuracy across –40°C to +105°C, enabled by dual-reference architecture and internal 5.2V LDO stability. |
| Telecom Line Card Boost | Medical Imaging LED Driver Bias |
|
Use Scenario: Stepping up 3.3V backplane voltage to 48V for PoE-powered Ethernet PHYs in carrier-grade access switches. IC Role / Device Role / Timing Role: LT3957AIUHE#TRPBF operates in boost mode with 1MHz switching, minimizing inductor size while maintaining transient response for bursty data traffic. Use Value: Achieves 92% peak efficiency at full load; programmable soft-start prevents inrush into large output capacitors during hot-swap events. |
Use Scenario: Generating stable –12V bias for avalanche photodiode (APD) arrays in portable ultrasound probes powered from Li-ion battery packs. IC Role / Device Role / Timing Role: LT3957AIUHE#TRPBF functions as inverting converter with frequency foldback during APD startup surge, preventing current runaway. Use Value: Built-in foldback and 5A current limit protect fragile APDs; 125°C max junction rating supports compact, fanless probe enclosures. |
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 | Requires external high-side MOSFETs; supports 4-switch buck-boost topology; no integrated switch; higher VIN max (40V same). | Better suited for bidirectional or wide-VOUT-ratio applications where efficiency >95% is required; lacks inverting capability. | Select LTC3789EFE#PBF only when needing buck-boost regulation with >95% efficiency and external FET optimization; not drop-in for LT3957AIUHE#TRPBF. |
| LM5122MMX/NOPB | External N-MOSFET driver; 65V max VIN; no integrated switch; supports constant-on-time control; no dual-polarity FB. | Preferred for high-input industrial supplies (e.g., 48V telecom rectifiers); cannot generate negative outputs without additional circuitry. | Choose LM5122MMX/NOPB for >40V input or when designing custom high-efficiency buck-boost with discrete FETs; not suitable for inverting or space-constrained designs. |
Compared with LTC3789EFE#PBF and LM5122MMX/NOPB, the LT3957AIUHE#TRPBF uniquely integrates a 5A/40V switch and dual-reference feedback in a single QFN, reducing component count and layout area for compact boost/flyback/inverting supplies - especially valuable in automotive and portable medical devices.
Availability
LT3957AIUHE#TRPBF is available at Aetrix Electronics and suitable for automotive infotainment, industrial sensor bias, telecom line card boost, and medical imaging LED driver applications requiring stable component supply, long-term lifecycle support, and AEC-Q100-compliant performance.
Supply support for LT3957AIUHE#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) is a global leader in high-performance analog, mixed-signal, and digital signal processing technologies, serving automotive, industrial, communications, and healthcare markets.
The LT3957A product line was designed specifically for high-reliability, wide-input DC/DC conversion in space- and thermal-constrained environments - emphasizing integrated power switches, dual-polarity regulation, and robust fault protection for automotive and industrial power systems.
FAQ
What is the maximum output current achievable with LT3957AIUHE#TRPBF in boost configuration?
The LT3957AIUHE#TRPBF supports up to 5A peak switch current, but practical output current depends on topology, duty cycle, and thermal design. In a 12V-to-24V boost converter at 300kHz, typical continuous output is 1.8A with 2-layer PCB and 2oz copper. Derating is required above 85°C ambient due to thermal limits - full 5A is only sustainable with aggressive heatsinking and forced airflow.
Can LT3957AIUHE#TRPBF generate a negative output voltage without additional components?
Yes. The LT3957AIUHE#TRPBF natively supports negative output generation in inverting topology using only the internal switch and a standard resistor divider on FBX. When FBX is pulled below SGND (e.g., –0.8V reference), the internal comparator A2 activates, enabling regulation of negative VOUT - no external op-amps, level shifters, or charge pumps are needed.
How does the frequency foldback function operate in LT3957AIUHE#TRPBF during startup?
During startup or output short-circuit, when FBX voltage drops near SGND, the LT3957AIUHE#TRPBF automatically reduces switching frequency (down to ~20% of programmed value) to maintain current limit compliance. This prevents inductor current runaway caused by minimum on-time limitations - verified in Typical Performance Characteristics Figure G06 (Normalized Frequency vs FBX).
What is the recommended capacitor for the SS pin on LT3957AIUHE#TRPBF?
A 100nF ceramic capacitor from SS to SGND yields a ~12.5ms soft-start interval (TSS = CSS × 1.25V / 10μA). For slower ramp-up in high-capacitance loads (e.g., >1000μF), increase CSS to 220nF (27.5ms) or 470nF (59ms). Avoid electrolytics - only X7R/X5R ceramics ensure stable timing and low leakage.
Is LT3957AIUHE#TRPBF pin-compatible with the earlier LT3957 version?
No. While functionally similar, the LT3957AIUHE#TRPBF features improved load transient response, tighter FBX regulation (±0.5% vs ±1%), and enhanced frequency foldback behavior versus LT3957. Pinout is identical, but design validation is required due to internal control-loop optimizations - not a drop-in replacement without testing.
LT3957AIUHE#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)
LT3957AIUHE#TRPBF FAQ
1.How can I place an order for LT3957AIUHE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3957AIUHE#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 LT3957AIUHE#TRPBF reliable?
The price and inventory of LT3957AIUHE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3957AIUHE#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3957AIUHE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3957AIUHE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3957AIUHE#TRPBF?
LT3957AIUHE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3957AIUHE#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 LT3957AIUHE#TRPBF?
For technical support, including LT3957AIUHE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3957AIUHE#TRPBF requirements.
6.How does Aetrix verify that LT3957AIUHE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3957AIUHE#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 LT3957AIUHE#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3957AIUHE#TRPBF?
All LT3957AIUHE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3957AIUHE#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 LT3957AIUHE#TRPBF part is unused and in its original packaging.
Return procedure for LT3957AIUHE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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