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Analog Devices Inc. LT3437HFE#PBF
- Part No.:
- LT3437HFE#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 16-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LT3437HFE#PBF.pdf
- Description:
- IC REG BUCK ADJ 500MA 16TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:171
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Product details
Overview
LT3437HFE#PBF from Analog Devices (formerly Linear Technology) is a high-voltage, current-mode monolithic buck switching regulator designed for automotive and industrial power systems. It operates from 3.3V to 60V input, delivers up to 500mA peak switch current with 0.8Ω on-resistance, features 200kHz fixed-frequency operation, 1.25V feedback reference, and supports load dump transients up to 80V - enabling robust 14V/42V automotive supply regulation.
For engineers reviewing the LT3437HFE#PBF datasheet, LT3437HFE#PBF pinout, LT3437HFE#PBF application, or LT3437HFE#PBF equivalent, key selection criteria include its –40°C to 140°C junction temperature rating, Burst Mode™ operation delivering 100µA quiescent current at no load, defeatable light-load mode via SYNC, soft-start control via CSS pin, and thermally enhanced 16-pin TSSOP package with exposed GND pad.
Technical Context
The LT3437HFE#PBF implements constant-frequency current-mode control using an internal 200kHz oscillator and dual-loop regulation: the error amplifier sets the peak switch current threshold, while cycle-by-cycle current sensing ensures fast transient response and stable loop behavior across wide duty cycles. Its patented architecture maintains consistent 500mA peak switch current over full duty cycle range, even under low-VIN/high-VOUT conditions.
It integrates a high-voltage NPN power switch with BOOST-driven saturation, reducing VCE(SAT) to 400mV at 500mA. The BIAS pin enables output-sourced biasing for improved efficiency at high input-to-output ratios, and the SYNC pin accepts logic-level inputs (240–500kHz) to disable Burst Mode or synchronize externally - with automatic foldback disabling when FB < 0.9V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.3V to 60V continuous; withstands 80V/100ms transients - supports cold-crank and load-dump immunity in 12V/42V automotive systems. |
| Output Current Capability | 500mA peak switch current with 95% max duty cycle - enables high-step-down ratios (e.g., 42V → 3.3V) without external MOSFET. |
| Quiescent Current | 100µA in Burst Mode at no load - extends battery life in always-on vehicle modules and IoT edge nodes. |
| Switch On-Resistance | 0.8Ω typical - minimizes conduction loss and thermal rise in compact 16-pin TSSOP package with exposed GND pad. |
| Feedback Reference | 1.25V ±2.4% over –40°C to 140°C - enables precise output voltage setting with standard resistor dividers. |
| Operating Junction Temp | –40°C to 140°C - qualified for under-hood automotive applications and high-ambient industrial power supplies. |
| Switching Frequency | 200kHz nominal (140–240kHz over temp) - balances EMI, inductor size, and efficiency for cost-sensitive DC/DC designs. |
Pinout & Package
LT3437HFE#PBF is housed in a 16-lead plastic TSSOP package (3.0mm × 4.4mm × 1.1mm) with exposed thermal pad (Pin 17 = GND). The package features low θJA = 45°C/W and θJC(PAD) = 10°C/W, requiring soldering of the exposed pad to PCB ground plane for thermal integrity and EMI reduction.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Pin 1 (NC) | No Connection | Electrically isolated; may be used for PCB layout routing or thermal relief - no internal connection. |
| Pin 2 (SW) | Switch Emitter | Connects to inductor and catch diode cathode; swings negative during off-time - requires Schottky clamp diode. |
| Pin 3 (NC) | No Connection | Electrically isolated; usable for mechanical stability or trace routing. |
| Pin 4 (VIN) | Power Input / Switch Collector | Supplies internal circuitry and powers NPN switch collector; handles 80V transients - must use low-inductance input bypass. |
| Pin 5 (NC) | No Connection | Electrically isolated; no functional role. |
| Pin 6 (BOOST) | Switch Drive Boost | Accepts external boost capacitor/diode to raise gate drive above VIN - ensures NPN saturation and low VCE(SAT). |
| Pin 7 (NC) | No Connection | Electrically isolated; no functional role. |
| Pin 8 (GND) | Analog & Power Ground | Reference for FB, VC, and output regulation; must tie directly to PCB ground plane - critical for load regulation and thermal performance. |
| Pin 9 (NC) | No Connection | Electrically isolated; no functional role. |
| Pin 10 (SHDN) | Shutdown Control | Logic-compatible enable: >1.3V activates regulator; <0.8V reduces supply current to <1µA - supports low-power sleep states. |
| Pin 11 (SYNC) | External Sync Input | Accepts 25–75% duty-cycle logic signals (240–500kHz); disables Burst Mode when high - enables EMI reduction and multi-regulator coordination. |
| Pin 12 (FB) | Feedback Input | Senses resistive divider output; regulates VOUT to 1.25V reference; triggers frequency foldback and soft-start when <0.9V. |
| Pin 13 (VC) | Error Amplifier Output | Drives current limit comparator; used for compensation, current clamping, or forced shutdown - sinks 55µA max at 1.35V. |
| Pin 14 (BIAS) | Efficiency Bias Supply | Accepts ≥2.7V external voltage (e.g., VOUT) to source internal bias - improves efficiency at high VIN/low IOUT. |
| Pin 15 (CSS) | Soft-Start Control | Current-sourced node tied to VOUT; controls dV/dt ramp rate via capacitor - limits inrush and stabilizes startup under heavy capacitive loads. |
| Pin 16 (NC) | No Connection | Electrically isolated; no functional role. |
| Pin 17 (Exposed Pad) | Thermal & Electrical GND | Mandatory solder connection to PCB ground plane - provides primary thermal path and reduces EMI coupling. |
Key Features
| Feature | Design Value |
|---|---|
| Load Dump Protection | Withstands 80V/100ms input transients - eliminates need for external TVS in 12V/42V automotive front-end designs. |
| Burst Mode™ Operation | Reduces no-load IQ to 100µA while maintaining regulation - enables always-on functionality in telematics and ADAS modules. |
| Defeatable Light-Load Mode | SYNC pin logic-high disables Burst Mode - trades 100µA IQ for lower output ripple at light loads without changing layout. |
| Thermally Enhanced TSSOP | 16-pin package with exposed GND pad (θJC = 10°C/W) - supports 500mA output in space-constrained automotive ECUs. |
| Wide Temperature Rating | –40°C to 140°C operating junction range - qualified for under-hood placement without derating or heatsinking. |
| Integrated Soft-Start | CSS pin + external capacitor enables controlled VOUT ramp - prevents inrush into large output caps and avoids input voltage droop during startup. |
Applications
| Automotive Body Control Module (BCM) | Industrial PLC I/O Power Supply |
|---|---|
Use Scenario: Regulating 42V battery rail to 3.3V/5V for microcontroller, CAN transceiver, and sensor interfaces in body electronics. IC Role / Device Role / Timing Role: Primary step-down regulator handling cold-crank (4.5V), load dump (80V), and wide-temp operation in BCM subassembly. Use Value: Eliminates need for external surge protection and discrete biasing - reduces BOM count by 3–4 components versus discrete solutions. | Use Scenario: Providing isolated 5V/200mA bias for analog input conditioning and digital isolation in programmable logic controller backplanes. IC Role / Device Role / Timing Role: High-reliability DC/DC converter powering field-side circuitry in harsh factory environments with 0–70°C ambient. Use Value: Maintains regulation during 100ms brownouts and withstands 2kV EFT noise - meets IEC 61000-4-4 compliance without added filtering. |
| Powered Ethernet (PoE) PD Interface | High-Voltage Battery-Powered Instrumentation |
Use Scenario: Converting 57V PoE Class 4 input to 3.3V for MCU and Ethernet PHY in networked sensors and IP cameras. IC Role / Device Role / Timing Role: Secondary-stage buck regulator after PoE interface IC, managing wide-input variation and thermal constraints. Use Value: Achieves >85% efficiency at 200mA while surviving 100V surges - enables compact, fanless enclosure design. | Use Scenario: Powering portable test equipment from 24–60V Li-ion packs with ultra-low standby drain between measurements. IC Role / Device Role / Timing Role: Main system regulator enabling 10-year shelf life via 100µA Burst Mode quiescent current. Use Value: Extends runtime by 3× vs. standard buck regulators - critical for unattended field deployments. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar high-voltage buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3642EMSE#PBF | 40V max input, 1.2A output, 3mm × 4mm MSOP; lacks 80V transient rating and 140°C rating. | Targeted at industrial non-automotive applications where 42V rail suffices and ambient ≤125°C. | Select when higher output current is needed and 80V transient immunity is not required. |
| MAX5033BASA+T | 76V max input, 500mA, SO-8; no Burst Mode, 2.5mA IQ; no SYNC or CSS pins; only 125°C rating. | Suitable for cost-sensitive industrial supplies where light-load efficiency and soft-start are secondary. | Choose for simpler designs without advanced control features and where thermal margin is adequate. |
Compared with LTC3642EMSE#PBF and MAX5033BASA+T, LT3437HFE#PBF uniquely combines 80V transient tolerance, 140°C operation, and 100µA Burst Mode IQ - making it the only option qualified for under-hood automotive power conversion without external protection or derating.
Availability
LT3437HFE#PBF is available at Aetrix Electronics and suitable for automotive body control modules, industrial PLC power rails, PoE-powered devices, and high-voltage battery instrumentation requiring stable component supply across extended temperature and transient conditions.
Supply support for LT3437HFE#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, Inc. (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and power management semiconductors.
The LT3437 product line was engineered specifically for high-input-voltage DC/DC conversion in automotive and industrial environments - emphasizing transient robustness, wide-temperature reliability, and integrated protection features without external components.
FAQ
What is the maximum input voltage transient rating for LT3437HFE#PBF?
The LT3437HFE#PBF is rated for 80V input transients at <15% duty cycle for up to 100ms, meeting ISO 7637-2 Pulse 5a requirements for 12V automotive systems. This allows direct connection to vehicle battery rails without external TVS diodes in most BCM and lighting control applications. Continuous operation remains limited to 60V, and the BOOST pin has separate 85V transient rating.
How does LT3437HFE#PBF achieve 100µA quiescent current?
The LT3437HFE#PBF achieves 100µA quiescent current through Burst Mode™ operation: during light loads, the IC shuts down oscillator, gate drive, and most internal circuitry between energy bursts, reducing supply current to 45µA and BIAS pin current to 110µA. This mode is automatically engaged below ~10mA load and is disabled only when SYNC is pulled high - preserving regulation while minimizing standby power.
Can LT3437HFE#PBF operate at 140°C junction temperature continuously?
Yes, the LT3437HFE#PBF is fully tested and specified over –40°C to 140°C junction temperature, unlike the EFE/IFE variants rated to 125°C. Its electrical characteristics table explicitly includes data verified at 140°C, and thermal design must ensure θJA and power dissipation keep TJ ≤140°C - achievable with proper PCB copper area on the exposed pad per Linear's AN136 guidelines.
What is the function of the CSS pin on LT3437HFE#PBF?
The CSS pin on LT3437HFE#PBF controls soft-start by sourcing current into an external capacitor tied to VOUT. As VOUT ramps, current through the capacitor increases; when it exceeds the CSS threshold (4–16µA, proportional to FB voltage), the error amplifier limits VC voltage to maintain constant dV/dt. This prevents inrush into large output capacitors and avoids input voltage sag during startup - critical for systems with >1000µF output capacitance.
Does LT3437HFE#PBF require an external boost diode and capacitor?
Yes, LT3437HFE#PBF requires an external boost capacitor and Schottky diode connected between SW and BOOST pins to saturate the internal NPN switch. Without this network, VCE(SAT) rises to ~1.5V, degrading efficiency and thermal performance. A typical implementation uses a 100nF ceramic capacitor and Diodes Inc. B1100 Schottky diode - values validated in Linear's LT3437 demo board DC986A.
LT3437HFE#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 3.5V
- Voltage - Input (Max):
- 60V
- Voltage - Output (Min/Fixed):
- 1.25V
- Voltage - Output (Max):
- 57V
- Current - Output:
- 500mA (Switch)
- Frequency - Switching:
- 200kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 140°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-TSSOP-EP
LT3437HFE#PBF FAQ
1.How can I place an order for LT3437HFE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3437HFE#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 LT3437HFE#PBF reliable?
The price and inventory of LT3437HFE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3437HFE#PBF is usually 5 days.
3.What payment methods are accepted for LT3437HFE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3437HFE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3437HFE#PBF?
LT3437HFE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3437HFE#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 LT3437HFE#PBF?
For technical support, including LT3437HFE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3437HFE#PBF requirements.
6.How does Aetrix verify that LT3437HFE#PBF is sourced from the original manufacturer or authorized distributors?
All LT3437HFE#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 LT3437HFE#PBF meets industry standards.
7.What is the process for return or replacement of LT3437HFE#PBF?
All LT3437HFE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3437HFE#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 LT3437HFE#PBF part is unused and in its original packaging.
Return procedure for LT3437HFE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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