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Analog Devices Inc. LT3437IFE#PBF
- Part No.:
- LT3437IFE#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 16-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LT3437IFE#PBF.pdf
- Description:
- IC REG BUCK ADJ 500MA 16TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,340
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Product details
Overview
LT3437IFE#PBF from Analog Devices (formerly Linear Technology) is a high-voltage, current-mode monolithic buck switching regulator with integrated 500mA NPN power switch, 0.8Ω on-resistance, and 200kHz fixed-frequency operation. It supports 3.3V–60V input, delivers regulated output down to 1.25V via external feedback, and maintains 100µA quiescent current in Burst Mode for automotive cold-crank and battery-powered systems.
For engineers reviewing the LT3437IFE#PBF datasheet, LT3437IFE#PBF pinout, LT3437IFE#PBF application, or LT3437IFE#PBF equivalent, key selection criteria include input transient tolerance (80V load dump), thermally enhanced 10-pin DFN package with exposed GND pad, defeatable Burst Mode, soft-start control via CSS pin, and guaranteed –40°C to +125°C operation.
Technical Context
The LT3437IFE#PBF implements constant-frequency current-mode control with cycle-by-cycle peak current limiting and internal 2.4V bias rail. Its architecture uses BOOST pin voltage (up to 85V transient) to fully saturate the internal NPN switch, reducing conduction loss and enabling high efficiency across wide VIN/VOUT ratios.
Burst Mode operation reduces quiescent current to 100µA at light loads by disabling oscillator and control circuitry, while SYNC pin logic-high disables Burst Mode for lower output ripple. The VC pin serves dual role as error amplifier output and current limit clamp, and FB pin enables frequency foldback below 0.4V and soft-start ramp control below 0.9V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.3V to 60V continuous; withstands 80V/100ms transients (load dump) |
| Switch Current Limit | 500mA typical peak; maintained over full duty cycle range |
| Quiescent Current | 100µA in Burst Mode; <1µA in shutdown |
| Switching Frequency | 200kHz nominal; synchronizable from 240kHz to 700kHz |
| Feedback Reference | 1.25V ±2.5% over –40°C to +125°C; sets output via resistor divider |
| On-Resistance | 0.8Ω typical at ISW = 250mA; enables high efficiency at high VIN/VOUT ratios |
| Package | 10-pin 3mm × 3mm DFN with exposed thermal pad (GND) |
Pinout & Package
LT3437IFE#PBF is housed in a thermally enhanced 10-pin (3mm × 3mm) DFN package with exposed GND pad (Pin 11) requiring solder connection to PCB ground plane for thermal and electrical performance. Pin 1 is SHDN; Pin 2 is SYNC; Pin 3 is FB; Pin 4 is VC; Pin 5 is BIAS; Pin 6 is SW; Pin 7 is VIN; Pin 8 is BOOST; Pin 9 is GND; Pin 10 is CSS.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SHDN (Pin 1) | Shutdown control input | Logic-high >1.3V enables regulation; <1µA shutdown supply current |
| SYNC (Pin 2) | External clock synchronization input | Accepts 25–75% duty cycle logic-level signal; disables Burst Mode when high |
| FB (Pin 3) | Feedback reference node | Senses 1.25V reference; triggers frequency foldback below 0.4V and soft-start below 0.9V |
| VC (Pin 4) | Error amplifier output / current limit clamp | Controls peak switch current; clamped at 1.5–2.1V; drives to GND to force sleep mode |
| BIAS (Pin 5) | Efficiency-boost bias supply | Accepts ≥2.7V external source (e.g., VOUT) to reduce VIN current and improve light-load efficiency |
| SW (Pin 6) | Switch emitter terminal | Connects to inductor; swings negative during off-time; requires Schottky catch diode |
| VIN (Pin 7) | Main power input | Supplies internal circuitry when BIAS is unconnected; handles 80V/100ms transients |
| BOOST (Pin 8) | Switch driver boost supply | Driven 3.3V above VIN via external capacitor/diode; ensures NPN saturation and low VCE(sat) |
| GND (Pin 9) | Power and signal reference | Primary ground return; must be shorted to load ground and soldered to PCB thermal pad |
| CSS (Pin 10) | Soft-start ramp control | Capacitor to VOUT sets dV/dt; current threshold (4–16µA) scales with FB voltage |
Key Features
| Feature | Design Value |
|---|---|
| Load dump protection | Withstands 80V/100ms input transients without derating or external clamping |
| Thermal performance | θJA = 45°C/W; exposed pad (Pin 11) must be soldered to GND for specified junction temperature margin |
| Defeatable Burst Mode | SYNC pin logic-high eliminates light-load ripple at cost of higher IQ (~475µA at 5V BIAS) |
| Wide temperature operation | Guaranteed –40°C to +125°C junction temperature; tested across full range |
| Current-mode stability | Single-pole compensation; avoids 180° phase shift near LC resonance for robust loop design |
Applications
| Automotive Power Supply | Industrial 24V/48V Systems |
|---|---|
Use Scenario: 14V battery system powering infotainment head unit with cold-crank immunity (4.5V input dip). IC Role / Device Role / Timing Role: Primary step-down regulator delivering 3.3V/400mA with 100µA no-load IQ to extend battery life. Use Value: Maintains regulation during 4.5V cold-crank events and survives 80V load dump transients without external TVS. | Use Scenario: Distributed 48V DC power rail feeding isolated point-of-load converters in factory automation PLC. IC Role / Device Role / Timing Role: Pre-regulator converting 48V to 12V intermediate bus with high efficiency across 10mA–500mA load range. Use Value: 0.8Ω switch and BOOST-driven saturation enable >85% efficiency at 48V→12V, reducing thermal stress in enclosed enclosures. |
| Battery-Powered Telemetry | Powered Ethernet (PoE) Interface |
Use Scenario: Solar-charged LiFePO₄ battery (3.6V–36V) powering wireless sensor node with ultra-low sleep current. IC Role / Device Role / Timing Role: Main power converter delivering 3.3V with 100µA Burst Mode IQ and <1µA shutdown current. Use Value: Extends multi-year battery life by minimizing quiescent draw during extended sleep cycles. | Use Scenario: PoE-powered IP camera receiving 44–57V from midspan injector, requiring regulated 5V/1A for imaging subsystem. IC Role / Device Role / Timing Role: Primary buck stage stepping down PoE voltage to 5V before secondary LDO or DC-DC stage. Use Value: Input transient rating up to 80V eliminates need for upstream TVS, simplifying BOM and layout in space-constrained modules. |
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 |
|---|---|---|---|
| LTC3639EMSE#PBF | 40V max input; 1.5A switch; integrated MOSFET; 3mm × 4mm MSOP | Lower voltage range; higher current; no BOOST pin or load dump rating | Select for ≤40V systems needing higher output current and simpler layout (no external diode/BOOST cap) |
| LM5164QPWPRQ1 | 65V max input; 300mA switch; integrated MOSFET; 1.5µA shutdown IQ | No Burst Mode; fixed 2.1MHz frequency; AEC-Q100 qualified | Select for automotive applications requiring AEC-Q100 qualification and ultra-low shutdown current, but accept higher light-load ripple |
Compared with LTC3639EMSE#PBF and LM5164QPWPRQ1, LT3437IFE#PBF uniquely combines 80V transient tolerance, 100µA Burst Mode IQ, and BOOST-assisted saturation for high-efficiency operation across 3.3V–60V inputs-making it optimal for ruggedized industrial and automotive front-end regulation where input transients and low standby power are critical.
Availability
LT3437IFE#PBF is available at Aetrix Electronics and suitable for automotive power supplies, industrial 24V/48V systems, battery-powered telemetry, and Powered Ethernet interfaces requiring stable component supply across extended temperature and high-reliability environments.
Supply support for LT3437IFE#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 acquired Linear Technology in 2017 and maintains its high-performance analog and power management portfolio with rigorous automotive and industrial qualification standards.
The LT3437IFE#PBF belongs to Linear's high-voltage monolithic buck regulator family, designed specifically for harsh-environment power conversion in automotive, industrial, and distributed power systems where input transients, wide VIN range, and low quiescent current are mandatory.
FAQ
What is the maximum input voltage rating for LT3437IFE#PBF during transient conditions?
The LT3437IFE#PBF is rated for 80V input transients with <15% duty cycle and duration ≤100ms, per Absolute Maximum Ratings. This applies to load dump events in automotive 12V systems and enables direct use without external TVS diodes in many designs. Continuous operation remains limited to 60V. The 80V rating is validated across the full –40°C to +125°C operating junction temperature range for the LT3437IFE#PBF.
How does the BOOST pin function in LT3437IFE#PBF and what external components are required?
The BOOST pin in LT3437IFE#PBF provides a voltage higher than VIN to fully saturate the internal NPN power switch, reducing VCE(sat) and improving efficiency. It requires an external flying capacitor (typically 100nF ceramic) and Schottky diode (e.g., BAS21) connected between SW and BOOST. During switch on-time, BOOST charges to VIN + Vf(diode); during off-time, it supplies gate drive to ensure saturation. The LT3437IFE#PBF datasheet specifies minimum BOOST voltage of 1.8V at 500mA switch current.
Can LT3437IFE#PBF operate with input voltage below 3.3V, and what is the minimum start-up voltage?
The LT3437IFE#PBF has a minimum operating input voltage of 3.3V for continuous regulation, but can start switching at as low as 2.5V (per Electrical Characteristics). However, maintaining regulated output at low VIN depends on VOUT and load current - e.g., a 3.3V output requires VIN > ~3.5V under 250mA load due to dropout. The LT3437IFE#PBF achieves this via BOOST-assisted saturation and current-mode control, enabling usable operation down to 3.3V input in most configurations.
What is the purpose of the CSS pin in LT3437IFE#PBF and how is soft-start configured?
The CSS pin in LT3437IFE#PBF controls soft-start by sourcing current into an external capacitor connected to VOUT. When CSS current exceeds the threshold (4–16µA, scaling with FB voltage), the VC pin is clamped to limit output dV/dt. A typical 10nF capacitor yields ~10ms ramp time for 3.3V output. Soft-start activates automatically when FB < 0.9V (e.g., during startup or brown-out) and is defeated above that threshold. This protects input sources and reduces inrush in the LT3437IFE#PBF design.
Is LT3437IFE#PBF pin-compatible with other variants in the LT3437 family, such as LT3437EDD#PBF?
No, LT3437IFE#PBF is not pin-compatible with LT3437EDD#PBF. The LT3437IFE#PBF uses a 10-pin 3mm × 3mm DFN package (Pin 1 = SHDN), while LT3437EDD#PBF uses a 10-pin DFN with different pinout (Pin 1 = SHDN but Pin 6 = SW vs Pin 6 = VIN in IFE). The FE and DD packages share footprint dimensions but differ in pin mapping and thermal pad configuration. Migration requires PCB redesign; always verify pin functions against the specific variant's datasheet for LT3437IFE#PBF.
LT3437IFE#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):
- 3V
- 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 ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-TSSOP-EP
LT3437IFE#PBF FAQ
1.How can I place an order for LT3437IFE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3437IFE#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 LT3437IFE#PBF reliable?
The price and inventory of LT3437IFE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3437IFE#PBF is usually 5 days.
3.What payment methods are accepted for LT3437IFE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3437IFE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3437IFE#PBF?
LT3437IFE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3437IFE#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 LT3437IFE#PBF?
For technical support, including LT3437IFE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3437IFE#PBF requirements.
6.How does Aetrix verify that LT3437IFE#PBF is sourced from the original manufacturer or authorized distributors?
All LT3437IFE#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 LT3437IFE#PBF meets industry standards.
7.What is the process for return or replacement of LT3437IFE#PBF?
All LT3437IFE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3437IFE#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 LT3437IFE#PBF part is unused and in its original packaging.
Return procedure for LT3437IFE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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