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Analog Devices Inc. LT3740EDHC#TRPBF
- Part No.:
- LT3740EDHC#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 16-WFDFN Exposed Pad
- Datasheet:
-
LT3740EDHC#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 16-DFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,199
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Product details
Overview
LT3740EDHC#TRPBF from Analog Devices (formerly Linear Technology) is a synchronous step-down switching regulator controller driving dual N-channel MOSFETs in valley current mode, operating from 2.2V to 22V input, delivering up to 10A output at 1.8V with no external sense resistor, and featuring programmable 300kHz fixed-frequency operation for high-step-down-ratio DC/DC conversion in portable power systems.
For engineers reviewing the LT3740EDHC#TRPBF datasheet, LT3740EDHC#TRPBF pinout, LT3740EDHC#TRPBF application, or LT3740EDHC#TRPBF equivalent, key selection considerations include its valley-mode control architecture, three selectable current limit thresholds (50/80/105mV), internal boost for gate drive bias ≥7.8V above VIN, XREF-based output voltage tracking/soft-start, and PGOOD monitoring - all integrated in a 16-pin 5mm × 3mm DFN package.
Technical Context
The LT3740EDHC#TRPBF implements constant-frequency valley current mode control using internal ramp compensation synchronized to a 300kHz oscillator, with bottom-FET current sensing via SN+/SN– pins and adaptive dead-time management to prevent shoot-through. Its internal boost converter generates BIAS ≈ VIN + 7.8V to enable top-gate drive down to 2.2V input.
Control logic includes a gm error amplifier comparing FB/XREF against 0.8V reference, VC-compensated loop stability, and three-range current limiting selected by RANGE pin (GND/open/VIN), each with distinct slope compensation to maintain stability across duty cycles. The PGOOD open-collector output asserts low when FB falls below 720mV, independent of XREF voltage.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.2V to 22V - enables direct battery-to-core-voltage conversion from single-cell Li-ion (2.7–4.2V) or multi-cell supplies without pre-regulation. |
| Switching Frequency | 300kHz (typ) - balances EMI, inductor size, and efficiency for compact high-current buck designs. |
| Current Sense Thresholds | 50mV / 80mV / 105mV - selectable via RANGE pin to match MOSFET RDS(ON) or external sense resistor for precise overcurrent protection. |
| Feedback Reference | 0.8V internal or externally adjustable down to 0V via XREF - supports output voltage tracking, soft-start, and dynamic regulation. |
| Gate Drive Bias | BIAS = VIN + 7.8V - ensures sufficient top-gate overdrive even at 2.2V input, eliminating need for external bootstrap circuitry. |
| Power Good Threshold | 720mV on FB - provides reliable output voltage monitoring with 40mV hysteresis, independent of XREF setting. |
| Operating Temperature | –40°C to +85°C - qualified for industrial and portable computing environments with full parameter guarantees. |
Pinout & Package
LT3740EDHC#TRPBF is housed in a thermally enhanced 16-lead (5mm × 3mm) plastic DFN package with exposed pad (Pin 17) soldered to PCB ground for thermal and electrical integrity. Package thermal resistance θJA = 43°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SN– (1) | Negative Current Sense Input | Connects to bottom MOSFET source (No RSENSE) or low-side of external sense resistor - sets current limit threshold with SN+. |
| PGND (2) | Power Ground Return | Low-impedance return path for bottom MOSFET source current - must be routed directly to exposed pad for minimal noise and thermal resistance. |
| BGATE (3) | Bottom N-Channel Gate Driver Output | Drives gate of synchronous rectifier MOSFET with 5.5V on/0.2V off levels - supports logic-level FETs when BGDP ≥7V. |
| BGDP (4) | Bottom Gate Drive Power Supply | Accepts ≥7V supply - tied to BIAS for VIN <7V, or to VIN for reduced loss at higher inputs. |
| SN+ (5) | Positive Current Sense Input | Connects to bottom MOSFET drain (No RSENSE) or high-side of external sense resistor - completes current sense differential pair with SN–. |
| SW (6) | Switch Node | Connects to source of top MOSFET and drain of bottom MOSFET - carries high dv/dt switching waveform; requires tight layout to minimize EMI. |
| TGATE (7) | Top N-Channel Gate Driver Output | Drives gate of high-side MOSFET referenced to BIAS - delivers 5.5V on/0.2V off with 30ns rise/fall times into 3300pF load. |
| BIAS (8) | Top Gate Drive Boost Supply | Output of internal boost converter - maintains ~7.8V above VIN to ensure robust top-gate drive across full input range. |
| SWB (9) | Internal Boost Switch Node | Connects to boost inductor - forms charge-pump stage generating BIAS voltage; requires low-ESR ceramic capacitor to VIN. |
| VIN (10) | Main Input Supply | Primary power input - must be locally bypassed with ≥10μF low-ESR capacitor to suppress ripple and support peak current demands. |
| RANGE (11) | Current Limit Range Select | Ground = 50mV, open = 80mV, connect to VIN = 105mV - selects both current threshold and corresponding slope compensation gain. |
| PGOOD (12) | Open-Collector Power Good Output | Pulled low when FB <720mV - used for system sequencing, fault indication, or enabling downstream rails. |
| SHDN (13) | Shutdown / Soft-Start Control | ≤0.5V disables controller and boost; ≥1.1V enables; ramped voltage implements controlled soft-start via VC clamping. |
| XREF (14) | External Reference Input | Accepts 0–0.8V to override internal 0.8V reference - enables output voltage tracking, programmable soft-start, or dynamic regulation. |
| FB (15) | Feedback Input | Regulated to lower of XREF voltage or 0.8V internal reference - connects to resistor divider from VOUT to set output voltage. |
| VC (16) | Error Amplifier Compensation | Connects external RC network for loop compensation - voltage determines PWM comparator threshold and thus output current delivery. |
Key Features
| Feature | Design Value |
|---|---|
| No external current sense resistor required | Enables high-efficiency, low-component-count designs using bottom MOSFET RDS(ON) as current sensor - eliminates I²R loss and board space of discrete shunt. |
| Valley current mode control with slope compensation | Provides inherent cycle-by-cycle current limiting, excellent transient response, and stable operation across wide duty cycles - slope automatically adjusted per RANGE setting. |
| Integrated boost converter for gate drive bias | Generates BIAS ≈ VIN + 7.8V internally - allows operation from 2.2V input without external charge pump or auxiliary supply. |
| Programmable output voltage tracking and soft-start | XREF pin accepts external ramp or reference signal - enables coordinated power-up with other rails or controlled inrush current during startup. |
| Three selectable current limit thresholds | 50/80/105mV thresholds set via RANGE pin - matches diverse MOSFET RDS(ON) tolerances or external sense resistors while maintaining optimal slope compensation. |
Applications
| Portable Computing Power | Distributed Point-of-Load |
|---|---|
Use Scenario: Regulating 1.8V/10A core voltage from 3–12V battery or intermediate bus in notebook computers and palmtop devices. IC Role / Device Role / Timing Role: Synchronous step-down controller managing dual N-MOSFET power stage with valley-mode current sensing and adaptive dead time. Use Value: Achieves >94% efficiency at 5V input due to no-RSENSE architecture and optimized gate drive, extending battery runtime without thermal derating. | Use Scenario: Providing tightly regulated 2.5V/5A supply to FPGA or ASIC cores in telecom base stations with distributed 12V or 24V backplanes. IC Role / Device Role / Timing Role: High-step-down-ratio buck controller supporting wide input range and fast load transients via valley current mode control. Use Value: Maintains ±1% output regulation across –40°C to +85°C with PGOOD monitoring for system-level fault detection and recovery. |
| Industrial Portable Instruments | High-Efficiency DC/DC Modules |
Use Scenario: Generating 3.3V/3A supply from 9–22V industrial battery packs in handheld test equipment with strict EMI limits. IC Role / Device Role / Timing Role: Fixed-frequency (300kHz) synchronous buck controller with internal boost and programmable soft-start via SHDN/XREF. Use Value: Reduces input ripple and conducted EMI through controlled switching frequency and minimized component count - no external sense resistor or bootstrap diode needed. | Use Scenario: Serving as main controller in compact, high-density 12V-to-1.2V DC/DC modules for server CPU VRMs requiring high current density. IC Role / Device Role / Timing Role: Valley-mode controller with three current limit ranges and BIAS-driven top-gate drive enabling efficient high-side switch operation. Use Value: Supports scalable current capability up to 10A+ with external MOSFET selection, while maintaining thermal performance via exposed-pad DFN package. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous step-down controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3891EMSE#PBF | Wider input range (4–60V), dual-output capability, and integrated LDO - but lacks No RSENSE™ and requires external sense resistor. | Targeted at automotive and industrial high-voltage systems rather than low-VIN portable applications. | Select LTC3891EMSE#PBF only when input exceeds 22V or dual-rail regulation is required; not suitable for 2.2V start-up or No RSENSE designs. |
| MP24894GQKT-Z | Monolithic 4A buck converter (integrated MOSFETs), fixed 500kHz frequency, no valley-mode control - uses peak current mode and requires external sense resistor. | Designed for cost-sensitive, medium-current applications where board space is constrained but high efficiency at light load is less critical. | Choose MP24894GQKT-Z for simpler, lower-BOM-cost solutions under 4A; LT3740EDHC#TRPBF remains preferred for >5A, low-VIN, or No RSENSE requirements. |
Compared with LTC3891EMSE#PBF and MP24894GQKT-Z, the LT3740EDHC#TRPBF uniquely combines sub-2.5V start-up capability, valley-mode control without external sense resistor, and programmable output tracking - making it the only option among the three for high-efficiency, high-current, low-input-voltage synchronous buck controller applications.
Availability
LT3740EDHC#TRPBF is available at Aetrix Electronics and suitable for portable computing power, distributed point-of-load regulation, and industrial portable instrumentation requiring stable component supply, long-term lifecycle support, and guaranteed industrial temperature performance.
Supply support for LT3740EDHC#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 and maintains full product support, documentation, and manufacturing continuity for the LT® family of high-performance analog ICs.
The LT3740EDHC#TRPBF belongs to Linear's high-efficiency DC/DC controller product line, designed specifically for synchronous step-down conversion in space-constrained, high-current portable and industrial power systems where low-VIN operation and precision current limiting are critical.
FAQ
What is the minimum input voltage supported by the LT3740EDHC#TRPBF?
The LT3740EDHC#TRPBF supports a minimum input voltage of 2.2V, enabled by its internal boost converter that generates a BIAS voltage approximately 7.8V higher than VIN. This allows reliable top-gate drive even at ultra-low input conditions, such as single-cell Li-ion battery discharge endpoints. The controller begins operation when BIAS reaches ~7.2V above VIN, ensuring robust startup across the full –40°C to +85°C temperature range.
How does the RANGE pin affect current limiting and stability in the LT3740EDHC#TRPBF?
The RANGE pin on the LT3740EDHC#TRPBF selects one of three current sense thresholds - 50mV (RANGE = GND), 80mV (RANGE = open), or 105mV (RANGE = VIN) - and simultaneously configures the corresponding slope compensation gain. Each setting adjusts the ramp added to the current sense signal to prevent subharmonic oscillation, with higher thresholds providing stronger compensation for high-duty-cycle operation. This dual function ensures both accurate overcurrent protection and stable valley-mode control across varying input/output conditions.
Can the LT3740EDHC#TRPBF operate without an external current sense resistor?
Yes, the LT3740EDHC#TRPBF implements Linear's No RSENSE™ architecture, allowing direct current sensing using the on-resistance (RDS(ON)) of the bottom N-channel MOSFET. Pins SN+ and SN– connect across the MOSFET's drain and source terminals to measure the voltage drop, eliminating I²R losses and board area associated with discrete shunts. For improved accuracy, an external sense resistor can be substituted - the same pins interface either method without circuit modification.
What is the role of the XREF pin in LT3740EDHC#TRPBF operation?
The XREF pin on the LT3740EDHC#TRPBF allows external override of the internal 0.8V feedback reference, accepting any voltage from 0V to 0.8V to set the regulated output voltage. This enables precise output voltage tracking (e.g., matching another rail), programmable soft-start (by ramping XREF from 0V), or dynamic output adjustment during operation. When XREF ≥1V, the internal 0.8V reference is used; below 0.8V, the XREF voltage becomes the regulation target - all without changing feedback resistor values.
Does the LT3740EDHC#TRPBF provide power-good monitoring, and how is it implemented?
Yes, the LT3740EDHC#TRPBF includes an open-collector PGOOD output (Pin 12) that pulls low when the FB pin voltage falls below 720mV, indicating undervoltage on the regulated output. This threshold is independent of the XREF voltage setting, ensuring consistent monitoring regardless of whether internal or external reference is active. PGOOD supports system-level power sequencing, fault flagging, or enabling downstream converters, and requires an external pull-up resistor to a compatible logic voltage.
LT3740EDHC#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-WFDFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Output Type:
- Transistor Driver
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Number of Outputs:
- 1
- Output Phases:
- 1
- Voltage - Supply (Vcc/Vdd):
- 2.2V ~ 22V
- Frequency - Switching:
- 300kHz
- Duty Cycle (Max):
- -
- Synchronous Rectifier:
- Yes
- Clock Sync:
- No
- Serial Interfaces:
- -
- Control Features:
- Current Limit, Enable, Power Good
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-DFN (5x3)
LT3740EDHC#TRPBF FAQ
1.How can I place an order for LT3740EDHC#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3740EDHC#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 LT3740EDHC#TRPBF reliable?
The price and inventory of LT3740EDHC#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3740EDHC#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3740EDHC#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3740EDHC#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3740EDHC#TRPBF?
LT3740EDHC#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3740EDHC#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 LT3740EDHC#TRPBF?
For technical support, including LT3740EDHC#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3740EDHC#TRPBF requirements.
6.How does Aetrix verify that LT3740EDHC#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3740EDHC#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 LT3740EDHC#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3740EDHC#TRPBF?
All LT3740EDHC#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3740EDHC#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 LT3740EDHC#TRPBF part is unused and in its original packaging.
Return procedure for LT3740EDHC#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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