LTC3309AEV#TRMPBF - 6A Synchronous Step-Down Silent Switcher | Analog Devices
MPN: LTC3309AEV#TRMPBF ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $4.37 | $4.37 |
| 10 | $3.93 | $39.30 |
| 100 | $3.49 | $349.00 |
| 500 | $2.96 | $1,480.00 |
| 1,000 | $2.62 | $2,620.00 |
LTC3309AEV#TRMPBF Overview
A buck DC/DC switching regulator is a type of switched-mode power supply (SMPS) that steps a higher DC input voltage down to a lower regulated DC output voltage by rapidly switching an inductor-capacitor filter network. In the broader system hierarchy, a buck converter belongs to the voltage regulator family, which sits under power management ICs and ultimately under analog and mixed-signal semiconductors. Compared to linear regulators (LDOs), buck converters achieve far higher efficiency at large VIN-VOUT differentials because they do not dissipate the drop-out voltage as heat.
Key features of the LTC3309AEV include 6A continuous output current, a 0.5V to VIN output range with ±1% reference accuracy, internal synchronous switches that eliminate the need for an external Schottky diode, and Silent Switcher technology that enables CISPR 22/25 Class B compliance with proper PCB layout. The 2mm x 2mm LQFN package provides low thermal resistance for compact, high-current designs.
The LTC3309AEV uses peak current-mode control with internal compensation, which simplifies loop stabilization across a wide range of output LC filters. The architecture supports parallel operation of multiple ICs for higher load current and offers programmable switching frequency for trade-offs between efficiency, solution size, and noise spectrum placement.
Typical applications include point-of-load (POL) conversion in space-constrained systems such as FPGA/ASIC rails, portable instruments, optical modules, and battery-powered devices that require high current from a 5V or 3.3V bus. The combination of small size, low noise, and high efficiency makes the LTC3309AEV particularly well suited to dense PCBAs.
When designing with this part, prioritize the recommended PCB layout for Silent Switcher performance - the exposed pad must be soldered to a continuous ground plane with adequate thermal vias, and input/output capacitors must be placed as close to the IC as possible to minimize switching noise.
This page synthesizes distributor pricing, drop-in same-package alternatives, and practical layout guidance for the LTC3309AEV#TRMPBF that go beyond the manufacturer datasheet.
Drop-in alternatives for LTC3309AEV#TRMPBF — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
LTC3309AJV-7#TRMPBF
✅ Drop-In📋 Reference alternative (not in catalog)
LTC3309AEV#WTRMPBF
✅ Drop-In📋 Reference alternative (not in catalog)
LTC3309AEV#TRPBF
✅ Drop-In📋 Reference alternative (not in catalog)
LTC3309AEV#WTRPBF
✅ Drop-In📋 Reference alternative (not in catalog)
LTC3309AEV#TRMPBF Maximum Ratings & Electrical Characteristics
| Topology | Synchronous Buck (Step-Down) |
| Input Voltage Range | 2.25 V to 5.5 V |
| Output Voltage Range | 0.5 V to V_IN (programmable) |
| Continuous Output Current | 6 A |
| Switching Frequency Range | 1 MHz to 3 MHz (programmable) |
| Switching Architecture | Silent Switcher (low EMI) |
| Control Method | Constant-Frequency Peak Current-Mode |
| Reference Accuracy | ±1 % (over temperature) |
| Internal Switches | Yes (synchronous MOSFETs, no external Schottky) |
| Operating Temperature Range | -40 °C to +125 °C (TJ) |
| Package | 12-Lead 2 mm x 2 mm LQFN with Exposed Pad |
| Mounting Type | Surface Mount |
| RoHS Status | Compliant |
| Packing Method | Tape & Reel (TRMPBF = 500-unit reel, Pb-free) |
LTC3309AEV#TRMPBF Pin Configuration
| Pin 1 | VIN — Input supply voltage (2.25 V to 5.5 V) |
| Pin 2 | PGND — Power ground - return for synchronous switch |
| Pin 3 | SW — Switch node - connects to external inductor |
| Pin 4 | SW — Switch node (continued) |
| Pin 5 | BST — Bootstrap supply for high-side gate driver |
| Pin 6 | RUN — Run / enable pin (active high) |
| Pin 7 | RT — Timing resistor - sets switching frequency |
| Pin 8 | AGND — Analog ground - quiet ground reference |
| Pin 9 | FB — Feedback input - resistor divider sets VOUT |
| Pin 10 | PGOOD — Power-good indicator (open-drain) |
| Pin 11 | SYNCI/SYNCO — Frequency synchronization input/output |
| Pin 12 | VIN — Input supply voltage (continued) |
| Pin EP | EPAD — Exposed thermal pad - solder to ground plane |
Typical Applications
LTC3309AEV#TRMPBF is suitable for 6 applications: FPGA/ASIC Point-of-Load (POL) Conversion, Portable / Battery-Powered Instrumentation, Optical Modules and High-Speed Data Converters, Industrial 5V-Bus Distributed Power, Automotive-Grade Power (with #W variant), PCIe and Server Card Power.
FPGA/ASIC Point-of-Load (POL) Conversion
The LTC3309AEV#TRMPBF is ideal for FPGA and ASIC point-of-load rails where space is at a premium. The 2mm x 2mm LQFN footprint and 6A continuous current let the part sit within millimeters of the load, minimizing PCB parasitic inductance and IR drops on high-current core and transceiver rails. Programmable output from 0.5V to V_IN covers all common FPGA core voltages (0.85V, 0.9V, 1.0V, 1.2V, 1.8V) and DDR rails. The Silent Switcher architecture keeps switching noise below CISPR 22/25 Class B limits, which is essential when adjacent to gigabit transceivers. Recommended companion MPNs: LT8640EUDC#TRPBF (Site MPN, higher input alternative), LTC2974IUP#PBF (Site MPN, for power supply sequencing of multiple rails).
Recommended
Portable / Battery-Powered Instrumentation
The LTC3309AEV's high efficiency over the 2.25V-5.5V input range maximizes battery runtime in portable instruments. Operating from a single-cell Li-ion (3.0V-4.2V), the part delivers 6A with peak current-mode control, eliminating the efficiency penalty that linear regulators would incur. The Silent Switcher EMI performance means the converter can be placed near sensitive analog front-ends without filtering penalties. The exposed pad and 2x2 LQFN footprint allow handheld designs where board area is severely constrained. Recommended companion MPNs: LTC2415IGN#TRPBF (Site MPN, precision 24-bit ADC for the analog front-end), LTC2955ITS8-2 (Site MPN, push-button controller for clean power-on sequencing).
Recommended
Optical Modules and High-Speed Data Converters
Optical transceivers and high-speed ADCs/DACs require ultra-clean low-voltage rails for laser drivers and sampling clocks. The LTC3309AEV's Silent Switcher technology keeps peak EMI low enough to meet CISPR 22/25 Class B without bulky pi-filters, while peak current-mode control provides fast transient response to handle the dynamic load steps of burst-mode data transmission. The 0.5V-5V output range supports laser bias supplies, TIA supply rails, and modulator drivers. The 12-lead 2x2 LQFN footprint fits directly under or beside the optical package. Recommended companion MPNs: LTC2358HLX-18#PBF (Site MPN, simultaneous-sampling SAR ADC), LTC2335ILX-16#PBF (Site MPN, 16-bit low-noise ADC).
Recommended
Industrial 5V-Bus Distributed Power
On industrial 5V backplanes, the LTC3309AEV#TRMPBF steps the bus down to the local voltages needed by mixed-signal ICs and MCUs. With 6A per phase and synchronization, multiple parts can be paralleled for higher currents. The exposed pad provides robust thermal performance in factory-floor temperature ranges, and the wide -40°C to +125°C TJ range covers harsh environments. Industrial-grade robustness plus Pb-free compliance makes the part drop-in compatible with most factory automation backplanes. Recommended companion MPNs: LM5180NGUR (Site MPN, alternative wide-Vin buck for factory 24V rails), LPC4330FET256 (Site MPN, dual-core Cortex-M4 MCU for industrial control).
Recommended
Automotive-Grade Power (with #W variant)
While the LTC3309AEV#TRMPBF itself is industrial grade, the same silicon is available as the LTC3309AEV#WTRMPBF (drop-in, same package) with controlled manufacturing for AEC-Q100 automotive applications. This enables designers to prototype on the standard part and migrate to the automotive-qualified version with zero PCB changes. The 6A capability suits ADAS sensor boards, infotainment modules, and body controllers requiring low-EMI step-down from the 5V or 3.3V automotive rails. The 2x2 LQFN footprint survives the automotive thermal profile. Recommended companion MPNs: LM34936QPWPRQ1 (Site MPN, AEC-Q100 wide-Vin buck), ISO7762FDWR (Site MPN, automotive-grade digital isolator for ECU communications).
Recommended
PCIe and Server Card Power
The LTC3309AEV#TRMPBF powers local core and auxiliary rails on PCIe cards, mezzanine modules, and small-form-factor server cards. Its 5V input capability directly accommodates standard PCIe slot power; its 6A output handles memory, controllers, and small FPGAs; and its Silent Switcher EMI behavior lets the card pass FCC Class B in dense chassis. The 2mm x 2mm footprint fits under BGA packages with minimal height penalty, and parallel operation enables higher current when needed. Recommended companion MPNs: KSZ9031RNXIC-TR (Site MPN, gigabit Ethernet PHY sharing the rail), LMZ14203HTZ/NOPB (Site MPN, integrated 3A module for chassis-level pre-regulation).
Recommended
Recommended Products Summary
Engineering reference data for LTC3309AEV#TRMPBF — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | LTC3309AJV-7#TRMPBF | LTC3309AEV#WTRMPBF | LTC3309AEV#TRPBF | LTC3309AEV#WTRPBF |
|---|---|---|---|---|---|
| Brand | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices |
| Package | 12-LQFN 2mm x 2mm | 12-LQFN 2mm x 2mm (same) | 12-LQFN 2mm x 2mm (same) | 12-LQFN 2mm x 2mm (same) | 12-LQFN 2mm x 2mm (same) |
| Input Voltage | 2.25 V to 5.5 V | 2.25 V to 5.5 V | 2.25 V to 5.5 V | 2.25 V to 5.5 V | 2.25 V to 5.5 V |
| Output Current | 6 A | 6 A | 6 A | 6 A | 6 A |
| Switching Frequency | 1 MHz to 3 MHz | 1 MHz to 3 MHz | 1 MHz to 3 MHz | 1 MHz to 3 MHz | 1 MHz to 3 MHz |
| Reference Accuracy | ±1 % | ±1 % | ±1 % | ±1 % | ±1 % |
| Automotive Grade (#W suffix) | No | No | Yes (AEC-Q100) | No | Yes (AEC-Q100) |
| Packing Reel | Mini-Reel (500-unit) | Mini-Reel (500-unit) | Mini-Reel (500-unit) | Standard Reel | Standard Reel |
Key Differentiators
- Smallest 6A synchronous buck in 2mm x 2mm LQFN (vs Typical 6A buck competitors in 3mm x 3mm QFN or larger)
- Silent Switcher EMI architecture (vs Standard buck converters without EMI cancellation)
- 1-3 MHz programmable switching frequency (vs Fixed-frequency 1MHz competitors)
Design Notes
For Silent Switcher performance, follow the LTC3309A datasheet PCB layout recommendation exactly: place input capacitors as close as possible to the VIN and PGND pins with short, wide traces; expose a continuous ground plane on inner layers; and stitch multiple thermal vias under the exposed pad to the ground plane. The hot loop (VIN-to-PGND-to-SW) area must be minimized to keep EMI below CISPR 22/25 Class B limits without additional filtering.
At VIN=5V, VOUT=3.3V, and 6A continuous load, internal dissipation is approximately 6A × (5V-3.3V) × (1-efficiency). With ~90% efficiency the IC dissipates ~1.1W. The 12-lead 2mm x 2mm LQFN exposed pad must be soldered to at least 4 thermal vias to a 1 oz copper pour on the opposite side. Without proper thermal design, junction temperature may exceed +125°C at full load in ambient temperatures above 60°C.
Use a low-ESR ceramic input capacitor (e.g. 22µF X7R 10V 0805) within 2mm of VIN/PGND. The output capacitor should be 2x 22µF X7R 10V ceramic for typical applications, or a polymer/aluminum-polymer combination if the application demands lower output ripple. Inductor selection: 0.47µH to 1.5µH shielded ferrite with DCR below 10mΩ for best efficiency at 6A.
Estimated: at the maximum 5.5V input and minimum 0.5V output, the duty cycle is ~9% and the IC dissipates substantial power at full load. Do not operate above 6A without confirming the exposed pad thermal design meets your ambient temperature target. Also avoid connecting AGND and PGND at a single point inside the IC footprint - keep AGND quiet and tie it to PGND at a single point near the exposed pad per the datasheet.
Compliance Information
Pb-free per Analog Devices product page (#PBF suffix). For AEC-Q100 automotive, use the #W-suffix variant LTC3309AEV#WTRMPBF which shares the same silicon and package. RoHS and REACH compliance inferred from #PBF suffix and Analog Devices standard product compliance.
