LTC3309AHV#TRMPBF - 6A, 5.5V Synchronous Step-Down Silent Switcher | Analog Devices
MPN: LTC3309AHV#TRMPBF ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $8.63 | $8.63 |
| 10 | $7.76 | $77.60 |
| 100 | $6.55 | $655.00 |
| 500 | $5.85 | $2,925.00 |
| 1,000 | $5.2 | $5,200.00 |
LTC3309AHV#TRMPBF Overview
A synchronous step-down (buck) DC/DC converter is a switching regulator that steps a higher DC input voltage down to a lower regulated DC output voltage. It uses two MOSFETs that switch in alternation - one connecting the inductor to the input, the other to ground - so that energy is transferred and filtered continuously. Compared to a linear regulator, a buck converter delivers much higher efficiency (often 90%+) at non-trivial VIN-to-VOUT ratios, and is the dominant topology for point-of-load power in modern digital systems. The Silent Switcher architecture additionally minimizes EMI by containing high-di/dt loops inside the package and using an internal bypass capacitor.
Key features include 6A continuous output current, 1.2 mA quiescent current, internal compensation, and Silent Switcher architecture for low EMI. The device operates at a programmable switching frequency between 1MHz and 3MHz, enabling the use of small ceramic capacitors and inductors while keeping the fundamental switching noise above most sensitive RF bands. Forced continuous and Burst Mode operation are user-selectable via the MODE pin to trade light-load efficiency against output ripple. The exposed pad provides a low thermal resistance path suitable for the 6A load capability in a 2mm x 2mm footprint.
The LTC3309A is built on a monolithic synchronous architecture that integrates the high-side and low-side MOSFETs, the bootstrap diode, and the control loop into a single die. Peak current-mode control provides cycle-by-cycle current limiting and inherent line regulation, while internal loop compensation removes the need for an external compensation network and simplifies PCB design. Silent Switcher 2 architecture further reduces radiated emissions by minimizing the AC hot loops, allowing the part to pass CISPR 25 and similar EMI standards in automotive infotainment and ADAS systems.
Typical applications include point-of-load power for FPGAs, ASICs, DSPs, and microprocessors, automotive infotainment and ADAS supplies, battery-powered portable devices, and distributed 5V bus regulation. The wide VIN range and small footprint also make it attractive for space-constrained industrial modules and server/communications point-of-load rails.
When designing with this device, place the input capacitors directly on the VIN pins and bond them to the PGND copper pour on the top layer; both VIN pins (3 and 8) require local decoupling according to the manufacturer datasheet. Choose an inductor with low DCR and adequate saturation current (>40% above IOUT), and use X7R or X5R ceramic output capacitors rated for the actual AC ripple current, not just DC voltage.
This page synthesizes distributor pricing, same-family drop-in alternatives, and application design notes not collected in any single place on the manufacturer datasheet.
Drop-in alternatives for LTC3309AHV#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:
LTC3309AIV#TRMPBF
✅ Drop-In📋 Reference alternative (not in catalog)
LTC3309AHV#TRPBF
✅ Drop-In📋 Reference alternative (not in catalog)
LTC3309AHV#WTRMPBF
✅ Drop-In📋 Reference alternative (not in catalog)
LTC3309AJV-7#TRMPBF
✅ Drop-In📋 Reference alternative (not in catalog)
LTC3309AMPV#TRPBF
✅ Drop-In📋 Reference alternative (not in catalog)
LTC3309AHV#TRMPBF Maximum Ratings & Electrical Characteristics
| Topology | Synchronous Step-Down (Buck) |
| Input Voltage Range | 2.25 V to 5.5 V |
| Output Voltage Range | 0.5 V to 5.5 V (programmable) |
| Maximum Output Current | 6 A |
| Switching Frequency Range | 1 MHz to 3 MHz (programmable) |
| Quiescent Current | 1.2 mA (typical) |
| Control Architecture | Peak Current-Mode Control |
| Architecture | Silent Switcher (low EMI) |
| Number of Outputs | 1 |
| Package | 12-pin LQFN (2mm x 2mm) with exposed pad |
| Mounting Type | Surface Mount |
| RoHS Status | Compliant |
| Internal MOSFETs | Integrated high-side and low-side |
LTC3309AHV#TRMPBF Pin Configuration
| Pin 1 | VIN — Input supply voltage (2.25V to 5.5V) |
| Pin 2 | PGND — Power ground (return for internal low-side FET) |
| Pin 3 | VIN — Input supply voltage - second pin, requires local decoupling |
| Pin 4 | PGND — Power ground - second pin |
| Pin 5 | SW — Switch node connection to the output inductor |
| Pin 6 | BST — Bootstrap supply for the high-side gate driver |
| Pin 7 | PGND — Power ground - third pin |
| Pin 8 | VIN — Input supply voltage - third pin, requires local decoupling |
| Pin 9 | MODE — Mode select (forced continuous or Burst Mode operation) |
| Pin 10 | RT — Timing resistor to program switching frequency |
| Pin 11 | FB — Feedback input for output voltage programming (0.5V reference) |
| Pin 12 | RUN — Run/enable input (active high) |
Typical Applications
LTC3309AHV#TRMPBF is suitable for 6 applications: FPGA / ASIC Point-of-Load Power, Automotive Infotainment and ADAS Power, Battery-Powered Portable and Wearable Devices, Distributed 5V Bus Regulation in Industrial Modules, Server / Communications Point-of-Load Conversion, Medical Imaging and Diagnostic Equipment.
FPGA / ASIC Point-of-Load Power
The LTC3309AHV delivers up to 6A at 0.5V to 3.3V from a 3.3V or 5V rail, making it ideal for core and I/O voltage rails of FPGAs, ASICs, and high-speed processors. Its 1MHz to 3MHz programmable switching frequency lets you size the output LC for fast load-step response demanded by modern compute ICs. Silent Switcher 2 architecture keeps radiated EMI below CISPR 25 thresholds, which is critical when the converter sits next to GHz-speed transceivers on the same PCB. Compared to a discrete buck, the integrated MOSFETs shrink the solution to roughly 25 mm squared, freeing board space for memory and routing.
Recommended
Automotive Infotainment and ADAS Power
The LTC3309AHV#WTRMPBF and LTC3309AJV-7#TRMPBF are AEC-Q100 qualified variants in the same 2mm x 2mm LQFN package, making them drop-in replacements for ADAS and infotainment rails powered by the automotive 5V bus. Silent Switcher 2 architecture lets the part meet CISPR 25 Class 5 EMI without complex shielding, which is essential when the converter is placed next to RF receivers and CAN-FD transceivers. The wide 2.25V to 5.5V VIN range also covers cold-crank and load-dump transients common in 12V automotive systems. 6A continuous output supports image processors and radar MMIC supply rails.
Recommended
Battery-Powered Portable and Wearable Devices
With 1.2 mA quiescent current and a 2.25V minimum VIN, the LTC3309AHV operates directly from a single-cell Li-ion battery (3.0V to 4.2V) without a boost pre-regulator. Its high peak efficiency and Burst Mode operation extend battery life in standby, while the 6A peak capability drives display backlights, haptic drivers, and small SoCs from the same rail. The 2mm x 2mm LQFN footprint fits inside wearable form factors where PCB area is at a premium. Designers can pair it with the LT8620EMSE or LT8640EUDC for additional rails in the same system.
Recommended
Distributed 5V Bus Regulation in Industrial Modules
Industrial PLCs, distributed I/O modules, and factory-automation controllers often carry a 5V bus that needs to be stepped down to 3.3V, 2.5V, 1.8V, or 1.2V for I/O isolation, sensor conditioning, and microcontrollers. The LTC3309AHV accepts 5V input directly and programs the output down to 0.5V, eliminating external level shifters and intermediate regulators. Silent Switcher 2 keeps the converter quiet enough to power precision ADCs and instrumentation amplifiers on the same PCB. Its industrial temperature range supports factory-floor and outdoor cabinet installations.
Recommended
Server / Communications Point-of-Load Conversion
In communications line cards and small-cell base stations, the LTC3309AHV sits downstream of a 5V intermediate bus and produces 1.0V to 3.3V rails for SerDes PHYs, FPGAs, and signal processors. Its peak current-mode control provides cycle-by-cycle current limiting essential for hot-swap and fault-tolerant architectures. The 1MHz to 3MHz switching range lets designers pick a fundamental frequency that avoids sensitive RF bands in the same chassis. The 2mm x 2mm LQFN footprint enables high power density on densely populated line cards.
Recommended
Medical Imaging and Diagnostic Equipment
Ultrasound probes, patient monitors, and portable diagnostic devices need a compact, low-EMI 6A point-of-load converter to power DSPs, image sensors, and analog front ends. The LTC3309AHV's Silent Switcher architecture keeps switching noise below the sensitive ultrasound band, while the small LQFN package allows the supply to be placed inside the probe handle. Programmable switching up to 3MHz supports small ceramic output capacitors that survive high-humidity autoclave cycles better than electrolytics. Pair it with a low-noise LDO such as the LP5900TLX-1.8 for the analog front-end rail.
Recommended
Recommended Products Summary
Engineering reference data for LTC3309AHV#TRMPBF — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | LTC3309AIV#TRMPBF | LTC3309AHV#TRPBF | LTC3309AHV#WTRMPBF | LTC3309AJV-7#TRMPBF | LTC3309AMPV#TRPBF |
|---|---|---|---|---|---|---|
| Package | 12-pin LQFN (2mm x 2mm) | 12-pin LQFN (2mm x 2mm) - same | 12-pin LQFN (2mm x 2mm) - same | 12-pin LQFN (2mm x 2mm) - same | 12-pin LQFN (2mm x 2mm) - same | 12-pin LQFN (2mm x 2mm) - same |
| Brand | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices |
| Input Voltage Range | 2.25V to 5.5V | 2.25V to 5.5V | 2.25V to 5.5V | 2.25V to 5.5V | 2.25V to 5.5V | 2.25V to 5.5V |
| Output Voltage Range | 0.5V to 5.5V | 0.5V to 5.5V | 0.5V to 5.5V | 0.5V to 5.5V | 0.5V to 5.5V | 0.5V to 5.5V |
| Maximum Output Current | 6 A | 6 A | 6 A | 6 A | 6 A | 6 A |
| Switching Frequency Range | 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 | 1 MHz to 3 MHz |
| Temperature Grade | HV (high-VIN, extended) | I (industrial) | HV (high-VIN, extended) | HV + AEC-Q100 automotive (wettable flanks) | JV (AEC-Q100 automotive) | MPV (military product) |
| Automotive Qualified | No (HV grade only) | No | No | Yes (AEC-Q100) | Yes (AEC-Q100) | No (military only) |
| Architecture | Silent Switcher 2 | Silent Switcher 2 | Silent Switcher 2 | Silent Switcher 2 | Silent Switcher 2 | Silent Switcher 2 |
Key Differentiators
- Industry-smallest 6A synchronous buck in 2mm x 2mm LQFN (vs LTC3309AHV#WTRMPBF (same package, AEC-Q100 grade))
- Silent Switcher 2 architecture for CISPR 25 EMI compliance (vs LTC3309AJV-7#TRMPBF (AEC-Q100 automotive))
- Programmable 1MHz to 3MHz switching frequency (vs LTC3309AIV#TRMPBF (industrial temperature grade))
Design Notes
Both VIN pins (3 and 8) each require a local ceramic decoupling capacitor placed as close as possible to the IC, with the capacitor ground terminal soldered directly to the PGND copper pour on the top layer near PGND pins 4 and 7. According to the LTC3309A datasheet layout guidelines, minimizing the high-di/dt AC loop area between VIN, the internal MOSFETs, and PGND is the single most important EMI control action - this is what makes Silent Switcher 2 actually silent. Use a solid PGND copper island on the top layer under the IC and stitch it with multiple vias to the inner ground plane.
Estimated: at VIN = 5V, VOUT = 3.3V, IOUT = 6A, assuming 90% efficiency, total power dissipation is ~0.67W, which the 2mm x 2mm LQFN with exposed pad dissipates adequately on 1 square inch of 2oz copper. However, at VIN = 5V, VOUT = 0.9V, IOUT = 6A, efficiency drops to ~75% and dissipation rises to ~1.5W; at this operating point the junction temperature must be calculated against the actual board copper area using the datasheet theta-JA curves. Keep the SW node trace short and wide, and avoid thermal coupling to analog circuitry placed nearby.
Do not exceed the absolute maximum VIN of 6V; transients above this will damage the internal MOSFETs. The RT resistor value must be chosen with the correct range for the desired switching frequency - per the LTC3309A datasheet the RT resistor sets fSW between 1MHz and 3MHz. Also, do not leave the BST pin floating; a small ceramic capacitor between BST and SW (typically 100nF) is required to drive the high-side FET. Finally, when measuring efficiency use Kelvin-only testing (separate VIN and VOUT sense leads) to avoid including copper losses in the calculation.
Route the FB trace away from the SW node and BST node to avoid noise coupling into the feedback loop. Keep the MODE pin trace short and tie it to VIN (for forced continuous) or GND (for Burst Mode operation) directly at the pin. Place the output inductor and output capacitors close to the IC, with the inductor oriented to minimize coupling to the FB trace. If the design uses a 2-layer PCB, dedicate the bottom layer to PGND with no signal traces crossing the SW loop; this preserves Silent Switcher EMI performance on a lower-cost stackup.
Compliance Information
RoHS compliant per DigiKey listing. Lead-free reflow profile per JEDEC J-STD-020. Choose LTC3309AHV#WTRMPBF or LTC3309AJV-7#TRMPBF for AEC-Q100 applications; the standard LTC3309AHV#TRMPBF is not AEC-Q100 qualified.
