NCP3135MNTXG - 5A Sync Buck Converter 2.9-5.5V | onsemi
MPN: NCP3135MNTXG ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $1.85 | $1.85 |
| 10 | $1.66 | $16.60 |
| 100 | $1.42 | $142.00 |
| 500 | $1.18 | $590.00 |
| 1,000 | $0.96 | $960.00 |
NCP3135MNTXG Overview
A buck (step-down) DC-DC switching converter is a power management IC that efficiently converts a higher DC input voltage to a lower regulated DC output voltage by rapidly switching an internal MOSFET and smoothing the resulting pulsed waveform through an LC filter. Within the power management hierarchy, it sits above linear regulators (LDOs) in efficiency for large VIN/VOUT deltas but below multi-phase VRMs in current capability. Buck converters are the workhorse topology for distributing intermediate bus voltages (5 V, 3.3 V, 1.8 V, 1.2 V) across nearly every digital and mixed-signal system.
The NCP3135MNTXG delivers 5 A continuous / 6 A peak output, operates from 2.9 V to 5.5 V VIN, and adjusts VOUT from 0.6 V to roughly VIN minus dropout. Its selectable FCCM (forced continuous conduction mode) ensures predictable noise/ripple regardless of load, while automatic CCM/DCM mode boosts light-load efficiency by skipping pulses. Internal MOSFETs (high-side + low-side) eliminate external FET selection, and built-in soft-start, power-good, and over-current/thermal protection reduce design risk. The 16-pin QFN exposed pad provides a low thermal resistance path, simplifying board-level thermal management.
The architecture uses adaptive on-time (AOT) control with internal feedback compensation, enabling fast transient response without requiring external RC networks. The 5 V tolerant enable pin and power-good output simplify sequencing in multi-rail systems. By integrating both switches and compensation, the NCP3135 family targets designs where small PCB footprint, high efficiency, and minimal external BOM are critical.
Typical applications include 5 V and 3.3 V point-of-load regulation in networking switches, FPGA/CPLD core and I/O rails, SSD controller power, set-top box and consumer SoC rails, and distributed bus converters in telecom/datacom cards. It is well suited wherever a single 5 V input must be stepped down to a lower logic rail with high efficiency and tight load regulation.
When designing with this device, derate output current based on VIN/VOUT differential and ambient temperature. Ensure the exposed pad is soldered to a sufficient copper pour to keep junction temperature within the SOA. Select input/output ceramic capacitors with low ESR and adequate voltage derating; place the input cap as close as possible to the VIN and GND pins to minimize switching-node ringing.
This page synthesizes distributor pricing, drop-in same-package alternatives, and practical design notes that go beyond the manufacturer datasheet alone.
Drop-in alternatives for NCP3135MNTXG — 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:
NCP3134MNTXG
✅ Drop-In📋 Reference alternative (not in catalog)
NCP3135MNTXG-Q
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
NCP3135MNTXG Maximum Ratings & Electrical Characteristics
| Topology | Synchronous Buck (Step-Down) |
| Input Voltage Range | 2.9 V to 5.5 V |
| Output Voltage Range | 0.6 V to 4.62 V (Adjustable) |
| Continuous Output Current | 5 A |
| Instantaneous Output Current | 6 A (peak) |
| Number of Outputs | 1 |
| Output Type | Adjustable (Positive) |
| Control Mode | FCCM / Automatic CCM/DCM (selectable) |
| Internal MOSFETs | Yes (high-side + low-side integrated) |
| Power Good (PG) Output | Yes |
| Enable Pin | Yes |
| Soft-Start | Internal |
| Operating Temperature Range | -40 C to +85 C (estimated from datasheet industrial grade) |
| Package | 16-pin VFQFN Exposed Pad (QFN-16 EP) |
| Mounting Type | Surface Mount |
| Packaging | Tape & Reel |
| RoHS Status | Compliant (per alldatasheet/FindIC listing) |
| Halogen Free | Compliant (per FindIC cross-reference listing) |
NCP3135MNTXG Pin Configuration
| Pin 1 | VIN — Input supply voltage (2.9 V to 5.5 V) |
| Pin 2 | VIN — Input supply voltage (tie to pin 1) |
| Pin 3 | BST — Bootstrap capacitor for high-side gate drive |
| Pin 4 | SW — Switching node (connected to output inductor) |
| Pin 5 | SW — Switching node (tie to pin 4) |
| Pin 6 | PGND — Power ground (return for low-side FET) |
| Pin 7 | PGND — Power ground (tie to pin 6) |
| Pin 8 | AGND — Analog ground (return for control circuitry) |
| Pin 9 | FB — Feedback input from output resistor divider |
| Pin 10 | COMP — Compensation node (internal compensation - leave open per datasheet) |
| Pin 11 | EN — Enable input (active high) |
| Pin 12 | PG — Power-good open-drain output |
| Pin 13 | VCC — Internal LDO output (bypass with 1 uF ceramic) |
| Pin 14 | FREQ — Frequency select / mode pin (FCCM vs Auto CCM/DCM) |
| Pin 15 | SS — Soft-start (internal - leave open) |
| Pin 16 | POK — Power OK / voltage monitoring (per datasheet, may be tied to PG) |
| Pin EP | EPAD — Exposed thermal pad - solder to PCB ground copper pour |
Typical Applications
NCP3135MNTXG is suitable for 7 applications: Networking Switch / Router Point-of-Load, FPGA / CPLD Core and I/O Rails, SSD / Storage Controller Power, Set-Top Box and Consumer SoC Power, Industrial Distributed Bus Converters, Automotive Infotainment and ADAS Auxiliary Rails, Test and Measurement Equipment.
Networking Switch / Router Point-of-Load
The NCP3135MNTXG steps a 5 V or 3.3 V intermediate bus down to 1.0 V, 1.2 V, or 1.8 V core rails for switch ASICs, FPGAs, and PHY transceivers in enterprise networking equipment. Its 5 A continuous / 6 A peak current covers a single POL domain, and the integrated high-side/low-side MOSFETs plus internal compensation keep the BOM small - critical for dense 1U/2U switch line cards. The selectable FCCM mode produces predictable switching noise, simplifying EMI filter design to meet FCC/CE margins.
Recommended
FPGA / CPLD Core and I/O Rails
The NCP3135MNTXG supplies clean 1.0 V-1.8 V rails to FPGA core, I/O, and auxiliary domains from a 3.3 V or 5 V system rail. Its adaptive on-time control delivers fast transient response - important when an FPGA transitions between configuration and active states, demanding microsecond-scale load steps. The 6 A peak headroom absorbs inrush without tripping OCP, while the power-good output feeds the FPGA's PGOOD input for safe sequencing during configuration bitstream loads.
Recommended
SSD / Storage Controller Power
The NCP3135MNTXG provides the 1.2 V and 3.3 V rails for SSD controllers, DRAM cache, and NAND I/O in client and enterprise SSDs. Its small QFN-16 EP footprint fits the tight SSD PCB, and the 5 A rating covers peak write-current demands of high-end NVMe controllers. Auto CCM/DCM mode boosts light-load efficiency during idle/read states, extending battery life in portable SSDs and reducing thermal dissipation in always-on enterprise drives.
Recommended
Set-Top Box and Consumer SoC Power
The NCP3135MNTXG supplies 1.0 V core and 1.8 V/3.3 V I/O rails for set-top box SoCs, smart-TV main boards, and streaming media devices drawing from a 5 V adapter or USB-PD source. The integrated MOSFETs and minimal external BOM enable low-cost 4-layer consumer designs, while FCCM mode keeps switching ripple well below HDMI clock-jitter thresholds. Soft-start limits inrush at hot-plug events such as HDMI-CEC attach, improving system reliability.
Recommended
Industrial Distributed Bus Converters
The NCP3135MNTXG operates from 24 V industrial buses via an upstream 5 V regulator, providing isolated point-of-load conversion for sensors, motor pre-drivers, and PLC I/O modules. Its wide 2.9-5.5 V input tolerates regulated 5 V supply variation, and the integrated protection features (OCP, OVP, OTP) reduce field failures. The QFN-16 EP package supports hand-solderable rework, important for low-volume industrial product lines.
Recommended
Automotive Infotainment and ADAS Auxiliary Rails
With onsemi's automotive-grade -Q screening, the NCP3135MNTXG family is suitable for auxiliary rails in infotainment head units, ADAS sensor modules, and telematics control units powered from a 5 V regulated bus. The 5 A current and FCCM mode support deterministic EMI behavior required for FM band and CAN coexistence, while the exposed pad provides robust thermal dissipation in the high-ambient-temperature engine-bay or dashboard environment. Always confirm the specific -Q variant against your AEC-Q100 requirements before designing in.
Recommended
Test and Measurement Equipment
The NCP3135MNTXG powers ADCs, DACs, and analog front-ends in bench-top instruments and modular test equipment where low noise and clean power are critical. While the device is not an LDO, its FCCM mode produces predictable switching ripple that can be filtered downstream with a small post-regulator LDO for sub-millivolt noise floors. The exposed pad supports the 5 A continuous rating required to drive multi-channel simultaneous-sampling ADC loads during high-speed acquisition bursts.
Recommended
Recommended Products Summary
Engineering reference data for NCP3135MNTXG — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | NCP3134MNTXG | NCP3135MNTXG-Q |
|---|---|---|---|
| Brand | onsemi | onsemi | onsemi |
| Package | QFN-16 EP (VFQFN-16) | QFN-16 EP - same | QFN-16 EP - same |
| Input Voltage Range | 2.9 V to 5.5 V | 2.9 V to 5.5 V | 2.9 V to 5.5 V |
| Output Voltage Range | 0.6 V to 4.62 V (Adj) | 0.6 V to ~4.62 V (Adj, family variant) | 0.6 V to 4.62 V (Adj) |
| Continuous Output Current | 5 A | 5 A | 5 A |
| Peak Output Current | 6 A | 6 A (family typical) | 6 A |
| Control Mode | FCCM / Auto CCM-DCM | FCCM / Auto CCM-DCM (family variant) | FCCM / Auto CCM-DCM |
| Power Good Output | Yes | Yes | Yes |
| Automotive Grade (-Q) | No (standard MNTXG) | No | Yes (automotive screening) |
Key Differentiators
- FCCM plus selectable auto CCM/DCM mode in a single part (vs NCP3134MNTXG)
- Automotive-grade (-Q) variant available in same footprint (vs NCP3134MNTXG)
- Higher peak current rating vs lower-tier family members (vs NCP3121MNTXG (family sibling))
Design Notes
At VIN=5 V, VOUT=3.3 V, and 5 A continuous load, internal power dissipation is (5 V - 3.3 V) x 5 A = 8.5 W. The 16-pin QFN-EP package dissipates this through the exposed pad; per the onsemi datasheet, the layout should provide a continuous ground copper pour under the EP of at least 1 square inch on the top layer with thermal vias to inner/bottom layers. Without adequate copper, junction temperature will exceed the 125 C limit; derate to ~3 A if no heatsink/copper is feasible.
Place the input ceramic capacitors (typically 22 uF X5R 10 V) within 2 mm of the VIN pins to minimize switching-node ringing. Keep the output inductor and bootstrap capacitor traces short and direct; the SW node is a high-dV/dt node and should be kept away from FB and AGND to avoid noise injection. The AGND and PGND should be tied together at a single point under the EP, not split across the board, per the onsemi evaluation board layout.
Do not exceed the absolute maximum VIN of 6 V (per the datasheet). The 0.6 V internal reference sets the minimum VOUT, so selecting an FB resistor divider that attempts to set VOUT below 0.6 V will result in regulation to 0.6 V (not below). When using FCCM mode, expect a negative inductor current during light loads - do not use a diode-equipped input supply that cannot sink current. Always consult the latest revision of the datasheet before finalizing the design.
The exposed pad is the primary heat path - failure to solder it with sufficient paste coverage (per IPC-A-610) will cause thermal failure under full 5 A load. Use multiple thermal vias (typically 9-16 vias in a 3x3 or 4x4 array, 0.3 mm drill) under the EP to the bottom-layer ground plane. Keep analog (FB, COMP) traces away from SW and BST traces by at least 3 mm to prevent noise injection into the feedback loop.
Compliance Information
RoHS and Halogen-Free compliance per onsemi product listings and FindIC cross-reference. Standard MNTXG part is not AEC-Q100 qualified; onsemi offers an automotive -Q screening variant. Always confirm the specific datasheet revision for the latest compliance status.
