LM5117MHX/NOPB - 5.5-65V Sync Buck Controller | TI
MPN: LM5117MHX/NOPB ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $3.42 | $3.42 |
| 10 | $3.08 | $30.80 |
| 100 | $2.74 | $274.00 |
| 500 | $2.47 | $1,235.00 |
| 1,000 | $2.2 | $2,200.00 |
LM5117MHX/NOPB Overview
A synchronous buck controller is a type of DC-DC switching regulator that uses external MOSFETs to step down a higher input voltage to a lower output voltage with high efficiency. Unlike linear regulators, buck controllers achieve efficiency often above 90% by switching power devices rather than dissipating excess energy as heat. The LM5117 employs current mode control with an emulated current ramp, providing inherent line feed-forward, cycle-by-cycle current limiting, and ease of loop compensation. This control method ensures stable operation across a wide range of input voltages and load conditions.
Key features of the LM5117 include an analog current monitor output, which allows precise monitoring of the output current for system protection and telemetry. The device also features a wide 5.5V to 65V input range, programmable output voltage, and a switching frequency that can be set from 50kHz to 750kHz via an external resistor. The controller supports both high-side and low-side external N-channel MOSFETs, enabling designs with high efficiency and flexible power stage configurations.
Technically, the LM5117 integrates a high-voltage startup regulator, a precision 1.5V reference, and a robust gate drive capability. The emulated current ramp eliminates the need for a sense resistor in the high-current path, reducing power loss and improving efficiency. The device also includes features such as soft-start, hiccup mode overcurrent protection, and thermal shutdown, enhancing system reliability.
Typical applications include industrial power supplies, automotive infotainment and body electronics, telecom and networking equipment, and general-purpose step-down converters. The wide input range and high efficiency make it ideal for systems that must operate from 12V, 24V, or 48V rails with varying input transients.
When designing with the LM5117, ensure proper PCB layout with short, low-inductance paths for the high-current switching loops. The exposed pad must be soldered to a copper area for adequate thermal performance. Additionally, select the external MOSFETs and output inductor based on the required output current and efficiency targets.
Drop-in alternatives for LM5117MHX/NOPB — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with LM5117MHX/NOPB (same form factor and footprint) — differing in Control Method, Input Voltage Range, Package, RoHS Status, Switching Frequency.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
LM5117PMHX/NOPB
✅ Drop-In📋 Reference alternative (not in catalog)
LM5117QPMH/NOPB
✅ Drop-In📋 Reference alternative (not in catalog)
LM5116MHX/NOPB
✅ Drop-In📋 Reference alternative (not in catalog)
LM5116MH/NOPB
✅ Drop-In📋 Reference alternative (not in catalog)
LM25117MHX/NOPB
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
LM5117MHX/NOPB Maximum Ratings & Electrical Characteristics
| Input Voltage Range | 5.5V to 65V |
| Output Voltage Range | 1.5V to 80V |
| Output Current | External MOSFETs (up to 20A) |
| Switching Frequency | 50kHz to 750kHz |
| Control Method | Current Mode with Emulated Ramp |
| Number of Outputs | 1 |
| Package | HTSSOP-20 (PWP) |
| Operating Temperature Range | -40°C to +125°C |
| Analog Current Monitor | Yes |
| Soft-Start | Yes |
| Overcurrent Protection | Hiccup Mode |
| Thermal Shutdown | Yes |
| Reference Voltage | 1.5V |
| RoHS Status | Compliant |
| Mounting Type | Surface Mount |
LM5117MHX/NOPB Pin Configuration
| Pin 1 | VIN — Input supply voltage |
| Pin 2 | VCC — Internal regulator output |
| Pin 3 | VCCX — External VCC input |
| Pin 4 | RT — Switching frequency set resistor |
| Pin 5 | RAMP — Emulated ramp set |
| Pin 6 | SS — Soft-start timing |
| Pin 7 | COMP — Error amplifier output |
| Pin 8 | FB — Feedback input |
| Pin 9 | CS — Current sense input |
| Pin 10 | CM — Current monitor output |
| Pin 11 | AGND — Analog ground |
| Pin 12 | PGND — Power ground |
| Pin 13 | HO — High-side gate drive |
| Pin 14 | HB — High-side bootstrap |
| Pin 15 | SW — Switch node |
| Pin 16 | LO — Low-side gate drive |
| Pin 17 | VCC — Internal regulator output |
| Pin 18 | EN — Enable input |
| Pin 19 | UVLO — Under-voltage lockout set |
| Pin 20 | PAD — Exposed thermal pad |
Typical Applications
LM5117MHX/NOPB is suitable for 6 applications: Industrial Power Supplies, Automotive Infotainment, Telecom and Networking Equipment, General-Purpose Step-Down Converters, Battery-Powered Systems, LED Lighting Drivers.
Industrial Power Supplies
The LM5117MHX/NOPB is ideal for industrial power supplies due to its wide 5.5V to 65V input range and high efficiency. It can step down from 24V or 48V rails to lower voltages with minimal heat dissipation. The analog current monitor enables precise load monitoring for system protection. With switching frequencies up to 750kHz, it allows compact magnetics, reducing board space in industrial control systems.
Recommended
Automotive Infotainment
In automotive infotainment systems, the LM5117MHX/NOPB provides a robust power solution from the 12V battery or 24V truck systems. Its wide input range handles load dumps and cold crank transients. The -40°C to +125°C operating range ensures reliability in harsh environments. The current monitor can be used for diagnostic functions, detecting overcurrent conditions in audio amplifiers or displays.
Recommended
Telecom and Networking Equipment
Telecom equipment often operates from 48V backplane rails. The LM5117MHX/NOPB efficiently steps down 48V to 3.3V or 5V for logic and interface circuits. Its current mode control provides excellent line and load transient response, crucial for maintaining stable voltages during data bursts. The high switching frequency reduces the size of output filters, saving valuable board space in dense networking hardware.
Recommended
General-Purpose Step-Down Converters
The LM5117MHX/NOPB serves as a flexible building block for general-purpose step-down converters. Designers can configure output voltage from 1.5V to 80V and output current from a few amps to over 20A by selecting appropriate external components. The emulated current ramp eliminates the need for a sense resistor, simplifying layout and improving efficiency. This makes it suitable for a wide range of prototyping and production designs.
Recommended
Battery-Powered Systems
In battery-powered systems, the LM5117MHX/NOPB efficiently regulates voltage from a battery that can vary from 5.5V to 65V. Its high efficiency extends battery life, and the low quiescent current in standby modes helps meet energy regulations. The analog current monitor can be used for fuel gauging or to detect low battery conditions. The wide input range accommodates multiple battery cells in series.
Recommended
LED Lighting Drivers
The LM5117MHX/NOPB can be configured as a constant-current LED driver by using the analog current monitor to sense and regulate LED current. Its wide input range supports various LED string voltages, and the high switching frequency allows small inductors, reducing fixture size. The hiccup mode overcurrent protection prevents damage during LED faults. This makes it suitable for industrial and automotive LED lighting.
Recommended
Recommended Products Summary
Engineering reference data for LM5117MHX/NOPB — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | LM5117PMHX/NOPB | LM5117QPMH/NOPB | LM5116MHX/NOPB |
|---|---|---|---|---|
| Package | HTSSOP-20 (PWP) | HTSSOP-20 (PWP) | HTSSOP-20 (PWP) | HTSSOP-20 (PWP) |
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments |
| Input Voltage Range | 5.5V to 65V | 5.5V to 65V | 5.5V to 65V | 5.5V to 65V |
| Switching Frequency | 50kHz to 750kHz | 50kHz to 750kHz | 50kHz to 750kHz | 50kHz to 750kHz |
| Analog Current Monitor | Yes | Yes | Yes | No |
| Automotive Grade | No | No | Yes (AEC-Q100) | No |
| Operating Temperature Range | -40°C to +125°C | -40°C to +125°C | -40°C to +125°C | -40°C to +125°C |
| Control Method | Current Mode with Emulated Ramp | Current Mode with Emulated Ramp | Current Mode with Emulated Ramp | Current Mode with Emulated Ramp |
Key Differentiators
- Analog current monitor output (vs LM5116MHX/NOPB)
- Wide input voltage range up to 65V (vs LM5116MHX/NOPB)
- Automotive-grade variant available (vs LM5117PMHX/NOPB)
Design Notes
For optimal performance, place the input capacitor, high-side MOSFET, low-side MOSFET, and output inductor in a tight loop to minimize parasitic inductance. The switch node (SW) should have a small copper area to reduce EMI. Use a solid ground plane and connect the exposed pad (PAD) to the ground plane with multiple vias for thermal relief.
The LM5117MHX/NOPB itself dissipates minimal power, but the external MOSFETs and inductor generate heat. Ensure adequate copper area and airflow for these components. The exposed pad must be soldered to a large copper pour to keep the controller cool. For high-current designs, consider using a heatsink on the MOSFETs.
Avoid using a sense resistor in the high-current path; the emulated current ramp eliminates this need. Ensure the bootstrap capacitor (HB) is placed close to the HO and SW pins. Do not exceed the absolute maximum ratings on VIN or SW. Use a proper UVLO resistor divider to prevent operation below the minimum input voltage.
Compliance Information
RoHS compliant per TI product page. Not AEC-Q100 qualified; use LM5117QPMH/NOPB for automotive.
