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Texas Instruments LM5168FDDAR
- Part No.:
- LM5168FDDAR
- Manufacturer:
- Texas Instruments
- Package:
- 8-PowerSOIC (0.154", 3.90mm Width)
- Datasheet:
-
LM5168FDDAR.pdf
- Description:
- IC REG BUCK FLYBACK ADJ 8SOPWR
- Quantity:
- Payment:
- Shipping:
Inventory:1,972
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Product details
Overview
LM5168FDDAR from Texas Instruments is a 0.3A, FPWM-mode synchronous step-down DC/DC converter with Fly-Buck™ capability, designed for wide-input industrial and battery-pack applications. It operates from 6V to 115V input, integrates 1.9Ω high-side and 0.71Ω low-side NFETs, features 50ns minimum on/off times, and delivers regulated output with COT control architecture - used in e-bike battery packs and isolated auxiliary rails.
For engineers reviewing the LM5168FDDAR datasheet, LM5168FDDAR pinout, LM5168FDDAR application, or LM5168FDDAR equivalent, key selection criteria include its 120V absolute maximum rating, hiccup-mode overcurrent protection, FPWM operation enabling isolated Fly-Buck topologies, and SOIC PowerPAD-8 package compatibility with thermal pad grounding.
Technical Context
The LM5168FDDAR implements constant-on-time (COT) control with VIN feed-forward to maintain quasi-fixed switching frequency across 6–115V input range. Its FPWM mode enforces continuous conduction across all loads, enabling stable isolated Fly-Buck operation with transformer-coupled secondary outputs.
It integrates both high-side (1.9Ω RDSON) and low-side (0.71Ω RDSON) NFETs, uses internal 1.2V reference and open-drain PGOOD indicator, and applies smart peak/valley current limiting (0.42A hiccup) with thermal shutdown at 175°C and 10°C hysteresis.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 6 V to 115 V - supports direct step-down from 48V/60V/96V battery stacks without pre-regulation |
| Output Current | 0.3 A - sufficient for low-power isolated rails or bias supplies in industrial controllers |
| Switching Frequency | 100 kHz to 1 MHz - adjustable via RT resistor; enables compact magnetics and EMI optimization |
| Min On/Off Time | 50 ns - allows >20:1 step-down ratios (e.g., 48V → 2.5V) and near-100% duty cycle at low VIN |
| Quiescent Current | 3 µA shutdown / <10 µA auto mode - preserves battery life in always-on e-scooter subsystems |
| Overcurrent Protection | Hiccup mode at 0.42 A peak - limits average fault current to ~0.3 A while enabling automatic recovery |
| Junction Temp Range | –40°C to +150°C - rated for under-hood or enclosed industrial environments without derating |
Pinout & Package
LM5168FDDAR is housed in an 8-pin SOIC PowerPAD™ package (DDA), featuring exposed thermal pad (EP) soldered to GND for enhanced thermal dissipation. Pin pitch is 1.27 mm to support high-voltage creepage.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 GND | Ground reference | Primary return path for internal circuits and thermal pad connection point |
| 2 VIN | Power input | Connects directly to 6–115V supply; powers high-side FET and internal VCC regulator |
| 3 EN/UVLO | Enable & UVLO control | 1.5V enable threshold; 1.1V standby entry; enables programmable input undervoltage lockout |
| 4 RT | On-time programming | Resistor-to-GND sets COT pulse width; determines switching frequency in CCM |
| 5 FB | Voltage feedback | Compares output against 1.2V internal reference; requires ≥20mV ripple for COT stability |
| 6 PGOOD | Power-good indicator | Open-drain output signaling valid regulation; requires external 10–100kΩ pull-up |
| 7 BST | Bootstrap supply | Connects 2.2nF X7R capacitor to SW; biases high-side gate driver during switching |
| 8 SW | Switching node | Internal connection between high-side drain and low-side source; drives external inductor |
Key Features
| Feature | Design Value |
|---|---|
| FPWM operation | Maintains CCM at all loads - essential for stable isolated Fly-Buck converter performance |
| Integrated power FETs | 1.9Ω HS + 0.71Ω LS NFETs - eliminates external MOSFETs and drivers, reducing BOM count by ≥4 components |
| 50ns min on/off time | Enables 48V→3.3V conversion in single stage - avoids cascaded regulators and improves efficiency |
| Hiccup overcurrent | 0.42A peak limit with automatic restart - protects against sustained shorts without latch-off |
| Thermal shutdown | 175°C trip with 10°C hysteresis - prevents permanent damage during overload or poor heatsinking |
Applications
| Industrial Battery Pack Monitoring | E-Bike Auxiliary Power Supply |
|---|---|
|
Use Scenario: Real-time cell voltage sensing and MCU supervision in 12–20S Li-ion battery packs. IC Role / Device Role / Timing Role: Primary buck regulator generating 3.3V rail for microcontroller, ADC, and CAN transceiver. Use Value: 6–115V input range accommodates full pack voltage swing (e.g., 42V–58V); 0.3A output supports low-power telemetry without external LDO. |
Use Scenario: Isolated 5V/12V auxiliary supply for display, lighting, and brake controller in e-bike main board. IC Role / Device Role / Timing Role: Fly-Buck™ converter providing galvanically isolated secondary output via coupled inductor. Use Value: FPWM mode ensures CCM operation across load range - critical for stable isolation and minimal cross-regulation. |
| Communications Brick Module | Smart Grid Sensor Node |
|
Use Scenario: Secondary bias rail generation inside 48V telecom power brick for fan control and status LEDs. IC Role / Device Role / Timing Role: Non-isolated buck converter stepping 48V down to 5V/12V for peripheral circuitry. Use Value: 50ns min on-time supports direct 48V→5V conversion; SOIC PowerPAD enables 22°C/W thermal resistance on 49 cm² copper. |
Use Scenario: Powering RF module and precision analog front-end in outdoor smart meter sensor nodes. IC Role / Device Role / Timing Role: Input-supervised buck regulator with EN/UVLO monitoring grid voltage dips below 6V. Use Value: 3µA shutdown IQ extends battery backup life; –40°C to +150°C rating ensures reliability in uncontrolled enclosures. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous buck converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM5168PDDAR | Auto mode (PFM/diode emulation) instead of FPWM; hiccup disabled; 0.42A no-hiccup current limit | Better light-load efficiency but cannot support Fly-Buck isolation; unsuitable for transformer-coupled outputs | Select LM5168PDDAR only when isolated auxiliary rails are not required and ultra-low IQ (<10µA) is prioritized. |
| LM5164FDDAR | Higher 1.5A output; same FPWM mode and 120V abs max; different current limit (1.2A hiccup) | Supports higher-power isolated rails or dual-output Fly-Buck designs; larger thermal footprint required | Choose LM5164FDDAR when >0.3A secondary output is needed - retains identical pinout and layout compatibility. |
Compared with LM5168FDDAR, LM5168PDDAR trades Fly-Buck capability for superior light-load efficiency, while LM5164FDDAR scales output current without changing interface or isolation topology - enabling drop-in power upgrades in existing Fly-Buck designs.
Availability
LM5168FDDAR is available at Aetrix Electronics and suitable for industrial battery packs, e-bike auxiliary power supplies, and communications brick modules requiring stable component supply across extended temperature and high-voltage operating conditions.
Supply support for LM5168FDDAR 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
Texas Instruments is a global semiconductor leader delivering analog, embedded processing, and connectivity solutions for industrial, automotive, and communications markets.
The LM516x family was developed to simplify high-input-voltage DC/DC conversion in rugged battery-powered systems - emphasizing integration, wide VIN tolerance, and Fly-Buck™ isolation capability for space-constrained applications.
FAQ
What is the absolute maximum input voltage rating for LM5168FDDAR?
The LM5168FDDAR has an absolute maximum input voltage rating of 120 V on the VIN pin. This allows robust operation in high-cell-count battery systems (e.g., 20S Li-ion ≈ 84V max) with margin for transient surges. Operation above 115 V is outside recommended conditions and may reduce reliability or lifetime.
Does LM5168FDDAR support isolated Fly-Buck™ converter topologies?
Yes, LM5168FDDAR supports Fly-Buck™ operation because it is factory-configured for FPWM mode, which maintains continuous conduction across all load conditions. This ensures stable regulation of both primary and transformer-coupled secondary outputs - a requirement not met by auto-mode variants like LM5168PDDAR.
What is the purpose of the RT pin on LM5168FDDAR?
The RT pin on LM5168FDDAR sets the constant on-time (COT) pulse width via an external resistor to GND. It inversely scales with VIN to maintain quasi-fixed switching frequency in CCM. For example, a 75 kΩ RT resistor yields ~5 µs on-time at 6 V input, enabling precise frequency tuning between 100 kHz and 1 MHz.
How does the hiccup overcurrent protection work in LM5168FDDAR?
LM5168FDDAR triggers hiccup protection when high-side peak current exceeds 0.42 A (typical). The device disables switching for 64 ms, then attempts restart. If fault persists, it repeats the cycle - limiting average power dissipation and preventing thermal runaway during sustained short circuits or overload conditions.
Can LM5168FDDAR operate with input voltage as low as 6 V?
Yes, LM5168FDDAR is fully operational down to 6 V input, supporting near-100% duty cycle operation. At low VIN, it enters frequency fold-back mode after reaching minimum off-time (50 ns), maintaining regulation even during brownout events common in battery discharge profiles or unregulated industrial supplies.
LM5168FDDAR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 8-PowerSOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Function:
- Step-Down, Step-Up/Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck, Flyback
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 6V
- Voltage - Input (Max):
- 120V
- Voltage - Output (Min/Fixed):
- 1.2V
- Voltage - Output (Max):
- 120V
- Current - Output:
- 300mA
- Frequency - Switching:
- 100kHz ~ 1MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SO PowerPad
LM5168FDDAR FAQ
1.How can I place an order for LM5168FDDAR through Aetrix?
Please submit a Request for Quotation (RFQ) for LM5168FDDAR 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 LM5168FDDAR reliable?
The price and inventory of LM5168FDDAR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM5168FDDAR is usually 5 days.
3.What payment methods are accepted for LM5168FDDAR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM5168FDDAR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM5168FDDAR?
LM5168FDDAR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM5168FDDAR 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 LM5168FDDAR?
For technical support, including LM5168FDDAR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM5168FDDAR requirements.
6.How does Aetrix verify that LM5168FDDAR is sourced from the original manufacturer or authorized distributors?
All LM5168FDDAR 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 LM5168FDDAR meets industry standards.
7.What is the process for return or replacement of LM5168FDDAR?
All LM5168FDDAR units undergo pre-shipment inspection (PSI). If there is an issue with LM5168FDDAR, 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 LM5168FDDAR part is unused and in its original packaging.
Return procedure for LM5168FDDAR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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