LGS5145
Asynchronous Buck ConverterThe LGS5145 is a asynchronous buck converter from Legend-Si. View the full LGS5145 datasheet below including key specifications, pinout.
Manufacturer
Legend-Si
Category
Asynchronous Buck Converter
Package
SOT23-6
Key Specifications
| Parameter | Value |
|---|---|
| Output Current | 1A (continuous) |
| Package Height | 1.45mm |
| Soft-Start Time | 2.4 ms (typical) |
| Feedback Voltage | 0.812V (typical) |
| SW Current Limit | 1.2 A (typical) |
| Shutdown Current | 4 µA (typical) |
| Quiescent Current | 150 µA (typical) |
| Input Voltage Range | 4.5V to 55V |
| Operating Frequency | 1.2 MHz (fixed) |
| ESD Protection (HBM) | 3000V |
| High-Side MOSFET R DS(ON) | 600 mΩ (typical) |
| Operating Junction Temperature Range | -40°C to +125°C |
Overview
Part: LGS5145 — Legend-Si
Type: Asynchronous Buck Converter
Description: 4.5–55 V input, 1 A asynchronous buck converter with internal switching, 1.2 MHz fixed operating frequency, and SKIP mode for high light-load efficiency.
Operating Conditions:
- Supply voltage: 5–55 V
- Operating temperature: -40 to +105 °C
- Output current: At least 1000 mA continuous
Absolute Maximum Ratings:
- Max supply voltage (VIN, SW, EN): 60 V
- Max storage temperature: 150 °C
- Max operating temperature: 105 °C
Key Specs:
- Recommended Input Voltage Range: 5–55 V
- Static operating current (IQ): 150 μA (typical, no load, VIN=12V)
- Shutdown Current (IS): 4 μA (typical, EN=0, VIN=12V)
- BUCK upper tube RDSON: 600 mΩ (typical, TJ=25°C)
- FB Feedback Voltage (VFB): 0.812 V (typical, TJ=25°C)
- Switching frequency (FSW): 1.2 MHz (typical, TJ=25°C)
- SW Current Limit (Peak): 1.2 A (typical, TJ=25°C)
- Soft start time (tSS): 2.4 mS (typical, TJ=25°C)
Features:
- SKIP mode for high light load efficiency
- 1.2 MHz fixed operating frequency
- Integrated 600 mΩ high-side power MOSFET
- Internal compensation
- Soft-start
- Thermal shutdown protection
- UVLO undervoltage lockout
- Gate driver undervoltage lockout
- Maximum duty cycle limit timer
- Smart current limit shutdown timer
- Output short-circuit protection with Frequency FOLD-BACK mode
- ESD protected to 3000V (HBM)
Applications:
- 42V automotive power bus range
Package:
- SOT23-6
Pin Configuration
LGS5145 Pinout – SOT-23-6 Package
| Pin Number | Pin Name | Type | Description |
|---|---|---|---|
| 1 | BST | P | Bootstrap gate driver power supply. Connect a high-quality 100nF ceramic capacitor between BST and SW to bias the internal high-voltage side gate driver. Capacitor withstand voltage ≥16V recommended. |
| 2 | GND | P | Ground pin |
| 3 | FB | I | Feedback Input Pin. Connected to external resistor divider. Internal comparator reference voltage: 0.812V |
| 4 | EN | I | Regulator output enable pin. High = enable output; Low/GND = disable output. Internal 100nA weak pull-down. |
| 5 | VIN | P | Regulator power input (4.5V–55V). Bypass with ≥2.2μF ceramic capacitor to GND, placed as close as possible. |
| 6 | SW | O | Internal power switching node. Connect external power inductor, Schottky diode, and bootstrap capacitor (CBST). |
Notes
- EN Pin (Pin 4): Has internal 100nA weak pull-down. For reliable shutdown, use external pull-down resistor or drive with logic signal. Do not leave floating. For automatic startup, connect directly to VIN (Pin 5).
- Bootstrap Capacitor: Use 100nF ceramic (X7R/X5R, ≥16V rated) between BST (Pin 1) and SW (Pin 6).
- Input Capacitor: Use ≥2.2μF ceramic (X7R/X5R) between VIN (Pin 5) and GND (Pin 2), placed as close as possible.
- FB Pin Impedance: High impedance; keep traces short and shielded from SW node noise.
- Soft-Start: Internal ~2.4ms soft-start prevents inrush current and overshoot.
- Thermal Protection: OTP triggers at ~150°C (typical), releases at ~130°C.
- Frequency Foldback: When FB ≤ 0.25V (short-circuit condition), switching frequency reduces to ~1/4 nominal to limit output current.
Typical Application
Figure 5.a Typical application topology for DC-DC buck mode
Ordering Information
| MPN | Package | Temperature Range | Packing |
|---|---|---|---|
| LGS5145 | SOT23-6 | -40°C to +105°C | null |
Data on this page is extracted from publicly available manufacturer datasheets using automated tools including AI. It may contain errors or omissions. Always verify specifications against the official manufacturer datasheet before making design or purchasing decisions. See our Terms of Service. Rights holders can submit a takedown request.
Get structured datasheet data via API
Get started free