The LM27241 is a single-channel high-voltage synchronous buck regulator controller from Texas Instruments. It features a 200kHz-500kHz operating frequency and is ideal for battery-powered applications such as laptops. The LM27241 uses N-channel field-effect transistors and does not require an external resistor for current limiting. It also features line feedforward and a unique adaptive duty cycle clamping technique to improve the response to input transients. The input voltage range is 5.5V-28V, and the output voltage can be adjusted down to 0.6V. The LM27241 also has soft-start, undervoltage lockout, power good signal, and enable control functions.
The LM27241 is an adjustable 200 kHz‑500 kHz single‑channel voltage‑mode synchronous buck regulator controller designed for battery‑powered applications such as laptops. It uses N‑channel FETs for both the upper and lower switches, features line feed‑forward, lossless bottom‑side current sensing, adaptive duty‑cycle clamping, and selectable Forced‑PWM or Pulse‑skip modes.
The device includes a comprehensive set of supervisory functions: soft‑start, power‑good flag, under‑ and over‑voltage protection, under‑voltage lockout, soft‑shutdown, and an enable pin. Detailed pin descriptions, absolute maximum ratings, and electrical characteristics are provided for designers.
| Input voltage range | 5.5 V to 28 V |
|---|---|
| Switching frequency range | 200 kHz to 500 kHz (adjustable) |
| Output voltage range | down to 0.6 V |
| Reference voltage accuracy | ±1.5 % |
| Soft‑start pin typical capacitance | 0.1 pF |
EN is the IC enable pin; pulling it high enables the output with a soft‑start sequence, while pulling it low disables the output and triggers a power‑good low condition.
The switching frequency is set by a resistor connected between the FREQ pin and ground; a 22.1 kΩ resistor gives a nominal 300 kHz frequency.
The controller provides soft‑start, power‑good flag, under‑voltage and over‑voltage protection, under‑voltage lockout, soft‑shutdown, and an enable function.
The ILIM pin sources a typical current of 62 µA when the bottom FET is on.