TD1728 High-Performance PWM Controller

(DATASHEET)

The TD1728 is a single-phase, constant-on-time, synchronous PWM controller, which drives N-channel MOSFETs. The TD1728 steps down high voltage to generate low-voltage chipset or RAM supplies in notebook computers.

The TD1728 provides excellent transient response and accurate DC voltage output in either PFM or PWM Mode. In Pulse Frequency Mode (PFM), the TD1728 provides very high efficiency over light to heavy loads with loading- modulated switching frequencies. In PWM Mode, the converter works nearly at constant frequency for low-noise requirements.

The TD1728 is equipped with accurate positive current- limit, output under-voltage, and output over-voltage protections, perfect for NB applications. The Power-On- Reset function monitors the voltage on VCC to prevent wrong operation during power-on. The TD1728 has a 1ms digital soft-start and built-in an integrated output discharge method for soft-stop. An internal integrated soft-start ramps up the output voltage with programmable slew rate to reduce the start-up current. A soft-stop function actively discharges the output capacitors with controlled reverse inductor current.

Features

l  Adjustable Output Voltage from +0.7V to +5.5V

Applications

l  Notebook

l  Table PC

l  Hand-Held Portable

l  AIO PC

l  LCD Monitor / TV

l  Battery Charger

l  ADSL Modem

Typical Application Circuit