描述 Description

The HM1468 is a single phase, constant on time, synchronous PWM controller, which drives N‐channel MOSFETs. The HM1468 steps down high voltage to generate low‐voltage chipset or RAM supplies in notebook computers.

The HM1468 provides excellent transient response and accurate DC voltage output in either PFM or PWM Mode. In Pulse Frequency Mode (PFM), the HM1468 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 HM1468 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 HM1468 has a 1 ms 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.

The HM1468 is available in 10 pin TDFN 3x3 package.

特性 Features

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

● 0.7V Reference Voltage

● ±1 Accuracy Over‐Temperature

● Operates from an Input Battery Voltage Range of +1.8V to +32V

● Power‐On‐Reset Monitoring on VCC Pin

● Excellent Line and Load Transient Responses

● PFM Mode for Increased Light Load Efficiency

● Selectable PWM Frequency from 4 Preset Values

● Integrated MOSFET Drivers

● Integrated Bootstrap Forward P‐CH MOSFET

● Adjustable Integrated Soft‐Start and Soft‐Stop

● Selectable Forced PWM or Automatic PFM/PWM Mode

● Power Good Monitoring

● 70 Under‐Voltage Protection

● 125 Over‐Voltage Protection

● Adjustable Current‐Limit Protection

● Using Sense Low‐Side MOSFET’s RDS(ON)

● Over‐Temperature Protection

● Auto Rework from Protection Mode

● TDFN‐10 3x3 Package

● Lead Free and Green Devices Available (RoHS Compliant)

Applications

● Notebook

● Table PC

● Hand‐Held Portable

● AIO PC

● LCD Monitor / TV

● Battery Charger

● ADSL Modem

● Telecom / Networking Equipment