3V to 28V Input, Low-Cost, Hysteretic Synchronous Step-Down Controllers

The MAX8576–MAX8579 synchronous PWM buck controllers use a hysteretic voltage-mode control algorithm to achieve a fast transient response without requiring loop compensation. The MAX8576/MAX8577 contain an internal LDO regulator allowing the controllers to function from only one 3V to 28V input supply. The MAX8578/MAX8579 do not contain the internal LDO and require a separate supply to power the IC when the input supply is higher than 5.5V. The MAX8576–MAX8579 output voltages are adjustable from 0.6V to 0.9 x VIN at loads up to 15A.

Nominal switching frequency is programmable over the 200kHz to 500kHz range. High-side MOSFET sensing is used for adjustable hiccup current-limit and short-circuit protection. The MAX8576/MAX8578 can start up into a precharged output without pulling the output voltage down. The MAX8577/MAX8579 have startup output overvoltage protection (OVP), and will pull down a precharged output.

Applications

* AGP and PCI Express® Power Supplies * Graphic-Card Power Supplies * Motherboard Power Supplies * Point-of-Load Power Supplies * Set-Top Boxes

* 3V to 28V Supply Voltage Range

* 1.2% Accurate Over Temperature

* Adjustable Output Voltage Down to 0.6V

* 200kHz to 500kHz Switching Frequency

* Adjustable Temperature-Compensated Hiccup Current Limit

* Lossless Peak Current Sensing

* Monotonic Startup into Prebias Output (MAX8576/MAX8578)

* Startup Overvoltage Protection (MAX8577/MAX8579)

* Enable/Shutdown

* Adjustable Soft-Start