MAX8650

4.5V to 28V Input Current-Mode Step-Down Controller with Adjustable Frequency

Wide Input Voltage Range with Programmable Foldback Current Limit

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Overview

Operates from 4.5V to 28V Supply
1% FB Voltage Accuracy Over Temperature
Adjustable Output Voltage Down to 0.7V or REFIN
Adjustable Switching Frequency or External Synchronization from 200kHz to 1.2MHz
180° Phase-Shifted Clock Output
Adjustable Overcurrent Limit
Adjustable Foldback Current Limit
Adjustable Slope Compensation
Selectable Current-Limit Mode: Latch-Off or Automatic Recovery
Monotonic Output-Voltage Rise at Startup
Output Sources and Sinks Current
Enable Input
Power-OK (POK) Output
Adjustable Soft-Start
Independently Adjustable Overvoltage Protection

The MAX8650 synchronous PWM buck controller operates from a 4.5V to 28V input and generates an adjustable 0.7V to 5.5V output voltage at loads up to 25A.

The MAX8650 uses a peak current-mode control architecture with an adjustable (200kHz to 1.2MHz) constant switching frequency and is externally synchronizable. The IC's current limit uses the inductor's DC resistance to improve efficiency or an external sense resistor for high accuracy. The current-limit threshold is adjusted with an external resistor. Foldback-type current limit can be implemented to reduce the power dissipation in overload or short-circuit conditions. Short-circuit protection is provided based on sensing the current in the low-side MOSFET. A reference input is provided for use with a high-accuracy external reference or for double-data-rate (DDR)-tracking applications.

Monotonic prebiased startup is available for a safe-start in applications where the output capacitor may have an initial charge. This feature prevents the output from pulling low during startup, which is a common characteristic of conventional buck regulators.

A 180° out-of-phase synchronization output is available for synchronizing with another converter.

Applications