The MAX8545/MAX8546/MAX8548 are voltage-mode pulse-width-modulated (PWM), step-down DC-DC controllers ideal for a variety of cost-sensitive applications. They drive low-cost n-channel MOSFETs for both the high-side switch and synchronous rectifier, and require no external current-sense resistor. These devices can supply output voltages as low as 0.8V. The MAX8545/MAX8546/MAX8548 have a wide 2.7V to 28V input range, and do not need any additional bias voltage. The output voltage can be precisely regulated from 0.8V to 0.83 x VIN. These devices can provide efficiency up to 95%. Lossless short-circuit and current-limit protection is provided by monitoring the RDS(ON) of the low-side MOSFET. The MAX8545 and MAX8548 have a current-limit threshold of 320mV, while the MAX8546EUB+TG51 has a current-limit threshold of 165mV. All devices feature foldback-current capability to minimize power dissipation under short-circuit condition. Pulling the COMP/EN pin low with an open-collector or low-capacitance, open-drain device can shut down all devices. The MAX8545/MAX8546EUB+TG51 operate at 300kHz and the MAX8548 operates at 100kHz. The MAX8545/MAX8546/MAX8548 are compatible with low-cost aluminum electrolytic capacitors. Input undervoltage lockout prevents proper operation under power-sag operations to prevent external MOSFETs from overheating. Internal soft-start is included to reduce inrush current. These devices are offered in space-saving 10-pin μMAX packages.
Feature
- 2.7V to 28V Input Range
- Foldback Short-Circuit Protection
- No Additional Bias Supply Needed
- 0.8V to 0.83 x VIN Output
- Up to 95% Efficiency
- Low-Cost External Components
- No Current-Sense Resistor
- All n-Channel MOSFET Design
- Adaptive Gate Drivers Eliminate Shoot-Through
- Lossless Overcurrent and Short-Circuit Protection
- 300kHz Switching Frequency (MAX8545/MAX8546)
- 100kHz Switching Frequency (MAX8548)
- Pin-Compatible with the MAX1967
- Thermal Shutdown
Applications
- Cable Modems and Routers
- Desktops and Desknotes
- Graphic Card and Video Supplies
- Networking Power Supplies
- Notebook Docking Station Supplies
- PCI Express? Power Supplies
- Set-Top Boxes
- Telecom Power Supplies
