The MAX1762/MAX1791EUB+T PWM step-down controllers provide high efficiency, excellent transient response, and high DC output accuracy needed for stepping down, high-voltage batteries to generate low-voltage CPU core, I/O, and chipset RAM supplies in notebook computers and PDAs. Maxim's proprietary Quick-PWM pulse-width modulator is a free-running constant on-time type with input feed-forward. Its high operating frequency (300kHz) allows small external components to be utilized in PC board area-critical applications such as subnotebook computers and smart phones. PWM operation occurs at heavy loads, and automatic switchover to pulse-skipping operation occurs at lighter loads. The external high-side p-channel and low-side n-channel MOSFETs require no bootstrap components. The MAX1762/MAX1791EUB+T are simple, easy to compensate, and do not have the noise sensitivity of conventional fixed-frequency current-mode PWMs. These devices achieve high efficiency at a reduced cost by eliminating the current-sense resistor found in traditional current-mode PWMs. Efficiency is further enhanced by their ability to drive synchronous-rectifier MOSFETs. The MAX1762/MAX1791EUB+T come in a 10-pin μMAX package and offer two fixed voltages (Dual Mode) for each device, 1.8V/2.5V/adj (MAX1762) and 3.3V/5.0V/adj (MAX1791).
Feature
- High Operating Frequency (300kHz)
- No Current-Sense Resistor
- Accurate Current Limit
- ±1% Total DC Error over Line and During Continuous Conduction
- Dual Mode Fixed Output
- 1.8V/2.5V/adj (MAX1762)
- 3.3V/5.0V/adj (MAX1791)
- 0.5V to 5.5V Output Adjust Range
- 5V to 20V Input Range
- Automatic Light-Load Pulse Skipping Operation
- Free-Running On-Demand PWM
- Foldback Mode? UVLO
- PFET/NFET Synchronous Buck
- 4.65V at 25mA Linear Regulator Output
- 5μA Shutdown Supply Current
- 230μA Quiescent Supply Current
- 10-Pin μMAX Package
Applications
- 2-Way Pagers
- Analog Cellular Phones
- Digital Cellular Phones
- Digital Still Cameras
- Notebook Computers
