The MAX887HESA high-efficiency, step-down DC-DC converter provides an adjustable output from 1.25V to 10.5V. It accepts inputs from 3.5V to 11V and delivers 600mA. Operation to 100% duty cycle minimizes dropout voltage (300mV typ at 500mA). Synchronous rectification reduces output rectifier losses, resulting in efficiency as high as 95%. Fixed-frequency pulse-width modulation (PWM) reduces noise in sensitive communications applications. Using a high-frequency internal oscillator allows tiny surface-mount components to reduce PC board area, and eliminates audio-frequency interference. A SYNC input allows synchronization to an external clock to avoid interference with sensitive RF and data-acquisition circuits. The MAX887HESA features current-mode operation for superior load/line-transient response. Cycle-by-cycle current limiting protects the internal MOSFET and rectifier. A low-current (2.5μA typ) shutdown mode conserves battery life.
Feature
- 95% Efficiency
- 600mA Output Current
- Cycle-by-Cycle Current Limiting
- Low-Dropout, 100% Duty-Cycle Operation, 300mV at 500mA
- Internal 0.6Ω (typ) MOSFET
- Internal Synchronous Rectifier
- High-Frequency Current-Mode PWM
- External SYNC or Internal 300kHz Oscillator
- Guaranteed 260kHz to 340kHz Internal Oscillator Frequency Limits
- 2.5μA Shutdown Mode
Applications
- Cell Phones
- Computer Peripherals
- Distributed Power Systems
- Personal Communicators
- Portable Instrumentation