The MAX1718EEI-C71059 step-down controller is intended for core CPU DC-DC converters in notebook computers. It features a dynamically adjustable output, ultra-fast transient response, high DC accuracy, and high efficiency needed for leading-edge CPU core power supplies. Maxim's proprietary Quick-PWM quick-response, constant-on-time PWM control scheme handles wide input/output voltage ratios with ease and provides 100ns "instant-on" response to load transients while maintaining a relatively constant switching frequency. The output voltage can be dynamically adjusted through the 5-bit digital-to-analog converter (DAC) over a 0.6V to 1.75V range. The MAX1718EEI-C71059 has an internal multiplexer that accepts three unique 5-bit VID DAC codes corresponding to Performance, Battery, and Suspend modes. Precision slew-rate control provides "just-in-time" arrival at the new DAC setting, minimizing surge currents to and from the battery. The internal DAC of the MAX1718B is synchronized to the slew-rate clock for improved operation under aggressive power management of newer chipsets and operating systems that can make incomplete mode transitions. A pair of complementary offset control inputs allows easy compensation for IR drops in PC board traces or creation of a voltage-positioned power supply. Voltage-positioning modifies the load-transient response to reduce output capacitor requirements and total system power dissipation. Single-stage buck conversion allows these devices to directly step down high-voltage batteries for the highest possible efficiency. Alternatively, two-stage conversion (stepping down the 5V system supply instead of the battery) at a higher switching frequency allows the minimum possible physical size. The MAX1718EEI-C71059 is available in a 28-pin QSOP package.
Feature
- Quick-PWM Architecture
- ±1% VOUT Accuracy Over Line and Load
- 5-Bit On-Board DAC with Input Muxes
- Precision-Adjustable VOUT Slew Control
- 0.6V to 1.75V Output Adjust Range
- Precision Offset Control
- Supports Voltage-Positioned Applications
- 2V to 28V Battery Input Range
- Requires a Separate 5V Bias Supply
- 200/300/550/1000kHz Switching Frequency
- Over/Undervoltage Protection
- Drives Large Synchronous-Rectifier FETs
- 700μA (typ) ICC Supply Current
- 2μA (typ) Shutdown Supply Current
- 2V ±1% Reference Output
- VGATE Blanking During Transition
- Small 28-Pin QSOP Package
Applications
- 2-Cell to 4-Cell Li+ Battery to CPU Core Supply Converters
- 5V to CPU Core Supply Converters
- IMVP-II Notebook Computers