The MAX1717 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) inputs over a 0.925V to 2V range. A unique feature of the MAX1717 is an internal multiplexer (mux) that accepts two 5-bit DAC settings with only five digital input pins. Output voltage transitions are accomplished with a proprietary precision slew-rate control† that minimizes surge currents to and from the battery while guaranteeing "just-in-time" arrival at the new DAC setting.
High DC precision is enhanced by a two-wire remote-sensing scheme that compensates for voltage drops in the ground bus and output voltage rail. Alternatively, the remote-sensing inputs can be used together with the MAX1717's high DC accuracy to implement a voltage-positioned circuit that modifies the load-transient response to reduce output capacitor requirements and full-load 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 MAX1717 is available in a 24-pin QSOP package.
Key Features
Applications/Uses
Quick-PWM Architecture
±1% VOUT Accuracy Over Line and Load
5-Bit On-Board DAC with Input Mux
Precision-Adjustable VOUT Slew Control
0.925V to 2V Output Adjust Range
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 Transition-Complete Indicator
Small 24-Pin QSOP Package
2-Cell to 4-Cell Li+ Battery to CPU Core Supply Converters
Notes: **This pricing is BUDGETARY, for comparing similar parts. Prices are in
U.S. dollars and subject to change. Quantity pricing may vary
substantially and international prices may differ due to local
duties, taxes, fees, and exchange rates. For volume-specific prices
and delivery, please see the price and availability page
or contact an authorized distributor.
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