Simplified Block Diagram
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- 3- and 4-Cell Li+ Battery-Powered Devices
- Notebook and Subnotebook Computers
- PDAs and Mobile Communication Devices
Maxim's proprietary Quick-PWM quick-response, constant on-time PWM control scheme operates without sense resistors and provides 100ns response to load transients while maintaining a relatively constant switching frequency. The unique ultrasonic pulse-skipping mode maintains the switching frequency above 25kHz, which eliminates noise in audio applications. Other features include pulse skipping, which maximizes efficiency in light-load applications, and fixed-frequency PWM mode, which reduces RF interference in sensitive applications.
The MAX1777 features a 200kHz/5V and 300kHz/3.3V SMPS for highest efficiency, while the MAX1977 features a 400kHz/5V and 500kHz/3.3V SMPS for “thin and light” applications. The MAX1999 provides a pin-selectable switching frequency, allowing either 200kHz/300kHz or 400kHz/500kHz operation of the 5V/3.3V SMPSs, respectively. The MAX1777/MAX1977/MAX1999 are available in 28-pin QSOP packages and operate over the extended temperature range (-40°C to +85°C). The MAX1777/ MAX1977/MAX1999 are available in lead-free packages.