PWM Buck Converters with Bypass FET for N-CDMA/W-CDMA Handsets

All versions are No Longer Available. See Ordering Information for recommended replacements.

The MAX8500-MAX8504 PWM DC-to-DC buck converters are optimized with integrated bypass FET (0.25Ω typ) to provide power to the PA in N-CDMA and W-CDMA cell phones. The devices have a low on-resistance FET to bypass the external inductor for low dropout of only 150mV at 600mA load, regardless of inductor series resistance. The supply voltage range is from 2.6V to 5.5V and the guaranteed converter output current is 600mA. The 1MHz PWM switching frequency allows for small external components.

The MAX8500-MAX8503 are dynamically controlled to provide varying output voltages from 0.4V to V_BATT. The LDO regulation point is slightly lower than the PWM converter such that the transition into and out of dropout is smooth, regardless of the inductor resistance. The MAX8504 is programmed for fixed 1.25V to 2.5V output with external resistors. It features a high-power bypass mode that connects the output directly to the battery. All devices are designed to achieve an output settling time of less than 30µs for a full-scale change in output voltage and load current.

The MAX8500-MAX8504 are available in a 12-lead 4mm x 4mm thin QFN package (0.8mm max height).

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