Simplified Block Diagram
Click any title below to view the detail page where available.
- Two 500mA Step-Down Converters
- Up to 4MHz Switching Frequency
- Adjustable Output from 0.6V to 3.3V
- Four Low-Noise LDOs with Pin-Programmable Output Voltages
- One Open-Drain Driver
- 60ms (typ) Reset Timer
- Power-On/Off Control Logic and Sequencing
- 4mm x 4mm x 0.8mm 24-Pin Thin QFN
- Cellular Handsets
- Digital Cameras
- MP3 Players
- Smartphones and PDAs
- Wireless Local Area Networks (WLANs)
The step-down DC-DC converters utilize a proprietary 4MHz hysteretic-PWM control scheme that allows for ultra-small external components. Internal synchronous rectification improves efficiency and eliminates the external Schottky diode that is required in conventional step-down converters. The output voltage is adjustable from 0.6V to 3.3V. The output current is guaranteed up to 500mA.
The four LDOs offer low 45µVRMS output noise and low dropout of only 100mV at 100mA. OUT1 and OUT2 deliver 300mA (min) of continuous output current. OUT3 and OUT4 deliver 150mA (min) of continuous output current. The output voltages are pin selectable by SEL1 and SEL2 for flexibility. The MAX8621Y/MAX8621Z offer different sets of LDO output voltages.
A microprocessor reset output (active-low RESET) monitors OUT1 and warns the system of impending power loss, allowing safe shutdown. Active-low RESET asserts during power-up, power-down, shutdown, and fault conditions where VOUT1 is below its regulation voltage.
A 200mA driver output is provided to control LED backlighting or provide an open-drain connection for resistors such as in feedback networks.