Simplified Block Diagram
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- 2.7V to 5.5V Input Range
- Output Voltages
- 9V Output at 200mA (Step-Up Switching)
- 20V Output >10mA (Positive Charge-Pump Regulator)
- -7V Output >10mA (Negative Charge-Pump Regulator)
- Resistor-Adjustable Outputs
- Up to Three Positive and Three Negative Charge-Pump Stages
- Up to +28V and -22V Linear-Regulated Output (As Configured)
- 90&% Efficiency
- 500kHz/1MHz Step-Up Switching Frequency
- Overcurrent Protection
- Low Profile
- Surface-Mount Components
- Fully Assembled and Tested
- Car-Navigation Displays
- LCD Monitors
- Notebook Computer Displays
The positive charge-pump and linear regulator are configured for a 20V output using two charge-pump stages providing up to 10mA. The negative charge pump and linear regulator are configured for a -7V output using a single charge-pump stage providing up to 10mA. Power for the positive charge-pump input can be provided by the DC input source or the step-up switching regulator output. Power for the negative charge-pump input can be provided by the DC input source or the power ground.
The MAX1889 EV kit demonstrates low quiescent current and high efficiency (up to 90%) for maximum battery life. The EV kit features overload protection for the input and all outputs. Operation at 1MHz allows the use of tiny surface-mount components. The MAX1889 QFN package (1.0mm max) with low-profile external components allows this circuit to be 1.25mm high.