Simplified Block Diagram
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- +2.7V to +5.5V Input Range
- Output Voltages
- +8V, >200mA (Step-Up Switching Regulator)
- +20V, >10mA (Positive Charge-Pump Regulator)
- -5V, >20mA (Negative Charge-Pump Regulator)
- +2.5V, >200mA (LDO Linear Regulator)
- +4V, >150mA Peak (VCOM Buffer)
- All Outputs Are Adjustable with Resistors
- >91% Efficiency
- Internal MOSFET Switches
- <1µA (typ) IC Shutdown Current
- 1MHz Step-Up Switching Regulator Frequency
- 500kHz Charge-Pump Regulator Switching Frequency
- Adjustable Fault-Trip Level
- Low-Profile External Components
- Built-In Transient Load Tester
- Surface-Mount Components
- Fully Assembled and Tested
- TFT LCD Desktop Monitor Panels
- TFT LCD Notebook Displays
The positive charge-pump circuit is configured for a +20V output that provides more than 10mA of current. The negative charge-pump circuit is configured for a -5V output and provides more than 20mA of current. Power for both charge-pump inputs is provided from the step-up switching regulator output.
The EV kit also features an LDO linear regulator circuit, which is configured for a +2.5V output that provides more than 200mA of current. Power for the LDO regulator circuit is provided from the input supply. The VCOM buffer provides a +4V output and more than 150mA of peak current. The step-up switching regulator output provides power to the VCOM buffer.
The MAX1778 EV kit demonstrates low quiescent current and high efficiency (over 91%). High-frequency operation (500kHz/1MHz) allows the use of tiny surface-mount components and fast transient response. The MAX1778 TSSOP package (1.1mm max) with low-profile external components allows this circuit to be less than 1.2mm in height. A built-in transient load tester facilitates transient load tests. The MAX1778 EV kit can also be used to evaluate the MAX1880, MAX1881, and MAX1882 ICs.