- +0.7V to MAINOUT Battery Input Voltage
- Dual Output Voltages
- +3.3V Main Output and +20V LCD Bias Output
- +3.3V Main Output and -20V LCD Bias Output
- All Outputs Also Adjustable with External Resistors
- Up to 350mA from 2-Cell Input (Main Output )
- Up to 140mA from 1-Cell Input (Main Output)
- Up to 12mA Output Current (LCD Bias Output)
- Internal N-Channel Switches and Synchronous Rectifier
- 1µA IC Shutdown Current
- 300kHz Switching Frequency
- Surface-Mount Components
- Fully Assembled and Tested
The second circuit converts a +0.7V to +3.3V battery voltage to a +3.3V main output and a -20V LCD bias voltage. The main +3.3V output supplies up to 350mA from a 2-cell input, or 140mA from a 1-cell input, while the LCD bias output supplies 10mA at -20V.
The MAX1677 features internal N-channel MOSFET switches, a synchronous rectifier, low-battery comparator, and selectable PFM/PWM mode. The MAX1677 EV kit provides low quiescent current and high efficiencyup to 95% for maximum battery life. Operation at 300kHz allows the use of tiny surface-mount inductors.