MAX685

19-1353; Rev 0; 4/98 KIT ATION EVALU E L B AVAILA Dual-Output (Positive and Negative), DC-DC Converter for CCD and LCD General Description Features o Dual Output Using a Single Inductor o Low-Noise Output, 30mVp-p Ripple o Output Voltages up to 24V and down to -9V (up to 45V and down to -16V with added components) o Internal Switches in a Small Package o 220kHz/400kHz Fixed-Frequency PWM Operation o Frequency Can Be Synchronized to External Clock o Power-OK Indicator o Selectable Power-On Sequencing o 0.1µA Logic-Controlled Shutdown MAX685 The MAX685 DC-DC converter provides low-noise dual outputs for powering CCD imaging devices and LCDs. This device uses a single inductor to provide independently regulated positive and negative outputs. Integrated power switches are included in the small 16-pin QSOP package (same size as an 8-pin SO) to save space and reduce cost. Each output delivers up to 10mA from a +2.7V to +5.5V input voltage range. Output voltages are set independently up to 24V and down to -9V. With a few additional low-cost components, the output voltages can be set at up to 45V and down to -16V. Output ripple magnitude is 30mVp-p. The MAX685 uses a fixed-frequency, pulsewidth-modulated (PWM) control scheme at 220kHz or 400kHz to permit output noise filtering and to reduce the size of external components. The frequency can also be synchronized to an external clock signal between 200kHz and 480kHz. The MAX685 has a power-OK indicator output (POK) that signals whe...