DC1793A

DEMO MANUAL DC1793A LTC3260EMSE High Voltage, Low Noise, Dual Supply Inverting Charge Pump DESCRIPTION Demonstration circuit 1793A is a high voltage inverting mode operation, plus select an operating frequency of charge pump with low noise dual-polarity LDO regula- 500kHz, 200kHz, and 50kHz. tors featuring the LTC 3260EMSE. The LTC3260 operates The LTC3260 data sheet gives a complete description of with an input voltage from 4.5V to 32V. The demo board the device, operation and application information. The provides selectable LDO output set magnitudes of data sheet must be read in conjunction with this quick 3.3V, 5V, 12V and 24V for each polarity. Additional LDO start guide for demo circuit 1793A. set point jumper selections and optional topside ADJ Design files for this circuit board are available at resistors allow the user to set other desired LDO output DEMO MANUAL DC1793A QUICK START PROCEDURE 3. Slowly increase the load on LDO to 50mA and 12. Turn on and set PS1 to 32V. observe how the output ripple on V changes and OUT 13. Repeat steps 3 through 6. how the burst frequency increases. When the load 14. Turn on and set PS1 to 12V. is large enough, the charge pump will run constant frequency to keep V in regulation. OUT 15. Slowly increase the load on V to 100mA and OUT observe the output ripple and output voltage on V . 4. Slowly increase the load on LDO+ to 50mA and observe OUT the output ripple and the output voltage on LDO+. 16. Set the load on V to 0mA. OUT 5. Set the LDO+ load and the LDO load to 0mA and 17. Change the JP3 MODE jumper from Burst Mode op- turn off PS1. eration to constant-frequency mode and repeat steps 14 and 15. NOTE: To avoid applying an overvoltage to the ADJ pins, power must be turned off before changing the 18. Change the JP4 FREQ jumper from 500kHz to 200kHz, LDO+ or LDO jumpers. then slowly increase the load on V from 0mA to OUT 50mA and observe the output ripple and output volt- 6. Set the JP5 LDO+ jumper to the 3.3V position and JP6 age on V . LDO to the 3.3V position. OUT 19. Set the load on V to 0mA. 7. Repeat steps 2 through 5. OUT 20. Change the JP4 FREQ jumper from 200kHz to 8. Set the JP5 LDO+ jumper to the 12V position and JP6 50kHz. Slowly increase the load on V from 0mA LDO to the 12V position. OUT to 10mA and observe the output ripple and output 9. Turn on and set PS1 to 15V. voltage on V . OUT 10. Repeat steps 3 through 5. Figures 4 and 5 illustrate how the efficiency varies with 11. Set the JP5 LDO+ jumper to the 24V position and JP6 load current in Burst Mode operation and in constant- LDO to the 24V position. frequency mode operation. 0-50mA 0-50mA Figure 1. Proper Measurement Equipment Setup for DC1793A dc1793afa 2