QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 630 PIEZOCERAMIC MICROACTUATOR DRIVER WITH BOOST REGULATOR LT3469ETS8 DESCRIPTION Demonstration circuit 630 is a gm amplifier circuit using the LT®3469ETS8 and can drive an output up to 34V at 25mA from 5V or 12V supply. An internal Boost converter of the LT3469 generates a supply voltage up to 36V for the gm amplifier. This regulator switches at 1.5MHz, allowing the use of a tiny external inductor and capacitor. The 36V output capability of the switching regulator along with the high supply voltage of the amplifier combine to allow the wide output voltage range needed to drive a piezoceramic microactuator. Design files for this circuit board are available. Call the LTC factory. LT is a trademark of Linear Technology Corporation QUICK START PROCEDURE Demonstration circuit 630 is easy to set up to evaluate the performance of the LT3469ETS8. Refer to Figure 1 for proper measurement equipment setup and follow the procedure below: NOTE: When measuring the input or output voltage ripple, care must be taken to avoid a long ground lead on the oscilloscope probe. Measure the input or output voltage ripple by touching the probe tip directly across the VIN or VOUT and GND terminals. See Figure 2 for proper scope probe technique. 1. With power off, connect the input power source VIN to the VIN and GND terminals, connect Vinput to INPUT+ and GND terminals. and the input current Iin within the range of 34mA to 50mA. 4. Apply VIN=16V, Vinput=1V, and Iout=0A (no load). Verify the boost regulator output Vcc=35.2±5%. 5. Apply VIN =5V, Vinput=0.1V, check the amplifier output VOUT = within the range of 0.87V to 1.12V. 6. Apply VIN =5V, Vinput=3V, check the amplifier output VOUT = 33V±2%, 7. Apply VIN =5V and pulsed square wave input that swings from 0.1V to 2.8V and has period of 300µs to Vinput, and apply 27nF capacitor load to the output. Verify VOUT and Iout as shown in Figure 3. 2. Apply VIN =4.75V, Vinput=1V, and Iout=0mA (no load). Check the boost regulator output Vcc=34.8V±5%, and input current Iin within the range of 21mA to 35mA. 3. Apply VIN =4.75V, Vinput=1V, and Iout=2mA (2mA load at VOUT). Check the boost regulator output Vcc=34.6V±5%, 1 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 630 PIEZOCERAMIC MICROACTUATOR DRIVER WITH BOOST REGULATOR IOUT VIN Figure 1. Proper Measurement Equipment Setup GND VIN Figure 2. Measuring Input or Output Ripple 2 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 630 PIEZOCERAMIC MICROACTUATOR DRIVER WITH BOOST REGULATOR Figure 3. Ch2: Vinput. Ch3: Vout. Ch4: Iout, 100mA/Div 3 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 630 PIEZOCERAMIC MICROACTUATOR DRIVER WITH BOOST REGULATOR 4