GND VIN QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 445 TRIPLE OUTPUT POWER SUPPLY FOR LCD PANELS LT1944-1 DESCRIPTION Demonstration circuit 445 is a highly integrated three- are adjustable with a change in the feedback resistors. output converter designed as a low-cost, small size so- The third output is a negative level shifted voltage off the lution to provide bias voltages in small portable TFT-LCD main regulators. panels. It is capable of providing 5V/30mA, 15V/2.5mA, Design files for this circuit board are available. Call and 10V/1mA using the LT1944-1 dual step-up con- the LTC factory. verter from an input as low as 2.7V. 5V and 15V outputs QUICK START PROCEDURE Refer to Figure 1 for proper measurement equipment NOTE: The 6V maximum is set by the voltage rating of setup and follow the procedure below: the input capacitor, the absolute maximum rating for Vin and shutdown pins of LT1944-1 is 15V. NOTE: When measuring the output ripple, see Figure 2 for proper scope probe technique. 2. Attach voltmeters or oscilloscope probes between each output and its closest GND terminal to monitor 1. Apply a voltage source to the input of the circuit be- the outputs. Switch on the desired channel(s) by set- tween the Vin and GND terminals. The circuit will start ting JP1 and JP2 to the run position. up at an input voltage higher than 1.2V. Do not apply more than 6V to the input. 3. Connect the proper load at each output. + + LOAD LOAD + + + LOAD + + + Figure 1. Proper Measurement Equipment Setup Figure 2. Scope Probe Placement for Measuring Output Ripple 1 + + +QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 445 TRIPLE OUTPUT POWER SUPPLY FOR LCD PANELS Table 1. Performance Summary PARAMETER CONDITION VALUE Minimum Input Voltage 1.2V Maximum Load Current at 5V Output (minimum) Vin = 2.7V to 4.2V 30mA Maximum Load Current at 15V Output (minimum) Vin = 2.7V to 4.2V 2.5mA Maximum Load Current at -10V Output (minimum) Vin = 2.7V to 4.2V 1mA Typical Output Ripple at 5V Vin=3.3V, Iout1=30mA, Iout2=2.5mA, Iout3=1mA 120mV Typical Output Ripple at 15V Vin=3.3V, Iout1=30mA, Iout2=2.5mA, Iout3=1mA 50mV Typical Output Ripple at -10V Vin=3.3V, Iout1=30mA, Iout2=2.5mA, Iout3=1mA 15mV 2