DC767A Analog Devices

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 767 SINGLE LI-ION BATTERY POWERED BUCK REGULATOR FOR PDA APPS LTC3447 DESCRIPTION Demonstration Circuit 767 is an I2C controlled high effi- start-up voltage (equal to VCCC) can be set by changing ciency synchronous current mode buck regulator featur- the R4 and R5 values). Automatic Burst Mode at light ing the LTC3447. The circuit is ideally suited for single loads extends battery life in portable systems. The Burst Li-Ion battery powered applications such as PDAs and Mode feature can be disabled using the I2C command. other Handheld Devices. The I2C Power Rail, VCCD, can be connected to the main Supply Voltage VCCC. Both Design files for this circuit board are available. Call input voltage ranges are 2.5V 5.5V. The buck regula- the LTC factory. tor has a programmable output range of 0.7V to 2.00V with a 1A switch. The initial start-up voltage is set to LT is a trademark of Linear Technology Corporation 1.35V by feedback resistors R4 and R5 (the maximum Table 1. Performance Summary (T = 25C) A PARAMETER CONDITION VALUE VCCC Input Voltage Range 2.5V 5.5V VCCD Input Voltage Range 2.5V 5.5V V Buck Output Voltage 0.7V 2.0V OUT Maximum Output Current VCCC = 3V, V = 1.3V 600mA OUT Switching Frequency 1.0MHz Const. QUICK START PROCEDURE DC767 is easy to set up to evaluate the performance of 6. Connect the DC767 to the DC410 via their 5 pin con- the LTC3447. Refer to Figure 1 for proper measurement nectors. equipment setup and follow the procedure below: 7. Run the LVDC767.exe User Interface program pro- 1. Connect a 100mA load, LOAD1, between the VOUT vided to issue the I2C command with the relevant in- and GND terminals on the right hand side of the formation (note: the serpdrv file must be stored in the board. same directory as the LVDC767.exe file). 2. Apply 3.3V between the VCCC and GND terminals on 8. To change the Buck voltage ... set the Buck Voltage the left hand side of the board. slider to whatever voltage you want the output to be and click on the Buck Voltage slider s Write button. 3. Apply 3.3V between the VCCD and GND terminals on the left hand side of the board. 4. Connect the DC410 to the Computers serial port via a 9-pin RS232 cable. 5. Connect 8V 10V to the VinExt and Gnd terminals on the DC410 (ensure the JP2 jumper on the DC410 is in the VinExt position and the JP1 JP3 jumpers are in their RES positions). 1 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 767 SINGLE LI-ION BATTERY POWERED BUCK REGULATOR FOR PDA APPS Figure 1. Proper Measurement Equipment Setup 2