QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 862 MICROPWER REGULATED CHARGE PUMP DC/DC CONVERTER LTC3221-3.3, LTC3221-5 and LTC3221 DESCRIPTION Demonstration circuit 862 is a micropower regulated and is rather constant over the full input voltage range. charge pump DC/DC converter with the LTC3221 in a This minimizes output capacitor size and reduces solu- 2mmx2mm DFN package. It comes in three assembly tion cost and space. Built-in soft-start prevents exces- versions, DC862A-A, DC862A-B and DC862A-C, featur- sive inrush current at turn-on and short-circuit current ing LTC3221EDC-3.3, LTC3221EDC-5, and LTC3221EDC, limit/thermal protection helps the part survive continu- respectively. The DC862A-A generates a fixed 3.3V out- ous short-circuit. All these features make the circuit ideal put. The DC862A-B generates a fixed 5V output. The for the low power and space-constrained applications in DC862A-C generates a programmable regulated 3V out- battery powered portable systems. put. The maximum output current is 60mA. Design files for this circuit board are available. Call The LTC3221 draws ultra low quiescent current at no the LTC factory. load to extend battery life. The quiescent current is even LTC is a trademark of Linear Technology Corporation lower than the self-discharging current of many batter- ies. By adopting a constant current to charge the output, the output ripple is low even at high input and light load Table 1. Performance Summary (T = 25C) A PARAMETER CONDITION MINIMUM TYPICAL MAXIMUM DC862A-A 1.8V 4.4V Input Voltage Range DC862A-B 2.7V 5.5V DC862A-C 1.8V 3.8V DC862A-A: V > 2V DC862A-B: V > 3V IN IN Maximum Output Current 60mA DC862A-C: V > 1.8V IN V > 2V, I < 60mA IN OUT DC862A-A 3.168 3.3 3.432 1.8V < V < 2V, I < 25mA IN OUT Output Voltage V V > 3V, I < 60mA OUT IN OUT DC862A-B 4.8 5 5.2 2.7V < V < 3V, I < 25mA IN OUT DC862A-C V > 1.8V, I < 60mA 2.88 3 3.12 IN OUT I = 0mA DC862A-A V = 4.4V 40mV PP OUT IN Output Ripple V (20MHz BW) DC862A-B V = 5.5V 90mV OUT PP IN I = 60mA DC862A-C V = 3.8V 57mV PP OUT IN Nominal Switching Frequency 600kHz DC862A-A V = 2V, I = 60mA 82% IN OUT Efficiency DC862A-B V = 2.7V, I = 60mA 86% IN OUT DC862A-C V = 1.8V, I = 60mA 82.8% IN OUT 1 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 862 MICROPWER REGULATED CHARGE PUMP DC/DC CONVERTER QUICK START PROCEDURE Demonstration circuit 862 is easy to set up to evaluate 4. Turn on the power at the input. the performance of the LTC3221EDC-3.3, LTC3221EDC- NOTE: Make sure that the input voltage does not ex- 5, and LTC3221EDC. Refer to Figure 1 for proper meas- ceed the corresponding maximum voltage (e.g. 4.4V urement equipment setup and follow the procedure be- for DC862A-A, 5.5V for DC862A-B, 3.8V for DC862A- low: C). NOTE: When measuring the input or output voltage rip- 5. Check for the proper output voltages. For DC863A-A, ple, care must be taken to avoid a long ground lead on Vout should be within 3.168V to 3.432V. For DC862A- the oscilloscope probe. Measure the input or output B, Vout should be within 4.8V to 5.2V. For DC862A-C, voltage ripple by touching the probe tip directly across Vout is should be within 2.88V to 3.12V. the Vin or Vout and GND terminals. See Figure 2 for NOTE: If there is no output, temporarily disconnect the proper scope probe technique. load to make sure that the load is not set too high. 1. Place jumper JP1 to the ON position. 6. Once the proper output voltages are established, ad- 2. With power off, connect a 1.8V-5.5V power supply to just the loads within the operating range and observe Vin and GND. The supply should be capable of provid- the output voltage regulation, ripple voltage, efficiency ing 200mA current. and other parameters. 3. Connect a load to Vout and GND. Figure 1. Proper Measurement Equipment Setup 2