QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 916 LOW NOISE REGULATED CHARGE PUMP IN 2X2 DFN LTC3204B-5 and LTC3204B-3.3 DESCRIPTION Demonstration circuit 916 is a low noise regulated charge pump in 2X2 DFN. There are two assembly versions, DC916A-A and DC916A-B for featuring LTC3204B-5 and LTC3204B-3.3 respectively. The DC916A-A produces a regulated 5V output from a 2.7V to 5.5V input. The guaranteed output load current is 150mA for VIN between 3.1V and 5.5V, and 65mA for VIN less than 3.1V. The DC916A-B produces a regulated 3.3V output from a 1.8V to 4.5V input. The guaranteed output current is 50mA from VIN between 1.9V and 4.5V, and 40mA for VIN less than 1.9V. The circuit requires only three tiny 0603 surface mount capacitors and consumes minimal board space. No inductor and diode are needed. The circuit features constant frequency operation at any load. Built-in soft-start circuitry prevents excessive inrush current during start-up. Thermal shutdown and current-limit circuitry allow the parts to survive a continuous output short circuit from VOUT to GND. These circuits are particularly useful in applications that require low VOUT ripple and extremely small size. Design files for this circuit board are available. Call the LTC factory. , LTC and LT are registered trademarks of Linear Technology Corporation. PERFORMANCE SUMMARY PARAMETER CONDITION MIN TYP MAX DC916A-A (LTC3204B-5) 2.7V 5.5V DC916A-B (LTC3204B-3.3) 1.8V 4.5V Input Voltage Range DC916A-A (LTC3204B-5) Output Voltage VOUT 3.1V< VIN <5.5V, IOUT<150mA 4.8V 5V 5.2V 3.168V 3.3V 3.432V VIN = 3.6V, IOUT = 150mA (DC916A-A) 20mVP–P 50mVP–P VIN = 2.4V, IOUT = 50mA (DC916A-B) 10mVP–P 20mVP–P 2.7V< VIN <5.5V, IOUT<65mA DC916A-B (LTC3204B-3.3) 1.9V< VIN <4.5V, IOUT<50mA 1.8V< VIN <4.5V, IOUT<40mA Output Ripple VOUT Nominal Switching Frequency Efficiency 1.2MHz VIN = 3.0V, IOUT = 100mA (DC916A-A) 81.2% VIN = 1.8V, IOUT = 20mA (DC916A-B) 90.2% 1 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 916 LOW NOISE REGULATED CHARGE PUMP IN 2X2 DFN QUICK START PROCEDURE 3. Connect the load between VOUT and GND terminals. 4. Turn on the power at the input. NOTE: Make sure that the input voltage does not exceed 5.5V for DC916A-A or 4.5V for DC916A-B. To prevent input voltage overshoot when the circuit is connected to a live supply, an aluminum electrolytic capacitor can be added to bypass the VIN at the input terminals. See Linear Technology Application Note 88 for a complete discussion. Demonstration circuit 916 is easy to set up to evaluate the performance of the LTC3204B-5 and LTC3204B-3.3. 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. ON 6. With power off, connect the input power supply to VIN and GND terminals. Check for the proper output voltages. VOUT = 4.8V to 5.2V for DC916A-A, VOUT = 3.168V to 3.432V for DC916A-B NOTE: If there is no output, temporarily disconnect the load to make sure that the load is not set too high. Place jumpers in the following positions: JP1 2. 5. Once the proper output voltages are established, adjust the loads within the operating range and observe the output voltage regulation, ripple voltage, efficiency and other parameters. Figure 1. Proper Measurement Equipment Setup GND VIN Figure 2. Measuring Input or Output Ripple 2 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 916 LOW NOISE REGULATED CHARGE PUMP IN 2X2 DFN OPERATING PRINCIPLES The LTC3204B-5/LTC3204B-3.3 use switched capacitor charge pump to boost VIN to a regulated voltage. Regulation is achieved by sensing the output voltage through an internal resistor divider and by modulating the charge pump output current based on the error signal. A 2-phase non-overlapping clock activates the charge pump switches. The flying capacitor is charged from VIN on the first phase of the clock. On the second phase of the clock, it is stacked in series with VIN and connected to VOUT. This sequence of charging and discharging the flying capacitor continues at a free running frequency of 1.2MHz. The LTC3204B datasheet gives complete description of the part, operation and application information. The datasheet must be read in conjunction with this quick start guide for demo circuit 916. 3 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 916 LOW NOISE REGULATED CHARGE PUMP IN 2X2 DFN 4