QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 761 LOW NOISE REGULATED CHARGE PUMP IN 2X2 DFN LTC3204-5 and LTC3204-3.3 DESCRIPTION Demonstration circuit 761 is a low noise regulated space. No inductor and diode are needed. The circuit charge pump in 2X2 DFN. There are two assembly features automatic Burst Mode operation at light versions, DC761A-A and DC761A-B for featuring the loads to maintain low supply current. Built-in soft- LTC3204-5 and LTC3204-3.3 respectively. The start circuitry prevents excessive inrush current dur- DC761A-A produces a regulated 5V output from a ing start-up. Thermal shutdown and current-limit cir- 2.7V to 5.5V input. The guaranteed output load cur- cuitry allow the parts to survive a continuous output rent is 150mA for V between 3.1V and 5.5V, and short circuit. These circuits are particularly useful in IN 65mA for V less than 3.1V. The DC761A-B produces systems that require extremely low quiescent current, IN a regulated 3.3V output from a 1.8V to 4.5V input. such as battery-powered systems. The guaranteed output current is 50mA from V be- IN Design files for this circuit board are available. Call tween 1.9V and 4.5V, and 40mA for V less than IN the LTC factory. 1.9V. The circuit requires only three tiny 0603 surface , LTC and LT are registered trademarks of Linear Technology Corporation. mount capacitors and consumes minimal board PERFORMANCE SUMMARY PARAMETER CONDITION MIN TYP MAX DC761A-A (for LTC3204-5) 2.7V 5.5V Input Voltage Range DC761A-A (for LTC3204-3.3) 1.8V 4.5V DC761A-A (for LTC3204-5) 3.1V< V <5.5V, I <150mA 4.8V 5V 5.2V IN OUT Output Voltage V OUT 2.7V< V <5.5V, I <65mA IN OUT DC761A-B (for LTC3204-3.3) 1.9V< V <4.5V, I <50mA 3.168V 3.3V 3.432V IN OUT 1.8V< V <4.5V, I <40mA IN OUT Output Ripple V V = 3.6V, I = 150mA (DC761A-A) 20mV 50mV OUT IN OUT PP PP V = 2.4V, I = 50mA (DC761A-B) 10mV 20mV IN OUT PP PP Nominal Switching Frequency 1.2MHz Efficiency V = 3.0V, I = 150mA (DC761A-A) 81.3% IN OUT V = 1.8V, I = 25mA (DC761A-B) 88.7% IN OUT 1 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 761 LOW NOISE REGULATED CHARGE PUMP IN 2X2 DFN 4. Turn on the power at the input. NOTE: Make sure that the input voltage does not ex- QUICK START PROCEDURE ceed 5.5V for DC761A-A or 4.5V for DC761A-B. To prevent input voltage overshoot when the circuit is Demonstration circuit 761 is easy to set up to evalu- connected to a live supply, an aluminum electro- ate the performance of the LTC3204-5 and LTC3204- lytic capacitor can be added to bypass the V at 3.3. Refer to Figure 1 for proper measurement IN the input terminals. See Linear Technology Applica- equipment setup and follow the procedure below: tion Note 88 for a complete discussion. NOTE: When measuring the input or output voltage 5. Check for the proper output voltages. V = 4.8V ripple, care must be taken to avoid a long ground lead OUT to 5.2V for DC761A-A, V = 3.168V to 3.432V for on the oscilloscope probe. Measure the input or out- OUT DC761A-B put voltage ripple by touching the probe tip directly across the V or V and GND terminals. See IN OUT NOTE: If there is no output, temporarily disconnect Figure 2 for proper scope probe technique. the load to make sure that the load is not set too high. 1. Place jumpers in the following positions: 6. Once the proper output voltages are established, JP1 ON adjust the loads within the operating range and ob- 2. With power off, connect the input power supply to serve the output voltage regulation, ripple voltage, V and GND terminals. IN efficiency and other parameters. 3. Connect the load between V and GND terminals. OUT Figure 1. Proper Measurement Equipment Setup 2