DEMO MANUAL DC1596A LTC3607EUD Dual 600mA 15V Monolithic Synchronous Step-Down Regulator DESCRIPTION Demonstration circuit DC1596 is a dual output regulator package, which has an exposed pad on the bottom side consisting of two constant-frequency step-down convert- of the IC for better thermal performance. These features, ers, based on the LTC 3607 monolithic dual channel plus a set operating frequency range of 2.25MHz, make synchronous buck regulator. The DC1596 has an input the DC1596 demo board an ideal circuit for industrial or voltage range of 4.5V to 15V, with each regulator capable of distributed power applications. delivering up to 600mA of output current. The DC1596 can Design files for this circuit board are available at operate in either Burst Mode operation or pulse-skipping DEMO MANUAL DC1596A QUICK START PROCEDURE The DC1596 is easy to set up to evaluate the performance 5. Set the load current of both outputs to 600mA and the of the LTC3607. For a proper measurement equipment input voltages to 12V, and then measure each output configuration, set up the circuit according to the diagram ripple voltage (refer to Figure 2 for proper measure- in Figure 1. ment technique) they should each measure less than 20mVAC. Also, observe the voltage waveform at either Note: When measuring the input or output voltage ripple, switch node (Pin 5 for reg.1 and Pin 8 for reg.2) of each care must be taken to avoid a long ground lead on the regulator. The switching frequencies should be about oscilloscope probe. Measure the input or output voltage 2.25MHz 20% (T = 555ns and 370ns). Both switch ripple by touching the probe tip directly across the V IN node waveforms should be rectangular in shape, and or V and GND terminals. See the proper scope probe OUT 180 out-of-phase with each other. technique in Figure 2. 6. To operate the ckt.s in Burst Mode operation, change Please follow the procedure outlined below for proper the shunt position of header JP3 to BURST MODE. operation. 7. Regulators 1 (PVIN1) and 2 (PVIN2) are completely 1. Connect the input power supply to the PVIN1/PVIN2 and separated from each other thus, they can be powered GND terminals (V and V are separate nodes but IN1 IN2 from different individual input supplies (if R11 is re- are connected). Connect the loads between the VOUT moved), as can the signal input supply, SVIN. However, and GND terminals. Refer to Figure 1 for the proper SVIN must powered for either regulator to function measurement equipment setup. (SVIN is connected to PVIN1 through a filter on the Before proceeding to operation, insert jumper shunts demo board.). XJP1 and XJP2 into the OFF positions of headers JP1 8. When finished, insert shunts XJP1 and XJP2 to the OFF and JP2, shunt XJP3 into the pulse-skip position of position(s) and disconnect the power. MODE header JP3, and shunt XJP4 into the VOUT1 voltage options of choice of header JP4: 1.2V, 1.5V, or Warning: If the power for the demo board is carried in 1.8V, and shunt XJP5 into the VOUT2 voltage options long leads, the input voltage at the part could ring, which of choice of header JP5: 2.5V, 3.3V, or 5V. could affect the operation of the circuit or even exceed the maximum voltage rating of the IC. To eliminate the ring- 2. Apply 5.5V at PVINs 1, 2. Measure both VOUTs they ing, a small tantalum capacitor (for instance, AVX part should read 0V. If desired, one can measure the shut- TPSY226M035R0200) is inserted on the pads between down supply current at this point. The supply current the input power and return terminals on the bottom of the will be less than 1A in shutdown. demo board. The (greater) ESR of the tantalum capacitor 3. Turn on VOUT1 and VOUT2 by shifting shunts XJP1 will dampen the (possible) ringing voltage caused by the and XJP2 from the OFF positions to the ON positions. long input leads. On a normal, typical PCB, with short Both output voltages should be within a tolerance of traces, this capacitor is not needed. 2%. 4. Vary the input voltages from 5.8V (the minimum V is IN dependent on V ) to 15V, and the load currents from OUT 0A to 600mA. Both output voltages should be within 4% tolerance. dc1596afa 2