DEMO MANUAL DC2190A-A/DC2190A-B LTC3892EFE-1 PolyPhase High V OUT Synchronous Buck Converter DESCRIPTION Demonstration circuit 2190A is a high output voltage, The demo circuit senses inductor current with a sense high efficiency synchronous PolyPhase buck converter resistor but also has an optional DCR sense circuit that featuring the LTC 3892EFE-1. This demo circuit is available allows using the inductors DCR as the current sensing in two versions. The input voltage range of both versions element to save cost, footprint and improve efficiency. is from 16V to 55V. The DC2190A-A is configured using The LTC3892EFE-1 data sheet gives a complete description two each LTC3892EFE-1 devices with 4-phase interleav- of these parts, operation and application information and ing operation which provides a 12V/60A output, while must be read in conjunction with this quick start guide the DC2190A-B is configured using one LTC3892EFE-1 for DC2190A. device with 2-phase interleaving operation which provides Design files for this circuit board are available at a 12V/30A output. DEMO MANUAL DC2190A-A/DC2190A-B QUICK START PROCEDURE Demonstration circuit DC2190A is easy to set up to evalu- For synchronizing to an external clock source, apply the ate the performance of the LTC3892-1. Refer to Figure 1 external clock from SYNC turret to GND. for proper measurement equipment setup and follow the Refer to Table 1 and to the data sheet for more details. procedure below. Table 1. Mode Selection and Synchronizing Operation Options NOTE: When measuring the input or output voltage ripple, JP3 care must be taken to avoid a long ground lead on the CONFIGURATION JP1 (DC2190A-A ONLY) oscilloscope probe. Measure the input or output voltage Forced Continuous Conduction Int. SYNC Int. ripple by touching the probe tip directly across the V IN Operation or V and GND terminals or directly across relevant OUT Pulse-Skip Mode Operation Ext.SYNC/ Ext./Pulse-Skip capacitor. See Figure 2 for proper scope probe technique. Pulse-Skip. Burst Mode Operation Burst Ext./Pulse-Skip 1. Place jumpers in the following positions: Synchronize to Ext. Clock (Ext. Ext. SYNC/ Ext./Pulse-Skip JP1: Int. SYNC Clock Apply to SYNC Turret) Pulse-Skip JP2: ON OPTIONAL INDUCTOR DCR CURRENT SENSING JP3: Int. (DC2190A-A Only) Demonstration circuit 2190A provides an optional circuit 2. With power off, connect the input power supply to V for inductor DCR current sensing. Inductor DCR current IN and GND. Connect the load to the output. The load sensing uses the DCR of the inductor to sense the inductor current should be smaller than 60A for DC2190A-A current instead of discrete sense resistors. The advantages and smaller than 30A for DC2190A-B. of DCR sensing are lower cost, reduced board space and higher efficiency, but the disadvantage is a less accurate 3. Turn on the power at the input. current limit. If DCR sensing is used, be sure to select an NOTE: Make sure that the input voltage is between inductor with sufficiently high saturation current or use 16Vand 55V. an iron powder type material. 4. Check for the proper output voltages. Refer to Table 2 for optional inductor DCR current sensing setup and to the data sheet for more details. V = 11.8V to 12.2V OUT NOTE: If there is no output, temporarily disconnect the POWER THE EXTV FROM EXTERNAL SUPPLY CC load to make sure that the load is not set too high. The DC2190A EXTV turret is tied to the 12V V by CC OUT 5. Once the proper output voltages are established, adjust default. To power the EXTV from external supply: CC the loads within the operating range and observe the output voltage regulation, ripple voltage, efficiency and 1. Remove the R7. other parameters. 2. Solder a 16V, 1F MLCC between EXTV and GND CC turret. FREQUENCY SYNCHRONIZATION AND MODE 3. Apply a DC voltage (<14V) between the EXTV and CC SELECTION GND turret, after the input voltage is established. Ensure The DC2190As mode selector allows the converter to that EXTV V . CC IN run in FCC operation, pulse-skip operation, Burst Mode or be synchronizing to an external clock by changing the position of JP1 and JP3. dc2190afa 2