DEMO CIRCUIT 1510A LTC3858EUH Demo Manual LTC3858EUH POLYPHASE HIGH VOUT SYNC. BUCK CONVERTER DESCRIPTION Demonstration circuit 1510A is a high output voltage, The demo circuit senses inductor current with sensing high efficiency synchronous poly-phase buck converter resistor but also has an optional DCR sense circuit that featuring the LTC3858EUH. The demo circuit is available allows using the inductors DCR as the current sensing in two versions. The input voltage of both versions is element to save cost, footprint and improve efficiency. 16V to 26V. DC1510A-A is configured using 2 piece of The LTC3858EUH datasheet gives a complete description LTC3858EUH with 4 phase interleaving operation which of these parts, operation and application information and provides 12V/50A output, while the DC1510A-B is confi- must be read in conjunction with this quick start guide gured with 1 piece of LTC3858EUH with 2 phase inter- for Demonstration circuit 1510A. leaving operation which provides 12V/25A output. Design files for this circuit board are available. Call The board has a Mode selection jumper that allows the the LTC factory. converter to run in Forced CCM Mode, Pulse Skip Mode L, LTC, LTM, LT, Burst Mode, OPTI-LOOP, Over-The-Top and PolyPhase are registered or Burst Mode operation. Synchronization to an external trademarks of Linear Technology Corporation. Adaptive Power, C-Load, DirectSense, Easy Drive, FilterCAD, Hot Swap, LinearView, Module, Micropower SwitcherCAD, Multimode clock (frequency range 150kHz to 500kHz) is also possi- Dimming, No Latency , No Latency Delta-Sigma, No R , Operational Filter, PanelPro- SENSE ble on this board. tect, PowerPath, PowerSOT, SmartStart, SoftSpan, Stage Shedding, SwitcherCAD, ThinSOT, UltraFast and VLDO are trademarks of Linear Technology Corporation. Other product names may be trademarks of the companies that manufacture the products. Table 1. Performance Summary (T =25C) A PARAMETER CONDITIONS MIN TYP MAX UNITS Input Supply Range 16 26 V Output Voltage Range V = 24V, V = 12 V 11.82 12 12.18 V IN OUT Nominal Switching Frequency 250 kHz Full Load Efficiency V = 24V, V = 12V, 97.3 % IN OUT (See Figure 3 for efficiency curves) I = 50A (-A) / 25A (-B) LOAD QUICK START PROCEDURE Demonstration circuit 1510A is easy to set up to evaluate 1. Place jumpers in the following positions: the performance of the LTC3858EUH. Refer to Figure 1 CCM JP1 MODE for proper measurement equipment setup and follow the ON JP2 RUN procedure below: NOTE. When measuring the input or output voltage ripple, care must be ON JP3 RUN taken to avoid a long ground lead on the oscilloscope probe. Measure the 2. With power off, connect the input power supply to 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 VIN and GND. Connect the load to the output. The technique. load current should be smaller than 50A for DC1510A-A and smaller than 25A for DC1510A-B. 1 LTC3858EUH 3. Turn on the power at the input. the output voltage regulation, ripple voltage, efficien- cy and other parameters. NOTE. Make sure that the input voltage does not exceed 36V. 6. Different operating modes can be evaluated by 4. Check for the proper output voltage. VOUT = 11.82V changing the position of JP1 MODE jumper and are to 12.18V discussed in the next section. 5. Once the proper output voltages are established, ad- just the loads within the operating range and observe Vin - Supply + A Vin + - VIN (J11, J5) GND (J6, J12) V VOUT (J1, J2, J7, J8) GND (J3, J4, J9, J10) - + V Iout A Vout + - load Figure 1. Proper Measurement Equipment Setup 2