DEMO MANUAL DC2044A LTC4020EUHF High Voltage Buck-Boost Multi-Chemistry Battery Charger Description Demonstration circuit 2044A is a 55V buck-boost multi- MODE pin floated), or charging with an optimized 4-step, chemistry battery charger featuring the LTC4020. The board 3-stage lead-acid battery charge profile (connect MODE pin will accept an input voltage between 15V and 55V. The to INTV , with a 0 jumper at the optional R29 position). CC float voltage of the battery output (BAT) is 25.2V, with 3.3A The LTC4020 data sheet gives a complete description of the maximum charge current. The converter output (VOUT) IC operation and application information. The data sheet has a voltage range of 21V to 28V, with 3A maximum load must be read in conjunction with this quick start guide. current. The LTC4020 contains a high efficiency synchro- Design files for this circuit board are available at nous buck-boost DC/DC controller and uses a proprietary DEMO MANUAL DC2044A Quick s p D Demonstration circuit 2044A is easy to set up to evaluate Additional Notes: the performance of the LTC4020. Refer to Figure 1 for 1. CAUTION: Be careful when testing with high voltage. the proper measurement equipment setup and follow the High voltage can result in an electric shock if care procedure below: is not taken. 1. With power off, connect the input power supply (set 2. CAUTION: Batteries are potentially dangerous high for 0V) to V and GND (input return). IN energy sources. Improper connection, overcharge, or 2. Connect the converter output load between V and rapid discharge could result in explosion and/or file. OUT GND (Initial load: no load). Please read the specification/manual of the battery before test. 3. Connect the DVMs to the input and outputs. 3. The combined converter output load current and bat- 4. Turn on the input power supply and slowly increase tery charging current should not exceed 3.3A. to 24V. Check for the proper output voltages, V of OUT 25.2V and BAT of 25.2V. 4. Without a proper battery, BAT output can be open or connected with other suitable loads for test purposes. 5. Once the proper output voltages are established, adjust It may be a good practice to add low ESR electrolytic the converter output load within the operating range (3A capacitors to the BAT output (1000F at 35V, for maximum) and/or adjust input voltage (15V to 55V) and 25.2V float voltage). observe the output voltage regulation, ripple voltage, efficiency and other parameters. Note: These capacitors help simulate the low impedance of a battery and maintain stability of the charge current Note: When measuring the output or input voltage ripple, loop. Its only needed for test purposes with electronic do not use the long ground lead on the oscilloscope probe. or resistive loads, and not needed in the actual battery See Figure 2 for the proper scope probe technique. Short, application/test (where the BAT load is a battery). stiff leads need to be soldered to the (+) and () terminals of an output capacitor. The probes ground ring needs to 5. BAT float voltage can be easily adjusted with the resis- touch the () lead and the probe tip needs to touch the tor divider R8/R10. Converter output voltage V can OUT (+) lead. be adjusted with the resistor divider R9/R11. Adjust/ optimize the loop compensations if necessary. dc2044af 2 ure roce tart