QUICK START GUIDE FOR DEMONSTRATION CIRCUIT DC674B STANDALONE NIMH/NICD BATTERY CHARGER BOARD LTC4011 DESCRIPTION Demonstration circuit DC674B is a complete Fast Bat- and an external system load when the input power is tery Charger capable of charging 3, 4, 8 or 10 series removed connected NiMH or NiCd cells. Other cell counts can Charge termination includes -V, T/t, peak voltage also be charged (up to 16 cells) by installing an appro- and a safety timer. The thermistor function is set by the priate resistor on the board. NTC jumper, JP1. Battery chemistry is set by the CHEM The power portion of the circuit consists of a 550kHz jumper, JP2. The number of series cells is set by the synchronous step-down constant current source which CELLS jumper, J1. Finally, the safety timer length is set provides 2A of charge current. Other charge currents by the TIME jumper, J2. Four LEDs indicate charger can be selected by changing the sense resistor value, ready, top-off charge, charging, and FAULT status. and for higher charge current (2 to 4A), the PC board Design files for this circuit board are available. Call has a dual layout for the top switch to allow a larger the LTC factory. FET to be used. A PowerPath FET is also included that L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and Power- provides a low voltage drop path between the battery Path is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. Performance Summary T = 25C A PARAMETER CONDITIONS / NOTES VALUE Minimum Input Voltage 3 series cells (Default) 6.3V 4 series cells 8.3V 6 series cells 12.3V 10 series cells 20.3V n series cells n 2.0V + 0.3V Maximum Input Voltage Limited by Input Capacitor Volt Ratings. 25V Maximum Charge Current 2A 8% V Termination CHEM=NiCd 20mV 2mV CHEM=NiMH 10mV 1.5mV T/t Termination CHEM=NiCd 2C/min 0.16C Temperature Rise CHEM=NiMH 1C/min 0.14C Temperature Rise Precharge Current 350mV < VCELL < 900mV 400mA 80mA Top Off Charge Current CHEM=NiMH, T/t Termination Only 200mA 50mA 1 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT DC674B STANDALONE NIMH/NICD BATTERY CHARGER BOARD QUICK START PROCEDURE Demonstration circuit 674B is easy to set up to eva- 2. To use a system load up to 1A in parallel with luate the performance of the LTC4011. Refer to Fig- the charging circuit, connect to SYSTEM LOAD. ure 1 for proper measurement equipment setup and Adjust load and input supply current limit as follow the procedure below. necessary. 1. Set the jumpers according to the type and specifi- 3. For external thermistor connection, set jumper cations of the pack under evaluation. JP1 to BAT. For the on-board thermistor, set JP1 to BRD. To remove the thermistor from the circuit, 2. With all power off, connect input power supply, set JP1 to OUT. and meters as shown in Figure 1. 4. For custom cell count, set jumper J1 to XCELLS 3. Preset the system load to 0A and the input and install R14 with the appropriate value. supply to 0V, 0A current limit. 5. For alternative timer settings, set jumper J2 as 4. Turn on the supplies, setting the current limit to necessary. For custom timer settings, set J2 to 2A. 4.3Hr and install R23 with the appropriate val- 5. Adjust the input voltage to the desired value, up ue. to 25V. Note: This value also affects Precharge and TOC times as well. 6. Connect the battery to begin charging. 6. To measure the average voltage per cell, connect a meter to VCELL. Optional 7. To pause the charge cycle, connect a lead from 1. To use a battery with a 5-pin blade connector, PAUSE to GND. use J3. Note: This pauses the timer as well, but status outputs remain active. Please refer to the LTC4011 datasheet for additional information. 2