Datasheet LT8491 (Analog Devices) - 78

link to page 61 LT8491
APPLICATIONS INFORMATION
Choose RDACI2 = 5.76k which is the closest standard • The 10A maximum charge current limit and 2.5A trickle value. charge current limit are set by choosing RSENSE2, 1 RIMON_OUT and RIOW using the following formulas: RFBIN2= Ω ⎛ 1 ⎞ ⎛ 1 ⎞ 0.0497 0.0497 RSENSE2 = Ω = ≅ 5mΩ ⎝⎜ 100k –R I 10 FBIN1⎠⎟ – ⎝⎜ RDACI2 ⎠⎟ OUT M ( AX) 1 = Ω 1208 ⎛ 1 ⎞ ⎛ 1 ⎞ RIMON_OUT = Ω IOUT M ( AXS0) •RSENSE2 ⎝⎜ 100k –97,865⎠⎟ –⎝⎜ 5726⎠⎟ 1208 = 3404Ω = Ω 2.5•5m Choose RFBIN2 = 3.4k which is the closest standard = 96.64kΩ value. where the nearest standard value is 97.6kΩ RDACI1 = 0.2 • RDACI2 Ω 24.3k •R = 0.2 • 5726Ω R IMON_OUT IOW = Ω R = 1145Ω IMON_OUT – 24.3k 24.3k • 47.6k Choose RDAC1 = 1.1k which is the closest standard = Ω value. 97.6k – 24.3k 1 = 32,356Ω CDACI = F 1000 •RDACI1 where the nearest standard value is 32.4kΩ 1 = F • The input current limit is set by properly choosing 1000 •1,145 RSENSE1. In this example, the panel can deliver up to = 873nF 5.4A. Choosing a margin of 30% yields... • Like the output feedback resistors, the final input feed- 0.0505 0.0505 RSENSE1= = = 7.2MΩ back resistors were chosen to be standard values using IIN M ( AX) 1.3•5.4 an iterative process. The VX1 and VX2 equations in the HW Config: Input Voltage Sensing and Modulation net- • For greater charging voltage accuracy, it is recom- work section were used to validate the selections: mended that 0.1% tolerance resistors be used for the output feedback resistor network. RFBIN1 = 93.1kΩ • Please reference the LT8705 data sheet for completing RFBIN2 = 3.24kΩ the remaining power portions of the LT8491. RDACI1 = 1.05kΩ RDACI2 = 5.49kΩ CDACI = 1µF where: VX1 = 6V VX2 = 53V Rev. 0 78 For more information www.analog.com Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Order Information Pin Configuration Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Overview I2C Serial Interface I2C: START and STOP Conditions I2C: ACKnowledge I2C: Chip Addressing I2C: Clock Stretching I2C: Data Transfer Transactions I2C: Powering the Interface I2C Data Data: Memory Regions Data: Bytes, Words and Long Words Data: Min/Max Register Values Data: Access Permissions Startup Sequence Battery Charging Algorithm Stage 0: Trickle Charging Stage 1: Full Constant Current Stage 2: Constant Voltage Stage 3: (Optional) Reduced Constant Voltage Done Charging Charging Faults Maximum Power Point Tracking Telemetry Operation Telemetry: Configuration Settings Telemetry: Acquisition CRC Operation EEPROM Operation EEPROM: Startup EEPROM: Reading EEPROM: Writing I2C Register Map I2C Register Descriptions Telemetry Registers TELE_TBAT TELE_POUT TELE_PIN TELE_EFF TELE_IOUT TELE_IIN TELE_VBAT TELE_VIN TELE_VINR Status Registers STAT_CHARGER STAT_SYSTEM STAT_SUPPLY STAT_TSx_REMAIN STAT_CHRG_FAULTS STAT_VERSION STAT_BOOT_CRC STAT_CFG_CRC Control The EEPROM CTRL_WRT_TO_BOOT CTRL_EE_WRT_EN Control Other Functions CTRL_HALT_STARTUP CTRL_CHRG_EN CTRL_RESTART_CHIP CTRL_RESET_FLAG CTRL_UPDATE_TELEM Configure The Telemetry CFG_RSENSE1 CFG_RIMON_OUT CFG_RSENSE2 CFG_RDACO CFG_RFBOUT1 CFG_RFBOUT2 CFG_RDACI CFG_RFBIN2 CFG_RFBIN1 Configure Initial Charger Enable CFG_INIT_CHRG_EN Configure VBAT for Stages 0, 1 and 3 CFG_VS3_25C CFG_UV_S0 CFG_S0_UV CFG_S0_S1 CFG_S1_S0 Configure Temperature Fault Limits CFG_TBAT_MIN CFG_TBAT_MAX Configure Stage Timeout Limits CFG_TMR_S0 CFG_TMR_S1 CFG_TMR_S2 CFG_TMR_S3 Configure Automatic Restart CFG_RSTRT_IN_FLT CFG_RSTRT_IN_DONEA CFG_RSTRT_IN_DONEB CFG_RSTRT_IN_S3 Configure Charge Termination CFG_TERMINATE Configure Misc. CFG_SCAN_RATE_LP CFG_SCAN_RATE CFG_CHRG_MISC Configure Temperature Compensation CFG_TC3, CFG_TC2, CFG_TC1 Configure User Code CFG_USER_CODE Manufacturer Data MFR_DATA1 MFR_DATA2 MFR_DATA3 Applications Information Hardware Configuration HW Config: Input Voltage Sensing and Modulation HW Config: VINR Pin Connections HW Config: Solar Panel Powered Charging HW Config: DC Supply Powered Charging HW Config: VBAT in Stage 2 (VS2) HW Config: Input Current Sense and Limit HW Config: Output Current Sense and Limit HW Config: Current Sense Filtering HW Config: Battery Temperature and Disconnect Sensing HW Config: SHDN Pin Connections HW Config: MODE Pin – Current Conduction Mode HW Config: Driving an LED with the STATUS Pin HW Config: I2C Chip Address Pin In-Situ Battery Charging Hot-Plugging Considerations STATUS Indicator Pin Lithium-Ion Battery Charging Lead-Acid Battery Charging Optional Features Optional: Low Power Mode Optional: Output Feedback Resistor Disconnect Optional: EXTVCC Disconnect Optional: Remote Battery Voltage Sensing Optional: DC Supply Detection Circuit Board Layout Considerations Design Example Typical Applications Package Description Typical Application Related Parts