Datasheet LTC4015 (Analog Devices) - 20
| Manufacturer | Analog Devices |
| Description | Multichemistry Buck Battery Charger Controller with Digital Telemetry System |
| Pages / Page | 76 / 20 — OPERATION. Table 2. Shows a Summary of LTC4015 Charger State Alerts. … |
| File Format / Size | PDF / 1.6 Mb |
| Document Language | English |
OPERATION. Table 2. Shows a Summary of LTC4015 Charger State Alerts. Measurement Subsystem
Model Line for this Datasheet
Text Version of Document
LTC4015
OPERATION Table 2. Shows a Summary of LTC4015 Charger State Alerts. Measurement Subsystem Each Alert Has an Associated Enable (or Mask), and Bit That Is Set to 1 to Indicate the Alert Has Occurred.
The LTC4015 includes a 14-bit analog-to-digital converter (ADC) and signal channel multiplexer to monitor several
ALERT ALERT ENABLE REPORTING
analog parameters. It can measure the voltages at VIN,
CHARGER STATE ALERTS BITS (0x0E) BITS (0x37)
SYS and BATSENS, the current into the SYS node (voltage Equalize 10 10 across RSNSI), the battery charge current (voltage across Absorb 9 9 RSNSB), the voltage across the battery pack thermistor, Charger Suspended 8 8 and its own internal die temperature. After a charge Precharge 7 7 cycle begins the LTC4015 uses the appropriate analog CC_CV 6 6 parameters to calculate the series resistance of the battery. NTC Pause 5 5 To save battery power the measurement system will not Timer Termination 4 4 run if the battery is the only source of power, unless the C/x Termination 3 3 force_meas_sys_on bit is set. Max Charge Time Fault 2 2 The converter is automatically multiplexed between all Battery Missing Fault 1 1 of the measured channels and its results are stored in Battery Short Fault 0 0 registers accessible via the I2C port.
Table 3. Shows a Summary of LTC4015 Charger Status Alerts.
The seven channels measured by the ADC each take ap-
These Alerts Indicate Which Control Loop Is in Control During
proximately 1.6ms to measure. The result of the analog-
Charging. Each Alert Has an Associated Enable (or Mask), and
to-digital conversion is stored in a 16-bit register as a
Bit That Is Set to 1 to Indicate the Alert Has Occurred.
signed, two’s complement number. The lower two bits
ALERT ALERT ENABLE BITS REPORTING
of this number are sub-bits. These bits are ADC outputs
CHARGER STATUS ALERTS (0x0F) BITS (0x38)
which are too noisy to be reliably used on any single UVCL (VIN Undervoltage Charge Current 3 3 conversion, however, they may be included if multiple Limiting) samples are averaged. The maximum range of the ADC ICL (IIN Charge Current Limiting) 2 2 is ±1.8V, which gives a LSB size of 3.6V/65535 (216 – 1). CC (Constant-Current Mode) 1 1 Table 4 summarizes the LSB scaling and resultant LSB CV (Constant-Voltage Mode) 0 0 size for these ADC measurements.
Table 4. Measurement Subsystem Scaling and LSB Size ADC LSB (3.6V/65535) = 54.932479 µV REGISTER REGISTER MEASUREMENT SYMBOL NUMBER LSB SCALING LSB SIZE UNITS
VBATSENS/Cellcount (Lithium Chemistries) VBAT 0x3A *7/2 192.264 µV VBATSENS/Cellcount (Lead-Acid) VBAT 0x3A *7/3 128.176 µV VIN VIN 0x3B *30 1.648 mV VSYS VSYS 0x3C *30 1.648 mV VRSNSB (VCSP – VCSN) IBAT 0x3D /37.5 1.465 µV VRSNSI (VCLP – VCLN) IIN 0x3E /37.5 1.465 µV Die Temperature (Note 1) DIE_TEMP 0x3F 1 54.932 µV
Note 1:
DIE_TEMP is the ADC conversion of a internal PTAT (proportional to absolute temperature) voltage. DIE temperature = (DIE_TEMP – 12010)/45.6 in °C. 4015fb 20 For more information www.linear.com/LTC4015 Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Order Information Data Sheet Conventions Pin Configuration Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram I2C Timing Diagram Operation Applications Information Register Description DETAILED Register Descriptions Typical Applications Package Description Revision History Typical Application Related Parts
OPERATION Table 2. Shows a Summary of LTC4015 Charger State Alerts. Measurement Subsystem Each Alert Has an Associated Enable (or Mask), and Bit That Is Set to 1 to Indicate the Alert Has Occurred.
The LTC4015 includes a 14-bit analog-to-digital converter (ADC) and signal channel multiplexer to monitor several
ALERT ALERT ENABLE REPORTING
analog parameters. It can measure the voltages at VIN,
CHARGER STATE ALERTS BITS (0x0E) BITS (0x37)
SYS and BATSENS, the current into the SYS node (voltage Equalize 10 10 across RSNSI), the battery charge current (voltage across Absorb 9 9 RSNSB), the voltage across the battery pack thermistor, Charger Suspended 8 8 and its own internal die temperature. After a charge Precharge 7 7 cycle begins the LTC4015 uses the appropriate analog CC_CV 6 6 parameters to calculate the series resistance of the battery. NTC Pause 5 5 To save battery power the measurement system will not Timer Termination 4 4 run if the battery is the only source of power, unless the C/x Termination 3 3 force_meas_sys_on bit is set. Max Charge Time Fault 2 2 The converter is automatically multiplexed between all Battery Missing Fault 1 1 of the measured channels and its results are stored in Battery Short Fault 0 0 registers accessible via the I2C port.
Table 3. Shows a Summary of LTC4015 Charger Status Alerts.
The seven channels measured by the ADC each take ap-
These Alerts Indicate Which Control Loop Is in Control During
proximately 1.6ms to measure. The result of the analog-
Charging. Each Alert Has an Associated Enable (or Mask), and
to-digital conversion is stored in a 16-bit register as a
Bit That Is Set to 1 to Indicate the Alert Has Occurred.
signed, two’s complement number. The lower two bits
ALERT ALERT ENABLE BITS REPORTING
of this number are sub-bits. These bits are ADC outputs
CHARGER STATUS ALERTS (0x0F) BITS (0x38)
which are too noisy to be reliably used on any single UVCL (VIN Undervoltage Charge Current 3 3 conversion, however, they may be included if multiple Limiting) samples are averaged. The maximum range of the ADC ICL (IIN Charge Current Limiting) 2 2 is ±1.8V, which gives a LSB size of 3.6V/65535 (216 – 1). CC (Constant-Current Mode) 1 1 Table 4 summarizes the LSB scaling and resultant LSB CV (Constant-Voltage Mode) 0 0 size for these ADC measurements.
Table 4. Measurement Subsystem Scaling and LSB Size ADC LSB (3.6V/65535) = 54.932479 µV REGISTER REGISTER MEASUREMENT SYMBOL NUMBER LSB SCALING LSB SIZE UNITS
VBATSENS/Cellcount (Lithium Chemistries) VBAT 0x3A *7/2 192.264 µV VBATSENS/Cellcount (Lead-Acid) VBAT 0x3A *7/3 128.176 µV VIN VIN 0x3B *30 1.648 mV VSYS VSYS 0x3C *30 1.648 mV VRSNSB (VCSP – VCSN) IBAT 0x3D /37.5 1.465 µV VRSNSI (VCLP – VCLN) IIN 0x3E /37.5 1.465 µV Die Temperature (Note 1) DIE_TEMP 0x3F 1 54.932 µV
Note 1:
DIE_TEMP is the ADC conversion of a internal PTAT (proportional to absolute temperature) voltage. DIE temperature = (DIE_TEMP – 12010)/45.6 in °C. 4015fb 20 For more information www.linear.com/LTC4015 Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Order Information Data Sheet Conventions Pin Configuration Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram I2C Timing Diagram Operation Applications Information Register Description DETAILED Register Descriptions Typical Applications Package Description Revision History Typical Application Related Parts