BQ24725A_17 Datasheet, PDF (23/47 Pages) Texas Instruments – 1-4 Cell Li+ Battery SMBus Charge Controller with N-Channel Power MOSFET Selector and Advanced Circuit Protection

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bq24725A
SLUSAL0A – SEPTEMBER 2011 – REVISED AUGUST 2014
Bit
[12:11]
[10]
[9]
[8]
[7]
[6]
[5]
[4]
[3]
[2]
[1]
[0]
Table 3. Charge Options Register (0x12H) (continued)
Field
BAT Depletion Comparator
Threshold Adjust
Type
Reset
R/W
EMI Switching Frequency Adjust
R/W
EMI Switching Frequency Enable
R/W
IFAULT_HI Comparator Threshold
R/W
Adjust
IFAULT_LOW Comparator
R/W
Threshold Adjust
LEARN Enable
R/W
IOUT Selection
R/W
AC Adapter Indication (Read Only)
R/W
Not in use
R/W
Not in use
R/W
ACOC Threshold Adjust
R/W
Charge Inhibit
R/W
Description
This is used for LEARN function battery over discharge
protection. During LEARN cycle, when the IC detects battery
voltage is below depletion voltage threshold, the IC turns off
BATFET and turned on ACFET to power the system from AC
adapter instead of the battery. The rising edge hysteresis is
340mV. Set ChargeVoltage() register value to 0V will disable
this function.
00: Falling Threshold = 59.19% of voltage regulation limit
(~2.486V/cell)
01: Falling Threshold = 62.65% of voltage regulation limit
(~2.631V/cell)
10: Falling Threshold = 66.55% of voltage regulation limit
(~2.795V/cell)
11: Falling Threshold = 70.97% of voltage regulation limit
(~2.981V/cell) < default at POR>
0: Reduce PWM switching frequency by 18% <default at
POR>
1: Increase PWM switching frequency by 18%
0: Disable adjust PWM switching frequency <default at
POR>
1: Enable adjust PWM switching frequency
Short circuit protection high side MOSFET voltage drop
comparator threshold.
0: function is disabled
1: 750mV <default at POR>
Short circuit protection low side MOSFET voltage drop
comparator threshold.
0: 135mV <default at POR>
1: 230mV
Set this bit 1 start battery learn cycle. IC turns off ACFET and
turns on BATFET to discharge battery capacity. When battery
voltage reaches threshold defined in bit [12;11], the BATFET is
turned off and ACFET is turned on to finish battery learn cycle.
After finished learn cycle, this bit is automatically reset to 0. Set
this bit 0 will stop battery learn cycle. IC turns off BATFET and
turns on ACFET.
0: Disable LEARN Cycle <default at POR>
1: Enable LEARN Cycle
0: IOUT is the 20x adapter current amplifier output <default
at POR>
1: IOUT is the 20x charge current amplifier output
0: AC adapter is not present (ACDET < 2.4V) <default at
POR>
1: AC adapter is present (ACDET > 2.4V)
0 at POR
0 at POR
0: function is disabled
1: 3.33x of input current regulation limit <default at POR>
0: Enable Charge <default at POR>
1: Inhibit Charge
8.5.3 Setting the Charge Current
To set the charge current, write a 16bit ChargeCurrent() command (0x14H or 0b00010100) using the data format
listed in Table 4. With 10mΩ sense resistor, the bq24725A provides a charge current range of 128mA to 8.128A,
with 64mA step resolution. Sending ChargeCurrent() below 128mA or above 8.128A clears the register and
terminates charging. Upon POR, charge current is 0A. A 0.1µF capacitor between SRP and SRN for differential
mode filtering is recommended, 0.1µF capacitor between SRN and ground for common mode filtering, and an
optional 0.1µF capacitor between SRP and ground for common mode filtering. Meanwhile, the capacitance on
SRP should not be higher than 0.1µF in order to properly sense the voltage across SRP and SRN for cycle-by-
cycle under-current and over current detection.
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