BQ25700A Datasheet, PDF (50/82 Pages) Texas Instruments – SMBus Multi-Chemistry Battery Buck-Boost Charge Controller With System Power Monitor and Processor Hot Monitor

bq25700A
SLUSCQ8 – MAY 2017
www.ti.com
8.6.4 MaxChargeVoltage Register (SMBus address = 15h) [reset value based on CELL_BATPRESZ pin
setting]
To set the output charge voltage, write a 16-bit ChargeVoltage register command (REG0x15()) using the data
format listed in Table 27 and Table 28. The charger provides charge voltage range from 1.024 V to 19.200 V,
with 16-mV step resolution. Any write below 1.024 V or above 19.200 V is ignored. Upon POR or when charge is
disabled, the system is regulated at the MaxChargeVoltage register.
Upon POR, REG0x15() is by default set as 4192 mV for 1 s, 8400 mV for 2 s, 12592 mV for 3 s or 16800 mV for
4 s. After CHRG_OK, if host writes REG0x14() before REG0x15(), the charge will start after the write to
REG0x14().If the battery is different from 4.2 V/cell, the host has to write to REG0x15() before REG0x14() for
correct battery voltage setting. Writing REG0x15() to 0 will set REG0x15() to default value on CELL_BATPRESZ
pin, and force REG0x14() to zero to disable charge.
The SRN pin is used to sense the battery voltage for voltage regulation and should be connected as close to the
battery as possible, and directly place a decoupling capacitor (0.1 µF recommended) as close to the device as
possible to decouple high frequency noise.
Figure 27. MaxChargeVoltage Register (SMBus address = 15h) [reset value based on CELL_BATPRESZ
pin setting]
15
Reserved
R/W
14
Max Charge
Voltage, bit 10
R/W
13
Max Charge
Voltage, bit 9
R/W
12
Max Charge
Voltage, bit 8
R/W
11
Max Charge
Voltage, bit 7
R/W
10
Max Charge
Voltage, bit 6
R/W
9
Max Charge
Voltage, bit 5
R/W
8
Max Charge
Voltage, bit 4
R/W
7
6
5
4
3
2
1
0
Max Charge Max Charge Max Charge Max Charge
Voltage, bit 3 Voltage, bit 2 Voltage, bit 1 Voltage, bit 0
Reserved
R/W
R/W
R/W
R/W
R/W
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 27. MaxChargeVoltage Register (SMBus address = 15h) Field Descriptions
SMBus
BIT
15
14
13
12
11
10
9
8
FIELD
TYPE
RESET
DESCRIPTION
Reserved
R/W
0b
Not used. 1 = invalid write.
Max Charge Voltage, bit 10
R/W
0b
0 = Adds 0 mV of charger voltage.
1 = Adds 16384 mV of charger voltage.
Max Charge Voltage, bit 9
R/W
0b
0 = Adds 0 mV of charger voltage.
1 = Adds 8192 mV of charger voltage
Max Charge Voltage, bit 8
R/W
0b
0 = Adds 0 mV of charger voltage.
1 = Adds 4096 mV of charger voltage.
Max Charge Voltage, bit 7
R/W
0b
0 = Adds 0 mV of charger voltage.
1 = Adds 2048 mV of charger voltage.
Max Charge Voltage, bit 6
R/W
0b
0 = Adds 0 mV of charger voltage.
1 = Adds 1024 mV of charger voltage.
Max Charge Voltage, bit 5
R/W
0b
0 = Adds 0 mV of charger voltage.
1 = Adds 512 mV of charger voltage.
Max Charge Voltage, bit 4
R/W
0b
0 = Adds 0 mV of charger voltage.
1 = Adds 256 mV of charger voltage.
Table 28. MaxChargeVoltage Register (SMBus address = 15h) Field Descriptions
SMBus
BIT
7
FIELD
Max Charge Voltage, bit 3
TYPE
R/W
RESET
0b
DESCRIPTION
0 = Adds 0 mV of charger voltage.
1 = Adds 128 mV of charger voltage.
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