SC8913 EVM USER GUIDE
SOUTHCHIP SEMICONDUCTOR
SOUTHCHIP CONFIDENTIAL
Copyright © 2018, Southchip Semiconductor Technology (Shanghai) Co., Ltd
7
VBUS voltage can be calculated as below:
VBUS = VBUSREF_E x (1+
RUP
RDOWN
)
External setting is chosen as the default configuration on the EVM board. R27(RUP) value is 100kΩ,
R28(RDOWN) value is 24kΩ, so the default output voltage of VBUS is 5.17V.
Note: If more accurate voltage value is needed, 0.1% accuracy resistor is suggested.
1.1.4
IBUS Current Limit Setting
IBUS current limit function is effective in both charging and discharging mode.
IBAT current limit is decided by
IBUS_LIM_SET
and
IBUS_RATIO
.
IBUS_LIM_SET
: Reg 0x05<7:0>
IBUS_RATIO
: Reg 0x08<3:2>
When Reg 0x08<3:2> (IBAT_RATIO) =01, IBUS_RATIO=6;
When Reg 0x08<3:2> (IBUS_RATIO) =10, IBUS_RATIO=12;
RS1 is the IBUS sense resistor value.
IBUS_LIM (A) =
(IBUS_L1)
256
× IBUS_RATIO ×
10 mΩ
RS1
RS1 value is 10
mΩ
, the default IBUS current limit is 3A.
1.1.5
IBAT Current Limit setting
IBAT current limit function is effective in both charging and discharging mode.
IBAT current limit is decided by:
IBAT_LIM_SET
and
IBAT_RATIO
.
IBAT_LIM_SET
: Reg 0x06<7:0>
IBAT_RATIO
: Reg 0x08<4>
When Reg 0x08<4> (IBAT_RATIO) =0, IBUS_RATIO=6;
When Reg 0x08<4> (IBAT_RATIO) =1, IBUS_RATIO=12.
RS2 is the IBAT sense resistor.
IBAT_LIM (A) =
IBAT_1
256
× IBAT_RATIO ×
10 mΩ
RS2
RS2 value is 5
mΩ
, the default IBUS current limit is 24A.
1.1.6
VINREG Setting
During charging, if the IBUS charging current is higher than adapter’s current capability, the adapter will be
overloaded and the VBUS voltage is pulled low. Once the IC detects the VBUS voltage drops at VINREG
threshold, it reduces the charging current automatically and regulates the VBUS voltage at VINREG threshold.
VINREG value is decided by:
VINREG_SET
and
VINREG_RATIO
.
VINREG_SET
: Reg 0x07<7:0>
VINREG_RATIO
: Reg 0x09<4>
