SC8913 EVM USER GUIDE
SOUTHCHIP SEMICONDUCTOR
SOUTHCHIP CONFIDENTIAL
Copyright © 2018, Southchip Semiconductor Technology (Shanghai) Co., Ltd
9
1.2
Other Settings
1.2.1
Loop compensation setting
COMP pin is used for loop compensation setting. R25=10kΩ and C28=22nF is suggested for typical application.
Once loop instability occurs, R25 and C28 should be adjusted according to practical situation.
1.2.2
MOSFET driver resistor setting
R9/R10 is driver resistor which connects LD/HD with LG/HG respectively on the EVM board. The default value
of R9/R10 is 0 ohm. Increasing R9/R10 value will slow down switching speed and improve EMI performance,
but with the cost of decreased efficiency at the same time.
1.2.3
Power path management Q2/Q4 driver setting
Q2/Q4/Q1 is the power MOSFET used to control the power path. Q2’s driver signal is connected to GPO pin;
Q4’s driver signal is connected to PGATE pin; Q1’s driver signal is connected to MicroB_drv pin(P5);
Through I2C interface, Q4 and Q2 can be controlled by 0x0C<7> (EN_PGATE) and 0x0C<7> (GPO_CTRL)
respectively. When the corresponding setting bit is 1, Q4/Q2 will be on. Otherwise, Q4/Q2 will be off.
Specification description can be referred to
SC8913
datasheet.
1.2.4
Adapter Attachment/Detachment Detection
MicroUSB adapter attachment/detachment detection is realized by ACIN pin. When chip detects adapter
plug
-
in, it will set AC_OK interrupt bit, and INT pin will assert interrupt signal. Specification description can be
referred to
SC8913
datasheet
1.2.5
Dithering function test configuration
If switching frequency dithering function is tested, R17 should be removed and USB2 should disconnected. R15
value is set to 0 ohm, PGATE/DITH pin will be used for frequency dithering.
2.
Test Precautions
1)
When MicroUSB is used as input port, MicroB_drv pin should be connected with VHI (right pin) to open
MOS Q1.
2)
If power path function is not tested, USB interface can be always connected to VBUS port
，
battery can be
connected to VBAT port. Chip operation mode can be changed by EN_OTG bit.
3)
In the charging mode, USB charges the battery from VBUS to VBAT; in the reverse discharging mode,
battery discharges power from VBAT to VBUS.
4)
PSTOP pin should be floating or connected to ground to enable the power operation.
5)
SC8913 does not support starting up with CC mode electronic load. It’s suggested to start up with no load
or CR mode electronic load. Load can’t be so heavy that exceeds the current limit of SC8913, or it can not
start up normally.
6)
After starting up, if the electronic load CC mode is used as the load, it should be noted that the CC load
current should not exceed the output current limit, and the corresponding input current should not
exceed the input current value. Otherwise, the CC load will pull the output voltage down directly. If CR
mode loading is used, even if the input / output current limit occurs, the output voltage still can be
stabilized at a balance point and will not be forced down.
