Usb Interface - Quectel SC600Y-EM Series Hardware Design

Figure 11: Reference Design for Battery Charging Circuit
SC600Y&SC600T offer a fuel gauge algorithm that is able to accurately estimate the battery's state by
current and voltage monitor techniques. Using precise measurements of battery voltage, current, and
temperature, the fuel gauge provides a dependable state of charge estimate throughout the entire life of
the battery and across a broad range of operating conditions. It effectively protects the battery from
over-discharging, and also allows users to estimate the battery life based on the battery level so as to
timely save important data before completely power-down.
Mobile devices such as mobile phones and handheld POS systems are powered by batteries. When
different batteries are utilized, the charging and discharging curve has to be modified correspondingly so
as to achieve the best effect.
If thermistor is not available in the battery, or adapter is utilized for powering the module, then there is only
a need for VBAT and GND connection. In this case, the system may be unable to detect the battery,
which will cause power-on failure. In order to avoid this, BAT_THERM should be connected to GND with a
47KΩ resistor. BAT_PLUS and BAT_MINUS must be connected, otherwise there may be abnormalities in
use of the module. Among them, BAT_PLUS and BAT_MINUS are used for battery level detection, and
they should be routed as differential pair to ensure accuracy.

3.9. USB Interface

SC600Y&SC600T provide one integrated Universal Serial Bus (USB) interface which complies with the
USB 3.0/2.0 specifications and supports super speed (5Gbps) on USB 3.0, high speed (480Mbps) on
USB 2.0 and full speed (12Mbps) modes. The USB interface supports USB OTG function, and is used for
AT command communication, data transmission, software debugging and firmware upgrade.
The following table shows the pin definition of USB interface.
SC600Y&SC600T_Hardware_Design
R1
VBAT
0805
0R
NTC
GND
D1
Battery
ESD
SC600Y&SC600T Hardware Design
Adapter or USB
D2 C1 C2 C3
ESD 100uF 33pF
1uF
Smart LTE Module Series
USB _VBUS
VBAT
BAT_PLUS
BAT_THERM
BAT_MINUS
GND
Module
51 / 128