Usb Interface - SimCom SIM800 Hardware Design

Note: when a diode used to isolate voltage cross, customer should notice that there's voltage drop on the diode.
And the signal's voltage level should meet the customer's electrical character. The recommend diode is
Schottky diode e.g. RB551V-30TE-17 and SDM20U40.
If the voltage of UART is 5V on customer side, customer can use the following reference circuits:
UART1_TXD
Module
UART1_RXD
Note: The recommend Transistors' part numbers are 2SC4617TLR and PBHV8115Z.
4.5.3

USB Interface

USB interface supports software debug function. When power on the module, connect USB_VBUS, USB_DP,
USB_DN and GND to PC, then install the driver successfully, a UART port could be recognized by the PC,
customer could achieve the software Debug purpose with this UART port.
The following diagram is recommended:
SIM800_Hardware Design_V1.10
VDD_EXT
Module
VDD_EXT
47K
Figure 22: TX level converting by transistor
VDD_EXT
VDD_EXT
4.7K
Figure 23: RX level converting by transistor
31
VDD
4.7K
4.7K
RXD
DTE
VDD
4.7K
47K
TXD
Smart Machine Smart Decision
DTE
2018-08-13