SIM800L datasheet(32/73 Pages) SIMCOM

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Figure 24: RX level matching circuit

Note: When Figure22, Figure 23 and Figure 24 are used for electrical level isolation, if customers use serial port to upgrade SW,

please note VDD_EXT has no voltage output during the upgrading process, LDO output could be used as VDD_EXT in the

figure, upgrading through USB port is recommended.

4.5.3

Debug Interface

SIM800H&SIM800L could achieve software debug function through USB interface. When powering on the

module, connect VBUS, USB_DP, USB_DN, and GND to PC, then install the driver following the prompts, a

UART port could be recognized by PC, customer could achieve the software Debug with this UART port.

SIMCom recommended the following connected diagram:

Figure 25: USB reference circuit

The TVS on USB data line should be less than 5pf, and traced by differential forms.

Note: please reserve the USB interface or test point for the further debugging

Table 11: VBUS operation voltage

Min

Typ

Max

Unit

VBUS

4.3

5.0

7.0

SIM800H&SIM800L_Hardware Design_V2.02

2015-07-27

SIM800L 数据表(PDF) 32 Page - SIMCom