Specifications

SIM7028 Hardware Design V1.00
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Pin name
Pin number
I/O
Description
Comment
SIM_DATA
15
I/O
SIM data input/output
SIM_RST
16
DO
SIM reset
SIM_CLK
17
DO
SIM clock
SIM_VDD
18
PO
Voltage supply for SIM card.
Support 1.8V or 3V SIM card
depends on SIM card type
3.0 V < VBAT ≤ 4.5 V, 1.8/3.0 V SIM card is supported;
2.2 V ≤ VBAT ≤ 3 V, only 1.8 V SIM card is supported.
The following figure is the reference circuit for SIM card. The component of circuit should be placed as
close as possible to the SIM card holder.
Figure 14: Reference circuit of SIM card interface
SIM card signal could be interference by some high frequency signal, it is strongly recommended to
follow these guidelines while designing:
 Add some TVS which parasitic capacitance should not exceed 50pF
 SIM card holder should be far away from GSM antenna
 SIM traces should keep away from RF lines, VBAT and high-speed signal lines, the traces should be as
short as possible

Keep SIM card holder’s GND connect to main ground directly

Shielding the SIM_CLK to prevent the interference to other signals
3.9 Network Status
NETLIGHT pin to indicate the current network status, which is used to control Network Status LED, its
reference circuit is shown in the following figure.
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Note