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FM350-GL Hardware Guide
Page 29 of 59
PCIe Difference Pair 1
W
S
S1<2S
≥
3W
≥
13
5
°
≥
20mil
PCIe Difference Pair 2
≥
1.5W
Figure 3-14 Requirement of PCIe line
The difference in length of two data lines in difference pair should be within 5mil, and the length match
is required for all parts. When the length match is conducted for the differential lines, the designed
position of correct match should be close to that of incorrect match, as shown in Figure 3-15. However,
there is no specific requirements for the length match of transmit pair and receiving pair, which means
the length match is only required by intra differential pair rather than inter differential pair.
Correct match
Dismatched end
Incorrect match
Matched end
Figure 3-15 Length match design of PCIe difference pair
3.5
USIM Interface
The FM350 module supports dual SIM, one is a built-in eSIM and another is a SIM card interface. The SIM
interface supports 1.8V and 3V SIM cards.
USIM Pins
The USIM1 pins description as shown in the following table:
Pin
Pin Name
I/O
Reset Value Description
Level
36
UIM_PWR
PO
-
USIM power supply
1.8V/3V
30
UIM_RESET
O
PD
USIM reset
1.8V/3V
32
UIM_CLK
O
PD
USIM clock
1.8V/3V
34
UIM_DATA
I/O
PD
USIM data,
internal pull up(4.7KΩ)
1.8V/3V