Question
When designing a carrier board for GigaBlox Nano that mates directly to the LSHM-120 connector and uses 8-pin Molex PicoBlade Ethernet connectors, what is the pin number for each Ethernet signal? Figure 7 in datasheet A_H shows C−, C+, D+, D−, B+, B−, A+, A− along the connector, but does not label pin 1.
Does Figure 11 use carrier-side LSHM-120 pin numbering, with VBUS on pins 2 and 4 and GND on pins 1, 3 and 39? Is the BB-PBRJ1-8-0.3 cable numerically 1:1 between PicoBlade and RJ45?
Answer
For the 8-pin PicoBlade connector in our PicoConn reference design, the signal mapping is:
- Pin 1: C−
- Pin 2: C+
- Pin 3: D+
- Pin 4: D−
- Pin 5: B+
- Pin 6: B−
- Pin 7: A+
- Pin 8: A−
Yes, Figure 11 in the GigaBlox Nano datasheet A_H uses carrier-side LSHM-120 numbering: VBUS on pins 2 and 4; GND on pins 1, 3 and 39. Table 3 uses module-side numbering, with the mating relationship shown in Table 2.
The BB-PBRJ1-8-0.3 cable is not numerically 1:1 to RJ45. PicoBlade pins 1–8 map to RJ45 pins 5, 4, 7, 8, 3, 6, 1, 2, as shown in the BB-PBRJ1-8-0.3 cable drawing.