IEEE 802.15.4 subsystem
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Source at commit 809a0935d8833dd463280293cf6075d91e7b62ab created 8 years 10 months ago. By Stefan Schmidt, atusb/fw: Bump minor version to mark first public release. | |
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1 | Replace balun and filter with integrated balun |
2 | |
3 | |
4 | We consider the balun needs for the AT86RF230 and the TI/Chipcon |
5 | CC2520 we may try as a design alternative. |
6 | |
7 | For the AT86RF230, Atmel recommend baluns with integrated filter, |
8 | namely the Wuerth 748421245 and the Johanson 2450FB15L0001, both in the |
9 | AR86RF230 data sheet. |
10 | |
11 | For the CC2520, TI recommend a microstrip-based design for the balun, |
12 | both in the CC2420/CC243x/CC2480 application note [1] and the reference |
13 | design [2], without fully characterizing neither the transceiver's RF |
14 | output nor all the components in the balun. |
15 | |
16 | Johanson lists the 2450FB15L0001 [3] and even a 2450BM15B0002 [3] for |
17 | the TI/Chipcon CC2520, but not even Octoparts is able to find a |
18 | distributor for these parts. |
19 | |
20 | Digging deeper, TI reveal more information about the balun in [5]. |
21 | |
22 | Finally, TI somewhat hesitatingly acknowledge that the Murata balun |
23 | LDB182G4510C-110 can be used for the CC2520 [6], with a 3.9 nH inductor |
24 | connecting RF_P and RF_N, the balun coupled to GND not directly but via |
25 | 10 nF, and finally an LC low-pass filter with 1.5 nH and 2.2 pF at the |
26 | output, for EMI compliance. |
27 | |
28 | Note that this also means that CC2520 and AT86RF230 both have an |
29 | impedance of 100 Ohm. |
30 | |
31 | A balun without filter similar to the Murata part would be the Johanson |
32 | 2450BL15K100. |
33 | |
34 | Manufacturer Part number Package Digi-Key Price/Qty |
35 | --------------- ----------------------- ------- --------------- --------------- |
36 | Wuerth 748421245 0805-6 732-2230-1-ND 2.15/25 |
37 | 732-2230-2-ND 0.753/4000 |
38 | Johanson 2450FB15L0001 0805-6 - - |
39 | Johanson 2450BM15B0002 0805-6 - - |
40 | Johanson 2450BL15K100 0805-6 712-1045-1-ND 0.488/10 |
41 | 712-1045-2-ND 0.225/4000 |
42 | Murata LDB182G4510C-110 0603-6 490-5023-1-ND 0.325/10 |
43 | 490-5023-2-ND 0.114/4000 |
44 | |
45 | [1] http://www.ti.com/litv/pdf/swra098d |
46 | [2] http://focus.ti.com/docs/toolsw/folders/print/cc2520em_refdes.html |
47 | [3] http://www.johansontechnology.com/images/stories/ip/baluns/Balun_Filter_Combo_Matched_2450FB15L0001_v11.pdf |
48 | [4] http://www.johansontechnology.com/images/stories/ip/baluns/balun_filter_combo_matched_2450bm15b0002_v2.pdf |
49 | [5] http://www.ti.com/litv/pdf/swra236a |
50 | [6] http://e2e.ti.com/support/low_power_rf/f/155/t/15910.aspx |
51 | |
52 | |
53 | Conclusion: the Wurth balun appears to be the safest choice for |
54 | prototyping the AT86RF230. Due to its high cost, a circuit with a |
55 | discrete filter may be considered for larger quantities. |
56 | |
57 | For the CC2520, it's probably safest to directly try the Muarta balun |
58 | with the recommended discrete filtering circuit. |
59 |