mirror of
git://projects.qi-hardware.com/ben-wpan.git
synced 2024-12-23 16:25:30 +02:00
59 lines
2.4 KiB
Plaintext
59 lines
2.4 KiB
Plaintext
Replace balun and filter with integrated balun
|
|
|
|
|
|
We consider the balun needs for the AT86RF230 and the TI/Chipcon
|
|
CC2520 we may try as a design alternative.
|
|
|
|
For the AT86RF230, Atmel recommend baluns with integrated filter,
|
|
namely the Wuerth 748421245 and the Johanson 2450FB15L0001, both in the
|
|
AR86RF230 data sheet.
|
|
|
|
For the CC2520, TI recommend a microstrip-based design for the balun,
|
|
both in the CC2420/CC243x/CC2480 application note [1] and the reference
|
|
design [2], without fully characterizing neither the transceiver's RF
|
|
output nor all the components in the balun.
|
|
|
|
Johanson lists the 2450FB15L0001 [3] and even a 2450BM15B0002 [3] for
|
|
the TI/Chipcon CC2520, but not even Octoparts is able to find a
|
|
distributor for these parts.
|
|
|
|
Digging deeper, TI reveal more information about the balun in [5].
|
|
|
|
Finally, TI somewhat hesitatingly acknowledge that the Murata balun
|
|
LDB182G4510C-110 can be used for the CC2520 [6], with a 3.9 nH inductor
|
|
connecting RF_P and RF_N, the balun coupled to GND not directly but via
|
|
10 nF, and finally an LC low-pass filter with 1.5 nH and 2.2 pF at the
|
|
output, for EMI compliance.
|
|
|
|
Note that this also means that CC2520 and AT86RF230 both have an
|
|
impedance of 100 Ohm.
|
|
|
|
A balun without filter similar to the Murata part would be the Johanson
|
|
2450BL15K100.
|
|
|
|
Manufacturer Part number Package Digi-Key Price/Qty
|
|
--------------- ----------------------- ------- --------------- ---------------
|
|
Wuerth 748421245 0805-6 732-2230-1-ND 2.15/25
|
|
732-2230-2-ND 0.753/4000
|
|
Johanson 2450FB15L0001 0805-6 - -
|
|
Johanson 2450BM15B0002 0805-6 - -
|
|
Johanson 2450BL15K100 0805-6 712-1045-1-ND 0.488/10
|
|
712-1045-2-ND 0.225/4000
|
|
Murata LDB182G4510C-110 0603-6 490-5023-1-ND 0.325/10
|
|
490-5023-2-ND 0.114/4000
|
|
|
|
[1] http://www.ti.com/litv/pdf/swra098d
|
|
[2] http://focus.ti.com/docs/toolsw/folders/print/cc2520em_refdes.html
|
|
[3] http://www.johansontechnology.com/images/stories/ip/baluns/Balun_Filter_Combo_Matched_2450FB15L0001_v11.pdf
|
|
[4] http://www.johansontechnology.com/images/stories/ip/baluns/balun_filter_combo_matched_2450bm15b0002_v2.pdf
|
|
[5] http://www.ti.com/litv/pdf/swra236a
|
|
[6] http://e2e.ti.com/support/low_power_rf/f/155/t/15910.aspx
|
|
|
|
|
|
Conclusion: the Wurth balun appears to be the safest choice for
|
|
prototyping the AT86RF230. Due to its high cost, a circuit with a
|
|
discrete filter may be considered for larger quantities.
|
|
|
|
For the CC2520, it's probably safest to directly try the Muarta balun
|
|
with the recommended discrete filtering circuit.
|