CTX10-1A-R has been discontinued by Eaton/Cooper Bussmann

Hello,

The CTX10-1A-R (Ref.des L1; Dual Winding Shielded Power Inductor/Transformer CTX OCTA-PAC® PLUS Serie) on the Fmc Adc 100M 14b 4cha (EDA-02063) has been discontinued by Eaton/Cooper Bussmann as of october 31, 2017.
Eaton still provides the CTX10-1-R and CTX10-1P-R, but both have different specifications.

Are there any alternatives known which can and may be used on the Fmc Adc 100M 14b 4cha?

Kind regards,
René Bakker

INCAA looked at it and wrote the text below.
Sundance will do an evaluation of the proposed alternative CTX10-1-R.


Part

Parallel open circuit inductance [uH]

Parallel full load current

[A (dc)]

Parallel DC resistance [Ohm (max)]

Series open circuit inductance

[uH]

Series full load current

[A(dc)]

Series DC resistance [Ohm (max)]

Height

[mm]

CTX10-1A-R

10.58

2.5

0.046

42.30

1.25

0.183

4.19

CTX10-2-R

10.58

2.5

0.031

42.30

1.25

0.125

5.97

CTX10-1-R

10.00

1.9

0.044

40.00

0.95

0.176

4.19

CTX10-1P-R

9.62

1.8

0.052

38.48

0.85

0.227

4.19

The big difference between the CTX10-1A-R and the CTX10-2-R, CTX10-1-R or CTX10-1P-R is the used core material. De CTX10-1A-R is an OCTA-PAC PLUS, the CTX10-2-R and CTX10-1-R are an OCTA-PAC, and the CTX10-1P-R is a ECONO-PAC…

OCTA-PAC’s are designed around high frequency, low loss core material.

ECONO-PAC’s are a lower cost version of OCTAPAC’s offering high saturation flux density, Iron powder core material.

OCTA-PAC PLUS’s offer higher current ratings and higher saturation flux densities than OCTAPAC and ECONO-PAC, Amorphous metal core material.

The advantage of the ‘higher current ratings and higher saturation flux densities’ for the originally used CTX10-1A-R in a lower size device can be replaced by the higher size CTX10-2-R device which has about the same specifications. Het problem of the CTX10-2-R is however its height. The FMC specification states that the height of the part located in component envelope (see ANSI/VITA 57.1 FPGA Mezzanine Card (FMC) Standard, Figure 3) can only be 4.7mm high (see Figure 9), so the CTX10-2-R is not allowed, as it is situated on the EDA-02063 Fmc Adc 100M 14b 4cha within that area.

The next best is the CTX10-1-R which has a slightly lower inductance and a slightly lower full load current specification.

The power circuit of the EDA-02063 Fmc Adc 100M 14b 4cha, using the inductor as L1 and the LT1931ES5 (IC21) as switching regulator, can only provide 350mA. The LT1931 datasheet states: “When using coupled inductors, choose one that can handle at least 1A of current without saturating, and ensure that the inductor has a low DCR (copper-wire resistance) to minimize I2R power losses.” The datasheet even suggests the CTX10-1.

So you could ask yourself why in the original design the CTX10-1A-R was chosen and not the CTX10-1-R. This seems to have been a choice based on tests. The EDA-02063 Fmc Adc 100M 14b 4cha V1.0 used a SDQ12-4R7-R which is 4.7uH. If a 10uH equivalent should have been the better value, a SDQ12-100-R could have been a drop in replacement. As of the V2.0 version of the design the CTX10-1A-R is used and not the CTX10-1-R. There are no design review documents available on the ohwr site regarding this design change to V2.0, so it is unknown why this part is changed.

A change from the CTX10-1A-R to the CTX10-1-R for the V5.0 version could have some potential influence on the characteristics of the LT1931ES5 circuit, which could be shown in the form of a difference noise floor or a different amplitude of spurious frequencies in the measured signals. This can only be checked by an investigation by means of measurements.

Here’s an older issue that also proposed some alternatives: