PM9525NL

## Power Transformers 

## _PTLA Series LLC Transformer_ 

- _3.6KW Transformer for OBC Applications PQ50/50 Platform, 52.8x52x43mm MAX Basic Insulation, 5mm Creepage 4.4KVrms Hi-pot Isolation Voltage Primary Side Concentrated Leakage Inductance_ 

|**Pulse PN**|**Electrical Specifications**|**ecifications@25°C – Operating Tem**|**Temperature -40°C to 125°C1**|**Temperature -40°C to 125°C1**|**Schematic**|
|---|---|---|---|---|---|
|**PM9525NL**|Pri. Inductance|(1-2)|42.4uH +/- 5%||2<br>1<br>4<br>3<br>340-435 VDC<br>220-470V@12A MAX<br>80-275KHz<br>1<br>2|
||Lk. Inductance|(1-2)W(3-4)<br>shorted|6.4uH +/- 8%|||
||DCR|(1-2)<br>(3-4)|12.5|mΩMax||
||||44|||
||Hi-Pot|Pri-Sec|4000 Vdc|||
||Capacitance|(1-2)to(3-4)|30pF Max|||



Notes: 

1. Storage Temperature: -40°C to 125°C 

2. The temperature of the component (ambient plus temperature rise) must be within the stated operating temperature range. 

3. Pri/Lk. Inductance value is measured at 100Khz/0.1Vrms. 

4. 3.6KW power based on thermal conductive potting within aluminium housing. 

5. Potting material provides additional mechanical fixation of the component in the OCB application. Therefore, shock and vibration testing is waived in the AEC-Q200 qualification test plan of the stand alone component 

## **Mechanical** 

## **PM9525NL** 

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PM9525NL<br>43.0 MAX<br>DATE CODE CTRY MFG<br>4.0±0.5<br>4X 2.0 +0.1-0.2 20.0±0.3 22.0<br>1 2<br>4 3<br>4X 2.5<br>46.5±0.3 46.5<br>52.8 MAX<br>Weight: 300g<br>Pan Size: 12pcs/Tray<br>4 3 1 2 Dimensions: mm<br>22.0±0.3 20.0<br>Unless otherwise specified,<br>eee 52.0 MAX all tolerance are ±0.25<br>FINAL OUTLINE SUGGESTED LAYOUT<br>**----- End of picture text -----**<br>


SUGGESTED LAYOUT 

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Power Transformers _PTLA Series LLC Transformer_ 

## **Application** 

## **PM9525NL** 

The benefits of the LLC topology for multi-KW  On Board Charger (OBC) applications are well understood, with the resonant inductor facilitating zero volt switching operation. The LLC transformer primary side leakage inductance (Lk_prim) can replace the need for a discrete external resonant inductor (Lext) if the value can be correctly sized and with the required tight tolerance. However, what is less understood is that the measured primary winding leakage inductance (primary inductance with secondary winding shorted) is a combination of LK_prim and the secondary side leakage inductance (Lk_sec) reflected on the primary side. So all of this measured leakage inductance is not available as primary side resonant inductance 

Figure 1 - Transformer Model including leakage inductance, and measure primary winding leakage inductance with secondary side leakage inductance reflected on primary side. 

PM9525NL implements a novel winding construction where the flux generated by the primary winding induction is loosely coupled with the secondary winding (i.e. high leakage inductance) while the flux generated by the secondary winding induction is tightly coupled with the primary winding (i.e. low leakage inductance) This is illustrated by the following simulation of the flux primary and secondary flux linkage, with the secondary winding occupying the centre winding segment over the air gap. The air gap provides a reluctance to the primary winding flux (outer winding segments) linking with the secondary winding. 

Figure 2 - Finite Element Modelling of the primary and secondary flux paths 

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Power Transformers 

_PTLA Series LLC Transformer_ 

**Application** 

## **PM9525NL** 

Based on the following measured inductance values 

- Primary Inductance, Secondary Open (Lso) 

- Primary Inductance, Secondary Shorted (Lss) 

- Secondary inductance, Primary Open Lpo 

Magnetising inductance (Lm), Lk_prim  and Lk_Sec can be calculated as follows 

- Lm = SQRT ((Lso-Lss) x Lpo/N[2] ) 

- Lk_prim = Lso – Lm 

- Lk_sec = Lpo - Lm x N[2] 

Of the 6.5uH measured primary winding leakage inductance on one PM9525NL sample, 6.48uH is calculated as primary side leakage inductance while just 0.04uH is calculated as secondary side leakage inductance. Therefore practically all of the 6.4uH ± 8% specified primary winding leakage inductance is available for the resonant circuit. 

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Measured Calculated<br>Lso Lss Lpo Lm Lk_Prim Lk_sec<br>µ H µ H µ H µ H µ H µ H<br>42.88 6.48 145.68 36.4 6.5 0.040<br>**----- End of picture text -----**<br>


Figure 3 – PM9525NL measured and calculated inductances 

This makes PM9525NL an well optimized solution, allowing for OBC cost and size reduction. 

## For More Information: 

**Americas -** prodinfo_power_americas@yageo.com  | **Europe -** prodinfo_power_emea@yageo.com  | **Asia -** prodinfo_power_asia@yageo.com 

Performance warranty of products offered on this data sheet is limited to the parameters specified. Data is subject to change without notice. Other brand and product names mentioned herein may be trademarks or registered trademarks of their respective owners. © Copyright, 2022. Pulse Electronics, Inc. All rights reserved. 

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