# Critical component placement

Source: [https://docs.qualcomm.com/doc/80-PV086-5P/topic/Critical-component-placement.html](https://docs.qualcomm.com/doc/80-PV086-5P/topic/Critical-component-placement.html)

The QRB5165 critical component placement is listed below.

- The following components should be placed close to their respective QRB5165 pins.
- In most cases, these signals should route to their components on layer 1 or layer 2 of the
        PCB.
- ZQ and EBIx\_CAL resistors tie to the VDDQ supply for LPDDR5 PoP memories.
- All the REXT resistors should be placed as close to the QRB5165 ball as possible, and the
        REXT routing should be short and isolated.

Table :  1. Critical component placement

| QRB5165 pin name | Component requirement | Pull-up/pull-down/series connection |
| --- | --- | --- |
| EBI02\_CAL | 240 Ω ± 1% | Pull-up – VDDQ |
| EBI13\_CAL | 240 Ω ± 1% | Pull-up – VDDQ |
| QREFS\_CXO\_REXT | 3 kΩ ± 1% | Pull-down |
| REFGEN\_REXT0 | 100 Ω ± 1% | Pull-down |
| REFGEN\_REXT1 | 100 Ω ± 1% | Pull-down |
| ZQ\_A (LPDDR5) | 240 Ω ± 1% | Pull-up – VDDQ |
| ZQ\_D (LPDDR5) | 240 Ω ± 1% | Pull-up – VDDQ |

**Parent Topic:** [PCB design considerations](https://docs.qualcomm.com/doc/80-PV086-5P/topic/PCB-design-considerations.html)

Last Published: Jul 07, 2023

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