Designing an M24LR64-R multi-bank application

AN3250

6/16

Doc ID 17761 Rev 1

decrease the antenna inductance by the same factor as the increase of the tuning

capacitance of a multi-bank circuit:

In the following example, four M24LR64-R devices are connected in parallel on the same

antenna. The inductance value of this antenna must be four times smaller than the one used

for a single M24LR64-R.

As a reference, Figure 6 represents a single antenna single M24LR64-R device as per

STMicroelectronics ANT1-M24LR-A reference design.

Figure 6.

Block diagram for ANT1-M24LR-A reference design

The ANT5-M24LR-A reference design (Figure 7) consists of four M24LR64-R devices in

parallel, resulting in 256 Kbits of equivalent user memory. The equivalent tuning capacitance

value is 4 times that of a single M24LR64-R device. So the antenna, whether it is designed

on a PCB or uses an SMD inductor, must be 4 times smaller than the one used for one

single M24LR64-R device.