RM310 NXP Semiconductors, RM310 Datasheet - Page 11

• Manufacturer Part Number: RM310
• Description: Ht Rm 310 Hitag Tm Mini Reader Module
• Manufacturer: NXP Semiconductors

HT RM310
2.4.5.
Use an oscilloscope to measure Û
The serial resistance R
2.4.6.
Before connecting the antenna to the read/write device (as shown in the graph below), you must
carry out a check calculation of the input level of the read/write device according to the formula
below in order to prevent damage.
The maximum value for Û
input (Pin RxA) of the read/write device.
With Û
With Û
Htrm310.doc/HS
L
L
< 32 Vp the resistor R
> 32 Vp you have to calculate and insert R
U

out
Checking the Antenna Voltage Û
Determining the Serial Resistance of the Antenna
2 5
.
R
Vp
e
I

S
L
(R
can be calculated with the following formula:
R
i
L
is the internal resistance of the output amplifier)
i
is 32 Vp. Based on this calculation damage is avoided at the receiver
U
U


U
R
L
e

out
I
max

U
s
out

can be omitted.
A
L
(
U
and Û
R

R
R
1
R
e
L
i
)
Page 11 of 41
with
Rev. 2.3
R
R
at a frequency of 125 kHz.
s

I
R
i
with
e
according to the following formula:
22
R
L
e
R
S
L
U

I

A
0 078
2
,
R
i
22
f
R
i
f
R
s
125
kHz
02-10-1998