P4095 EM Microelectronic, P4095 Datasheet - Page 10

• Manufacturer Part Number: P4095
• Description: P4095 Read/write Analog Front End For 125khz Rfid Basestation
• Manufacturer: EM Microelectronic

Equations
Antenna resonant frequency f
Where C
C
Usually antenna coil is specified by its inductance
(L
is defined by following equation:
The equations which follow are valid for bridge
configuration as defined on Figures 1, 2 and 3. For
figures 1 and 2 R
The AC current amplitude at resonant frequency is
defined as follows:
RMS antenna current (important for power
dissipation calculation):
EM Microelectronic-Marin SA cannot assume responsibility for use of any circuitry described other than circuitry entirely
embodied in an EM Microelectronic-Marin SA product. EM Microelectronic-Marin SA reserves the right to change the circuitry
and specifications without notice at any time. You are strongly urged to ensure that the information given has not been
superseded by a more up-to-date version.
© EM Microelectronic-Marin SA, 06/2000, Rev. C/296
10
DV1
A
) and Q factor (Q
and C
0
I
is resonant capacitor composed of C
ANT
DV2
C
0
:
=
=
EM Microelectronic-Marin SA, CH-2074 Marin, Switzerland, Tel. [phone], Fax. [phone]
R
SER
π
f
I
C
4
0
RMS
ANT
RES
R
A
=
has to be considered 0.
). Serial resistance of antenna
ANT
2
=
+
=
π
I
C
2
V
+
C
ANT
π
DV
dd
1
2
L C
DV
Q
R
f L
0
A
SER
1
0
A
−
1
:
∗
+
V
A
0
C
C
+
ss
DV
DV
2
R
2
2
AD
(2)
(1)
(3)
(5)
(4)
RES
,
Appendix
Peak to peak voltage on antenna is defined by
following equation:
To ensure correct operation of the AM demodulation
chain, the AC peak to peak voltage on DEMOD_IN
pin (V
range. Once peak to peak voltage on antenna is
known the capacitor divider division factor can be
calculated:
Power dissipation is composed of power dissipated
on ANT drivers and internal power consumption:
Temperature increase of die due to power
dissipation is:
Where R
P
DMOD_INpp
V
= ⋅
Th
DMOD
2
is Package thermal resistor.
I
_
RMS
) has to be inside common mode
INpp
V
∆
2
T
ANTpp
⋅
=
R
=
V
AD
P
ANTpp
=
+
⋅
π
R
I
I
f
Th
DDon
ANT
C
0
C
DV
0
(
C
1
V
+
DV
DD
P4095
C
1
−
DV
V
2
SS
)
(7)
(6)
(8)
(7)