tda5251f1 Infineon Technologies Corporation, tda5251f1 Datasheet - Page 51

• Manufacturer Part Number: tda5251f1
• Description: Ask/fsk 315mhz Wireless Transceiver
• Manufacturer: Infineon Technologies Corporation

Confidential
e.g.
with a frequency deviation of 30kHz.
Figure 3-15 shows the configuration of the switches and the capacitors to achieve the 2 desired
frequencies. Gray parts of the schematics indicate inactive parts. For FSK modulation the ASK-
switch is always open.
For FSK LOW the FSK-switch is closed and C
by:
For finetuning C tune1 can be varied over a range of 8 pF in steps of 125fF. The switches of this C-
bank are controlled by the bits D0 to D5 in the FSK register (subaddress 01H, see Table 3-6).
For FSK HIGH the FSK-switch is open. So the effective C
The C-bank C tune2 can be varied over a range of 16 pF in steps of 250fF for finetuning of the FSK
HIGH frequency. The switches of this C-bank are controlled by the bits D8 to D13 in the FSK
register (subaddress 01H, see Table 3-6).
Figure 3-15
Preliminary Specification
C
C
C
V
C v+
V1
V2
-
f
f
COSC HI
COSC LOW
=
=
C
f, C
C
(
-------------------------------------------------------------------------------------- -
V3
C v1
C
v
L
1
FSK modulation
v1
XSWA 22
XOUT 19
XSWF 20
XGND 23
+
+
XIN 21
+
C
C tune1
C
tune
tune1
= (315E6 + 30E3) / 24= 13.12625MHz
= (315E6 - 30E3) / 24= 13.12375MHz
FSK LOW
1
)
+
×
L
(
C
C v2
v2
+
+
C
C tune2
C
C
tune2
-R
tune2
tune1
)
v2
51
and C
C
C
V1
V2
tune2
C
f, C
v+
V3
are bypassed. The effective C
L
is given by:
XSWA 22
XSWF 20
XOUT 19
XGND 23
XIN 21
FSK HIGH
[3 – 20]
[3 – 21]
L
C
C
-R
tune2
tune1
TDA5251 F1
Version 1.0
Application
2003-02-18
QOSC_FSK.wmf
v-
is given