TDA5251 Infineon Technologies, TDA5251 Datasheet - Page 40

• Manufacturer Part Number: TDA5251
• Description: TXRX FSK/ASK SGL LP TSSOP-38
• Manufacturer: Infineon Technologies
• Type: Transceiverr

Specifications of TDA5251

• Package / Case: 38-TSSOP
• Frequency: 315MHz
• Data Rate - Maximum: 64kbps
• Modulation Or Protocol: ASK, FSK
• Applications: RKE, Remote Control Systems
• Power - Output: 13dBm
• Sensitivity: -109dBm
• Voltage - Supply: 2.1 V ~ 5.5 V
• Current - Receiving: 9.3mA
• Current - Transmitting: 14mA
• Data Interface: PCB, Surface Mount
• Antenna Connector: PCB, Surface Mount
• Operating Temperature: -40°C ~ 85°C
• Operating Frequency: 0.35 MHz
• Operating Supply Voltage: 2.5 V, 3.3 V, 5 V
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Mounting Style: SMD/SMT
• Operating Temperature (min): -40C
• Operating Temperature (max): 85C
• Operating Temperature Classification: Industrial
• Product Depth (mm): 4.4mm
• Product Length (mm): 9.7mm
• Operating Supply Voltage (min): 2.1V
• Operating Supply Voltage (max): 5.5V
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Memory Size: -
• Lead Free Status / Rohs Status: Compliant
• Other names: SP000014554; TDA5251; TDA5251INTR; TDA5251XT

The noise figure of the LNA-input-matching network is equal to its losses. The input matching
network is always a compromise of sensitivity and selectivity. The loaded Q should not get too high
because of 2 reasons:
more losses in the matching network and hence less sensitivity
tolerances of components affect matching too much. This will cause problems in a tuning-free mass
production of the application. A good CAE-tool will help to see the effects of component tolerances
on the input matching more accurate by tweaking each value.
A very high selectivity can be reached by using SAW-filters at the expense of higher cost and lower
sensitivity which will be reduced by the losses of the SAW-Filter of approx. 4dB.
Image-suppression:
Due to the quite high 1
frequency of the receiver is at:
The image suppression on the evalboard is about 12dB.
LO-leakage:
The LO of the 1
The LO-leakage of the evalboard on the RF-input is about –102dBm.
3.1.3
The evalboard can be set into the TX-Mode by grounding the RX/TX-jumper on the evalboard or
programming the TDA5251 to operate in the TX-Mode. If the IC is programmed to operate in the
TX-Mode, the RX/TX-pin will act as an open drain output at a logical LOW. Then a DC-current can
flow from VCC to GND via L1, L2, D1, R1 and D2.
Now both pin-diodes are biased with a current of approx. 0.3mA@3V and have a very low
impedance for RF.
Data Sheet
I
f
PIN
LO
f
IMAGE
−
=
DIODE
f
RECEIVE
Switch in TX-Mode
=
=
V
st
f
CC
SIGNAL
Mixer is at:
*
−
4
3
2
*
=
V
315
FORWARD
st
-IF of the frontend, the image frequency is quite far away. The image
+
MHz
2
R
1
*
*
f
,
IF
4
3
PIN
=
−
=
420
DIODE
315
MHz
MHz
+
2
40
*
105
=
525
MHz
TDA5251 F1
Version 1.1
Application
2007-02-26
[3 – 6]
[3 – 7]
[3 – 5]