T4260-IL Atmel, T4260-IL Datasheet - Page 14

• Manufacturer Part Number: T4260-IL
• Description: IC RECEIVER AM/FM FRONT 44-SSOP
• Manufacturer: Atmel

Specifications of T4260-IL

• Frequency: AM, FM
• Modulation Or Protocol: AM, FM
• Applications: AM/FM Radio Receiver
• Current - Receiving: 85mA
• Data Interface: PCB, Surface Mount
• Antenna Connector: PCB, Surface Mount
• Voltage - Supply: 8 V ~ 10 V
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 44-SSOP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Features: -
• Sensitivity: -
• Memory Size: -
• Data Rate - Maximum: -

IF Amplifier
VCO
RF-AGC
14
T4260
The IF gain amplifier can be used in AM and FM mode to compensate the loss of the
external ceramic bandfilters.
The IF gain can be controlled in 2-dB steps by setting bit 6 to bit 9 as given in Table 6.
Table 6. IF Gain
The selection of the IF amplifier input can be controlled by bit 11 as given in Table 7.
Table 7. IF-IN Operating Mode
Note:
The VCO HI/LO function is controlled by means of bit 10.
Table 8. VCO Operating Mode
The AM and FM RF-AGC controls the current into the AM and FM pin diodes (FM pin 3
and AM pin 9) to limit the level at the AM or FM mixer input. If the level at the AM or FM
mixer input exceeds the selected threshold, then the current into the AM or FM pin
diodes increases. If this step is not sufficient in AM mode, the source drain voltage of the
MOSFET (pin 11) can be decreased. In AM mode, the time constants can be selected
by the external capacitors at pin 42 (RFAGCA1) and at pin 12 (RFAGCAM2) and in FM
mode by an external capacitor at pin 33 (RFAGCFM). In AM mode, the double pole (by
the capacitors at pin 42 and pin 12) allows a better harmonic distortion by a higher time
constant.
The RF-AGC can be controlled in 1-dB steps by setting the bits 12 to 15. The values for
FM and AM are controlled by bit 17.
IF Gain
The AM input (pin 35) has an input impedance of 2.5 k for matching with a crystal filter.
The FM input (pin 36) has an input impedance of 330
12 dB
14 dB
16 dB
18 dB
20 dB
40 dB
42 dB
...
VCO high current
VCO low current
IF-IN AM/FM
VCO HI/LO
IF-IN AM
IF-IN FM
B9
...
0
0
0
0
0
1
1
B8
...
0
0
0
0
1
1
1
for matching with a ceramic filter.
B7
...
0
0
1
1
0
1
1
B11
B10
0
1
0
1
4528J–AUDR–11/04
B6
...
0
1
0
1
0
0
1