T4260-ILQ Atmel, T4260-ILQ Datasheet - Page 18

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

Specifications of T4260-ILQ

• 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: -

FM Mixer
PLL Loop Filter
Fractional Mode
18
T4260
Table 18. Divider Factor of the AM Prescaler
In the FM mixer stage, the FM reception frequency is down-converted to the IF
frequency. The VCO frequency is used as LO frequency for the mixer.
The PLL loop filter selection for AM and FM mode can be controlled by bit 145 as given
in Table 19.
Table 19. Loop Filter Operating Mode
The activated fractional mode (bit 144 = 0) in connection with the direct shift (bit 32 = 0)
allows fast frequency changes (with the help of the 2-bit shift) with a four times higher
step frequency. After the frequency change, the normal step frequency is active again.
If the fractional mode is deactivated (bit 144 = 1) and direct shift mode is active,
(bit 32 = 0) the VCO frequency is set to the next lower frequency which is many times
the amount frequency of 4 times step frequency. This means that the 2 shifted bits of the
active N-Divider are not used in this mode. The shift bits are interpreted as logic 0.
The fractional mode with direct shift mode deactivated (bit 32 = 1) allows normal fre-
quency changes with a step frequency of 12.5 kHz.
Table 20. Fractional Mode
Divider AM Prescaler
Divide by 10
Divide by 2
Divide by 3
Divide by 4
Divide by 5
Divide by 6
Divide by 7
Divide by 8
Divide by 9
PDAM/PDFM
PDFM active
PDAM active
Fractional
OFF
ON
B143
0
0
0
0
0
0
0
0
1
B142
0
0
0
0
1
1
1
1
x
B145
B144
B141
0
1
0
1
0
0
1
1
0
0
1
1
x
4528J–AUDR–11/04
B140
0
1
0
1
0
1
0
1
x