t4227-fbg3 ATMEL Corporation, t4227-fbg3 Datasheet - Page 3

• Manufacturer Part Number: t4227-fbg3
• Description: Time-code Receiver
• Manufacturer: ATMEL Corporation

IN1, IN2
A ferrite antenna is connected between IN1 and IN2. For
high sensitivity, the Q factor of the antenna circuit should
be as high as possible. Please note that a high Q factor
requires temperature compensation of the resonant
frequency in most cases. We recommend a Q factor
between 40 and 150. Depending on the application. An
optimal signal-to-noise ratio will be achieved by a reso-
nant resistance of 50 kW to 200 kW.
RFO
In order to achieve a high selectivity, a crystal is con-
nected between the Pins RFO and RFI. It is used with the
serial resonant frequency according to the time-code
transmitter (e.g., 60 kHz WWVB, 77.5 kHz DCF or
40 kHz Japan) and acts as a serial resonator. The given
parallel capacitor of the filter crystal (about 0.8 pF) is in-
ternally compensated so that the bandwidth of the filter
is about 10 Hz. The impedance of RFI is high. Parasitic
loads have to be avoided.
Rev. A2, 24-Jul-00
PAD 6
(Pin 7)
IN2
PAD5
(Pin 6)
GND
VCC
IN1
PAD 2
PAD 4
(Pin 5)
200k
200k
Figure 4.
Figure 5.
RF–Amp
Preliminary Information
from
AGC
RFI
DEM
Demodulator output. To ensure the function, a external
capacitor has to be connected at this output.
HLD
AGC hold mode: HLD high (V
function, SL low (V
AGC voltage. This can be used to prevent the AGC from
peak voltages, created by e.g. a stepper motor.
HDL
Figure 6.
Figure 7.
= 0) holds for a short time the
HDL
= V
T4227
CC
) sets normal
3 (13)