BA1604F

Communication ICs PLL tone decoder IC BA1604 / BA1604F The BA1604 and BA1604F are tone decoder ICs that enable the frequency to be selected in precise detail, using a PLL system. These ICs are configured of a PLL circuit, a detection circuit, a voltage comparator circuit and an output logic drive circuit. When the input signal is within the transmission range of the circuit, PLL is synchronized (locked) to the input signal. At this point, the output voltage of the decoder drops, and the change turns on the transistors for the voltage comparator and output logic drive circuits. A load of up to 100mA can be driven.The center frequency (f0) of the decoder is set by the mobile oscillation frequency of the current control oscillator. This frequency is determined by selecting a CR connected to Pins 5 and 6.
Applications Telephones Data communication systems Remote control systems
Features 1) The detection bandwidth can be varied independently between 0 and 14%. 2) The output circuit can withstand a load current of up to 100mA, and is directly coupled to the logic circuit. 3) The center frequency offers a high level of stability. 4) High out-of-band signal and noise rejection capability.
Block diagram 212 5) Frequency can be changed over a range of 20 : 1 using an external resistor. 6) Compatible with EXAR XR-567 and Signetics NE567. Communication ICs BA1604 / BA1604F FAbsolute maximum ratings (Ta=25_C) FRecommended operating conditions (Ta=25_C) FElectrical characteristics (unless otherwise noted, Ta=25_C, VCC=5V) 213 Communication ICs
Measurement circuit
Attached components (1) C1 and R1 : Setting f0 The center frequency (f0) is determined by the resistor R1 between Pins 5 and 6, and the capacitor C1 between Pin 6 and the ground. The constants at this point are determined as follows : f0 1 C1R1 (kHz) (C : µ F, R : kΩ) A rectangular-wave voltage is output at Pin 5; the peakto-peak amplitude is between VCC and 1.4 V, and the average DC value is VCC / 2. This pin can drive a load resistance of up to 1kΩ. (The recommended value for R1, however, is from 2kΩ to 20kΩ.) A 1V peak-to-peak exponential function triangular wave with an average DC voltage level of VCC / 2 is output at Pin 6. Since loading this pin adversely affects both the duty cycle and the temperature stability of the oscillator, it must only be connected to a high-impedance load. (2) C2 : Loop filter Connected between Pin 2 and the ground, C2 functions as a low pass filter for the PLL circuit, and the time constant is determined by T2 = R2C2 (R2 is the internal impedance for Pin 2, at 10 kΩ). The value of C2 also determines the detection bandwidth. The voltage at Pin 2 varies linearly at 20mV / % of f0 over the range 0.95 f0 to 1.05 f0. 214 BA1604 / BA1604F
Application example (3) C3 : Output filter Capacitor C3, connected between Pin 1 and the ground, is used as a low pass filter to suppress out-of-band signals. The time constant T3 is determined by T3 = R3C3 (R3 is the internal impedance for Pin 1, at 4.7kΩ). To prevent false detection of spurious signals, it is recommended that C3  2
C2. If C3 is made too large, however, this will increase the time required for voltage changes at Pin 1 to reach the threshold of the phase detector, thus slowing the response time. (4) C4 : Input coupling capacitor (5) C5 : Power supply filter capacitor
Input and output pins (1) Input : Pin 3 The input signal is applied through a coupling capacitor to Pin 3. Internal circuits set this pin to a DC potential of 2V with respect to the ground. The input impedance is approximately 20kΩ. (2) Output : Pin 8 The output logic section has an internal power transistor with its collector connected to Pin 8. The load is connected between Pin 8 and VCC. The transistor saturates when an in-band input signal is received, dropping the potential at Pin 8 to less than 1V (0.6V Typ.). The output can also drive a load connected to a separate supply voltage of up to 20V. Communication ICs BA1604 / BA1604F
Operation notes When setting the central frequency, which is determined by the capacitor and resistor connected to pins 5 and 6 of this IC, it is recommended to connect a variable resistor between pins 5 and 6 and align the central frequency of each component in order to prevent shifting of the central frequency caused by fluctuations in the IC, capacitor, or resistor.
Electrical characteristic curves 215 Communication ICs
External dimensions (Units: mm) 216 BA1604 / BA1604F