
Page 18
January 2000 TOKO, Inc.
TK14584
FIGURE 8 - EXAMPLE OF USING EXTERNAL REFERENCE SOURCE
Demodulated
Output Current
Demodulated
Output Voltage
VOUT
Vref
I to V convertor
io
VB
R1
C1
Demodulated Output Voltage V
OUT
= VB
±
R1 x io
Demodulated Bandwidth
1/gm is approximately 50 k
which is the output
resistance of the multiplier.
Pin 7 is disconnected.
Fc =
1
2
π
C1(1/gm)
Demodulated
Output Voltage
VOUT
R1
C1
R2
VCC
R1 = R2
Demodulated Output Voltage V
OUT
= V
CC
/2
±
R1 x io
Demodulated Bandwidth
1/gm is approximately 50 k
which is the output
resistance of the multiplier.
Pin 7 is disconnected.
Fc =
1
2
π
C1(1/gm)
FIGURE 9 - EXAMPLE OF DIVIDING SUPPLY VOLTAGE INTO HALVES BY THE RESISTORS
CIRCUIT DESCRIPTION (CONT.)
Power Save Function:
Pin 5 is the control terminal for the battery save function. The ON/OFF operation of the whole IC can be switched by
controlling the DC voltage at this terminal. Figure 10 shows the internal equivalent circuit of Pin 5.
Because it switches the bias circuit of the entire IC by using the transistor in standby mode, it reduces the supply current
to near zero. As the input terminal is connected with an electrostatic discharge protection diode at GND side only, it is
possible to control the voltage above the supply voltage. It is possible to go into standby mode by disconnecting Pin 5,
but it is not recommended because Pin 5 is a high impedance and may malfunction by an external disturbance.
When Pin 5 is disconnected, a suitable capacitor should be connected between Pin 5 and GND.
VCC
50 K
BIAS
Vs
FIGURE 10