Rohm BA335 Audio level sensor Datasheet

Audio ICs
Audio level sensor
BA335
The BA335 is a sensor amplifier which consists of three blocks : a small signal audio amplifier, a hysteresis comparator,
and a driver. Housed in a 9-pin SIP package, it is optimal for tape recorder end detection and tape mute detection.
Applications
Tape end detection
Tape mute detection
Features
1) Built-in comparator with stable hysteresis under
power supply voltage and temperature fluctuations.
2) Built-in transistor and diode capable of driving an inductive load at 600mA.
3) Time delays can be created as needed with an external CR circuit.
Absolute maximum ratings (Ta = 25C)
Internal circuit schematic
829
Audio ICs
Electrical characteristics (unless otherwise noted, Ta = 25C and VCC = 9.0V)
Measurement circuit
830
BA335
Audio ICs
BA335
Attached components
C1 : Input coupling capacitor. 1 to 2.2µF recommended.
C2 : AC bypass capacitor. 0.1 to 0.47µF recommended.
R1, C3 : Resistor and capacitor for setting time delay.
R2, C4 : Resistor and capacitor for ripple filter.
Input characteristics
As shown in Fig. 4, VP6 and VP8 invert when the input
reaches approximately 45dBm. VP8 is designed to be
able to directly drive the NPN small signal transistor at
this time. When on, VP6 is capable of accepting a maximum of 600mA of current (this will vary as shown in the
duty cycle table). A continuous ON should last for no
more than 3 seconds.
Time delay using the hysteresis comparator is as follows.
When an input signal of 45dBm or more goes to nothing ceases, the electrical potential of Pin 2 begins to fall
due to the CR circuit connected to Pin 2. The time until
the hysteresis comparator inverts is the time delay. When
deciding the values of the capacitor and resistor, select
a resistor value from 100 to 500kΩ.
831
Audio ICs
Electrical characteristic curves
External dimensions (Units: mm)
832
BA335
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