uPC1237 by a single power supply, operating voltage range of 25v ~ 60v, usually directly amplifier positive power source + VCC as a power supply. Voltage is DC relay coil 24v, because the drive pin relay terminal ⑥ maximum current of 80mA, energize the relay in a timely, ⑥ pin voltage about 0v, if the average voltage Vcc >24v, must be inserted down current limiting resistor R12 the relay is not activated and the integrated circuit overcurrent heat damage, the corresponding relationship between the resistance R12, the average power and voltage Vcc in Table 1. A look-up table may be determined enthusiasts R12 vcc average voltage value according to its own amplifier.
uPC1237⑦ foot end is power-on delay, it is determined by R7, c3 mute start time parameter, i.e. the power until the amplifier circuit reaches a stable equilibrium, let the delay circuit speaker relay contacts. This can eliminate the impulsive noise power-up, or increase c3 R7 extended power of silence.
uPC1237⑧ foot is the power end, the highest limit is 8v. When Vcc is not the same, R8 respective different resistance, a look-up table may be determined.
uPC1237④ foot AC power-off detection terminal for muting the amplifier off. When the power amplifier power switch is turned off, the AC voltage of the transformer secondary disappear immediately, c2 small capacitor discharges through the rapid resistance pin ④, ④ pin voltage decreased rapidly, the internal circuit control relay, the output of the amplifier and the speaker is disconnected, preventing during the transition after the power amplifier output of the zero level when a current imbalance between the impact of the speaker (i.e., off the impulsive noise). The maximum limit for the 10V voltage pin ④, when the power amplifier is monitored transformer secondary winding AC voltage values are different, voltage dividing resistors R6 limiting values corresponding to different, are too big too small speaker protection circuit will not work, The correspondence between the AC AC voltage and the R6 resistance value is shown in Table 2.
The UPC12372 feet are the DC offset detection end of the power amplifier output. The DC offset voltage of the power amplifier output will make the DC current flowing through the speaker's voice coil, the voice circle dynamic range is small, the sound is distortion, and the sound is overheated very easy to damage. In order to protect the speaker, the power amplifier output terminal is monitored by the 2 pin, once the power amplifier output is positive or negatively offset voltage exceeds the set threshold, the UPC1237 internal circuit makes the relay release, disconnect the speaker from the power amplifier output, to protect the speaker Purpose. FIG amplifier output circuit to correct the offset threshold is 1.24v, Kan negative offset value is -1.04v.
uPC1237① feet overcurrent detection terminal. Left, right channel overcurrent detection L-E terminal, the R-E end is separately discharged from the left, the right-sounding end-level NPN is amplified, and the electrode resistance is increased due to the increase of the output current. when the rated current value of the average output current exceeds the amplifier or loudspeaker, the voltage across the emitter resistor reaches the threshold voltage of the overcurrent protection circuit of the speaker set, T1, T3, or one of conduction, causing T2 is turned on, the voltage Vcc by T2, R9, R11 ① was added to the legs, as long as the inflow current exceeds 110Ua ① feet, the internal overcurrent protection circuit will release relay disconnect the speaker, the speaker achieve the purpose of over-current protection. FIG. L-E, R-E valve overcurrent detection voltage is 0.67v. Integrated circuit power amplifier, the final amplifier tube emitter resistor connected to a few, can be considered save Been flow detection function, can be simply ground pin ①.
uPC1237③ foot speaker protection circuit is operating mode selection terminal. ③ The pin is directly grounded automatic reset mode of operation, i.e., after the protection circuit, the relay disconnect the speaker, if the amplifier circuit is normal, the relay is turned on automatically restore the speaker. ③ the foot to the ground via the capacitor 0.022uF latch mode of operation, i.e., operation of the relay disconnect the speaker once, even if the normal power amplifier circuit, the relay remains open state continues until the power switch is turned off after once again turned up. Either works, speaker protection circuit function the same, uPC1237 parameters and figures mentioned in this article are the latches work.
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