How to judge the quality of ic chip
Article source:芯智力科技
Delivery time:2018-04-09
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One, not on the road detection
This method is performed when ic is not soldered into the circuit. Generally, a multimeter can be used to measure the forward and reverse resistance values of each pin corresponding to the ground pin, and compared with the intact ic.
Second, in the road detection
This is a method of detecting the DC resistance, the AC/DC voltage to ground, and the total operating current of the ic pins in the circuit (IC in the circuit) through the multimeter. This method overcomes the limitations of the substitution test method and the trouble of disassembling ic. It is the most common and practical method for detecting ic.
2. DC operating voltage measurement
This is a case in which the multimeter DC voltage block is used to measure the DC supply voltage and the operating voltage of the external components under a power-on condition. The ic pin voltage to the ground is measured and compared with the normal value to compress the fault range. Out of damaged components. When measuring, pay attention to the following eight:
(1) The multimeter must have a sufficiently large internal resistance, and less than 10 times the resistance of the circuit under test, so as not to cause a large measurement error.
(2) The potentiometer is usually rotated to the middle position. If it is a TV, the signal source should use the standard color bar signal generator.
3) Anti-skid measures should be taken for the pens or probes. It is easy to damage ic due to any short circuit. The following methods can be used to prevent the pens from sliding: Take a bicycle valve core and put it on the tip of the pen, and grow the pen tip about 0.5mm. This will not only make the tip of the pen well contact with the tested point, but also effectively prevent slippage. Even if it hits a nearby point, it will not short circuit.
(4) When the measured voltage of a certain pin does not match the normal value, it should be analyzed according to whether the voltage of the pin has important influence on the normal operation of ic and the corresponding changes of other pin voltages. It can be judged whether ic is good or bad.
(5) The ic pin voltage is affected by peripheral components. When the external components are leaky, short-circuited, open-circuited or variable, or the peripheral circuit is connected to a potentiometer with variable resistance, the position of the potentiometer slide arm will make the pin voltage change.
(6) If ic pin voltage is normal, it is generally considered ic normal; if ic part of the pin voltage is abnormal, it should start from the maximum deviation from the normal value, check the external components for failure, if there is no failure, then ic is likely to be damaged .
(7) For a dynamic receiving device, such as a TV set, the ic pin voltage is different when there is a signal. If it is found that the pin voltage does not change but it changes greatly, this change with the signal size and the position of the adjustable element does not change, and ic damage can be determined.
(8) For devices with multiple operating modes, such as video recorders, the ic pin voltage is different under different operating modes.
3. AC working voltage measurement
In order to grasp the change of the ic AC signal, a multimeter with a db jack can be used to approximate the ac operating voltage of ic. When testing, the multimeter is placed in the AC voltage block, and the test leads are inserted into the db jack. For a multimeter without a db jack, a 0.1-0.5 μf blocking capacitor must be connected in series with the front pen. This method is applicable to ICs with lower operating frequencies, such as TV video amplifier stages and field scan circuits. Since these circuits have different natural frequencies and different waveforms, the measured data are approximate and are for reference only.
4. Total current measurement
This method is a method of judging the good or bad of ic by detecting the total current of the incoming ic power supply. Since most of the internal ic is a direct coupling, when ic is damaged (such as a pn junction breakdown or open circuit) will cause the latter stage saturation and cut-off, so that the total current changes. Therefore, the method of measuring the total current can determine the quality of the ic. It is also possible to measure the voltage drop in the resistor in the power path and use Ohm's law to calculate the total current value.
One, not on the road detection
This method is performed when ic is not soldered into the circuit. Generally, a multimeter can be used to measure the forward and reverse resistance values of each pin corresponding to the ground pin, and compared with the intact ic.
Second, in the road detection
This is a method of detecting the DC resistance, the AC/DC voltage to ground, and the total operating current of the ic pins in the circuit (IC in the circuit) through the multimeter. This method overcomes the limitations of the substitution test method and the trouble of disassembling ic. It is the most common and practical method for detecting ic.
2. DC operating voltage measurement
This is a case in which the multimeter DC voltage block is used to measure the DC supply voltage and the operating voltage of the external components under a power-on condition. The ic pin voltage to the ground is measured and compared with the normal value to compress the fault range. Out of damaged components. When measuring, pay attention to the following eight:
(1) The multimeter must have a sufficiently large internal resistance, and less than 10 times the resistance of the circuit under test, so as not to cause a large measurement error.
(2) The potentiometer is usually rotated to the middle position. If it is a TV, the signal source should use the standard color bar signal generator.
3) Anti-skid measures should be taken for the pens or probes. It is easy to damage ic due to any short circuit. The following methods can be used to prevent the pens from sliding: Take a bicycle valve core and put it on the tip of the pen, and grow the pen tip about 0.5mm. This will not only make the tip of the pen well contact with the tested point, but also effectively prevent slippage. Even if it hits a nearby point, it will not short circuit.
(4) When the measured voltage of a certain pin does not match the normal value, it should be analyzed according to whether the voltage of the pin has important influence on the normal operation of ic and the corresponding changes of other pin voltages. It can be judged whether ic is good or bad.
(5) The ic pin voltage is affected by peripheral components. When the external components are leaky, short-circuited, open-circuited or variable, or the peripheral circuit is connected to a potentiometer with variable resistance, the position of the potentiometer slide arm will make the pin voltage change.
(6) If ic pin voltage is normal, it is generally considered ic normal; if ic part of the pin voltage is abnormal, it should start from the maximum deviation from the normal value, check the external components for failure, if there is no failure, then ic is likely to be damaged .
(7) For a dynamic receiving device, such as a TV set, the ic pin voltage is different when there is a signal. If it is found that the pin voltage does not change but it changes greatly, this change with the signal size and the position of the adjustable element does not change, and ic damage can be determined.
(8) For devices with multiple operating modes, such as video recorders, the ic pin voltage is different under different operating modes.
3. AC working voltage measurement
In order to grasp the change of the ic AC signal, a multimeter with a db jack can be used to approximate the ac operating voltage of ic. When testing, the multimeter is placed in the AC voltage block, and the test leads are inserted into the db jack. For a multimeter without a db jack, a 0.1-0.5 μf blocking capacitor must be connected in series with the front pen. This method is applicable to ICs with lower operating frequencies, such as TV video amplifier stages and field scan circuits. Since these circuits have different natural frequencies and different waveforms, the measured data are approximate and are for reference only.
4. Total current measurement
This method is a method of judging the good or bad of ic by detecting the total current of the incoming ic power supply. Since most of the internal ic is a direct coupling, when ic is damaged (such as a pn junction breakdown or open circuit) will cause the latter stage saturation and cut-off, so that the total current changes. Therefore, the method of measuring the total current can determine the quality of the ic. It is also possible to measure the voltage drop in the resistor in the power path and use Ohm's law to calculate the total current value.
