? semiconductor components industries, llc, 2002 may, 2002 rev.0 1 publication order number: tnd308/d tnd308 graphical data test circuits for the ncp1651 prepared by alan ball on semiconductor applications engineering the following circuits are the test configurations that were used to obtain the data for the graphical section of the ncp1651/d data sheet. each graph has a schematic associated with it and in some cases a description of the procedure. startup ac comp fb/sd ref fltr ac input output i s+ i avg i avg fltr v cc v ref gnd c t ramp comp 16 11 8 10 9 47 k 0.1 f 1.5 v 234 1 f 14 v 1 5 7 6 13 12 4.7 k 470 pf 0.5 nf figure 1. current sense amplifier gain re: ncp1651/d data sheet, figure 4 ncp1651 figure 2. fb/sd vi characteristics re: ncp1651/d data sheet, figure 5 + 01 v startup fb/sd ac comp ref fltr ac input output i s+ i avg i avg fltr v cc v ref gnd c t ramp comp 16 8 11 10 9 47 k 0.1 f r8 234 1 f 14 v 1 5 7 6 13 12 470 pf 1 nf ncp1651 energize all three power sources, beginning with the 14 volt supply. cycle the 14 volt supply down to 8 volts and back to 14 to start unit operating. adjust power supply on pin 5 and read voltages on pins 6 and 7. using a decade resistance box for r8, set it to 1 m . turn on the 14 volt source. cycle it down to 8 volts and back up to 14 to turn the unit on. read the voltage and pin 8 and note the resistance. reduce r8 until the unit shuts down. calculate the current for each reading. application note http://onsemi.com
tnd308 http://onsemi.com 2 startup ac comp fb/sd ref fltr ac input output i s+ i avg i avg fltr v cc v ref gnd c t ramp comp 16 11 8 10 9 47 k 0.1 f 1.5 v 234 1 f 13 12 470 pf figure 3. bias current versus v cc re: ncp1651/d data sheet, figures 6 and 7 ncp1651 figure 4. startup leakage re: ncp1651/d data sheet, figure 8 startup ac comp fb/sd ref fltr ac input output i s+ i avg i avg fltr v cc v ref gnd c t ramp comp 16 11 8 10 9 47 k 0.1 f 234 1 5 7 6 13 12 470 pf 1 nf ncp1651 1 5 7 6 1 nf v a v cc curve tracer apply voltage from 1.5 volt source. begin with v cc at 0 volts and take current readings over a range of 0 to 11 volts. reduce v cc to 8 volts, and then increase to 12 volts, unit should begin operation. reduce voltage to approximately 10 volts and take current readings up to 18 volts. if unit shuts down before 10 volts, note shutdown voltage. recycle input power (v cc to 12 volts, 8 volts and 12 again) and adjust v cc to just above shutdown threshold and take readings. device needs to be nonoperational for this test. begin with curve tracer set to about 20 volts for low voltage readings. as unit heats up, currents will drop. startup ac comp fb/sd ref fltr ac input output i s+ i avg i avg fltr v cc v ref gnd c t ramp comp 16 11 8 10 9 47 k 0.1 f 1.5 v 234 1 f 13 12 470 pf figure 5. startup current and leakage re: ncp1651/d data sheet, figure 9 ncp1651 figure 6. uvlo thresholds re: ncp1651/d data sheet, figure 10 1 5 7 6 1 nf v cc v a 0500 v startup ac comp fb/sd ref fltr ac input output i s+ i avg i avg fltr v cc v ref gnd c t ramp comp 16 11 8 10 9 47 k 0.1 f 1.5 v 234 1 f 13 12 470 pf 1 5 7 6 1 nf v a v cc ncp1651 apply voltage from 1.5 volt source. turn on v cc and bring up to 12 volts. reduce it to 8 volts and then increase it back to 12 volts. adjust high voltage to 500 volts and take current measurement. apply voltage from 1.5 volt source. turn on v cc and bring up to 12 volts. reduce it to 8 volts and then increase it slowly to the point when the unit begins operation. at that point the input current will jump from about 0.5 ma to roughly 5 ma. decrease the v cc voltage until the v cc current drops back to 0.5 ma, this is the turnoff voltage.
tnd308 http://onsemi.com 3 startup ac comp fb/sd ref fltr ac input output i s+ i avg i avg fltr v cc v ref gnd c t ramp comp 16 11 8 10 9 47 k 0.1 f 234 1 f 1 5 7 6 13 12 4.7 k 470 pf 0.5 nf figure 7. clamp voltage versus v cc re: ncp1651/d data sheet, figure 11 ncp1651 figure 8. reference multiplier family of curves re: ncp1651/d data sheet, figure 12 v cc v startup ac comp fb/sd ref fltr ac input output i s+ i avg i avg fltr v cc v ref gnd c t ramp comp 16 11 8 10 9 47 k 0.1 f 234 1 f 14 v 1 5 7 6 13 12 4.7 k 470 pf 0.5 nf ncp1651 v 05 v 1 f 05 v begin with v cc at 0 volts and increase to 11 volts taking measurements at frequent intervals. this will not allow the chip to go into the operational mode, as that would turn off the clamp. energize the 14 volt bias supply, and then the other two supplies on pins 8 and 9. adjust pin 8 to about 1 volt, then reduce the 14 volt supply to 8 volts and back up to 14. this will start the chip operating. adjust the supplies on pins 8 and 9, and measure the voltage on pin 10. figure 9. turnon time re: ncp1651/d data sheet, figure 13 figure 10. frequency versus c t re: ncp1651/d data sheet, figure 14 startup ac comp fb/sd ref fltr ac input output i s+ i avg i avg fltr v cc v ref gnd c t ramp comp 11 8 10 9 47 k 0.1 f 234 1 5 7 6 16 12 470 pf 1 nf ncp1651 13 + + c charge 50 vdc startup ac comp fb/sd ref fltr ac input output i s+ i avg i avg fltr v cc v ref gnd c t ramp comp 16 11 8 10 9 47 k 0.1 f 1.5 v 234 1 f 13 12 c t 1 5 7 6 14 v ncp1651 using a series of capacitors from 1 f to 1000 f, apply the 50 volt supply with a rise time of less than 100 s. measure time required for the v cc cap to charge to its peak. this is the point at which the chip will start operating if possible. since this is not an operable configuration, v cc will then decay to the turn off threshold. apply both voltage sources, reduce the 14 volt source to 8 volts and then increase to 14 volts. measure frequency. repeat for various values of c t , and measure the frequency at pin 4. do not measure directly from pin 3, as the impedance of the measuring device will cause errors in the reading.
tnd308 http://onsemi.com 4 figure 11. ramp peak versus frequency re: ncp1651/d data sheet, figure 15 figure 12. maximum duty cycle versus frequency re: ncp1651/d data sheet, figure 16 8 11 10 9 47 k 0.1 f 1.5 v 234 1 f 13 12 1 7 6 startup fb/sd ac comp ref fltr ncp1651 ac input output i s+ i avg i avg fltr v cc v ref gnd c t ramp comp 16 c t 5 8 11 10 9 47 k 0.1 f 2.5 v 234 1 f 13 12 1 7 6 startup fb/sd ac comp 14 v ref fltr ncp1651 ac input output i s+ i avg i avg fltr v cc v ref gnd c t ramp comp 16 c t 5 14 v apply both voltage sources, reduce the 14 volt source to 8 volts and then increase to 14 volts. measure ramp peak at pin 3 with an oscilloscope for various values of c t . apply both voltage sources, reduce the 14 volt source to 8 volts and then increase to 14 volts. measure frequency and duty cycle, using an oscilloscope on pin 1, for various values of c t . figure 13. driver rise and fall times versus capacitance re: ncp1651/d data sheet, figure 17 figure 14. v ref transient response re: ncp1651/d data sheet, figure 18 startup fb/sd ac comp ref fltr ac input output i s+ i avg i avg fltr v cc v ref gnd c t ramp comp 16 8 11 10 9 47 k 0.1 f 1.5 v 234 1 f 13 12 1 5 7 6 14 v ncp1651 8 11 10 9 47 k 0.1 f 1.5 v 234 1 f 13 12 1 7 6 startup fb/sd ac comp ref fltr ncp1651 ac input output i s+ i avg i avg fltr v cc v ref gnd c t ramp comp 16 470 pf 470 pf 5 680 c l 14 v apply both voltage sources, reduce the 14 volt source to 8 volts and then increase to 14 volts. adjust the voltage of the 1.5 volt source for approximately 50% duty cycle on the output driver pin. measure the waveform on pin 1 with an oscilloscope for the 10% and 90% rise and fall time. change c l as required. apply both voltage sources, reduce the 14 volt source to 8 volts and then increase to 14 volts. adjust the voltage of the 1.5 volt source for approximately 50% duty cycle on the output driver pin. measure the waveform on pin 12 with an oscilloscope.
tnd308 http://onsemi.com 5 figure 15. frequency versus temperature re: ncp1651/d data sheet, figures 19 and 20 figure 16. ramp peak versus temperature re: ncp1651/d data sheet, figure 21 startup ac comp fb/sd ref fltr ac input output i s+ i avg i avg fltr v cc v ref gnd c t ramp comp 16 11 8 10 9 47 k 0.1 f 1.5 v 234 1 f 13 12 470 pf 1 5 7 6 14 v ncp1651 startup fb/sd ac comp ref fltr ac input output i s+ i avg i avg fltr v cc v ref gnd c t ramp comp 16 8 11 10 9 47 k 0.1 f 1.5 v 234 1 f 13 12 470 pf 1 5 7 6 14 v ncp1651 apply both voltage sources, reduce the 14 volt source to 8 volts and then increase to 14 volts. measure the frequency at pin 1 using an oscilloscope or frequency counter. apply both voltage sources, reduce the 14 volt source to 8 volts and then increase to 14 volts. measure ramp peak at pin 3 with an oscilloscope. figure 17. v ref line/load regulation re: ncp1650/d data sheet, figures 22 and 23 0.1 f 1 f 14 v a v 2 ma 5 ma 10 ma 0 ma 1.30 k 3.25 k 0.65 k v startup fb/sd ac comp ref fltr ac input output i s+ i avg i avg fltr v cc v ref gnd c t ramp comp 16 8 11 10 9 47 k 1.5 v 234 13 12 470 pf 1 5 7 6 ncp1651 apply both voltage sources, reduce the 14 volt source to 8 volts and then increase to 14 volts. to measure load regulation, hold the v cc voltage constant and vary the load, measuring v ref a load current at various loads between 0 and 10 ma. to measure line regulation, hold the load constant and measure v ref and v cc at various v cc levels between 10 and 18 volts.
tnd308 http://onsemi.com 6 figure 18. v ref versus v cc in shutdown mode re: ncp1651/d data sheet, figure 24 startup ac comp fb/sd ref fltr ac input output i s+ i avg i avg fltr v cc v ref gnd c t ramp comp 16 11 8 10 9 47 k 0.1 f 234 1 f 13 12 470 pf 1 5 7 6 ncp1651 v v v cc r load connect desired load to pin 12. apply 14 volts to v cc pin, unit will be in shutdown mode. measure v ref voltage.
tnd308 http://onsemi.com 7 notes
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