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LTC6992HS6-1_Out issue

Dear team,

LTC6992HS6-1 is being tested but Out put signal is nothing.PDF

Could you check that there is any problem?(Circuit, PCB)

please refer to the attached file(Circuit and Simulation data, PCB ficture)

##test condition.

  • Supply Voltage : +5V
  • Duty cycle : 50%
  • DIVCODE : 2
  • POL : 0
  • Ndiv : 16
  • Fout : 16 kHz

Best & Regards,

Josh

Parents
  • Josh,

    I do not see anything obviously incorrect or wrong with the schematic. This looks like it should work if the PCB is the same as the schematic. It appears that the SET pin resistor is not a 195k part, but is two resistors in series to make 195k. This is not an issue, but is that yellow wire connected to the middle of these two resistors? If so what is this doing?

    I would check the voltage on each pin at the package to see if it is as expected. Pin 1 should be about 495mV if the supply is 5V. Pin 2 should be 0V (GND), pin 3 should be about 1V. pin 4 should be 785mV, pin 5 should be 5V (V+). Make sure to measure these at the device pins and it is probably best to use a scope and a DMM. The scope will not be accurate, but if there is an oscillation, you will see it while the DMM will not.

    Last, if all that you really want is a 50% duty cycle, you would be better served to use the LTC6990 or LTC6991. The LTC6992 is a voltage controlled PWM part that is great for PWM servos and applications like that, but to get a good 50% duty cycle, the other parts are better.

Reply
  • Josh,

    I do not see anything obviously incorrect or wrong with the schematic. This looks like it should work if the PCB is the same as the schematic. It appears that the SET pin resistor is not a 195k part, but is two resistors in series to make 195k. This is not an issue, but is that yellow wire connected to the middle of these two resistors? If so what is this doing?

    I would check the voltage on each pin at the package to see if it is as expected. Pin 1 should be about 495mV if the supply is 5V. Pin 2 should be 0V (GND), pin 3 should be about 1V. pin 4 should be 785mV, pin 5 should be 5V (V+). Make sure to measure these at the device pins and it is probably best to use a scope and a DMM. The scope will not be accurate, but if there is an oscillation, you will see it while the DMM will not.

    Last, if all that you really want is a 50% duty cycle, you would be better served to use the LTC6990 or LTC6991. The LTC6992 is a voltage controlled PWM part that is great for PWM servos and applications like that, but to get a good 50% duty cycle, the other parts are better.

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