We are using DRV103 to drive a 5V, 10Ω solenoid from 12V (at ~45% duty cycle). At first it behaves normally, but after being fully on for a second or so, some random chopping gets introduced into the on-time and the average output current drops as a result. You can see the behavior in the attached screenshots.
It seems to be thermal-related because I can blow on it with compressed air to make it revert back to normal behavior before it slides back into glitching. However, the OK pin stays high throughout so it doesn't appear to be tripping any internal protections. On a thermal camera, the case temp gets to about 70 °C at its highest.
CH2 = OUT, CH3 = +VS, CH4 = current(OUT)
CH2 = OUT, CH3 = OK, CH4 = current(OUT)
CH2 = OUT, CH3 = OK, CH4 = current(OUT)
As you can see, sometimes there is a normal on-time, a runt pulse, one chop cycle, or two chop cycles within the on-time. The spacing of the chopping pulses appear to be pretty consistent from cycle to cycle.
- 1µF directly across +VS and GND on IC
- 100 pF across OSC resistor as recommended in datasheet
- 100 nF across OSC and DC resistors
