Hi ADI Team,
I am using the LTC7001 device to control a Power Amplifier (PA). The circuit diagram is below (close to the Reference Board). Here are some parameters I used.
- The input voltage to the PA is 28V (via a high side, low RDS_ON switch).
- The control voltage (INP) is 3.3V
- VCC is set to 12V
- OVLO is configured to exceed 1.21V using a resistive divider and clamped with a 5.1V Zener for protection. If the input voltage to the PA exceeds 30V, the overvoltage protection will trigger.
When I test the circuit using a 10kOhm load in parallel with a 100uF capacitor, the circuit works as expected. I can turn it on and off, and the overvoltage level is correct.
However, when I use a real Power Amplifier (3A current consumption), I find that I can only turn it on once. Subsequent enable signals on the INP pin is ignored.
I later found that if I set the OVLO divider to trigger at 31V, then it is fine.
It appears that something has "latched up" the OVLO circuit of the LTC7001 after the first enable signal.
Can I ask what I can do besides raising the overvoltage level to overcome this "internal latchup" ?
Thanks.
