Hi,
I am trying to use the TC4432. I am doing the exact circuit of page 7 below. My Vdd is at 1v, and my input is coming from a pic chip running at 10khz 60% duty cycle.
What I am getting at the output is oscillation between 10v low to 12v high. The frequency is good, but it is not coming down to zero volt like expected. Any body used this chip and can show me a working circuit or have any ideas why that is?
thanks
K
TYPO :I am trying to use the TC4432. I am doing the exact circuit of page 7 below. My Vdd is at -- 12v --- and my input is coming from a pic chip running at 10khz 60% duty cycle.
Vdd is 1v? The minimum is 4.5V. I'm guessing you really meant something else.
The Vdd must be between 4.5 and 30V, and the logic input switches at
0.8V and 2.4V. The output is 'open collector', meaning that you need to pull it up to Vdd using a resistor in order to see any action.Watch out for a floating UVLock pin.
3.3 Lockout Disable (LOCK DIS) The lockout pin enables/disables the undervoltage lock-out feature of the device. If undervoltage lockout is desired (output is not enabled until the bias voltage reaches 8.4V (typical) on the rising edge and is disabled when the bias voltage reaches 7.7V (typical) on the falling edge), the lockout pin should be left floating. If operation below 7V is desired, the lockout pin should be tied to ground.Regards, Bob Monsen
Maybe I've missed something here, the spec's state that Vdd starts at 4.5 V up to 30, You stated 1 volt? Maybe this is a clerical error and should be like 10 volts ?
Also, the output Z is rated at 7 ohms, you must account for that as it will influence the drive to the fet.
Have you placed a series R of around 10 or so ohms driving the gate? If so, you could examine the signal via a scope and test for a drop. It's very possible the driver isn't able to sink the output enough.
You should try to test the output of the driver with no load or very little load to determine the problem here.
It's possible the capacitance on the gate is excessive for the driver to get the response you're looking for.
Firstly, I have seen your correction about the Vcc = 12V. Do you have the ground pin connected properly? Dry joints on this pin can cause you hours of undeserved fun.
Check this, then tie a load to the output (1k should be OK) and check the output.
Have you got the output connected to anything that could be keeping the output high?
Also, not related to this problem, make sure your decoupling caps are close to the Vcc pin to get best transient response from FET drivers once the circuit is working
Let me know
Rgds Bill Naylor Electronworks.co.uk - electronic kits for education and fun
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