Hi team,
Customer get 2 questions on ALM2402F-Q1:
1. what's the rated current of output transistor's internal reverse diode?
2. how to select the RC circuit of the output stage as shown below, please give some recommended value and select guide.
thanks!
Hi Terry,
1. what's the rated current of output transistor's internal reverse diode?
Are you referring to the output short current? Please see the captured image. The Isc is continuous up to rated current at 25C, but you can only short circuit one power amplifier at a time.
The output of power amplifiers (or output internal transistors in the IC) have to be source or sink the required current at the resolver transformer or load. Beyond the rated Isc above, output current protection circuits are required, see the attached link.
2. how to select the RC circuit of the output stage as shown below, please give some recommended value and select guide.
The image below is a typical resolver's output stage from ALM2402F-Q1 or ALM2403-Q1 resolver driver.
C14 and C15 are resemble the drawing presented in your Cemc capacitors above. Due to capacitor's tolerance issues (5-20%), R16 and R17 resistors are inserted in parallel with C14 and C15.
Since resolver's output driving waveform is differential and balanced AC signal (typically in sine wave), the peak and valley of the differential output are referenced to ground. Due to the variance of capacitors' tolerance (impedance variation at an excitation frequency), you'd like to center the differential driving output. By introducing the fixed resistors, the resolver's primary driving waveform may be centered at the reference ground at any given time.
In terms of Rcrs and Ccrs, these are RC snubber circuit for the transformer. If the output of amplifier is observed transient kickback events, high frequency spikes etc. from the rotary transformer, you may implement the snubber damping network to suppress high frequency noise or ringings at the primary side of resolver driver, which it may help to protect the power amplifier's output and dissipate the energy associated with these spikes or transients (basically short-out the high frequency components with the rotary transformer's primary winding), see the attached link below.
https://e2e.ti.com/blogs_/b/powerhouse/posts/calculate-an-r-c-snubber-in-seven-steps
If you have additional questions, please let us know.
Best,
Raymond
