Hello,
I'm working on a Class D amp with integrated DSP, based on the TI TAS3251 chip. This chip needs to be controlled by a microcontroller to load the DSP coefficients (I2C) and manage the power on and power off sequence. Especially, the /Reset_Amp of the TAS3251 shall stay to LOW up to the point where the DSP is started and configure. My design is heavily based on the TI TAS3251EVM which uses a TPS3802 as supervisor, controlled.
In my design, I would like to pair the TAS3251 with an independant Raspberry PI or STM32 Nucleo board. In that config, I can't ensure that the Microcontroller or RPi will always be powered before the amp. So, I would need that at power up of the amp, instead of having the TPS3802 (or equivalent) going to HIGH when voltage establishes, I would need it to stay low up to the moment the microcontroller will raise /MR to HIGH.
So I would need sort of a pull-down to GND on the /MR. But looking at the datasheets, this pin has a pull-up internal resistor (20kR for a MIC8114, did not found the info for the TPS3802).
So... How to get a pull-down defaut on chip with pull-up internals
and still controllable to HIGH and LOW by a Microcontroller ?
My electronic knowledge is very very rusty, and I'm looking for some help solve this beginners dilemna.
Best Regards,
JMF