Hello,
Could you please kindly let me know about TPS84259 ?
1.....Calculation of Input to Output Coupling Capacitor.
In the data sheet page 21, input to output coupling capacitor is 2.2uF as typical value.
But, there is not calculation.
Could you please kindly let me know calculation ?
I would like to set best capacitance for reduce Vout ripple voltage.
Current conditions is as below.
Vin=5V, Vout=-3.3V, Iout=500mA, Fsw=800kHz
If you have reccomend capacitance value for this condition , please let me know too.
2.....Reducing Output Ripple and Noise with the TPS84259 (Application Report )
Could you please let me know the Input to Output coupling capacitor value of this reports?
3.....LDO + 47uF output filter in Application Report.
In this report, using TPS7A3301 for reducing output ripple voltage.
And this result is 3mVpp as output voltage ripple.
I think that TPS7A3301 has very high PSRR.
If TPS84259 voltage ripple is 800kHz , PSRR will be 50dB.
So, I think that TPS7A3301 can more reduce Vout ripple.
In the report, Vout ripple reduced from 21mV to 3mV only.
Could you please kindly let me know the reason ?
4....Output voltage ripple 0.1mV
In my customer's output voltage ripple target is 0.1mV by below conditions.....
Vin=5V, Vout=-3.3V, Iout=500mA, Fsw=800kHz
Could you please kindly let me know the refference value of external components or method for achieve 0.1mV?
I expected TPS7A3301 achive this....
Best Regards,
Ryuji Asaka