Question on ADAU1452's internal LDO unit
Hello all,
I have 2 questions.
Question1
On the datasheet p.18, VDRIVE description says that the "STD2805" PNP pass transistor is recommended.
Also, on the datasheet p.32, "Voltage Regulator" section says as below.
"Ensure that the current gain of the transistor (β) is 200 or greater and the transistor is able to dissipate at least 1 W in the worst case."
Is it no problem to use another transistor if it satisfies the line above???
Question 2
Could you please tell me detailed information of how exactly the internal LDO works?
And how the external components work and why does the transistor needed?
For the hardware develop reason, the solid functional description is required.
Is it a switching regulator?
If so, could you tell me the switching frequency please.
Seems that the data sheet only has simplified description just as below.
Best Regards,
Yuta M
Hello Yuta,
Figure 23 does show exactly how it works. It is a linear regulator so there is no switching frequency.
Yes, you can use any transistor that satisfies the statement in the datasheet. The wattage is for worst case so if you develop your application and it will not change very much then you can measure the DVDD current your application requires to run and then you may be able to use a transistor with lower power dissipation.
Dave T
Please log in to reply.