Other Parts Discussed in Thread: LM5060-Q1, TIDA-01167, LM74700-Q1
Good morning,
I'm studying the Application Report SNVA683 (Surge Stopping and Reverse Voltage Protection with the LM5069). My task is to protect the regulator I've after the LM5069 from Load Dump and from Jump start in vehicles with 24V battery (trucks and tractors) and other industrial vehicles that have 12V battery. The regulator currently used in the vehicles cannot be changed and it works from 6.5 to max 36V, and provide about 1A continuously with 3A peak.
The whole system is directly connected to the Veichle's battery all the time and the user cannot access it to change a fuse.
Looking at the Figure 5 of the SNVA683 Application Report (that include the Zener Z2 on the gate for output voltage clamping) my questions are:
- is the circuit of Figure 5 safe to be used in a 24V truck as is, based on the above regulator's specs? If not, what do you suggest as modifications?
- in the case of a surge (like load dump or jump start), the use of the TVS Z1 and the use of the Zener Z2 protect the regulator so that NEVER the voltage will get close to 36Vcc, knowing that in 24V Vehicles the Load dump could reach 600V for about 400ms?
- The capacitors C3 and C4 are rated for 200V. Why so high voltage on that branch?
- Based on the above, what MOSFETs do you suggest for Q1 and Q2 ?
- There are special consideration to handle about conducted EMI, since the current regulator (that will be on the LM5069 Vout) have it's own pi-filter that is verified to be compliant with EN 55022 Class B?
I've considered also the TIDA-01167 that use the LM5060-Q1, but unfortunately abandoned because of the space available in the target application, too complex, costly and with too many parts.
The LM5069 seems to be the solution... unless you say different.
Thanks in advance for an answer.
