Other Parts Discussed in Thread: TPS3840
I am planning to use TPS389001 adjustable sense version to generate Power ON RESET to my ASIC.
I have 2 questions on this
My case:
VDD = 3.3V (comes 1st in power sequencing)
Vsense = 1.8V (comes 2nd in power sequencing)
MR = AND of ( 0.82V,1.0V,1.2V,3.3V, 2.5V, 0.6V(final rail) Open drain power goods)
My application,don't use any Manual RESET function, ONLY requirement is once all RAILS are in healthy state, need to send a RESET signal to ASIC.
1. To sense 1.8V for adjustable version,
Vitx(MON) = Vitx * (1+Rupper/Rlower) - (Equation1)
I see from Device comparison table from datasheet,
Vitn = 1.15V and Vitp = 1.157V.
Always Vitx(MON) is 1.8V,
By fixing Rlower = 100K, using equation1 Rupper is different for Vitn and Vitp.
Am i doing correct here ?
2. On the same lines as Question 1, datasheet sheet suggests(in Page 13) current through (Rtotal = Rupper+Rlower) should be Min 100times sense current.
sense current is in table mentioned as Max 8uA in one condition 100nA in another condition - These are not clear.
Which value needs to be taken as reference to calculate Rtotal.
3. I am connecting MR pin to combined (AND'ed) open drain Power good from all the rails.
All the regulators will be enabled at different instances,
My application,don't use any Manual RESET function, ONLY requirement is once all RAILS are in healthy state, need to send a RESET signal(configurable delay) to ASIC.
Is this device is intended for this kind of application?
4. if I don't want to use SENSE functionality, Is there any option to disable it?
My application,don't use any Manual RESET function, ONLY requirement is once all RAILS are in healthy state, need to send a RESET signal(configurable delay) to ASIC.
Is there any simple Power ON reset generation device which has below requirements
1. VDD should be Min 1.8V Max at-least 3.3V, Should be sensitive to VDD >10% for generating RESET
2. Need to generate RESET pulse(configured delay from 100uS to >100mS) once MR pin is LOW as like TPS3890 does.