TLV3501A-Q1: 5V supply back comparator

Ruoxin Chang

Part Number: TLV3501A-Q1
Other Parts Discussed in Thread: TLV9051, TLV7031-Q1

Tool/software:

Hi,

RT is NTC (TSM1D472H3953R01-8), the resistance value decreases as the temperature increases, requires the NTC to reach 85℃ ~ 100℃, the output low level, Turn the MOS off; after switching off, wait until the NTC has cooled to 60°C and put the output high.
Help calculate the resistance values of the surrounding using 3501a and 9051 respectively, and help to explain briefly the difference between these two operating devices in this case, thank you!

we hope that

The FET operates constantly on, and the Vout is high
FETs do not operate at all times off, Vout low

Best Regards

Ruoxin

10 months ago

0 Ron Michallick 10 months ago

TI__Guru**** 164626 points

Hello Ruoxin,

Ruoxin Chang said:
NTC to reach 85℃ ~ 100℃

I will assume any where in the range is fine, so I'll pick the middle, 0.4k. R1 will set the voltage and current of NTC. 806 ohms one of many options.

Next to to find the IN- voltage for NTC 0.1k and 0.4k. This is a simple voltage divider. [4.448V , 3.342V]

With these two voltages. Use the three resistor divider calculator here; [CALC] Voltage Scalar xls VIN range is comparator [VOH, VOL]. VREF is 5V. VOUT is the two voltages [4.448V , 3.342V]

R4 = A = 10k, R3 = B = 20k, R2 = C = 3.3k

0 Ron Michallick 10 months ago in reply to Ron Michallick

TI__Guru**** 164626 points

TLV9051 is a op amp. It could be used as a comparator, but that is not its intended purpose.

0 Ruoxin Chang 10 months ago in reply to Ron Michallick

TI__Intellectual 2900 points

Hi Michallick,

Do you have any suggestions abou the device?

I could supply for BYD.

Best Regards,

Ruoxin

0 Ron Michallick 10 months ago in reply to Ruoxin Chang

TI__Guru**** 164626 points

Ruoxin,

There are a lot of comparator choices, because propagation delay should not matter because temperature changes rather slowly. .

https://www.ti.com/amplifier-circuit/comparators/products.html#116=Push-Pull&480=1&1498=Automotive&sort=1130;asc&

TLV7031-Q1 is my suggestion

0 Ruoxin Chang 10 months ago in reply to Ron Michallick

TI__Intellectual 2900 points

Hi Michallick,

Thank you for your suggestions, I will give feedback to BYD!

The last given calculation result is wrong, at 60 °C the resistance value is 1k, the last given result is based on 0.1 k calculation, please help to recalculate
Demand Now:
RT is NTC (TSM1D472H3953R01-8) and the resistance decreases as the temperature increases. Normal operation with high output level; now requires that when NTC reaches 85°C, the flip output level is low, causing the MOS to shut down; after switching off, wait until NTC has cooled to 60°C (1K), the high output level is switched off.
Help to calculate the resistance value of the perimeter when using 9051. Thank you

Best Regards,

Ruoxin

0 Ron Michallick 10 months ago in reply to Ruoxin Chang

TI__Guru**** 164626 points

Ruoxin,

I want to keep TLV9051 IN- below VCC-1.4V for better CMRR and Vos ; that happens at 85C = 0.5k

That is resistive divider top = 0.5k, bottom = X. Vout = 3.6V ; 1.4V/0.5k = 3.6V/X ; so X max = 1.29k ; I'll pick 90% of that = 1.15k

R1 = 1. 15k ; so NTC at [0.5k, 1k] IN- voltages are [2.674418605, 3.484848485]

A = R4 = 10k; B = R3 = 5.35k (5.36k standard); C = R2 = 3.03k (3.01k standard)

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TLV3501A-Q1: 5V supply back comparator