Hello,
looking for a high precision and low power comparator I found the LMP7300. Trying to verify the behaviour and especially the settings for the trip point and the hysteresis, I used the the SPICE model I found on TI's website.
Unfortunately, the simulation does not behave as expected. I set up a basic configuration with the reference voltage connected to INN, and the terminals HYSTP and HYSTN were tied to a voltage smaller than 2.048 V in order to achieve a symmetrical hysteresis, e.g. to 2.028 V. According to the datasheet that should lead to hysteresis of +/-20 mV. The input test signal was tied between the terminal INP and GND. A DC offset > 1V on the input signal avoids problems with the limited common-mode range of the inputs.
In this configuration I would expect output transitions at 2.048 V + 20 mV for the upper trip point VIH and 2.048 V - 20 mV for the lower trip point VIL. Unfortunately, the result showed two transitions near 2.068 V with a small hysteresis of about 3 mV. What is that?
Removing the resistor divider for the hysteresis setup and replacing it by a voltage source did not change anything. But with two voltage sources, it was possible to setup two different voltages for HYSTP and HYSTN with V_HYSTP = 2.048 V + 20 mV and V_HYSTN = 2.048 V - 20 mV. With this setup the comparator behaved as expexted.
The simulator I use is ICAP/4 from Intusoft. To make sure that there are no issues with the simulator, I checked the behaviour of the LMP7300 model with TINA-TI - and found the same results.
That is all very confusing and hard to believe that the real component should behave this way. Is here somebody who has experience with the model of the LMP7300 and can help me to find out what is going wrong?
Many thanks in advance
Hans-Juergen
