Low-Power Comparator Response Time and Overdrive Voltage in PSoC® 4 – KBA89260

Version: *A

 

Question:

What is the minimum voltage difference that the Low Power Comparator Component can detect? The datasheet shows 50 mV.

 

Answer:

The DC and AC Electrical Characteristics section of the PSoC® 4 Low Power Comparator (LPComp) Component datasheet shows the following details under the heading LPComp AC Specifications.

 

Table 1. LPComp AC Specifications

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For example, in normal mode, a response time of 38 ns indicates that when the overdrive voltage is 50 mV (that is, the difference between the inverting and non-inverting terminal of the Comparator), then the response time from input to output will be 38 ns. The same also holds for both low-power and ultra-low-power modes

 

If the overdrive voltage is less than 50 mV, then the response time increases correspondingly. Therefore, the response time increases as the overdrive voltage reduces.

 

The minimum voltage difference the comparator may detect depends on the stability of the input signals. For example, if the input and reference voltage is very stable and hysteresis is enabled, it will increase the reference voltage by 10 mV. This is to avoid variation in the voltage and undesired output because of noise. This also implies that the comparator can detect a change as small as 10 mV. However, the corresponding response time will increase.