The heating element in heated apparel is simple: it warms up when current flows, and more current means more heat. Different temperatures come from the control circuit inside the switch.
Fast switching sets the average power
The usual approach is to switch the circuit on and off very quickly. A higher share of on-time means more average power and a higher temperature, and a lower share means less. The switching is fast enough that the wearer feels only the difference in warmth.
Three levels, three on-time ratios
High, medium and low correspond to three ratios. They can be tuned per product: a powerful element may want a lower low setting, and a product that should heat up quickly can run high at full power.
What the indicator does
Three indicator colors map to the three levels, so the user reads the current setting from the color instead of counting presses.
If your product has target temperatures for each level, tell us at the sampling stage and we will tune the parameters against measured results.