Does caffeine negate the effects of Adderall?

No there is no caffeine in Adderall. Adderall is composed of mixed amphetamine salts. However like caffeine, amphetamine is a stimulant and all stimulants increase the amount of the neurotransmitter dopamine in the brain, so in that sense they are similar. Adderall however is a much more powerful stimulant and also increases the amount of the neurotransmitter norephinehrine as well as dopamine.

Adderal is much more powerful since it is an amphetamine called dextroamphetamine, but it has the psychological attitude of "on top of the world to extremely depressed" which has to do with the dopamine not being released naturally anymore. But it can go back to normal if enough time passes.