The Fcom gives the following for an A320:
The maximum speedbrake deflection in manual flight is:
40 ° for spoilers 3 and 4
20 ° for spoiler 2.
The maximum speedbrake deflection with the autopilot engaged is:
25 ° for spoilers 3 and 4
12.5 ° for spoiler 2.
The maximum speedbrake deflection achievable with the autopilot engaged is obtained by setting the speedbrake lever to the half way position. On setting the position of the speedbrake lever from half to full, no increase in speedbrake deflection will be achieved.
The A321 gives:
The maximum deflection for the spoilers 2, 3 and 4 is 25 °.
The problem with the A320 was inadvertant alpha floor protection engaging giving Toga thrust just when you were trying to descend.