A request for a high voltage mode is received and a high voltage timer is started in response to determining that a remaining amount of high voltage credits exceeds a voltage switch threshold value. A switch to the high voltage mode is made in response to the request. A low voltage mode is switched to in response to an indication. The request may be received from an application running on a data processing system. If the indication is that the high voltage timer has expired, a low voltage timer is started in response to switching to low voltage mode. If the high voltage request is still active when the low voltage timer expires, a switch back to high voltage mode occurs and a new high voltage timer is started.