RH-53/54Nokia Customer Care 8-System Module22 COMPANY CONFIDENTIAL Issue 2 06/2005Copyright © 2005 Nokia. All Rights Reserved.Functional DescriptionAudio ExternalRH-53/54 is designed to support fully differential external audio accessory connection. A head-set and PnPHF can be directly connected to system connector. Detection of the different ac-cessories is made in analog way by reading the DC voltage value of EAD converter.Figure 4:External audio interfaceHeadset DetectionSupported headsets are 4-wire fully differential accessories. The hardware used to detect ac-cessories is contained in the UEM and BB area. For interrupt purposes the UEM inputsHOOKINT and HEADINT are used. The bottom connector contains a switch, which openswhen an accessory is connected. The switch is routed to the UEM HEADINT input.The current generators on the HOOKINT and HEADINT pins acts as internally pull-up resistorswith values equivalent to 675 k - 2.86 M, tolerances of the current source and VFLASH1 con-sidered. The HOOKINT input comparator threshold level can be set to two different values.Levels can be found in the table.1k0HookintHeadintHeadintEADMICB2MIC2PMIC2N 33NHFCMHFBottomConnectorUEM2.1V2.7V33N1k0/MBUSMicGnd1.8V0.3V0.8V3...25kMic_bias0.8VNot all components are shown
