User Guide

CCS Technical Documentation System Module
RH-25
Issue 1 10/2003 ©Nokia Corporation Confidential Page 21
voltage level is higher than the threshold of the comparator and thereby its output will
be changed to low. This changes is leading to an interrupt. These HeadInt interrupts are
initiated the accessory detection or removal sequence.
External Accessory Regulator
An external LDO Regulator is needed for accessory power supply purposes. All ACI-acces-
sories will require this power supply. Regulator input is connected to battery voltage
VBAT and output is connected to Vout pin in Tomahawk connector. Regulator ON/OFF
function is controlled via UPP.
The pull-down resistor on the enable input of the regulator is needed because in the
switch-off mode of the phone, the output level of the Genio(0) is not defined. If Genio(0)
is floating, the regulator may be enabled when it shouldn't be.
Figure 16: Accessory power supply diagram
PWB Strategy
PWB Construction
The PWB in RH-25 consists of a 6-layer board made up of FR4.
Via types are through hole, laser, buried, and blind vias.
The PWB build up is shown below:
Tomahawk btm conn
Voltage
regulator
LP
3985
UPP
GenIO(0)
VBAT
VOUT
En