User Guide

RM-11

Troubleshooting - Baseband CC Technical Documentation

Charge Control

In active mode, charging is controlled by the UEM's digital part. Charging voltage and

current monitoring is used to limit charging into a safe area. For that reason, the UEM

has the following programmable, charging cut-off limits:

• VBATLim1=3.6 V (Default)

• VBATLim2L=5.0 V

• VBATLim2H=5.25 V

VBATLim1, 2L, 2H are designed with hystereses. When the voltage rises above VBATLim1,

2L, 2H+ charging is stopped by turning the charging switch off. There is no change in the

operational mode. Charging restarts after the voltage decreases below VBATLim-.

There are two PWM frequencies in use depending on the type of the charger. A two-wire

charger uses a 1 Hz, and a three-wire charger uses a 32 Hz. The duty cycle range is 0% to

100%, and the maximum charging current is limited to 1.2 A.

Figure 17: Charging circuit at battery

Audio

The audio control and processing in RM-11 is supported by the UEM and the UPP. The

UEM contains the audio codec. The UPP contains the MCU and DSP blocks, handling and

processing the audio data signals.

The baseband supports three microphone inputs and two earpiece outputs. The micro-

phone inputs are:

• MIC1 = Used for the phone's internal microphone

• MIC2 = Used for headsets (HDB-4)

• MIC3 = Used for the Universal Headset

Every microphone input can have either a differential or single-ended AC connection to

the UEM circuit. In RM-11, the internal microphone (MIC1) and external microphone

(MIC2) are both differential for Tomahawk accessory detection. However, the Universal

Headset interface is single-ended. The microphone signals from different sources are

connected to separate inputs at the UEM. Inputs for the microphone signals are

differential types. Also, the MICB1 is used for MIC1, and MICB2 is used for both MIC2

and MIC3 (Universal Headset).

R200

.22 Ohms

N10

UEM Pins

M10

C237

1uF

C202

10nF

VBAT