User's Manual

Table Of Contents
38 novatelwireless.com
50 dB
Amplifier State in Power Down High
Z
The left and right channels of the headset speaker output are a single ended output. An
external audio amplifier should be used for loads of less than 32 W or if volume is inadequate.
Headset Output Common Mode (Pin 61)
The left and right headset amplifiers provide the stereo signal on terminals HSOL and HSOR.
A pseudo ground is provided on terminal HSOVMID to eliminate external capacitors.
HSOVMID Parameter/Conditions Min Typ Max Units
Maximum Capacitor Load 200 pF
DC Level 1.2 1.35 1.5 V
Headset Detect (Pin 47)
Headset Plug/Unplug detection. This pin is used to automatically switch to the headset audio
path when enabled with AT$VSELECT=3. The device will default to handset when no
Headset is detected.
2 modes:
l
Module already ON (Battery connected, VRIO ON) and plug event;
l
Module OFF and plug event: the plug detection will be effective once VRIO is set ON
Plug and unplug detections are digitally debounced (debouncing time = 8 ms).
The jack plug detection feature is addressed through the HSDET pin. The integrated pull up,
connected to the pin, forces a high level (VBAT) when the headset load is not connected. At
jack insertion headset load connection (32 W) imposes a low level on that node (Headset left
channel): as an example HSDET = 1 mV after jack plug for VBAT = 4 V.
Input comparator threshold voltages are defined as VTlow = VBAT/2 – 100 mV and VThigh =
VBAT/2 + 100 mV, VBATmin = 3.2 V. The plug and unplug detection remains functional if
there is no signal from HSOL amplifier output (stereo path is OFF) or if there is a signal from
HSOL (stereo path is ON): maximum level on HSOL when the stereo path is ON is 1 Vp-p which
stays far enough from the comparator threshold levels VBATmin/2 100 mV and VBATmin/2
+ 100 mV.