Medical Applications User Guide (pdf) - Freescale Semiconductor
Medical Applications User Guide (pdf) - Freescale Semiconductor
Medical Applications User Guide (pdf) - Freescale Semiconductor
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9.2<br />
Microphone Amplifier<br />
The microphone and amplifier are used to<br />
convert sound into electrical signals. The<br />
microphone is a transducer that converts<br />
vibrations in the air to electrical signals.<br />
The microphone can be connected to a<br />
preamplifier to couple the impedances and<br />
normalize the audio levels. The preamplifier<br />
output is connected to the amplifier input to<br />
condition the signal-in voltage levels used by<br />
the analog-to-digital converter (ADC).<br />
The ADC converter transforms the continuous<br />
audio signal into digital samples to be<br />
processed and filtered by a digital signal<br />
processor (DSP).<br />
9.3<br />
Li-Ion Battery Charger<br />
Circuit<br />
Because this device is designed to be worn<br />
in or behind the ear, the power source must<br />
be batteries. Using rechargeable batteries<br />
eliminates the need to replace or purchase<br />
batteries.<br />
MC13883: Integrated Charger,<br />
USB On-the-Go Transceiver and<br />
Carkit Interface<br />
The <strong>Freescale</strong> MC13883 is a monolithic<br />
integration of a lithium ion battery charger with<br />
a CEA-936 carkit with interfacing support and<br />
a USB OTG transceiver.<br />
Key Features<br />
• Li-ion battery charging through a USB<br />
connector<br />
• Multiple charger modes and configurations<br />
supported<br />
• Overvoltage protection for shielding<br />
products from faulty (high-voltage) charging<br />
sources<br />
• Trickle pre-charge of deeply discharged<br />
batteries<br />
• Reverse path capability allows power to be<br />
sourced to the VBUS pin from the battery<br />
and can be used to support phone-powered<br />
devices through the USB connector<br />
• Charge indicator LED driver<br />
Figure 9-1: Hearing Aid General Block Diagram<br />
Hearing Aid<br />
AC Mains<br />
Li-Ion Battery<br />
Charger Circuit<br />
Microphone<br />
Amplifier<br />
Power<br />
Management<br />
Voltage<br />
Regulation<br />
<strong>Freescale</strong> Technology Optional<br />
Figure 9-2: Signal Acquisition Block Diagram<br />
Figure 8-2: Signal Acquisition Block Diagram<br />
Pre-Amplifier<br />
Home Portable <strong>Medical</strong><br />
Non-Volatile<br />
Memory<br />
DSP/DSC<br />
Loudspeaker<br />
Class D Amplifier<br />
Wireless<br />
Comm<br />
Keypad<br />
Inertial<br />
Sensor<br />
freescale .com/medical 51<br />
Amplifier<br />
SPI/I 2 C<br />
High-Speed<br />
Analog-to-Digitial<br />
Converter<br />
Microphone Digital Signal Processor<br />
(DSP)<br />
Figure 9-3: MC13883 Block Diagram<br />
Figure 8-3: MC13883 Block Diagram<br />
10-bit ADC<br />
Battery Monitoring<br />
Li-Ion Battery Charger,<br />
USB Charging,<br />
Overvoltage Protection<br />
MC13883<br />
SPI/I 2 C<br />
Interface<br />
USB OTG<br />
Transceiver<br />
and Car Kit<br />
Interface<br />
n<br />
BB Processor
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