Design Specifications
| Inputs |
Output #1 |
Output #2 |
Output #3 |
| VinMin=4.5V | Vout1=3.3V | Vout2=5V | Vout3=12V |
| VinMax=6V | Iout1=0.9A | Iout2=1.5A | Iout3=0.1A |
Design Description
The High Efficiency Portable Media Player (PMP) Docking Station reference
design showcases National Semiconductor’s PowerWise® power converters,
battery charging circuitry, audio drivers and display interface. The reference
design saves more power by initiating a power-saving mode when the PMP is
unplugged from the wall power, automatically reducing the maximum brightness
of the display as well as the output power of the audio drivers. See Figure
1 which shows the power management and audio segments of the reference design.
The LM3658SD-A dual source, USB/AC Li chemistry charger IC receives a wall
wart or USB input and converts either input into a source voltage, using
the LM20124 synchronous buck regulator, powers the docking station as
well as providing the charging current to an external Lithium-Ion back-up
battery pack.
The LM20124 provides the source voltage which biases both the audio and
DS90UR241/124 serializer/deserializer (SERDES) segments of the video transport
sections of the system. The LM4674 stereo Class D audio amplifier drives
two 2W speakers. The LM2735Y Boost and SEPIC DC-DC Regulator boosts the
3.3VDC output to 5VDC, which supplies the bias voltage needed to charge
the PMP device when docked in the docking station connector. Additionally,
the wall wart also feeds an LM3478 Low-Side N-Channel Controller which
boosts the voltage to 12VDC and provides power to the AVP-1280 video interface
controller. The AVP-1280 converts the analog video output signal from
the docking station into digital inputs for processing by the DS90UR241
serializer segment. Finally, the output of the DS90UR124 deserializer
is taken and displayed by the Sharp LQ104S1DG21 TFT-LCD display, which
is illuminated by an LED backlight with dimming capability.
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Design Resources
Additional Product Resources
| • | DS90UR124 - 5-43MHz DC- Balanced 24-Bit LVDS Deserializer |
| • | DS90UR241 - 5-43MHz DC- Balanced 24-Bit LVDS Serializer |
| • | LM20124 - 4A, 1MHz PowerWise Synchronous Buck Regulator |
| • | LM2735Y - 520kHz - Space-Efficient Boost and SEPIC DC-DC Regulator |
| • | LM3658 - Dual Source USB/AC Li Chemistry Charger IC for Portable Applications |
- datasheet
- application notes
- samples
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Block Diagram
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Features
- 20W Wake-On-Load AC/DC Adapter provide source voltage to entire system.
- Wall wart adapter or USB charging capability to Lithium-Ion battery
backup.
- Provides charging current for PMP device when docked in docking station
connector.
- Detachable LCD Display can be removed at least 10 meters from base.
- Stereo Class D Audio Amplifier with logic selectable gain.
- Low profile, high efficiency power management design.
- Efficient LED Backlight Solution provides lighting to LCD Display.
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Design Source Files