LM49352RLX/NOPB National Semiconductor, LM49352RLX/NOPB Datasheet - Page 45

• Manufacturer Part Number: LM49352RLX/NOPB
• Description: IC AMP AUDIO MONO D1.4W 36USMD
• Manufacturer: National Semiconductor
• Series: Boomer®, PowerWise®r
• Type: Class Dr

Specifications of LM49352RLX/NOPB

• Output Type: 1-Channel (Mono) with Mono and Stereo Headphones
• Max Output Power X Channels @ Load: 1.4W x 1 @ 8 Ohm; 65mW x 2 @ 32 Ohm
• Features: Depop, Differential Inputs, I²C, I²S, Microphone, Shutdown, Volume Control
• Mounting Type: Surface Mount
• Package / Case: 36-MicroSMDxt
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Supply: -
• Other names: LM49352RLX

Headphone Amplifier Function
The LM49352 headphone amplifier features National’s ground referenced architecture that eliminates the large DC-blocking ca-
pacitors required at the outputs of traditional headphone amplifiers. A low-noise inverting charge pump creates a negative supply
(HP_V
amplifier outputs biased about GND, instead of a nominal DC voltage (typically V
no DC component to the headphone output signals, the large DC-blocking capacitors (typically 220μF) are not necessary, con-
serving board space and system cost, while improving frequency response.
Charge Pump Capacitor Selection
Use low ESR ceramic capacitors (less than 100mΩ) for optimum performance.
Charge Pump Flying Capacitor (C6)
The flying capacitor (C6) affects the load regulation and output impedance of the charge pump. A C6 value that is too low results
in a loss of current drive, leading to a loss of amplifier headroom. A higher valued C6 improves load regulation and lowers charge
pump output impedance to an extent. Above 2.2μF, the R
the output impedance. A lower value capacitor can be used in systems with low maximum output power requirements. Please refer
to the demonstration board schematic shown in Figure 27.
Bits
Bits
0
1
2
3
4
5
0
1
2
3
4
5
SS
) from the positive supply voltage (LS_V
MONO_HPR
MONO_HPL
DACR_HPR
DACR_HPL
DACL_HPR
DACL_HPL
AUX _HPR
AUX_HPL
RSVD
RSVD
RSVD
RSVD
Field
Field
FIGURE 14. EMI/RFI Filter for the Class D Amplifier
TABLE 17. RIGHT HEADPHONE_OUTPUT (0x12h)
TABLE 16. LEFT HEADPHONE_OUTPUT (0x11h)
The right DAC output is added to the left headphone output.
The left DAC output is added to the left headphone output.
Reserved
Reserved
The MONO input is added to the left headphone output.
The AUX input is added to the left headphone output.
The right DAC output is added to the right headphone output.
The left DAC output is added to the right headphone output.
Reserved
Reserved
The MONO input is added to the right headphone output.
The AUX input is added to the right headphone output.
DD
). The headphone amplifiers operate from these bipolar supplies, with the
DS(ON)
of the charge pump switches and the ESR of C6 and C5 dominate
45
Description
Description
DD
/2), like traditional amplifiers. Because there is
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