参数资料
型号: MAX9752AETI+
厂商: Maxim Integrated Products
文件页数: 15/29页
文件大小: 0K
描述: IC AMP AUDIO PWR 2.2W D 28TQFN
标准包装: 60
系列: DirectDrive®
类型: D 类
输出类型: 2-通道(立体声)带立体声耳机
在某负载时最大输出功率 x 通道数量: 2.2W x 2 @ 4 欧姆; 62mW x 2 @ 16 欧姆
电源电压: 4.5 V ~ 5.5 V
特点: 消除爆音,短路保护和热保护,关机,音量控制
安装类型: 表面贴装
供应商设备封装: 28-TQFN-EP(5x5)
封装/外壳: 28-WFQFN 裸露焊盘
包装: 管件
MAX9752/MAX9753/MAX9754
Power Supplies
The MAX9752/MAX9753/MAX9754 have different sup-
plies for each portion of the device allowing for the opti-
mum combination of headroom, power dissipation, and
noise immunity. The speaker amplifiers are powered from
PVDD. PVDD ranges from 4.5V to 5.5V. The headphone
amplifiers are powered from HPVDD and VSS. HPVDD is
the positive supply of the headphone amplifiers and
ranges from 3V to 5.5V. VSS is the negative supply input
for the headphone amplifiers. Connect VSS to CPVSS. The
charge pump is powered by CPVDD, which ranges from
3V to 5.5V. CPVDD should be the same potential as
HPVDD. The charge pump inverts the voltage at CPVDD,
and the resulting voltage appears at CPVSS. The remain-
der of the device is powered by VDD.
Component Selection
Input Filtering
The input capacitor (CIN), in conjunction with the ampli-
fier input resistance (RIN), forms a highpass filter that
removes the DC bias from an incoming signal (see the
Functional Diagrams). The AC-coupling capacitor
allows the amplifier to bias the signal to an optimum DC
level. Assuming zero source impedance, the -3dB point
of the highpass filter is given by:
RIN is the amplifier’s internal input resistance value given
in the Electrical Characteristics table. Choose CIN so
f-3dB is well below the lowest frequency of interest.
Setting f-3dB too high affects the amplifier’s low-frequency
response. Use capacitors with low-voltage coefficient
dielectrics, such as tantalum or aluminum electrolytic.
Capacitors with high-voltage coefficients, such as ceram-
ics, may result in increased distortion at low frequencies.
Optional Output Filtering
In most applications, the low-EMI, Class D outputs do not
require output filters. The device passes FCC emissions
standards with 76mm of unshielded speaker cables.
Output filtering can be used if lower EMI is desired. Use a
ferrite bead filter when radiated frequencies above
10MHz are of concern. Use an LC filter when radiated fre-
quencies below 10MHz are of concern, or when long
leads (> 76mm) connect the amplifier to the speaker.
BIAS Capacitor
BIAS is the output of the internally generated DC bias
voltage. The BIAS bypass capacitor, CBIAS, improves
PSRR and THD+N by reducing power supply and other
noise sources at the common-mode bias node, and
also generates the clickless/popless, startup/shutdown,
DC bias waveforms for the speaker amplifiers. Bypass
BIAS with a 1F capacitor to GND.
Charge-Pump Capacitor Selection
Use capacitors with less than 100m
Ω of equivalent
series resistance (ESR). Low-ESR ceramic capacitors
minimize the output impedance of the charge pump.
Capacitors with an X7R dielectric provide the best per-
formance over the extended temperature range.
Flying Capacitor (C1)
The value of the flying capacitor (C1) affects the load
regulation and output resistance of the charge pump.
Choosing C1 too small degrades the ability to provide
sufficient current drive, which leads to a loss of output
voltage. Increasing the value of C1 improves load regu-
lation and reduces the charge-pump output resistance.
See the Output Power vs. Charge-Pump Capacitance
and Load Resistance graph in the Typical Operating
Characteristics. Above 2.2F, the on-resistance of the
switches and the ESR of C1 and C2 dominate. The rec-
ommended range of capacitors is from 0.33F to 3.3F.
Output Capacitor (C2)
The output capacitor value and ESR directly affect the
ripple at CPVSS. Increasing the value of C2 reduces
output ripple. Decreasing the ESR of C2 reduces both
ripple and output resistance. Lower capacitance values
can be used in systems with low, maximum output
power levels. See the Output Power vs. Charge-Pump
Capacitance and Load Resistance graph in the Typical
Operating Characteristics. C2 must be greater than or
equal to C1. The recommended range of capacitors is
from 0.33F to 3.3F.
CPVDD Bypass Capacitor
The CPVDD bypass capacitor (C3) lowers the output
impedance of the power supply and reduces the
impact of the charge-pump switching transients on the
headphone driver outputs. Bypass CPVDD with C3, the
same value as C1, and place it physically close to
CPVDD and PGND.
Layout and Grounding
Proper layout and grounding are essential for optimum
performance. Use large traces for the power-supply
inputs and amplifier outputs to minimize losses due to
parasitic trace resistance. Large traces also aid in mov-
ing heat away from the package. Proper grounding
improves audio performance, minimizes crosstalk
between channels, and prevents any switching noise
from coupling into the audio signal. Connect CPGND,
PGND, and GND together at a single point on the PC
board. Route CPGND, PGND, and all traces that carry
switching transients away from GND and the traces and
components in the audio signal path.
f
RC
dB
IN IN
=
3
1
2
π
2.2W, Low-EMI, Stereo, Class D Power Amplifiers
with DirectDrive Headphone Amplifiers
22
______________________________________________________________________________________
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