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" k; e( I; R5 `0 w& T$ zMaxim公司的MAX98357A/MAX98357B是数字脉码调制(PCM)输入D类放大器,提供AB类音频性能和D类效率,有五个可选择的增益设定(3dB, 6dB, 9dB, 12dB和15dB),单电源2.5V-5.5V工作,5V 4Ω时的输出功率为3.2W,效率92% (RL = 8Ω, POUT = 1W),输出噪音25μVRMS (AV = 15dB),1kHz时的THD+N为0.015%,主要用在笔记本电脑和上网本(Netbook),手机和平板电脑.本文介绍了MAX98357A/MAX98357B主要特性,功能框图和几种应用电路,以及MAX98357开发板DEV(WLP)主要特性,框图,电路图,材料清单和PCB设计图.
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The MAX98357A/MAX98357B are digital pulse-code mod-ulation (PCM) input Class D power amplifiers that provide Class AB audio performance with Class D efficiency. These ICs offer five selectable gain settings (3dB, 6dB, 9dB, 12dB, and 15dB) in I2S/left-justified mode set by a single gain select input and a fixed 12dB gain in TDM mode. 7 B* [; F1 \3 [( {
) y8 l' W4 M# R" m8 RThe digital audio interface is highly flexible with the MAX98357A supporting I2S data and the MAX98357B supporting left-justified data. Both ICs support 8 channel time division multiplexed (TDM) data. The digital audio interface accepts specified sample rates between 8kHz and 96kHz for all supported data formats. The ICs can be configured to produce a left channel, right channel, or (left/2 + right/2) output from the stereo input data. The ICs operate using 16/24/32-bit data for I2S and left-justified modes as well as 16-bit or 32-bit data using TDM mode. The ICs eliminate the need for the external MCLK signal that is typically used for PCM communication. This reduc-es EMI and possible board coupling issues in addition to reducing the size and pin count of the ICs.
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6 {- ?: C. F- N# c0 f6 }The ICs also feature a very high wideband jitter toler-ance (12ns typ) on BCLK and LRCLK to provide robust operation.Active emissions-limiting, edge-rate limiting, and over-shoot control circuitry greatly reduce EMI. A filterless spread-spectrum modulation scheme eliminates the need for output filtering found in traditional Class D devices and reduces the component count of the solution. ' T3 b9 z, U6 s* h
1 ~& P+ J* a+ ]0 p. cThe ICs are available in 9-pin WLP (1.345mm x 1.435mm x 0.64mm) and 16-pin TQFN (3mm x 3mm x 0.75mm) packages and are specified over the -40 ℃ to +85℃ tem-perature range.' a, Z6 n& N# P' w3 P2 i" x0 t' C
0 |& B$ W+ P" z$ {& YMAX98357A/MAX98357B主要特性:
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Single-Supply Operation (2.5V to 5.5V) 2 Y! s- \" J' S( f" @$ Z
3.2W Output Power into 4Ω at 5V + x. Z3 j# z1 d3 D/ h9 b$ T- A
2.4mA Quiescent Current
( k) t+ k( h2 \0 d# D92% Efficiency (RL = 8Ω, POUT = 1W) ( Z2 N( \' h0 P5 }. s2 d. I l( x
25μVRMS Output Noise (AV = 15dB)
# M" s9 J. O' C" K; qLow 0.015% THD+N at 1kHz
8 G) I0 d& l4 |1 |No MCLK Required ( ]: i: I# }5 L) n& ^1 k, i5 c0 k
Sample Rates of 8kHz to 96kHz
) |! _. `5 o+ A$ I0 ]3 kSupports Left, Right, or (Left/2 + Right/2) Output & X2 I) s. s6 d1 ^; i( k/ }0 t
Sophisticated Edge Rate Control Enables Filterless Class D Outputs
' m- c" S, Q' g Y: Y9 z77dB PSRR at 1kHz! ]: W6 N1 ]5 y6 i* J
Low RF Susceptibility Rejects TDMA Noise from GSM Radios
* \8 A/ b% b4 R6 Y* b* iExtensive Click-and-Pop Reduction Circuitry ! P! f+ X" x. v* S& ^) c$ i
Robust Short-Circuit and Thermal Protection
9 A) J5 I/ }2 ?7 I V- cAvailable in Space-Saving Packages: 1.345mm x 1.435mm WLP (0.4mm Pitch) and 3mm x 3mm TQFN ! Q6 q: l7 ?3 ?3 }/ F3 W
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MAX98357A/MAX98357B应用:& Q; {- O' v! |( Z2 H1 A8 L
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Notebook and Netbook Computers
' ~) A0 h9 T4 @Cellular Phones
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图1.MAX98357A/MAX98357B功能框图
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图2.MAX98357A/MAX98357B增益6dB左路PCM工作电路( v9 j/ b' h4 y0 T4 _9 y O* @1 N
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图3.MAX98357A/MAX98357B增益12dB左路PCM工作电路
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& h! z0 s3 L1 f; {% |' ~( f+ ]: _# @图4.MAX98357A/MAX98357B增益6dB右路PCM工作电路
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图5.MAX98357A/MAX98357B增益6dB(左路/2+右路/2)PCM工作电路
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& z# j( l$ y" O! x- q图6.MAX98357A/MAX98357B采用两个IC的立体声PCM工作电路) E( j# e0 Q+ ?4 e% p. Z# S
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图7.MAX98357A/MAX98357B增益12dB通路TDM工作电路
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发表于 2004-3-21 00:13:00
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发表于 2004-3-22 03:10:00
