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HT868
2×6.5W Smart Audio Amplifier with Boost Converter, TFB and AGC
The HT868 is a smart audio power amplifier with TFB, AGC technology and an integrated adaptive sync boost converter that enhances efficiency at low output power. It drives up to continuous 10W (3% THD+N, boosted to 8.0V) into 3ohm speaker, or instantaneous 2×6.5W (1% THD+N, boosted to 8.0V) into 4ohm speaker from a Li-battery voltage.The built-in sync boost converter generates a supply voltage (6.5V, 7.5V, 8.0V optional to meet different out power demands) for the audio amplifier. The boost converter is adaptive and is automatically active only when the peak output audio signal exceeds a preset voltage threshold, which is optimized to prevent clipping while maximizing system efficiency. What more, there’s no need for an external diode.HT868 integrates Automatic Gain Control (AGC), including Limiter and Battery Tracking function. When Limiter function is active, the output music can be limited below a certain power and THD+N. When Battery Tracking function is active, HT868 monitors the battery voltage and the audio signal, automatically decreasing gain when battery is lower than preset voltage and the audio output power is high. It finds the optimal gain to maximize the loudness and minimize the battery current, providing louder audio and preventing early shutdown at end-of-charge battery voltages.The HT868 Thermal Foldback (TFB) is designed to protect the HT868 from excessive die temperature in case of the device being operated beyond the recommended temperature or power limit, or with a weaker thermal system than recommended. The TFB works by reducing the on-die power dissipation by reducing Gain if the temperature trig point is exceeded, so that the peak audio power is significantly increased.HT868 has a filter-less modulation circuit which can directly drive speakers. HT868 can be shut down so that the power consumption can be minimized. As for protection function, over current protection function for speaker output terminals, over temperature protection function and low supply voltage malfunction preventing function are also prepared.


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FEATURES
  • Automatic Gain Control (AGC) with Battery Tracking and Limiter function
    - Battery Tracking: automatically reduce system gain to extend battery life when the battery   voltage is low
    - Limiter: adjusts the amplifier gain to prevent heavy clipping

  • Integrated Adaptive Sync Boost Converter
    - Increases efficiency at low output power
    - No need for external diode

  • Integrated Thermal Foldback (TFB) function
    Particularly apply to applications with a weak thermal system, significantly increase the peak audio power

  • Power Supply/Output
    - VBAT from 2.8V to 5.0V
    - Multiple Boost Output VPOUT Settings: 6.5V, 7.5V, 8.0V

  • Output Power

    2×4.5 W (VBAT=4.2V, VPOUT = 6.5V, RL=4Ω, THD+N=1%)
    2×5.8W (VBAT=4.2V, VPOUT = 7.5V, RL=4Ω, THD+N=1%)
    2×6.5W (VBAT=4.2V, VPOUT = 8.0V, RL=4Ω, THD+N=1%)
    10.0W (VBAT=4.2V, VPOUT = 8.0V, RL=3Ω, THD+N=3%, PBTL)
    (Do contact and confirm with HT supplier before setting VPOUT = 8.0V, otherwise do not use this setting.)


  • Gain: 25dB
  • Quiescent current: 8.0mA (VBAT = 3.6V)
  • Efficiency: 88% (VBAT = 4.2V, RL = 4Ω+22uH, Po = 2×0.6W)
  • THD+N: 0.03% (VBAT = 4.2V, RL = 4Ω+22uH, Po = 2×0.5W)
  • Over Current /Thermal/Low voltage malfunction prevention function with auto recovery
  • Pb-free Packages,TSSOP28L-PP


APPLICATIONS

  • Portable Gamers       
  • MP4, GPS      
  • Tablet PC/Note Book     
  • LCD TV/Monitor


  • Bluetooth/Wi-Fi Speakers    
  • Portable Speakers  
  • 2.1Channel Speakers    
  • Megaphone

1. HT868 BTL MODE

2.HT868 PBTL MODE

image.png

TERMINAL FUNCTION

TerminalNo.NAMEI/ODescription
1,2,3DGNDGNDPower ground for boost converter
4

VBATL

PowerPower supply for left channel
5AGCLOTerminal that enables and selects Battery Tracking Function for left channel
6

image.png

IShut-down terminal
7INL-INegative input (differential-) for audio amplifier of left channel
8INL+IPositive input (differential+) for audio amplifier of left channel
9PBTLIParallel BTL mode switch
10

VBATR

PowerPower supply for right channel
11AGCROTerminal that enables and selects Battery Tracking Function for right channel
12

image.png

IShut-down terminal
13INR-INegative input (differential-) for audio amplifier of right channel
14INR+IPositive input (differential+) for audio amplifier of right channel
15BST_RO

Select boost converter output voltage VPOUT for right channel

16OUTR-ONegative output (BTL-) for audio amplifier of right channel
17PVDDRPowerPower supply terminal for audio amplifier of right channel
18PGNDRGNDPower ground for audio amplifier of right channel
19OUTR+OPositive output (BTL+) for audio amplifier of right channel
20BST_LO

Select boost converter output voltage VPOUT for left channel

21OUTL-ONegative output (BTL-) for audio amplifier of left channel
22PVDDLPowerPower supply terminal for audio amplifier of left channel
23PGNDLGNDPower ground for audio amplifier of left channel
24OUTL+OPositive output (BTL+) for audio amplifier of left channel
25,26

VPOUT

PowerBoost Converter output voltage
27,28SWIBoost and rectifying switch input
-PADGNDConnect to PGND


I: input   O: output 
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