HT37B90/HT37B70/HT37B50/HT37B30
The Integrated Power Amp.
SP0: Audio Negative output
SP1: Audio Positive output
OUTP Rising Time (tR)
The Power Amp. is an integrated class AB mono
speaker driver contained in HT37B90/70/50/30. It pro-
vides property of high S/N ratio, high slew rate, low dis-
tortion, large output voltage swing, excellent power
supply ripple rejection, low power consumption, low
standby current and power off control etc.
When AMP_EN enable, the Power Amp. need rising
time to output fully on OUTP pin. However, the rising
time depends on.
C1. (*The C1 connects with VBIAS and Vss)
Aud In: Audio input
VBIAS: Speaker non-inverting input voltage reference
Capacitor
tR
0.1mF
1mF
4.7mF
10mF
Voltage
2.2V
3V
4
15ms
15ms
15ms
30ms
30ms
30ms
90ms
90ms
90ms
185ms
185ms
185ms
For battery based applications, power consumption is a key issue, therefore the amplifier should be turned off when in
the standby state. In order to eliminate any speaker sound bursts while turning the amplifier on, the application circuit,
which will incorporate a capacitance value of C1, should be adjusted in accordance with the speaker s audio frequency
response. Agreater value of C1 will improve the noise burst while turning on the amplifier. The recommended operation
sequence is:
Turn On: audio signal standby (1/2VDD) ® enable amplifier ® wait tR for amplifier ready ® audio output
Turn Off: audio signal finished ® disable amplifier ® wait tR for amplifier off ® audio signal off
If the application is not powered by batteries and there is no problem with amplifier On/Off issue, a capacitor value of
0.1mF for C1 is recommended.
How to use integrated power Amp?
·
·
·
Connect the ²Internal Power Amp Circuit², please refer to Application Circuits.
Set DACC.3 to enable integrated power amp. Clear DACC.3 to disable integrated power amp.
User can control it at ²PowerAmpDisable² and ²PowerAmpEnable² of HT-MDS.
Rev. 1.00
47
June 22, 2017
HOLTEK [ HOLTEK SEMICONDUCTOR INC ]
