HT338

Stereo Class D Amplifier

Copyright©2023, Heroic Technology

-16-

8/2023 – V1.1

7 BSP and BSN Capacitors

The full H-bridge output stages use only NMOS transistors.

Therefore, they require bootstrap capacitors for the high side

of each output to turn on correctly. A 1uF ceramic capacitor of

quality X5R or better, rated for at least 16 V, must be

connected from each output to its corresponding bootstrap

input. The bootstrap capacitors connected between the BSx

pins and corresponding output function as a floating power

supply for the high-side N-channel power MOSFET gate drive

circuitry. During each high-side switching cycle, the bootstrap

capacitors hold the gate-to-source voltage high enough to keep

the high-side MOSFETs turned on.

全

H 桥输出级仅使用 NMOS 晶体管。因此，

它们需要引导电容器，以使每个输出的高端正确

开启。必须从每个输出端将额定电压至少为

16

V、质量为 X5R 或更高的 1uF 陶瓷电容器连接

到相应的自举输入端。连接在

BSx 引脚和相应

输出之间的自举电容器，用作高端

NMOS 栅极

驱动电路的电源。在每个高端开关周期中，自举

电容器保持栅极至源极电压足够高，以保持高端

MOSFET 导通。

8 Protection Function

HT338 has the protection functions such as Over-Current

Protection function, Thermal Protection function, DC Detect

Protection, Under-Voltage Protection and over voltage

protection.

(1) Over-current Protection function (OCP)

When a short circuit occurs between one output terminal and

Ground, PVDD, or the other output, the over-current

protection mode starts up. In the over current protection mode,

the differential output terminal becomes a high impedance

state. Once the short circuit conditions are eliminated, the over

current protection mode can be cancelled automatically.

(2) Thermal Protection function (OTP)

When excessive high temperature of HT338 (150 ℃ ) is

detected, the thermal protection mode starts up. In the thermal

protection mode, the differential output terminal becomes

Weak Low state (a state grounded through high impedance).

HT338 具有以下几种保护功能：输出端过

流保护、片内过温保护、直流监测保护、欠压保

护、过压保护。

（

1）过流保护

当检测到一输出端对电源、对地、或对另一

输出端短路时，过流保护启动，输出端切换至高

阻态，防止芯片烧毁损坏。短路情况消除后，通

过关断、唤醒一次芯片，或重新上电均能使芯片

退出保护模式。

（

2）过温保护

当检测到芯片内温度超过

150℃时，过温保护启

动，正负输出端切换至弱低电平状态（内部通过

高阻接地）

，防止芯片被热击穿损坏。

(3) DC Detect Protection (DCP)

The HT338 has circuitry which will protect the speakers from

DC current which might occur due to an internal amplifier

error. The DC Detect fault will cause the amplifier to

shutdown by changing the state of the outputs to Hi-Z.

A DCE event occurs when the output differential duty-cycle

of either channel exceeds 60% for more than 420 msec at the

same polarity. This feature protects the speaker from large DC

currents or AC currents less than 2 Hz.

When OCP, OTP or DCP is activated, the SD/FAULT pin

will be pulled low, and the error signal will be cleared.

Therefore, after a delay time (Typ 1.3s), HT338 will try

restart.

（

3）直流监测保护

HT338 具有保护扬声器免受由于内部放大

器错误而产生的直流电流影响的电路。直流检测

故障时，输出状态更改为

Hi-Z，致放大器关闭。

当任一通道在相同极性下的输出差占空比

超过

60%超过 420 毫秒时，就会发生 DCE 事

件。此功能可保护扬声器免受大直流电流或小于

2 Hz 的交流电流的影响。

当

OCP、OTP或DCP发生时，\SD/FAULT引脚拉

低，错误信号清除。因此，经过一段延迟时间

(Typ

1.3s)后，HT338将尝试重启。