What is a digital transistor?

数字晶体管是一种集成电阻器的双极晶体管。

A digital transistor is a bipolar transistor that integrates resistors.

• Concerning internal resistor R1 / 关于内部电阻 R1

R1 的作用是通过将输入电压转换为电流来稳定晶体管的工作。

如果将输入端（基极）直接连接到集成电路的输出端进行电压控制，双极运行往往会变得不稳定。在基极插入一个电阻可以稳定工作。请注意，输出电流将根据输入电压的变化呈指数变化，但与输入电流保持线性关系。

The role of R1 is to stabilize transistor operation by converting the input voltage to current.

Bipolar operation tends to become unstable if the input (Base) is connected directly to the output terminal of an IC for voltage control. Inserting a resistor at the Base stabilizes operation. Please note that the output current will vary exponentially based on changes to the input voltage, but will maintain a linear relationship with the input current.

接下来，我们比较电压控制和电流控制之间的差异。

Next we compare the difference between Voltage and Current control.

从上图可以看出，电压控制使输出电流根据输入电压呈指数变化，而电流控制则使输入和输出电流呈线性关系。

As we can see in the above graphs, Voltage Control results in an exponential change in the output current based on the input voltage, while Current Control exhibits a linear relationship between the input and output currents.

例如，在右边的电流控制图中，输入电流增加一倍，从 40uA 增加到 80uA，输出电流就增加一倍，从 9mA 增加到 18mA。然而，在电压控制图中，我们可以看到输入电压的微小变化（从 0.7V 到 0.8V）会导致输出电流增加 7 倍，从 10mA 增加到 70mA。这是不可取的，因为即使输入电压中引入了一点噪声，也会导致输出电流发生重大变化。

For example, in the Current Control graph at right a doubling of the input current, from 40uA to 80uA, results in twice the output current, from 9mA to 18mA. However, in the Voltage Control graph we see that a small change in the input voltage, from 0.7V to 0.8V, results in an increase in the output current by 7 times, from 10mA to 70mA. This is not desirable, since even a little noise introduced in the input voltage can result in significant changes to the output current.

由此可见，通过将电压转换为电流的基极电阻器进行电流控制可实现稳定的驱动。ROHM 提供的数字晶体管在基极上集成了一个电阻器，从而减少了外部元件的数量和安装面积。

Thus it is evident that current control via Base resistor that converts the voltage into current results in stable drive. ROHM offers digital transistors, which integrate a resistor at the Base, reducing the number of external components and mounting area.

• Regarding internal resistor R2

R2 的作用是吸收漏电流并将其分流到地，以防止发生故障。

The role of R2 is to absorb leakage current and shunt it to ground in order to prevent malfunction.

 

请注意，无论电阻器 R2 是否存在，较大的输入电流都可能导致晶体管导通。

Please note that a large input current may cause the transistor to turn ON,regardless of the presence of resistor R2.

   

所有电流都通过 R2 流向地线，从而防止 TR 电源接通（在漏电情况下可能导致故障）。

All of the current flows to ground via R2, preventing TR power ON (and possible malfunction in the case of leakage current).

VR2=VBE<(when E-B Forward Voltage ? 0.7V)

VR2=VBE<(when E-B Forward Voltage ? 0.7V)

部分电流流过基极，导致晶体管导通（在漏电流的情况下是无意导通）。

Part of the current flows through the Base, causing the transistor to turn ON (inadvertently in the case of leakage current).

VR2=VBE>(when E-B Forward Voltage ? 0.7V)

参考：

1，Rohm

What is a digital transistor? |FAQ|ROHM Semiconductor