6008BZ10000 DCS集散控制系统
白炽灯驱动器
高白炽灯通电/涌入电流会破坏半导体灯驱动器，导致灯的可靠性差。然而，可以使用UDN2549B驱动额定稳态电流高达600 mA的灯，而无需加温或限流电阻器。当白炽灯最初打开时，冷灯丝的电阻最小，通常允许10倍至12倍的涌入电流。对于UDN2549B，高涌入电流由内部感测电阻器感测。通过分流晶体管感测通过感测电阻器的输出电流，负载电流被限制为大约1A。在这个短暂的过渡期间，输出驱动器以线性方式被驱动。随着灯的预热，灯丝电阻增加到其最大值。然后，输出驱动器进入饱和状态并向灯施加全电源电压。
1 A或更大的涌入电流将迫使驱动器进行反向电流限制。为避免此问题，应在灯电路中使用加温或限流电阻器。感应负载驱动器-双线（单极）步进电机可以直接驱动。内部反冲二极管通过抑制关闭感应负载时出现的高压尖峰，防止对输出晶体管的损坏。故障条件-如果负载短路、绕组短路或电机失速，负载电流将尝试增加。如上所述，到输出级的驱动电流被分流（将负载电流限制为约1A），导致输出级变为线性。随着输出级的结温度升高，热限位电路将开始工作，进一步降低驱动电流。负载电流（结温度）是环境温度、剩余驱动器状态、电源电压和负载电阻的函数。如果故障条件得到纠正，输出驱动器将恢复到正常饱和状态。电源电压高达25 V时，为每个输出提供短路保护。
Incandescent lamp driver
Power on/inrush current of high incandescent lamps will damage the semiconductor lamp driver, resulting in poor lamp reliability. However, UDN2549B can be used to drive lamps with rated steady state current up to 600 mA without heating or current limiting resistors. When an incandescent lamp is initially switched on, the resistance of the cold filament is minimal, usually allowing 10 to 12 times the inrush current. For UDN2549B, the high inrush current is sensed by an internal sensing resistor. The output current through the sensing resistor is sensed by the shunt transistor, and the load current is limited to about 1A. During this transient period, the output driver is driven in a linear manner. As the lamp warms up, the filament resistance increases to its maximum value. The output driver then saturates and applies full supply voltage to the lamp.
An inrush current of 1 A or more will force the driver to reverse current limiting. To avoid this problem, use a heating or current limiting resistor in the lamp circuit. Inductive Load Driver - Two wire (single pole) stepping motors can be driven directly. The internal recoil diode prevents damage to the output transistor by suppressing the high voltage spike that occurs when the inductive load is turned off. Fault condition - If the load is shorted, the winding is shorted, or the motor stalls, the load current will attempt to increase. As described above, the drive current to the output stage is shunted (limiting the load current to about 1A), causing the output stage to become linear. As the junction temperature of the output stage increases, the thermal limit circuit will start to work, further reducing the drive current. The load current (junction temperature) is a function of ambient temperature, remaining driver status, supply voltage, and load resistance. If the fault condition is corrected, the output driver will return to normal saturation. Short circuit protection is provided for each output when the supply voltage is up to 25 V.
