并联稳压器提高功率放大器的电流限制精度-Shunt Regu
abstract: substituting a shunt regulator (u1) for the usual transistor in this power-amplifier circuit improves the current-limit accuracy.
adding current-limiting circuitry to an emitter follower protects both the pass transistor and downstream circuitry from excessive current damage. the classic way to implement such current limiting is to add a ballast resistor between the pass transistor's emitter and the circuit output, and then monitor the resistor drop with a small-signal transistor. see r4 and q2 in the power amplifier (or linear regulator) shown in figure 1.
figure 1. a small-signal transistor (q2) provides an output current limit for this power amplifier.
unfortunately, the base-emitter voltage of the small-signal transistor sets the current-limit threshold for this circuit. that vbe has a well-known temperature coefficient of -2mv/°c, which causes a substantial change in current limit across the operating temperature range.
an adjustable shunt regulator (u1 in figure 2) is preferable to the small-signal transistor for sensing current. this ic is chosen for its low-input threshold (0.6v), which is lower than that of common shunt regulators (1.25v to 2.5v). in addition, the ic's separate power-supply input allows it to maintain accuracy as the internal output transistor approaches saturation.
figure 2. substituting a shunt regulator (u1) for q2 in the figure 1 circuit improves the current-limit accuracy.
figure 3 compares current-limit accuracies of the small-signal-transistor version of figure 1 with the shunt-regulator version of figure 2. the transistor version exhibits a 25% change in current-limit threshold over the operating temperature range, while the shunt-regulator provides better than 2% accuracy over that range (neglecting the temperature coefficients of the sense resistors).
figure 3. current-limit accuracy versus temperature for the circuits of figure 1 (top trace) and figure 2 (bottom trace).
a similar article appeared as a design idea in the february 2, 2006 edition of edn.
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并联稳压器提高功率放大器的电流限制精度-Shunt Regu
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adding current-limiting circuitry to an emitter follower protects both the pass transistor and downstream circuitry from excessive current damage. the classic way to implement such current limiting is to add a ballast resistor between the pass transistor's emitter and the circuit output, and then monitor the resistor drop with a small-signal transistor. see r4 and q2 in the power amplifier (or linear regulator) shown in figure 1.
figure 1. a small-signal transistor (q2) provides an output current limit for this power amplifier.
unfortunately, the base-emitter voltage of the small-signal transistor sets the current-limit threshold for this circuit. that vbe has a well-known temperature coefficient of -2mv/°c, which causes a substantial change in current limit across the operating temperature range.
an adjustable shunt regulator (u1 in figure 2) is preferable to the small-signal transistor for sensing current. this ic is chosen for its low-input threshold (0.6v), which is lower than that of common shunt regulators (1.25v to 2.5v). in addition, the ic's separate power-supply input allows it to maintain accuracy as the internal output transistor approaches saturation.
figure 2. substituting a shunt regulator (u1) for q2 in the figure 1 circuit improves the current-limit accuracy.
figure 3 compares current-limit accuracies of the small-signal-transistor version of figure 1 with the shunt-regulator version of figure 2. the transistor version exhibits a 25% change in current-limit threshold over the operating temperature range, while the shunt-regulator provides better than 2% accuracy over that range (neglecting the temperature coefficients of the sense resistors).
figure 3. current-limit accuracy versus temperature for the circuits of figure 1 (top trace) and figure 2 (bottom trace).
a similar article appeared as a design idea in the february 2, 2006 edition of edn.
高通重回台积电怀抱，三星电子全力出击争夺新客户
国星光电在热管理上的研究成果以及第三代半导体市场的探索
升压变压器的工作原理_升压变压器型号解析
你必须知道的Minitab统计软件的强大功能
为什么选择LLCC68 LoRa模块CC68-C1，它有哪些优势？
并联稳压器提高功率放大器的电流限制精度-Shunt Regu
GD32开发实战指南(基础篇) 第17章 看门狗
TCL空调将面向社会各界发起重金征集广告语活动
未来机器人将代替人类,我们该何去何从
中车长春轨道客车发布新一代地铁列车，实现全自动无人运行
小米6震撼来袭，明天就是这么6！
基于AT89C2051单片机实现智能密码锁监控系统的设计
在智能摄像头应用中实现可扩展的边缘AI性能
使用安全元件的3大固件验证用例
变频器无法启动的原因 变频器的6种调速方法
华为云 CodeArts 开源治理服务，解锁软件安全新标准
出售Agilent86113A光/电模块
锂离子电池组无线监控系统设计
高通第三财季净利12.1亿美元 同比增长17%
小米POCO X2曝光Geekbench 或为Redmi K30海外版