Precision constant-current sin
precision constant-current sink provides wide, close-to-the-rail compliance
abstract: this precision constant-current sink produces a current of 1ma with a compliance range of 0.7v to 50v, and a dynamic output impedance of 106 ohms. it is stable with any load type (resistive or reactive), and stable over the allowed ranges of temperature, power-supply voltage, and compliance voltage (upper and lower limits).
a similar version of this article appeared in the february 2009 issue of portable design magazine.
a precision current sink can be used to generate a voltage bias for sensors, amplifiers, and other analog circuits. they can also generate a reference voltage (across a resistor in series with its output) referred to voltage levels that are variable or well above the common equipotential. such current sinks consist of a voltage reference, an error amplifier, a current-sense resistor, and an output device—usually one capable of handling a useful amount of power, and rated for voltages at the expected upper limit of the output-compliance range.
desirable characteristics for this type of circuit block include a very large dynamic output impedance, stability with any load type (resistive or reactive), and stability over the allowed ranges of temperature, power-supply voltage, and compliance voltage (upper and lower limits).
the circuit of figure 1a, with component values as shown, produces a current of 1ma with a compliance range of 0.7v to 50v, and a dynamic output impedance of 106 ohms. the circuit of figure 1b can do the same, with a compliance range that extends down to 0.25v, but it requires an extra, separate reference voltage.
figure 1. these current-sink circuits produce 1ma with an output-compliance range of 0.7v to 50v (a), and 0.25v to 50v (b).
the reference/amplifier function is implemented with a shunt regulator (max8515), and the power output device (bss123) is a small n-channel mosfet with maximum vds of 100v (vds is the current sink's higher compliance limit). the current sample is obtained from a resistor (rsource) in series with the bss123 source. you can adjust this current by changing the resistor value according to the following equation:
circuit of figure 1a: isink = 0.6v/rsource.
circuit of figure 1b: isink = 0.091v/rsource. other performance includes the stability of sink current with output voltage (figure 2), and the variation of sink current with temperature over the range 0°c to +50°c (±0.75%, figure 3).
figure 2. sink current vs. output voltage for the circuit of figure 1a.
figure 3. sink current varies ±0.75% over the temperature range shown, for the circuit of figure 1a.
历经5年，YAS扩产终获批！致力打造OLED蒸镀设备产业园区
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Precision constant-current sin
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abstract: this precision constant-current sink produces a current of 1ma with a compliance range of 0.7v to 50v, and a dynamic output impedance of 106 ohms. it is stable with any load type (resistive or reactive), and stable over the allowed ranges of temperature, power-supply voltage, and compliance voltage (upper and lower limits).
a similar version of this article appeared in the february 2009 issue of portable design magazine.
a precision current sink can be used to generate a voltage bias for sensors, amplifiers, and other analog circuits. they can also generate a reference voltage (across a resistor in series with its output) referred to voltage levels that are variable or well above the common equipotential. such current sinks consist of a voltage reference, an error amplifier, a current-sense resistor, and an output device—usually one capable of handling a useful amount of power, and rated for voltages at the expected upper limit of the output-compliance range.
desirable characteristics for this type of circuit block include a very large dynamic output impedance, stability with any load type (resistive or reactive), and stability over the allowed ranges of temperature, power-supply voltage, and compliance voltage (upper and lower limits).
the circuit of figure 1a, with component values as shown, produces a current of 1ma with a compliance range of 0.7v to 50v, and a dynamic output impedance of 106 ohms. the circuit of figure 1b can do the same, with a compliance range that extends down to 0.25v, but it requires an extra, separate reference voltage.
figure 1. these current-sink circuits produce 1ma with an output-compliance range of 0.7v to 50v (a), and 0.25v to 50v (b).
the reference/amplifier function is implemented with a shunt regulator (max8515), and the power output device (bss123) is a small n-channel mosfet with maximum vds of 100v (vds is the current sink's higher compliance limit). the current sample is obtained from a resistor (rsource) in series with the bss123 source. you can adjust this current by changing the resistor value according to the following equation:
circuit of figure 1a: isink = 0.6v/rsource.
circuit of figure 1b: isink = 0.091v/rsource. other performance includes the stability of sink current with output voltage (figure 2), and the variation of sink current with temperature over the range 0°c to +50°c (±0.75%, figure 3).
figure 2. sink current vs. output voltage for the circuit of figure 1a.
figure 3. sink current varies ±0.75% over the temperature range shown, for the circuit of figure 1a.
历经5年，YAS扩产终获批！致力打造OLED蒸镀设备产业园区
恩智浦全新MCUXpresso工具集为嵌入式应用简化软件开发
能耗监测系统属于消防还是智能化
工业和信息化部与国际电信联盟高级别研讨会在深圳举行
2019世界机器人博览会观众“分类”，看看你是什么观众？
Precision constant-current sin
独立按键检测技术讲解
Realtime Robotics 定制运动规划芯片,帮助自动驾驶汽车做出更好的决策
RFID 中间件的特征及作用介绍
小型室外气象站以及自动气象站的技术参数介绍
限流电抗器型号及参数详解，盘起来！
亚马逊新智能音箱Echo Show发布众人欢喜 却被指抄袭这家公司？
荣耀8青春版跑分曝光 单核和多核跑分成绩逆天！
智能家居市场大战，四大科技巨头智能家居PK战！
OmniVision新款图像传感器为智能手机提供高质量视频拍摄
一文看懂焊接机器人使用说明书
土壤含水率测定仪的功能及技术参数
化肥成分检测仪的仪器特点的详细介绍
自动控制系统的组成
ZLG：这篇推文，我们准备了一年