Quick-Charge IC Routes Step-Up
simplicity and high efficiency favor the step-down, switch-mode battery charger over other configurations, but sometimes the available supply voltage is too low for the battery's terminal voltage. examples include charging a backup battery from the supply it backs up, and using an automobile battery to charge a large number of cells in series.
such applications can be handled by a step-up switching regulator in conjunction with a fast-charge controller (figure 1). this circuit can charge five or more nicd or nimh cells from a 5v input. because cell voltages vary greatly during the charge cycle, you should resist the temptation to simply boost vin above the highest terminal voltage for the battery being charged (and then dropping the boosted voltage back to battery level with a linear regulator). that approach is inefficient and generates heat.
figure 1. a step-up switching regulator (ic1) and fast-charge controller (ic2) charge multi-cell batteries with speed and efficiency.
this circuit also supplies load current while charging the battery. because load current bypasses the battery and the r2 sense resistor, it has little effect on the charge current. (as an option to improve efficiency when the charger is not in use, you can greatly reduce the voltage drop across r2 by adding a low-rds(on) mosfet in parallel.)
the ic1 connection shown, which holds its feedback input (pin 3) below the internal set-point, causes the step-up converter to act as a current source producing its maximum output current. then, replacing the external current-sense resistor with a power mosfet (q2) allows ic2's drv output to set this output current via the q3-q4 current mirror, which controls q2's gate voltage and on-resistance.
to configure the overall circuit for a different range of input voltage, adjust r1 (if necessary) so the current into pin 15 of ic2 remains between 5ma and 20ma. this condition ensures that the shunt regulator in ic2 maintains the internal v+ at approximately 5v. if vin exceeds 16v, you should remove the direct connection to ic1 and power that chip with v+ from ic2 instead. output power should not exceed 20w for the q1 device shown, and r2 adjusts the charging current:
icharge = 0.25 / r2.
to charge batteries with other than six cells in series, re-program ic2 according to instructions in the data sheet. the zener voltage of d1, which prevents overvoltage on capacitor c1 if the battery is removed during charging, should approximate (in volts) twice the numerical cell count. c1 helps to smooth the otherwise chopped output current from ic1; take care not to exceed its ripple-current rating (the ripple current is approximately icharge + iload).
百度AI开发者大会：首次在国内以元宇宙形式举办科技大会
太阳能半导体制冷空调控制系统设计
深入剖析esp32c3的系统底层启动
多载波MS－DPD开发平台简化基站设计
什么是氢燃料电池汽车 氢燃料电池汽车发展正面临哪些挑战
Quick-Charge IC Routes Step-Up
乐视网股权质押违约，东方证券状告贾跃亭兄长
学好ametal_通用数码管接口技术，做项目事半功倍
低通滤波器与高通滤波器有什么不同
线下市场失败,OPPO的渠道策略将怎么调整?
ADC配合DMA采样规则是怎样的？
多核对嵌入式设计原则造成哪些影响
起因于RTN的SRAM误操作进行观测并模拟的方法
如今正在发生的是“物联网正在吃掉支付”
pcb板的热膨胀系数是什么意思啊？怎么测量出来的？
美日联盟形成 全球自动驾驶标准格局大变
中国机器视觉未来发展趋势及特性
基于柔性多层带材（FMLF）的单相逆变系统EMI滤波器
非车规级传感，60GHz毫米波崛起
纯电动大巴再获青睐 比亚迪再下一城
such applications can be handled by a step-up switching regulator in conjunction with a fast-charge controller (figure 1). this circuit can charge five or more nicd or nimh cells from a 5v input. because cell voltages vary greatly during the charge cycle, you should resist the temptation to simply boost vin above the highest terminal voltage for the battery being charged (and then dropping the boosted voltage back to battery level with a linear regulator). that approach is inefficient and generates heat.
figure 1. a step-up switching regulator (ic1) and fast-charge controller (ic2) charge multi-cell batteries with speed and efficiency.
this circuit also supplies load current while charging the battery. because load current bypasses the battery and the r2 sense resistor, it has little effect on the charge current. (as an option to improve efficiency when the charger is not in use, you can greatly reduce the voltage drop across r2 by adding a low-rds(on) mosfet in parallel.)
the ic1 connection shown, which holds its feedback input (pin 3) below the internal set-point, causes the step-up converter to act as a current source producing its maximum output current. then, replacing the external current-sense resistor with a power mosfet (q2) allows ic2's drv output to set this output current via the q3-q4 current mirror, which controls q2's gate voltage and on-resistance.
to configure the overall circuit for a different range of input voltage, adjust r1 (if necessary) so the current into pin 15 of ic2 remains between 5ma and 20ma. this condition ensures that the shunt regulator in ic2 maintains the internal v+ at approximately 5v. if vin exceeds 16v, you should remove the direct connection to ic1 and power that chip with v+ from ic2 instead. output power should not exceed 20w for the q1 device shown, and r2 adjusts the charging current:
icharge = 0.25 / r2.
to charge batteries with other than six cells in series, re-program ic2 according to instructions in the data sheet. the zener voltage of d1, which prevents overvoltage on capacitor c1 if the battery is removed during charging, should approximate (in volts) twice the numerical cell count. c1 helps to smooth the otherwise chopped output current from ic1; take care not to exceed its ripple-current rating (the ripple current is approximately icharge + iload).
百度AI开发者大会：首次在国内以元宇宙形式举办科技大会
太阳能半导体制冷空调控制系统设计
深入剖析esp32c3的系统底层启动
多载波MS－DPD开发平台简化基站设计
什么是氢燃料电池汽车 氢燃料电池汽车发展正面临哪些挑战
Quick-Charge IC Routes Step-Up
乐视网股权质押违约，东方证券状告贾跃亭兄长
学好ametal_通用数码管接口技术，做项目事半功倍
低通滤波器与高通滤波器有什么不同
线下市场失败,OPPO的渠道策略将怎么调整?
ADC配合DMA采样规则是怎样的？
多核对嵌入式设计原则造成哪些影响
起因于RTN的SRAM误操作进行观测并模拟的方法
如今正在发生的是“物联网正在吃掉支付”
pcb板的热膨胀系数是什么意思啊？怎么测量出来的？
美日联盟形成 全球自动驾驶标准格局大变
中国机器视觉未来发展趋势及特性
基于柔性多层带材（FMLF）的单相逆变系统EMI滤波器
非车规级传感，60GHz毫米波崛起
纯电动大巴再获青睐 比亚迪再下一城