微电路具有自动关机和低电池锁定功能-Micropower C
abstract: the following application note provides a circuit that automatically performs shutdown, power-up, and low-battery lockout functions without the need for software control.
this micropower circuit provides shutdown, power-up, and low-battery lockout functions automatically, without the need for software or operator control (figure 1). featuring 2.3v hysteresis, the circuit eliminates the use of microprocessor i/o pins for charger detection, battery-threshold monitoring, and shutdown control. under full load, the complete power-management circuit draws less than 200µa of supply current.
figure 1. this micropower circuit provides shutdown, power-up, and low-battery lockout functions for this three-cell nicd-based circuit without the need for software or operator control.
after the cutoff point for battery discharge is reached, the circuit locks out (disconnects) the battery from the load (load1). this action prevents circuit chatter and deep discharge until the battery is in its charger cradle. a common and annoying problem with battery-voltage monitors, chatter is the circuit's response to fluctuations in battery-terminal voltage. these fluctuations take place when the recurring load connections toggle the battery between its discharge and relaxed-open-circuit conditions.
for a three-cell nicd battery, the typical terminal voltage is 4.9v fully charged, 3.6v under load, and 2.5v at discharge. the load should be disconnected at 2.5v, but not reconnected, as the resulting terminal voltage (vbatt) floats to the open-circuit condition. the circuit in figure 1 disconnects the load at 2.5v and reconnects it while the battery is in its charger cradle (4.68v).
an ultra-low-power microprocessor (µp)-reset device (u1) generates an active-low output (active-low rsta) whenever vbatt equals 4.63v. the output of a micropower latching comparator (u2) causes active-low rstb to transition low if vbatt is less than 2.5v. these outputs from u1 and u2 are ored by diodes d1 and d2, generating a system-shutdown control (active-low rstc). figure 2 demonstrates the relationship between the various reset states and the battery-discharge profile.
figure 2. the response of the three reset signals in figure 1 is shown over a typical discharge-charge cycle. the battery voltage profile is displayed in the bottom waveform.
when vbatt is less than 2.5v, active-low rstc disconnects load1 from the battery by shutting down u3. u3 is a low-noise low-dropout linear regulator in an sot-23 package. it has a preset output of 2.5v, a maximum ground-pin current of 180µa (when supplying 150ma), and a supply current of only 10na during shutdown.
if vbatt is greater than 4.63v, the circuit releases active-low rstc. as a result, u3 comes out of shutdown and delivers power to the µp. another µp supervisor (u4) holds the active-low rstd signal low until the microprocessor's vcc exceeds 2.2v. once active-low rstd is released, the µp begins operating and clears u2 by pulsing its clr input high for 1µs.
a similar version of this article appeared in the april 30, 2001 issue of electronic design.
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this micropower circuit provides shutdown, power-up, and low-battery lockout functions automatically, without the need for software or operator control (figure 1). featuring 2.3v hysteresis, the circuit eliminates the use of microprocessor i/o pins for charger detection, battery-threshold monitoring, and shutdown control. under full load, the complete power-management circuit draws less than 200µa of supply current.
figure 1. this micropower circuit provides shutdown, power-up, and low-battery lockout functions for this three-cell nicd-based circuit without the need for software or operator control.
after the cutoff point for battery discharge is reached, the circuit locks out (disconnects) the battery from the load (load1). this action prevents circuit chatter and deep discharge until the battery is in its charger cradle. a common and annoying problem with battery-voltage monitors, chatter is the circuit's response to fluctuations in battery-terminal voltage. these fluctuations take place when the recurring load connections toggle the battery between its discharge and relaxed-open-circuit conditions.
for a three-cell nicd battery, the typical terminal voltage is 4.9v fully charged, 3.6v under load, and 2.5v at discharge. the load should be disconnected at 2.5v, but not reconnected, as the resulting terminal voltage (vbatt) floats to the open-circuit condition. the circuit in figure 1 disconnects the load at 2.5v and reconnects it while the battery is in its charger cradle (4.68v).
an ultra-low-power microprocessor (µp)-reset device (u1) generates an active-low output (active-low rsta) whenever vbatt equals 4.63v. the output of a micropower latching comparator (u2) causes active-low rstb to transition low if vbatt is less than 2.5v. these outputs from u1 and u2 are ored by diodes d1 and d2, generating a system-shutdown control (active-low rstc). figure 2 demonstrates the relationship between the various reset states and the battery-discharge profile.
figure 2. the response of the three reset signals in figure 1 is shown over a typical discharge-charge cycle. the battery voltage profile is displayed in the bottom waveform.
when vbatt is less than 2.5v, active-low rstc disconnects load1 from the battery by shutting down u3. u3 is a low-noise low-dropout linear regulator in an sot-23 package. it has a preset output of 2.5v, a maximum ground-pin current of 180µa (when supplying 150ma), and a supply current of only 10na during shutdown.
if vbatt is greater than 4.63v, the circuit releases active-low rstc. as a result, u3 comes out of shutdown and delivers power to the µp. another µp supervisor (u4) holds the active-low rstd signal low until the microprocessor's vcc exceeds 2.2v. once active-low rstd is released, the µp begins operating and clears u2 by pulsing its clr input high for 1µs.
a similar version of this article appeared in the april 30, 2001 issue of electronic design.
调参心得:如何优化超参数的，如何证实方法是有效的
美的、碧桂园对机器人领域虎视眈眈，会给机器人行业带来怎样的变革呢？
闪测仪案例|手机零部件尺寸轻松测量
磐石测控：PS-9604S系列手机侧键手感测试机的产品详情？
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华为升级鸿蒙操作系统需要备份吗 升级鸿蒙系统好不好
Alphabet前董事长Schmidt不赞同Musk的AI威胁论
大唐恩智浦电池CT检测技术开启全球商业化进程
交易所在未来还会存在吗