Low voltage operating LED scintillator

Low Voltage Microprocessor Supervisory Circuit recently released may constitute a low voltage, low power LED scintillator, and can adjust the light and flashing rate. Shown in Figure 1, P monitoring circuit (IC1) is composed of two Nicd or NiMH batteries, capable of driving high brightness LED, the circuit is suitable for display vendors, toys, emergency alarm, anti-theft alarm indicator and detector.

IC1 can use an external device, adjusting the reset threshold and watchdog reset time period, it also provides a set by the pin 500 times by the function of the watchdog period increased 500 times, have long delay with small capacitance. Graphical representation indicates that when the reset threshold is set to a minimum (1.22V), the battery energy is exhausted, the LED will continue to light. The capacitor C1 is usually used to set the reset cycle, but in this application, it is used to set the LED flashing cycle (about 100ms in the circuit, C2) value (440pF) provides the most ideal eye blink rate can be resolved, about flashes two times per second. Two capacitors are selected low leakage, this requirement is not a problem for these small capacity devices.

During charging, the maximum value of about Vcc 4V, and IC can withstand the maximum voltage of about 7V, so the circuit and the battery can be connected because the flicker is very short, so the battery discharge caused by LED emission reduced brightness is difficult to detect, when the circuit is composed of a single AA battery power supply, it can produce the dark flashing up for a week, for most applications, the circuit of two Nicd batteries can provide the best price.

IC1 can use an external device, adjusting reset threshold and watchdog reset time period, it also provides a set by the pin 500 times by the function of the watchdog period increased 500 times, have long delay with small capacitance. Graphical representation indicates that when the reset threshold is set to a minimum (1.22V), the battery energy is exhausted, the LED will continue to light.

The capacitor C1 is usually used to set the reset cycle, but in this application, it is used to set the LED flashing cycle (about 100ms in the circuit, C2) value (440pF) provides the most ideal eye blink rate can be resolved, about flashes two times per second. Two capacitors are selected low leakage, this requirement is not a problem for these small capacity devices.

During charging, the maximum value of about Vcc 4V, and IC can withstand the maximum voltage of about 7V, so the circuit and the battery can be connected because the flicker is very short, so the battery discharge caused by LED emission reduced brightness is difficult to detect, when the circuit is composed of a single AA battery power supply, it can produce the dark flashing up for a week, for most applications, the circuit of two Nicd batteries can provide the best price.