ON/OFF Power Control with Single Pushbutton

Today, simplicity and minimum controls is required for design of a handheld device. It will be very useful if a circuit allow us to turn the power on or of with a single push button. A single-pushbutton power control circuit that consist of only a few small components, and consumes little power is shown on circuit diagram below.

ON OFF Power Control with Single Pushbutton circuit schematic diagram

A debouncer (the MAX6816, IC1)is connected with a normally open (NO) single-contact pushbutton. This will guarantees a single output edge (rise or fall) each time the button is pushed or released. The clock input of a flip-flop (IC2) wired as a T-type 9toggle) flip-flop is driven by MAX6816’s output. A low-dropout (LDO) linear regulator (the MAX6484,IC3) is controlled by the flip-flop output. A handheld gadget is powered by MAX6484, which turns on or off each time that the pushbutton is operated. If the regulator features a logic-level power management input, the same circuit can also drive other types of power regulator.

To ensure that the circuit always powers up in the same state (OFF) when PWR_IN is connected firts, there is 1Mohm resistor and 100nF capacitor connected to the flip-flop’s CLR input. The operation range of the ON/OF control circuit (pushbutton, debouncer, and flip-flop) is 2V to 5.5V. When the supply voltage is 3.5 V, it draws about 3.5uA. You can buy MAX6816 in a4-pin SOT143 package, IC2 in an MO-187 package, and the MAX6484 in a 6-ball UCSP™ package. [Source: MAXIM Application Note]

This entry was posted in Control Electronics, Power Supply and tagged . Bookmark the permalink.,
Possibly Related to "ON/OFF Power Control with Single Pushbutton" Circuits

  • Discrete R/S Flip Flop
    This circuit is an example of a set/reset flip flop. Set/reset flip flop is the simplest flip flop. This circuit using discrete components. Here is the schematic diagram : When this circuit obtain the power, only one of the transistors … Continue reading →...
  • Opto-Coupled RS Flip-Flop
    RS flip-flop, or reset-set flip flop, is a kind of stable multivibrator with two input, namely reset and set. The output will be at one of two stable states, set (active) or unset (inactive). A pulse strobe on set input … Continue reading →...
  • Two Methods for Push Button Controlled Power Switch
    On these two following circuits, we can latch on the SCR (and thereby the lamp) by momentarily closing S1, thereby feeding gate drive to the SC via R1. The gate is tied to the cathode via R2 to improve circuit … Continue reading →...
  • MAX1703 Single-Cell Boost Converter Circuit
    When you design a circuit with only a single-cell battery, you will need boost-converter to provide enough voltage for most application. This circuit is a modification of the diode-OR connection circuit. The linear regulator is formed by the U1’s internal … Continue reading →...
  • Low-Power Switching Regulator
    A circuit of low-power switching regulator is shown in the schematic diagram below. This circuit can give output voltage of 5V from 9-V source. The efficiency of this circuit is 80% and the output capability of this circuit is 50-mA. … Continue reading →...

Comments are closed.