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 gain coupled with the PFET(Q1). The diode-OR connection is connected to Q1’s source that will act as USB power supply. […]

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Pulse Width (PWM) Controller Circuit

A LM3900 quad operational amplifier can be used to build a pulse width (PWM) controller. The LM3900 was chosen because it only need single supply voltage of 4 to 30 V. This circuit can give 100 percent pulse-width control.  A1 op-amp forms a 1 kHz oscillator, generating a square wave oscillator for the basic oscillation. A2 is a ramp generator […]

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Transformerless Dc -To- Symmetric DC Converter

A DC to DC converter is needed for a board that only has +5V supply but have to provide dual-polarity supplies for few device such as op-amp or some DAC. Using switched capacitors as the main converting element (diode-capacitor voltage-doubler), there is no inductors or transformers in this circuit. This circuit also does not require dc-to-dc converter ICs but uses […]

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