The NCP508 is a 50 mA low dropout regulator designed to exhibit fast turn on time and high ripple rejection. The NCP508 low dropout regulator is available in many voltage versions of 1.5, 1.8, 2.5, 2.8, 3.0, 3.3 V and other voltages in 100mV steps .NCP508 contains a voltage reference unit, an error amplifier, a PMOS power transistor, resistors for setting output voltage, current limit, and temperature limit protection circuits.
Also the NCP508 has been designed for use with ceramic capacitors and require few external components .
The main features of the NCP508 are : very low noise at 39 uVrms without a bypass capacitor ,high ripple rejection of 70 dB at 1 kHz , low dropout voltage of 140 mV (typ) at 30 mA , tight load regulation, typically 6 mV for Iout = 50 mA , fast enable turn−on time of 20 usec , logic level enable ,ESR can vary from a few mohms to 3 ohms .
Internal thermal shutdown circuitry is provided to protect the integrated circuit in the event that the maximum junction temperature is exceeded. (typically 125°C ).
This voltage regulator support a maximum input voltage of 13 volts , but the maximum recommended input voltage is 7 volts .
A very simple and useful switching power supply circuit can be constructed using the TOP204 switching controller integrated circuit manufactured by Power Integrations IN .
This TOP204 switching power supply circuit diagram can be very useful for applications that don’t need a huge power .
The design of the switching power supply using the TOP204 IC is not so complicate , an require few external components , making it ideally for compact power sources .
The TOP204 circuit is a part from the TOPSwitch family controllers that implements, with only three pins, all functions necessary for an off-line switched mode control system: high voltage N-channel power MOSFET with controlled turn-on gate driver, voltage mode PWM controller with integrated 100 kHz oscillator, high voltage start-up bias circuit, bandgap derived reference, bias shunt regulator/error amplifier for loop compensation and fault protection circuitry.
The switching power supply circuit shown in this figure is a highly accurate 15 V, 30 W secondary regulated flyback power supply that will operate from with a wide range of input voltage from 85 to 265 VAC . A TL431 shunt regulator directly senses and accurately regulates the output voltage. The output voltage of the circuit can be fine tuned by adjusting the resistor divider formed by R4 and R5. Also other output voltages are possible by adjusting the transformer turns ratios as well as the divider ratio.
A very interesting split power supply circuit can be constructed using this schematic diagram which is based on a LM380 audio power IC . The regulation of the output voltage depends of the upon circuit feeding the LM380 . The power dissipation is around 1 watt so an small heatsink may be required . If the power dissipation is exceeded , the device will go into thermal shut-down protection .
Current limiting occurs if the output current exceeds 1.3 A . The R1 linear potentiometer is , should be initially set to mid level , is used nullify any imbalance in the output .
This split power supply circuit should not be used for input voltages which exceed 20 volts . Use this circuit after a regulated power supply circuit , but try to keep the specifications for the maximum rating of this split voltage circuit .