The DCR01 series is a series of high efficiency, input-isolated, output regulated DC/DC converters. In addition to 1W nominal galvanically isolated output power capability, this range of DC/DCS provides very low output noise, thermal protection, and high accuracy. The DCR01 series implements standard die IC packages, offering standard JEDEC profile suit- capable for high volume assembly. The DCR01 is an IC package using the same technical manufacturing standards, thus achieving very high reliability.

Overview

The DCR01 series provides isolated unregulated power supply for selectable operation from the input voltage. The DCR01 provides a variety of regulated output voltages with a rated output power of 1W or more.

power stage

The input power is chopped at a frequency of 400kHz (internal oscillator divided by 2), which is used to drive the center-tapped toroidal transformer.

Rectifier cation

The output of the transformer is full-wave rectified and filtered by an external capacitor REC connected to V.

Regulator

The built-in low dropout voltage regulator provides a well regulated output voltage over the entire operating range of the device.

Oscillator and Watchdog

The DCR01 uses an internal sawtooth generator to provide a power switch circuit that is used to drive the 800kHz on-board oscillator. Oscillator operation is monitored by a watchdog, which will tri-state the output of the driver circuit if the oscillator fails, or if the SYNC pin is taken low (shutdown mode). When the SYNC pin is reset high, normal operation resumes.

Synchronize

If more than one DCR01 is being used, beat frequencies and other electrical interference can occur. This is due to small changes in the switching frequency between converters. The DCR01 allows devices to overcome this by synchronizing with each other. Up to eight devices can be connected together by connecting the SYNC pins, and synchronization must also be noted to reduce tracking capacitance. Significant parasitic capacitance on the SYNC pin will have the effect of reducing the frequency of the internal oscillator. If this is large, the DCR01 can take out its optimized operating parameters and magnetic saturation may result, damaging the device. If the devices are synchronized, however, it should be noted that all devices will start up at the maximum current at the same time. This may cause the input voltage to dip. If it falls below the minimum input voltage, the device may not start up. A 2.2µF capacitor (low ESR) is connected as close to the input pins of the device as possible for 5V input devices and a 0.47µF capacitor for 12V and 24V devices. If more than eight devices need to be synchronized, it is recommended to use external synchronization.

construction

The DCR01 is a standard IC package manufactured using the same technology. With and without substrate package. The DCR01 uses a driver IC consisting of low dropout voltage regulators, rectifier diodes and wound magnetic toroid, all mounted on a lead frame. The DCR01 does not require special handling of the PCB assembly as it is not soldered inside the package. The result is an inherently high reliability of isolated DC/DC converters.

PCB layout

Ripple and Noise Careful consideration should be given to the layout of the resulting PCB in order to achieve the best results. The DCR01 is a switching power supply and therefore can be placed on the input power supply peak current requirement. In order to avoid falling into the supply switching pulse, ground and power planes at fast instants, the input terminal of the tracking power supply DCR01 should be used, which will also reduce the noise of the circuit. If this is not possible, then the device must be connected in a star formation, with orbits made as wide as possible. If the SYNC pin is used, trace the SYNC pin between devices as short as possible to avoid stray capacitance. If the SYNC pin is not being used, it is recommended to place a guard ring (connected to input ground) around this pin to avoid any noise pickup. The output should be taken from the device layer and the power layer using the ground. This will ensure minimal losses. Good quality low ESR capacitors are placed as close as practicable at the input to reduce reflected ripple and ensure smooth start up. Good quality low ESR capacitors placed as close as possible to ground at the output of the rectifier and the output will give the best ripple and noise performance.

thermal management

Due to the high power density of this device, it is preferable to provide the output on a ground plane. The output regulator is mounted on a copper lead frame, and a ground plane will act as an effective heat sink.