The DCP02 series are 2W unregulated isolated DC/DC converters. Requiring minimal external COM ponents and including on-chip device protection, the DCP02 series provides additional features such as output disable and switching frequency synchronization. Using a highly integrated package design results in reliable products with power densitiesof at 79W/3(4.8W/cm3) for DIP-14, and 106W /3(6.5W/cm3) for SO-28. The properties of this compound and the small size bination make DCP02 suitable for a wide range of applications.

Overview

The DCP02 provides up to 2W of unregulated output power from a 5V, 12V, 15V, 24V or input source with typical efficiencies up to 89%. This is achieved through highly integrated packaging technology and implementing a custom power stage and control IC. The circuit design adopts advanced BiCMOS/DMOS technology.

power stage

This uses a push-pull, center-tapped topology to switch at 400kHz (divide by 2, from the oscillator at 800kHz).

Oscillator and Watchdog

The built-in 800kHz oscillator generates the switching frequency by dividing the circuit by 2. This oscillator can be synchronized to other DCP02 circuits or external sources and used to minimize system noise. The watchdog circuit checks the working circuit of the oscillator. The oscillator can be pulled low by pulling the SYNC stop pin. The output pins are tri-stated. This will happen within 2µs.

thermal shutdown

DCP02 is protected by a thermal shutdown circuit. If the on-chip temperature exceeds 150°C, the device will shut down. Once the temperature drops below 150°C, normal operation will resume.

Synchronization is onboard in case more than one DC/DC converter is required, difference frequency and other electrical interference can be generated. This is due to the change in switching frequency between the DC/DC converters. The DCP02 overcomes this by allowing devices to synchronize to each other. Up to eight devices can be synchronized by connecting the SYNC pins together to chronized care to minimize tracking capacitance. Significant stray capacitance (>10pF) will have the effect of reducing the switching frequency, or even stopping the oscillator circuit. It is also recommended that the power and ground wires be connected in a star. If synchronous devices are used, it should be noted that at startup, all devices will draw maximum current simulta-neously. This causes the input voltage to dip and should it dip below the minimum input voltage (4.5V), the device may not start. The 2.2µF capacitor should be connected close to the input pins. If more than 8 devices are synchronized, it is recommended that the SYNC pin be driven by an external device. Details are contained in a separate application bulletin (AB-153).

The basic structure of the construction of the DCP02 is the same as the standard integrated circuit. There is no substrate inside the molded package. The DCP02 is a magnetic toroid that utilizes an IC, rectifier diodes, and a magnetic toroid wrapped around a lead frame. Because there is no solder in the package, the DCP02 does not require any special PCB assembly processing. This results in a high reliability of the separate DC/DC converter itself.

disable/enable

The DCP02 can be disabled or enabled by driving the SYNC open-drain CMOS gate using the pin. If the SYNC pin is pulled low, DCP02 will be disabled. The disable time depends on the external load; the internal disable functionality is implemented within 2µs. Removing the pulldown causes the DCP02 to be activated. Capacitive loads on the SYNC pin should be minimized to prevent a reduction in the oscillation frequency.