DCP02 Series
www.ti.com
SBVS011C–MARCH 2000–REVISED DECEMBER 2005
FUNCTIONAL DESCRIPTION
This is due to the small variations in switching
frequencies between the DC/DC converters.
OVERVIEW
The DCP02 overcomes this by allowing devices to be
synchronized to one another. Up to eight devices can
be synchronized by connecting the SYNC pins
together, taking care to minimize the capacitance of
tracking. Stray capacitance (> 10pF) will have the
effect of reducing the switching frequency, or even
stopping the oscillator circuit. It is also recommended
that power and ground lines be star-connected.
The DCP02 offers up to 2W of unregulated output
power from a 5V, 12V, 15V, or 24V input source with
a typical efficiency of up to 89%. This is achieved
through highly integrated packaging technology and
the implementation of a custom power stage and
control IC. The circuit design uses an advanced
BiCMOS/DMOS process.
POWER STAGE
It should be noted that if synchronized devices are
used at start up, all devices will draw maximum
current simultaneously. This can cause the input
voltage to dip, and if it dips below the minimum input
voltage (4.5V), the devices may not start up. A 2.2µF
capacitor should be connected close to the input pins.
The DCP02 uses a push-pull, center-tapped topology
switching at 400kHz (divide-by-2 from an 800kHz
oscillator).
OSCILLATOR AND WATCHDOG
If more than eight devices are to be synchronized, it
is recommended that the SYNC pins be driven by an
external device. Details are contained in Application
Report SBAA035, External Synchronization of the
DCP01/02 Series of DC/DC Converters, available for
download from www.ti.com.
The onboard 800kHz oscillator generates the
switching frequency via a divide-by-2 circuit. The
oscillator can be synchronized to other DCP02
circuits or an external source, and is used to minimize
system noise.
A watchdog circuit checks the operation of the
oscillator circuit. The oscillator can be stopped by
pulling the SYNC pin low. The output pins will be
tri-stated. This will occur in 2µs.
CONSTRUCTION
The basic construction of the DCP02 is the same as
standard ICs. There is no substrate within the molded
package. The DCP02 is constructed using an IC,
rectifier diodes, and a wound magnetic toroid on a
leadframe. Since there is no solder within the
package, the DCP02 does not require any special
printed circuit board (PCB) assembly processing. This
results in an isolated DC/DC converter with inherently
high reliability.
THERMAL SHUTDOWN
The DCP02 is protected by a thermal-shutdown
circuit. If the on-chip temperature exceeds +150°C,
the device will shut down. Once the temperature falls
below +150°C, normal operation will resume.
SYNCHRONIZATION
In the event that more than one DC/DC converter is
needed onboard, beat frequencies and other
electrical interference can be generated.
V
V
V
SUPPLY
OUT 1
S
SYNC
DCP
02
0V
0V
V
+ V
OUT 2
OUT 1
V
V
OUT 2
S
SYNC
DCP
02
0V
0V
COM
Figure 7. Connecting the DCP02 in Series
6
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