7
DCP0115
FUNCTIONAL DESCRIPTION
OVERVIEW
The DCP0115 offers up to 1W of unregulated output power
from a 15V input source with a typical efficiency of 76%.
This is achieved through highly integrated packaging tech-
nology and the implementation of a custom power stage and
control IC.
POWER STAGE
This uses a pull-pull, center-tapped topology switching at
400kHz (divide by 2 from 800kHz oscillator).
OSCILLATOR AND WATCHDOG
The on-board 800kHz oscillator provides the switching
frequency via a divide by 2 circuit and allows synchroniza-
tion via the SYNC
IN
pins. To synchronize any number of
DCP0115 family of devices, simply tie the SYNC
IN
pins
together (see the Synchronization section). The watchdog
circuitry protects the DC/DC against a stopped oscillator and
checks the oscillator frequency which will shut down the
output stage if it drops below a certain threshold—i.e., it will
be tri-stated after approximately 10
μ
s.
FIGURE 1. Standard Interface.
THERMAL SHUTDOWN
The DCP0115 is also protected by thermal shutdown. If the
on-chip temperature reaches a predetermined value, the DC/
DC will shutdown. This effectively gives indefinite short
circuit protection for the DC/DC.
SYNCHRONIZATION
Any number of DCP01 family devices can be synchro-
nized by connecting the SYNC
IN
pins on the devices
together (see Figure 1). All the DCP01 devices will then
self-synchronize.
This same synchronization method applies to any V
IN
ver-
sion of the DCP01 family, allowing synchronization of
various V
OUT
and V
IN
DC/DCs.
The SYNC
OUT
pin gives an unrectified 400kHz signal from
the transformer. This can be used to set the timing of external
circuitry on the output side. In noise sensitive applications
any pick-up from the SYNC
OUT
pin can be minimized by
putting a guard ring round the pin (see Figure 2).
Bottom View
FIGURE 2. SYNC
OUT
Guard Ring.
DIVIDE BY 2 RESET
Isolated DC/DC converter performance normally suffers
after power reset. This is because a change in the steady state
transformer flux creates an offset after power-up. The DCP01
family does not suffer from this problem. This is achieved
through a patented
(1)
technique employed on the divide by 2
reset circuitry resulting in no change in output phase after
power interruption.
CONSTRUCTION
The DCP0115’s basic construction is the same as standard
ICs. There is no substrate within the molded package. The
DCP0115 is constructed using an IC, rectifier diodes, and a
wound magnetic toroid on a leadframe. As there is no solder
within the package, the DCP0115 does not require any
special PCB assembly processing. This results in an isolated
DC/DC with inherently high reliability.
ADDITIONAL FUNCTIONS
DISABLE/ENABLE
The DCP0115 can be disabled or enabled by driving the
SYNC
IN
pin with an open drain CMOS gate. If the SYNC
IN
pin is pulled low, the DCP0115 will disable. The disable time
depends on the output loading but the internal shutdown takes
DCP0115xxx
1
2
5
6
7
14
8
V
S
0V
0V
+V
OUT
–V
OUT
C
470nF
C
470nF
C
470nF
1 per DCP01
DCP0105xxx
1
2
5
6
7
14
8
V
S
0V
0V
Out+
C
470nF
DCP0105xxx
1
2
5
6
7
14
8
V
S
0V
0V
Out+
SYNC
IN
SYNC
IN
SYNC
IN
C
470nF
+5V
+15V
C
470nF
+15V
0V
+Out 1
–Out 1
0V
+5V
+Out 2
0V
+Out 3