Miniature, 2W Isolated
REGULATED DC/DC CONVERTERS
DCR02
Series
FEATURES
●UL1950 RECOGNIZED
●DIP-18 AND GULL-WING(1) PACKAGES
●55W/in3 (3.3W/cm3) POWER DENSITY
●DEVICE-TO-DEVICE SYNCHRONIZATION
●THERMAL PROTECTION
●1000Vrms ISOLATION
●400kHz SWITCHING
●125 FITS AT 55°C
●SHORT-CIRCUIT PROTECTED
●12V, 24V INPUTS
●5V OUTPUTS
NOTE: (1) Gull-wing package available Q1 2001.
DESCRIPTION
DCR02 family is a series of high-efficiency, input-
isolated, output-regulated DC/DC converters. In addi-
tion to 2W nominal, galvanically-isolated output power
capability, this range of DC/DCs offer very low out-
put noise, and high accuracy.
The DCR02 family is implemented in standard molded
IC packaging, giving standard JEDEC outlines suit-
able for high-volume assembly.
The DCR02 is manufactured using the same technol-
ogy as standard IC packages, thereby achieving very
high reliability.
APPLICATIONS
●POINT-OF-USE POWER CONVERSION
●DIGITAL INTERFACE POWER
●GROUND LOOP ELIMINATION
●POWER-SUPPLY NOISE REDUCTION
Input
Controller LDO
Regulator
ENABLE
V
REC
SYNC
V
S
ERROR
V
OUT
0V
IN
0V
OUT
DCR02
DCR02
Copyright © 2000, Texas Instruments Incorporated SBVS028 Printed in U.S.A. December, 2000
www.ti.com
DCR02 Series
2SBVS028
SPECIFICATIONS
At TA = +25°C, VS = nominal, IO = 10mA, CO = 0.1µF, unless otherwise specified.
DCR02 SERIES
PARAMETER CONDITIONS MIN TYP MAX UNITS
OUTPUT
Setpoint
DCR021205 5V
DCR022405 5V
Setpoint Accuracy 0.5 2.0 %
Maximum Output Current
DCR021205 400 mA
DCR022405 400 mA
Output Short-Circuit Protected Duration Infinite
Line Regulation
DCR021205 1 mV/V
DCR022405 1 mV/V
Over Line and Load
DCR021205 10mA to 400mA Load, 4.5V to 5.5V Line 1.0 2.5 %
DCR022405 10mA to 400mA Load, 4.5V to 5.5V Line 1.0 2.5 %
Versus Temperature –40°C to +70°C 1.0
%
Ripple and Noise
DCR0212 Ripple 20MHz Bandwidth, 50% Load(1) 18 mVp-p
DCR0212 Noise 100MHz Bandwidth, 50% Load(1) 20 mVp-p
DCR0224 Ripple 20MHz Bandwidth, 50% Load(1) 18 mVp-p
DCR0224 Noise 100MHz Bandwidth, 50% Load(1) 25 mVp-p
INPUT
Nominal Voltage (VS) DCR021205 12 V
DCR022405 24 V
Voltage Range –10 +10 %
Supply Current
DCR021205 IO = 0mA 15 mA
IO = 10mA 23 mA
IO = 400mA 250 mA
DCR022405 IO = 0mA 15 mA
IO = 10mA 17 mA
IO = 400mA 129 mA
Reflected Ripple Current
DCR021205, DCR022405 MHz Bandwidth, 100% Load 8 mAp-p
CIN = 2.2µF, CFILTER = 1µF
ISOLATION
Voltage 1s Flash Test 1 kVrms
60s Test, UL1950(2) 1 kVrms
Input/Output Capacitance 25 pF
OUTPUT ENABLE CONTROL
Logic High Input Voltage 2.0 VREC V
Logic High Input Current 2.0 < VENABLE < VREC 100 nA
Logic Low Input Voltage –0.2 0.5 V
Logic Low Input Current 0 < VENABLE < 0.5 100 nA
DCR021205 V
DCR022405 V
ERROR FLAG
Logic High Open Collector Leakage VERROR = 5V 10 µA
Logic Low Output Voltage Sinking 2mA 0.4 V
THERMAL SHUTDOWN
Junction Temperature
Temperature Activated 150 °C
Temperature Deactivated 130 °C
SYNCHRONIZATION PIN
Max External Capacitance on SYNC Pin 3pF
Internal Oscillator Frequency 720 800 880 kHz
External Synchronization Frequency 720 880 kHz
External Synchronization Signal High 2.5 2.5 5.0 V
External Synchronization Signal Low 0 0.4 V
TEMPERATURE RANGE
Operating –40 +70 °C
NOTE: (1) CIN = 2.2µF, CFILTER = 1µF, COUT = 0.1µF. (2) During UL approval only.
DCR02 Series 3
SBVS028
ELECTROSTATIC
DISCHARGE SENSITIVITY
This integrated circuit can be damaged by ESD. Burr-Brown
recommends that all integrated circuits be handled with
appropriate precautions. Failure to observe proper handling
and installation procedures can cause damage.
ESD damage can range from subtle performance degrada-
tion to complete device failure. Precision integrated circuits
may be more susceptible to damage because very small
parametric changes could cause the device not to meet its
published specifications.
Input Voltage:
DCR0212 .......................................................................................... 15V
DCR0224 .......................................................................................... 29V
Storage Temperature...................................................... –60°C to +125°C
Lead Temperature (soldering, 10s) ................................................. 270°C
ABSOLUTE MAXIMUM RATINGS
DCR02
Basic Model Number: 1W Product
Voltage Input:
12V In
Voltage Output:
5V Out
Package Code:
P = 18-Pin Plastic DIP, P-U = DIP-18 Gull Wing(1)
NOTE: (1) P-U available Q1 2001.
ORDERING INFORMATION
12 05 (P)
PACKAGE SPECIFIED
DRAWING TEMPERATURE PACKAGE ORDERING TRANSPORT
PRODUCT PACKAGE NUMBER RANGE MARKING NUMBER(1) MEDIA
DCR021205P DIP-18 218-1 –40°C to +70°C DCR021205P DCR021205P Rails
DCR022405P DIP-18 218-1 –40°C to +70°C DCR022405P DCR022405P Rails
DCR021205P-U(2) DIP-18 Gull Wing 218-2 –40°C to +70°C DCR021205P-U DCR021205P-U/700 Tape and Reel
DCR022405P-U(2) DIP-18 Gull Wing 218-2 –40°C to +70°C DCR022405P-U DCR022405P-U/700 Tape and Reel
NOTE: (1) Models with a slash ( / ) are available only in Tape and Reel in the quantities indicated (e.g., /700 indicates 700 devices per reel). Ordering 700 pieces
of “DCR021205P-U/700” will get a single 700-piece Tape and Reel. (2) P-U available Q1 2001.
PACKAGE/ORDERING INFORMATION
PIN DEFINITIONS
PIN # PIN NAME DESCRIPTION
1V
SVoltage Input
2 NC No Connection
7V
REC Rectified Output
80V
OUT Output Ground
9V
OVoltage Output
10 DNC Do Not Connect
11 ENABLE Output Voltage Enable
12 ERROR Error Flag Active Low
17 0VIN Input Ground
18 SYNC Synchronization Input
Top View DIP
PIN CONFIGURATION
DCR02
1
2
7
8
9
18
17
12
11
10
VS
NC
VREC
0VOUT
VO
SYNC
0VIN
ERROR
ENABLE
DNC
DCR02 Series
4SBVS028
FUNCTIONAL DESCRIPTION
OVERVIEW
The DCR02 series offers isolation from an unregulated
power supply operating from a choice of input voltages. The
DCR02s provide a variety of regulated output voltages at a
nominal output power of 2W.
POWER STAGE
The input supply is chopped at a frequency of 400kHz
(internal oscillator divided by 2), which is used to drive the
center-tapped toroidal transformer.
RECTIFICATION
The transformer’s output is full wave rectified and smoothed
by the external capacitor connected to VREC.
REGULATOR
The internal low dropout regulator provides a well-regulated
output voltage throughout the operating range of the device.
OSCILLATOR AND WATCHDOG
The DCR02 uses an internal saw-tooth generator to provide
the 800kHz on-board oscillator that is used to drive the
power switching circuit. The operation of the oscillator is
monitored by the watchdog, which will tri-state the output
driver circuit if the oscillator fails, or if the SYNC pin is
taken LOW, (shutdown mode). When the SYNC pin is
returned HIGH, normal operation resumes.
SYNCHRONIZATION
If more than one DCR02 is being used, beat frequencies and
other electrical interference can be generated. This is due to
the small variations in switching frequencies between the
converters.
The DCR02 overcomes this by allowing devices to be
synchronized to one another. Up to eight devices can be
synchronized by connecting the SYNC pins together, with
care being taken to minimize the capacitance of tracking.
Significant stray capacitance on the SYNC pin will have the
effect of reducing the frequency of the internal oscillator. If
this is large, the DCR02 may be taken out with its optimized
operating parameters, and saturation of the magnetics may
result, damaging the device.
If devices are synchronized, it should be noted that all
devices will draw maximum current simultaneously at start
up. This can cause the input voltage to dip. Should it fall
below the minimum input voltage, the devices may not start
up. A 2.2µF capacitor (low ESR) should be connected as
close to the device input pins as possible.
If more than eight devices are required to be synchronized,
it is recommended that external synchronization be used.
Details are contained in Burr-Brown’s Application Bulletin
AB-153 (literature number SBAA035) available at
www.ti.com.
CONSTRUCTION
The DCR02 is manufactured using the same technology as
standard IC packages. There is no substrate within the
package. The DCR02 is constructed using a driver IC, low-
dropout voltage regulator, rectifier diodes, and a wound
magnetic toroid, all mounted on a leadframe. The DCR02
requires no special PCB assembly processing, as there is no
solder within the package. The result is an isolated DC/DC
converter with inherently high reliability.
ADDITIONAL FUNCTIONS
DISABLE/ENABLE
The DCR02 can be disabled or enabled by driving the SYNC
pin using an open drain CMOS gate. If the SYNC pin is
pulled LOW, the DCR02 will be disabled. The disable time
depends upon the external loading. The internal disable
function is implemented in 2µs. Removal of the pull down
will enable the DCR02.
Capacitance loading on the SYNC pin should be minimized
in order to prevent a reduction in the internal oscillator‘s
frequency. See Application Bulletin AB-153, “External Syn-
chronization of the DCP01/02 Series of DC/DC Convert-
ers”. This document contains information on how to null the
effects of additional capacitance on the SYNC pin. The
oscillators frequency can be measured at VREC, as this is the
fundamental frequency of the ripple component.
OUTPUT ENABLE/DISABLE
The regulated output of the DCR02 can be disabled by
pulling the ENABLE pin LOW. Holding the ENABLE pin
HIGH enables the regulated output voltage, thus allowing
the output to be controlled from the isolated side.
ERROR FLAG
The DCR02 has an ERROR pin which provides a “power
good” flag, as long as the internal regulator is in regulation.
DECOUPLING
Ripple Reduction
Due to the very low forward resistance of the DMOS
switching transistors, high current demands are placed upon
the input supply for a short time. By placing a good quality
low Equivalent Series Resistance (ESR) capacitor of 2.2µF
close to the IC supply input pins, the effects on the power
supply can be minimized.
The high switching frequency of 400kHz allows relatively
small values of capacitors to be used for filtering the recti-
fied output voltage. A good quality low ESR capacitor of
1µF placed close to the VREC pin and output ground will
reduce the ripple.
It is not recommended that the DCR02 be fitted using an
IC socket as this will degrade performance.
The output at VREC is full wave rectified and produces a
ripple of 800kHz.
DCR02 Series 5
SBVS028
FIGURE 1. DCR02 with a Single Output.
FIGURE 2. Self-Synchronizing DCR02s with a Dual Output.
It is recommended that a 0.1µF low ESR capacitor is
connected close to the output pin and ground to reduce noise
on the output. The capacitor values listed are minimum
values. If lower ripple is required, the filter capacitor should
be increased in value to 0.47µF.
NOTE: As with all switching power supplies, the best
performance is only obtained with low ESR capacitors
connected close to the switcher. If low ESR capacitors are
not used, the ESR will generate a voltage drop when the
capacitor is supplying the load power. Often a larger capaci-
tor is chosen for this purpose when a low ESR smaller
capacitance would perform as well.
PCB LAYOUT
RIPPLE AND NOISE
Careful consideration should be given to the layout of the
PCB in order for the best results to be obtained.
The DCR02 is a switching power supply and as such can
place high peak current demands on the input supply. In
order to avoid the supply falling momentarily during the fast
switching pulses, ground and power planes should be used
to track the power to the input of DCR02; this will also serve
DCR 02
VOUT
VREC
VIN
CIN(1) COUT = 0.1µF
CFILTER = 1µF
VO1
0 VOUT
0V
VS
0V
NOTE: (1) 2.2µF capacitor with low ESR.
DCR 02
VOUT
VREC
VIN VO1
0 VOUT
0V
VS
SYNC
0V
DCR 02
VOUT
VREC
VIN VO2
0 VOUT
0 VOUT
0 VOUT
0V
VS
SYNC
0V
NOTE: (1) 2.2µF capacitor with low ESR.
CIN(1) COUT = 0.1µF
CIN(1) COUT = 0.1µF
CFILTER = 1µF
CFILTER = 1µF
to reduce noise on the circuit. If this is not possible, the
supplies must be connected in a star formation, with the
tracks made as wide as possible.
If the SYNC pin is being used, the tracking between device
SYNC pins should be short to avoid stray capacitance. If the
SYNC pin is not being used, it is advisable 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 using ground
and power planes. This will ensure minimum losses.
A good quality low ESR capacitor placed as close as
practicable across the input will reduce reflected ripple and
ensure a smooth start up.
A good quality low ESR capacitor placed as close as
practicable across the rectifier output terminal and output
ground will give the best ripple and noise performance.
THERMAL MANAGEMENT
Due to the high power density of this device, it is advisable
to provide a ground plane on the output. The output regula-
tor is mounted on a copper leadframe, and a ground plane
will serve as an efficient heatsink.
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TI’s standard warranty . T esting and other quality control techniques are utilized to the extent TI deems necessary
to support this warranty. Specific testing of all parameters of each device is not necessarily performed, except
those mandated by government requirements.
Customers are responsible for their applications using TI components.
In order to minimize risks associated with the customer’s applications, adequate design and operating
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