DCR DCR DCR02 Series 02 02 www.ti.com Miniature, 2W Isolated REGULATED DC/DC CONVERTERS FEATURES APPLICATIONS ● UL1950 RECOGNIZED ● ● ● ● ● DIP-18 AND ● 55W/in3 GULL-WING(1) (3.3W/cm3) PACKAGES POWER DENSITY ● DEVICE-TO-DEVICE SYNCHRONIZATION POINT-OF-USE POWER CONVERSION DIGITAL INTERFACE POWER GROUND LOOP ELIMINATION POWER-SUPPLY NOISE REDUCTION ● THERMAL PROTECTION ● 1000Vrms ISOLATION DESCRIPTION ● 400kHz SWITCHING DCR02 family is a series of high-efficiency, inputisolated, output-regulated DC/DC converters. In addition to 2W nominal, galvanically-isolated output power capability, this range of DC/DCs offer very low output noise, and high accuracy. The DCR02 family is implemented in standard molded IC packaging, giving standard JEDEC outlines suitable for high-volume assembly. The DCR02 is manufactured using the same technology as standard IC packages, thereby achieving very high reliability. ● 125 FITS AT 55°C ● SHORT-CIRCUIT PROTECTED ● 12V, 24V INPUTS ● 5V OUTPUTS NOTE: (1) Gull-wing package available Q1 2001. VREC SYNC ENABLE VS Input Controller LDO Regulator ERROR VOUT 0VOUT 0VIN Copyright © 2000, Texas Instruments Incorporated SBVS028 Printed in U.S.A. December, 2000 SPECIFICATIONS At TA = +25°C, VS = nominal, IO = 10mA, CO = 0.1µF, unless otherwise specified. DCR02 SERIES PARAMETER OUTPUT Setpoint DCR021205 DCR022405 Setpoint Accuracy Maximum Output Current DCR021205 DCR022405 Output Short-Circuit Protected Line Regulation DCR021205 DCR022405 Over Line and Load DCR021205 DCR022405 Versus Temperature Ripple and Noise DCR0212 Ripple DCR0212 Noise DCR0224 Ripple DCR0224 Noise INPUT Nominal Voltage (VS) Voltage Range Supply Current DCR021205 DCR022405 Reflected Ripple Current DCR021205, DCR022405 ISOLATION Voltage CONDITIONS MIN 5 5 0.5 ERROR FLAG Logic High Open Collector Leakage Logic Low Output Voltage MAX UNITS 2.0 V V % 400 400 Duration mA mA Infinite 1 1 mV/V mV/V 10mA to 400mA Load, 4.5V to 5.5V Line 10mA to 400mA Load, 4.5V to 5.5V Line –40°C to +70°C 1.0 1.0 1.0 20MHz Bandwidth, 50% Load(1) 100MHz Bandwidth, 50% Load(1) 20MHz Bandwidth, 50% Load(1) 100MHz Bandwidth, 50% Load(1) 18 20 18 25 mVp-p mVp-p mVp-p mVp-p DCR021205 DCR022405 12 24 V V % –10 2.5 2.5 +10 % % % IO = 0mA IO = 10mA IO = 400mA IO = 0mA IO = 10mA IO = 400mA 15 23 250 15 17 129 mA mA mA mA mA mA MHz Bandwidth, 100% Load CIN = 2.2µF, CFILTER = 1µF 8 mAp-p 25 kVrms kVrms pF 1s Flash Test 60s Test, UL1950(2) 1 1 Input/Output Capacitance OUTPUT ENABLE CONTROL Logic High Input Voltage Logic High Input Current Logic Low Input Voltage Logic Low Input Current DCR021205 DCR022405 TYP 2.0 2.0 < VENABLE < VREC VREC 100 –0.2 0 < VENABLE < 0.5 0.5 100 VERROR = 5V Sinking 2mA 10 0.4 THERMAL SHUTDOWN Junction Temperature Temperature Activated Temperature Deactivated 720 720 2.5 0 TEMPERATURE RANGE Operating –40 800 2.5 µA V °C °C 150 130 SYNCHRONIZATION PIN Max External Capacitance on SYNC Pin Internal Oscillator Frequency External Synchronization Frequency External Synchronization Signal High External Synchronization Signal Low V nA V nA V V 3 880 880 5.0 0.4 pF kHz kHz V V +70 °C NOTE: (1) CIN = 2.2µF, CFILTER = 1µF, COUT = 0.1µF. (2) During UL approval only. 2 DCR02 Series SBVS028 ELECTROSTATIC DISCHARGE SENSITIVITY ABSOLUTE MAXIMUM RATINGS Input Voltage: DCR0212 .......................................................................................... 15V DCR0224 .......................................................................................... 29V Storage Temperature ...................................................... –60°C to +125°C Lead Temperature (soldering, 10s) ................................................. 270°C ORDERING INFORMATION 12 DCR02 05 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 degradation 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. (P) 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. PACKAGE/ORDERING INFORMATION PRODUCT PACKAGE PACKAGE DRAWING NUMBER SPECIFIED TEMPERATURE RANGE PACKAGE MARKING ORDERING NUMBER(1) TRANSPORT MEDIA Rails DCR021205P DIP-18 218-1 –40°C to +70°C DCR021205P DCR021205P 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. PIN DEFINITIONS PIN CONFIGURATION Top View DIP VS 1 18 SYNC NC 2 17 0VIN DCR02 VREC 7 12 ERROR 0VOUT 8 11 ENABLE VO 9 10 DNC DCR02 Series SBVS028 PIN # PIN NAME DESCRIPTION 1 VS Voltage Input 2 NC No Connection 7 VREC Rectified Output 8 0VOUT Output Ground 9 VO Voltage Output 10 DNC Do Not Connect 11 ENABLE 12 ERROR 17 0VIN 18 SYNC Output Voltage Enable Error Flag Active Low Input Ground Synchronization Input 3 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. 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, lowdropout 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 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. 4 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 Synchronization of the DCP01/02 Series of DC/DC Converters”. 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 rectified 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 SBVS028 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 capacitor is chosen for this purpose when a low ESR smaller capacitance would perform as well. 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. 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 VIN THERMAL MANAGEMENT Due to the high power density of this device, it is advisable to provide a ground plane on the output. The output regulator is mounted on a copper leadframe, and a ground plane will serve as an efficient heatsink. VS CIN(1) VOUT DCR COUT = 0.1µF 02 VREC 0V VO1 0V 0 VOUT CFILTER = 1µF NOTE: (1) 2.2µF capacitor with low ESR. FIGURE 1. DCR02 with a Single Output. VIN VS CIN(1) SYNC VOUT DCR COUT = 0.1µF 02 VREC 0V VO1 0V 0 VOUT CFILTER = 1µF 0 VOUT VIN VS CIN(1) SYNC VOUT DCR 0V VO2 COUT = 0.1µF 02 VREC 0V 0 VOUT CFILTER = 1µF 0 VOUT NOTE: (1) 2.2µF capacitor with low ESR. FIGURE 2. Self-Synchronizing DCR02s with a Dual Output. DCR02 Series SBVS028 5 IMPORTANT NOTICE Texas Instruments and its subsidiaries (TI) reserve the right to make changes to their products or to discontinue any product or service without notice, and advise customers to obtain the latest version of relevant information to verify, before placing orders, that information being relied on is current and complete. All products are sold subject to the terms and conditions of sale supplied at the time of order acknowledgment, including those pertaining to warranty, patent infringement, and limitation of liability. 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