78xxSR Series www.murata-ps.com 3.3V/5V/12V Outputs High-Ef ciency Switching Regulators with LM78xx Pinouts Murata Power Solutions 7805SR-C (5V output), 7812SR-C (12V output) and 7803SR-C FEATURES (3.3V output) step-down switching regulators are modern drop-in replacements for older, 3.3V/0.5A, 5V/0.5A or 12V/0.4A outputs Pin and inef cient, LM7805 and LM7812 linear regulators. The 78XXSR s are pin- and size-compat- size-compatible with LM7805 & LM7812 regulators ible with industry-standard TO-220 SIP packages. A 260kHz switching frequency provides Up to 95% ef ciency no heat sinks or thermal for ef ciencies as high as 95%. Full-load (up to 0.5A) operation from 9V, 12V, 24V, or 36V derating required supplies at ambient temperatures up to +70C requires no heat sinks, no temperature derating, no forced-air cooling, and no external capacitors. Two SIP-packages t existing TO-220 footprints: 78SR switching regulators provide many signi cant improvements over their linear coun- - Vertical-pin models occupy less than 0.1 square in. terparts: lower quiescent current (3mA vs. 5 mA), higher input voltage (40V vs. 32V), and - Optional horizontal pins provide 0.350 in. installed better output accuracy (2% vs. 5%). All these features combine to make 78SR regulators height ideal for new or existing LM7805 & LM7812 applications requiring full-load operation at +7.5-36Vdc operating input range Low 3mA elevated voltages. quiescent current Built-in lter capacitors no external components TECHNICAL NOTES required 1. Input/Output (I/O) Filtering: As shown in the noise and ripple graphs, 78SR switching 40 to +70C operation at full load Short-circuit regulators exhibit excellent low-noise performance with no external I/O capacitors. protection However, if additional noise reduction is required, be sure to use low-ESR capacitors that are rated for continuous operation (with an additional 20% safety margin) at the Excellent load (0.2%) and line (0.3%) regulation highest system voltages and temperatures. Adding external output capacitors will also Ideal for powering instrumentation from improve the units load-transient response. 9V/12V/24V/28V supplies or batteries Applications in which 78SR regulators are located more than 24 inches (61cm) from Can be used with unregulated dc supplies the input power supply should include an external 47uF/50V (or greater) aluminum protection electrolytic capacitor, connected as close as possible to the regulators +Vin and GND terminals (pins 1 and 2). An external input capacitor is particularly important if the input voltage is applied to the regulator via a mechanical switch or relay. Contact bounce at turn-on can produce large inductive current-spikes, and these current spikes can generate damaging voltage transients at the regulators input terminals. 2. Input Fusing: 78SR switching regulators are not internally fused. If fusing their input and/or output terminals is required, use the data shown in the Ef ciency Curves as a Ordering Information guide to selecting an appropriate slow-blow fuse. 3. Input-Output Isolation: 78SR regulators internal input and output circuits share a MPS Part No. Output Output Input Voltage Current Voltage common connection (GND, pin 2) there is no electrical isolation between the INPUT (pin 1) and OUTPUT (pin 3) terminals. Standard Pin Package 4. Overvoltage Protection: 78SR switching regulators do not provide input or output 7803SR-C +3.3Vdc 0.5A +7.5-36Vdc overvoltage protection. In the extremely rare situation in which a catastrophic failure 7805SR-C +5.0Vdc 0.5A +7.5-36Vdc occurs, the output voltage may rise to excessively high levels. If your load must be 7812SR-C +12.0Vdc 0.4A +15-36Vdc protected against all possible overvoltage situations, external voltage-limiting circuitry Horizontal Pin Package must be provided. 7803SRH-C +3.3Vdc 0.5A +7.5-36Vdc 7805SRH-C +5.0Vdc 0.5A +7.5-36Vdc 5. Operation at 40Vdc: Operating with inputs up to 40Vdc is permissible if, for inputs 7812SRH-C +12.0Vdc 0.4A +15-36Vdc between 36 and 40Vdc, the maximum load current is reduced to 0.35A for 7805SR-C and 7803SR-C, and to 0.3A for 7812SR-C. Under no circumstances should the input voltage be allowed to exceed 45Vdc. For full details go to www.murata-ps.com/rohs www.murata-ps.com/support 30 Oct 2015 MDC 78xxSR Series.B07 Page 1 of 778xxSR Series 3.3V/5V/12V Outputs High-Ef ciency TECHNICAL NOTES (continued) Switching Regulators with LM78xx Pinouts 6. Soldering & Handling Precautions: All units are designed to be hand soldered to pc-boards using no-clean solders (+260C, 5 seconds max.). Water-soluble solders can also be used, but the units must be washed Performance/Functional Speci cations and dried using processes appropriate to the type of solder employed. Typical at TA = +25C See the Mechanical Speci cations section for pin 1 orientation and Input/Output recommended plated-through hole dimensions. Models 7803SR-C 7805SR-C 7812SR-C While 78SR regulators easily withstand a 2kV ESD discharge to any ter- minal (using human body model), they should always be treated as ESD Output Voltage +3.3Vdc +5.0Vdc +12.0Vdc sensitive devices. Rated Output Current 0.5A 0.5A 0.4A 7. Horizontal-Pin Models (78XXSRH-C): 78XXSRH-C switching regulators Output Voltage Accuracy 2% 2% 2% are pin-compatible replacements for TO-220 style LM78XX linear regula- Input Voltage Range +7.5-36Vdc +7.5-36Vdc +15-36Vdc tors that are installed with their metal tabs lying at on the surface of the Line Regulation (100% load) 0.3% 0.3% 0.3% pc-board. However, because the surface of inductor L1 on 78XXSRH-C Load Regulation (0-100% load) 0.2% 0.2% 0.2% models is electrically conductive, it must not be allowed to come in con- Quiescent Current 3mA typ., 5mA max. tact with any exposed pc-board traces, other than power ground (GND). Input Current See Performance Curves While the 2-mil-thick (0.05mm) polyester label attached to L1 provides Ef ciency See Performance Curves some degree of electrical insulation (only if L1 sits perfectly at on the Transient Response See Performance Curves pc-board), it is recommended that a 0.020 (0.5mm) clearance be main- Input & Output Noise See Performance Curves tained between L1 and all exposed pc-board traces. Short Circuit Protection Continuous 8. Dropout Voltage: 78SR series regulators described in this data sheet Isolation None specify a minimum input voltage at which full-load accuracy and output Overvoltage Protection None regulation are guaranteed (7.5V for 7803SR-C and 7805SR-C, and 15.0V Undervoltage Protection None for 7812SR-C). However, these devices will stay in regulation at lower input voltages if they are operated at less than their rated loads. Environmental The following dropout-voltage data, derived from sample testing Models 7803SR-C 7805SR-C 7812SR-C performed at an ambient temperature of +25C with resistive loads, Operating Temperature 40 to +70C should be used for information purposes only. For these tests, a unit was Storage Temperature 40 to +85C considered to be out of regulation when its output changed by more Cooling Free Air Convection +/0.005Vdc from its nominal value. All voltages were measured directly Humidity (Non-condensing) 0 to 85% at the regulators I/O pins. Physical Mechanical See Mechanical Speci cations Package Open-frame SIP Pins 0.025 (0.64mm) square, tin-plated bronze Typical Dropout Voltage Weight 0.08 ounces (2.2g) 0% Load 25% Load 50% Load 100% Load Pin Soldering +260C for 5 seconds 7803SR-C 6.0V 6.2V 6.2V 6.3V See Technical Note 5. 7805SR-C 6.3V 6.2V 6.2V 6.8V While these regulators can withstand a continuous short-circuit across their 7812SR-C 12.8V 13.0V 12.8V 13.0V output terminals, they will experience a signi cant temperature rise. Extended short-circuit operation will adversely affect the units reliability. www.murata-ps.com/support 30 Oct 2015 MDC 78xxSR Series.B07 Page 2 of 7