78SR 2 Amp Series www.murata-ps.com 2 Amp, 3.3V & 5V Output, High Ef ciency, Synchronous Switching Regulators FEATURES Muratas 78SR-3.3/2 (3.3V, 2 Amp output) and 78SR-5/2 (5V, 2 Amp output) step-down, switching regulators are ultra high-ef ciency, modern replacements for LM78xx series Up to 95% ef ciency no costly heat sinks or fans 1.5Amp linear regulators. They are pin- and size-compatible, drop-in replacements for required TO-220 style, 3-pin SIP or modular packages which require heat sinks. And, to ensure the 3.3V/2A & 5V/2A models pin compatible with 1.5A 78xx lowest installed cost, no messy thermal grease, no mounting hardware and no external regulators components are required for full operation. Wide 8 32Vdc input voltage range A 200KHz switching frequency, combined with a synchronous recti er buck regulator topology, provides for ef ciencies exceeding 95%. 78SR switchers can easily drive 2A loads Two package options: from 12V or 24Vsuppliesat ambient temperatures up to +70Cwithout heat sinks, 3-pin vertical mount SIP fans, or thermal derating. A thermally ef cient 3-pin vertical mount SIP occupies less than Low pro le, horizontal mount SIP 2 2 0.09in. (58mm ) of pc-board real estate, while a horizontal mount option has an installed No external Input/Output lter capacitors required height of less than 0.290in. (7.4mm). 40 to +70C full load operation at 24Vin with no 78SR Series 2A switching regulators are lower cost, improved-ef ciency upgrades for derating many 78HT2, 78SR1, 78ST1, and PT5100 series switchers. Their higher ef ciency ensures signi cantly lower heat generation and provides increased run time in battery-powered Excellent load (0.25%) and line (0.35%) regulation applications, making these regulators ideal for todays low power green applications. Low-cost upgrade for 78HT2, 78SR1, 78ST1, and PT5100 switchers TECHNICAL NOTES Open frame design minimizes self-heating & pc-board 1. Input/Output (I/O) Filtering: As shown in the accompanying noise and ripple graphs, footprint 78SR Series regulators exhibit excellent low noise performance with no additional I/O Includes output short-circuit protection and thermal lter components. However, if additional noise reduction is required, be sure to use low shutdown ESR capacitors that are rated for continuous operation (with an additional 20% safety Low noise output for powering sensitive instrumentation margin) at the highest input voltage and ambient temperatures. Adding external output capacitors will improve the units load-transient response. Applications in which 78SR regulators are located more than 24 inches (61cm) from the input power supply should include an external 47uF/50V (or greater) aluminum electrolytic capacitor, connected as close as possible to the regulators +Vin and GND Ordering Information terminals (pins 1 and 2). An external input capacitor is particularly important if the input Part No. Output Output Input voltage is applied to the regulator via a mechanical switch or relay. Contact bounce at Voltage Current Voltage turn-on can produce large inductive current spikes, and these current spikes can gener- ate potentially damaging voltage transients at the regulators input terminals. 78SR-3.3/2-C 3.3Vdc 2.0A 8.0-32Vdc 78SR-5/2-C 5.0Vdc 2.0A 8.0-32Vdc 2. Input Fusing: 78SR switching regulators are not internally fused. If fusing their input 78SRH-3.3/2-C 3.3Vdc 2.0A 8.0-32Vdc and/or output terminals is required, use the data shown in the Ef ciency Curves as a 78SRH-5/2-C 5.0Vdc 2.0A 8.0-32Vdc guide to select an appropriate slow-blow fuse. For full details go to www.murata-ps.com/rohs www.murata-ps.com/support MPM 78SR-2A B04 Page 1 of 678SR 2 Amp Series 2 Amp, 3.3V & 5V Output, High Ef ciency, Synchronous Switching Regulators Performance/Functional Speci cations TECHNICAL NOTES (continued) Typical at TA = +25C & VIN = 12V, unless otherwise noted 3. Input-Output Isolation: 78SR regulators internal input and output Input/Output circuits share a common connection (GND, pin 2), there is no Models 78SR-3.3/2 78SR-5/2 electrical isolation between their INPUT (pin 1) and OUTPUT (pin 3) Output Voltage 3.3Vdc 5.0Vdc terminals. Rated Output Current 2.0A 2.0A 4. Overvoltage Protection: 78SR switching regulators do not provide Output Voltage Accuracy 2% 2% input or output overvoltage protection. In the extremely rare situation Input Voltage Range 8.0-32Vdc 8.0-32Vdc where a catastrophic failure occurs, the output voltage may rise to Line Regulation (100% load) 0.35% 0.35% excessively high levels. If the load circuit must be protected against Load Regulation (0-100% load) 0.2% 0.2% all possible overvoltage situations, voltage-limiting circuitry must be Quiescent Current (mAdc) 25 typ., 30 max 20 typ., provided externally. 35max 5. Soldering & Handling Precautions: All units are designed to be Input Current vs. Input Voltage See Ef ciency Curves hand soldered to pc-boards, using lead-free no-clean solders Ef ciency See Ef ciency Curves (+260C, 5 seconds max.). See the Mechanical Speci cations sec- Transient Response See Performance Curves tion for pin 1 orientation and recommended pc-board hole dimen- Input & Output Noise See Performance Curves sions. Output Short Circuit Protection Continuous 78SR series regulators have limited built-in ESD protection there- Input/Output Isolation None fore they should always be treated as ESD susceptible devices. Overvoltage Protection None 6. Horizontal-Pin Models (78SRH): 78SRH switching regulators are Undervoltage Protection None pin-compatible replacements for TO-220 style LM78xx linear regula- Environmental tors which are installed with their metal tabs or heat sinks laying at Models 78SR-3.3/2 78SR-5/2 on the surface of the pc-board. In replacement applications, 78SRH Operating Temperature 40 to +70C units must be soldered to the pc-board such that the insulating body Storage Temperature 40 to +85C of diode D1 lies at and in contact with the pc-boards surface. Cooling Free Air Convection Humidity (Non-condensing) 0 to 85% Physical Mechanical See Mechanical Speci cations Package Open-frame SIP Pins 0.025 (0.64mm) square, tin-plated bronze Weight 0.15 ounces (4.2g) Pin Soldering +260C for 5 seconds Absolute Maximum Ratings Input Voltage: +36Vdc Operating Temperature +85C Output Current 3.0 Amps 78SR Series regulators can withstand a continuous short-circuit across their output terminals. However, extended short-circuit operation will decrease the units long-term reliability. These are stress ratings only Exposure of devices to any of these conditions may adversely affect long-term reliability. Proper operation under conditions other than those listed in the Performance/Functional Speci cations Table is not implied. See derating chart for more information. www.murata-ps.com/support MPM 78SR-2A B04 Page 2 of 6