GS-R51212S GS-R51515S 31W TRIPLE OUTPUT STEP-DOWN SWITCHING REGULATORS Type GS-R51212S GS-R51515S Vi 15 to 40 V 15 to 40 V Vo Io + 5,1 V 4,5 A ± 12 V 0,35 A + 5,1 V 4,5 A ± 15 V 0,3 A FEATURES 5.1V/4.5A and ±12V/0.35A or ±15V/0.3A output voltages ±12 or ±15V externally adjustable High efficiency (81% typ.) Short-circuit protection Reset output Power Fail programmable input Inhibit/Enable control input Soft-start PCB or chassis mounting DESCRIPTION The GS-R51212S and GS-R51515S are versatile triple output, high current step-down switching regulators that provide +5.1V/4.5A output voltage and an isolated ±12V/0.35A or ±15V/0.3A dual output voltage. They are ideal for microprocessor based boards because power the logic and the communication ports and have Reset output and Power Fail programmable input for the correct system start-up. The Inhibit/Enable pin allows the ON/OFF logic function with TTL/CMOS compatible input signal. The auxiliary outputs (±12V or ±15V) are externally adjustable in a very wide range, i.e. from ±4.25V to ±12.45V on GS-R51212S and from ±4.50V to ±15.25V (typical values) on GS-R51515S. ABSOLUTE MAXIMUM RATINGS Symbol Parameter Value Unit Vi DC Input Voltage 44 V Irs Reset Output Sink Current 20 mA June 1994 1/8 GS-R51212S/GS-R51515S ELECTRICAL CHARACTERISTICS (Tamb = 25°C unless otherwise specified) Symbol Parameter Test Conditions Min Typ Max Unit Vi Input Voltage GS-R51212S Vo1 = +5.1V Vo2 = +12V Vo3 = – 12V Io1 = 4.5A Io2 = 0.35A Io3 = – 0.35A 15 40 V Vi Input Voltage GS-R51515S Vo1 = +5.1V Vo2 = +15V Vo3 = – 15V Io1 = 4.5A Io2 = 0.3A Io3 = – 0.3A 15 40 V lir Input Reflected Current Vi = 24V Io1,2,3 = Full Load No external input capacitor 0.5 App lir Input Reflected Current Vi = 24V Io1,2,3 = Full Load Ci (external) = 100µF/50V 0.15 App Vien Enable Input Voltage Vi = 15 to 40V lien Enable Input Current Vi = 15 to 40V Viinh Inhibit Input Voltage Vi = 15 to 40V 1.2 Vo1 Output Voltage 1 Vi = 15 to 40V Io1 = 0 to 4.5A Io2 = 0 to 0.35/0.3A Io3 = 0 to – 0.35/– 0.3A +5 Vo2 Output Voltage 2 GS-R51212S Vi = 15 to 40V Io1 = 0 to 4.5A Io2 = 0 to 0.35A Io3 = 0 to – 0.35A Vo2 Output Voltage 2 GS-R51515S Vi = 15 to 40V Io2 = 0 to 0.3A Vo3 Output Voltage 3 GS-R51212S Vo3 0.8 V –1 mA +Vi V +5.1 +5.2 V +11.5 +12 +12.5 V +14.5 +15 +15.5 V Vi = 15 to 40V Io1 = 0 to 4.5A Io2 = 0 to 0.35A Io3 = 0 to – 0.35A – 11.5 – 12 – 12.5 V Output Voltage 3 GS-R51515S Vi = 15 to 40V Io2 = 0 to 0.3A Io1 = 0 to 4.5A Io3 = 0 to – 0.3A – 14.5 – 15 – 15.5 V Vor1 Output Ripple Voltage 1 Vi = 24V Io1 = 4.5A 30 50 mVpp Vor2,3 Output Ripple Voltage 2,3 Vi = 24V Io2,3 = 0.35/0.3A 50 100 mVpp δVOL1 Line Regulation 1 Vi = 15 to 40V Io1 = 2.5A Io2,3 = 0.35/0.3A 0.5 mV/V δVOL2,3 Line Regulation 2,3 Vi = 15 to 40V Io1 = 2.5A Io2,3 = 0.35/0.3A 1 mV/V δVOO1 Load Regulation 1 Vi = 24V Io1 = 0.5 to 4.5A Io2,3 = 0.35/0.3A 2 mV/A Load Regulation 2,3 Vi = 24V Io1 = 2.5A Io2,Io3 = 0.05 to 0.35/0.3A 500 mV/A Io1 Output Current 1 Vi = 15 to 40V Vo1 = 5.1V Io2,3 = 0 to 0.35/0.3A 0 4.5 A Io2 Output Current 2* GS-R51212S Vi = 15 to 40V Vo2 = +12V Io1 = 0 to 4.5A Io3 = 0 to – 0.35A 0 0.35 A Io2 Output Current 2* GS-R51515S Vi = 15 to 40V Vo2 = +15V Io1 = 0 to 4.5A Io3 = 0 to – 0.3A 0 0.3 A Io2 Output Current 2* GS-R51212S Vi = 15 to 40V Vo2 = +12V Io1 = 0 to 4.5A Io3 = 0A 0 0.7 A Io2 Output Current 2* GS-R51515S Vi = 15 to 40V Vo2 = +15V Io1 = 0 to 4.5A Io3 = 0A 0 0.6 A Io3 Output Current 3* GS-R51212S Vi = 15 to 40V Vo3 = – 12V Io1 = 0 to 4.5A Io2 = 0 to 0.35A 0 – 0.35 A δVOO2,3 2/8 0 Io1 = 0 to 4.5A Io3 = 0 to – 0.3A GS-R51212S/GS-R51515S ELECTRICAL CHARACTERISTICS (Tamb = 25°C unless otherwise specified) (cont’d) Symbol Parameter Test Conditions Min Typ Max Unit Io3 Output Current 3* GS-R51515S Vi = 15 to 40V Vo3 = – 15V Io1 = 0 to 4.5A Io2 = 0 to 0.3A 0 – 0.3 A Io3 Output Current 3* GS-R51212S Vi = 15 to 40V Vo3 = – 12V Io1 = 0 to 4.5A Io2 = 0A 0 – 0.7 A Io3 Output Current 3* GS-R51515S Vi = 15 to 40V Vo3 = – 15V Io1 = 0 to 4.5A Io2 = 0A 0 – 0.6 A Iosck1 Output Current Limit 1 Vi = 15 to 40V Overload Iosc1 Output Short-circuit Current 1 Iosc2,3 Output Short-circuit Current 2,3 5.5 A Vi = 15 to 40V 3 A Vi = 15 to 40V 0.8 A tss Soft-start time 10 ms tdr Reset Time Delay 100 ms fs Switching Frequency Vi = 15 to 40V Vo1 = 5.1V Io1 = 0.5 to 4.5A Vo2 = +12/+15V Vo3 = – 12/– 15V Io2, Io3 = – 0.05 to – 0.35/– 0.3A 100 kHz η Efficiency Vi = 24V 81 % 7.5 °C/W Io1,2,3 = Full Load 78 R th Thermal Resistance Tcop Operating Case Temperature Range 0 +85 °C Tstg Storage Temperature Range – 40 +105 °C * Note: when output current is less than 50mA, output ripple voltage increases due to discontinuous operation. 3/8 GS-R51212S/GS-R51515S CONNECTION DIAGRAM AND MECHANICAL DATA Package R. Dimensions in mm (inches). PIN DESCRIPTION Pin Function Description 1 GND IN Return for input voltage source. Internally connected to pin 7. 2 EN. Inhibit/Enable control input. The converter is ON (ENABLE) when the voltage applied to this pin is lower than 0.8V. The converter is OFF (INHIBIT) when this pin is unconnected or the input voltage is in the range of 1.2 to Vi. 3 P.F. Power Fail programmable input. If unconnected the Power Fail threshold voltage is 11V with 1V hysteresis (factory setting). 4 + Vin DC input voltage. Recommended maximum voltage is 40V. 5 RT Reset output (active high). When the supply voltage +Vin and the regulated output voltage +Vo1 are in the correct range this signal is generated after a delay time of 100ms typical. 6 Vo + 5V Regulated +5.1V output voltage. 7 GND 1 Return for output 1 current path. Internally connected to pin 1. 8 Vo + 12/15V Regulated +12 or +15V output. 9 Vo – 12/15V Regulated – 12 or – 15V output. 10 ADJ. External adjustment for output voltages ±12 and ±15V. 11 GND Aux. Return for ±12 and ±15V output current path. 4/8 GS-R51212S/GS-R51515S USER NOTES Input Voltage The recommended operating maximum DC input voltage is 40V inclusive of the ripple voltage. The use of an external low ESR, high ripple current capacitor located as close the module as possible is recommended; suggested value is 100µF/50V. Soft-start To avoid heavy inrush current the output voltage rise time is typically 10ms in any condition of load. Power Fail-Reset Circuit The module include a voltage sensing circuit that may be used to generate a power-on/power-off reset signal for a microprocessor system. The circuit sense the input supply voltage and the output generated voltage Vo1 (+5V) and will generate the required reset signal only when both the sensed voltages have reached the required value for correct system operation. When both the supply voltage and the regulated voltage are in the correct range the output Reset signal is generated after a delay time tDR of 100ms typical. A latch assures that if a spike is present on the sensed voltage the delay time circuit discharges completely before initialization of a new reset cycle. Reset output has internal pull-up resistor of 10kOhm connected to Vo +5V pin. Maximum sink ou tput current is 20mA at V RESET (sat) = 200mV. Fig. 1 and fig. 2 show reset waveforms. Power Fail Programmable Input This pin is internally connected via a divider to the +Vin pin for Power Fail function. The factory setting is for a value of 11V with 1V hysteresis. It is possible to program a different value of Power Fail threshold by connecting a resistor (Rpf) between pin 3 (Power Fail Input) and pin 1 (GND Input). The value of Rpf must be calculated according to the following formula: R pf = 5.1 = (kΩ) Vpf − 5.1 − 0.191 34 where Vpf is the desired value of Power Fail threshold voltage. Exampe: Vpf = 24V (must not be lower than 12V): Rpf = 5.1 = 14kΩ 24 − 5.1 − 0.191 34 Figure 1 - Reset and Power Fail waveforms. 5/8 GS-R51212S/GS-R51515S Figure 2 - Reset and Power Fail waveforms. Auxiliary Outputs The auxiliary outputs (±12V or ±15V) are externally adjustable in symmetric way by connecting a resistor Ra between pin 10 (ADJ.) and pin 8 (Vo + 12/+15V), according to the following formula: 6/8 GS−R51212S Ra = 32.66 × Vo − 4.229 12.485 − Vo GS−R51515S Ra = 38.66 × Vo − 4.39 15.252 − Vo where Vo is the desired dual output voltage. Example: Vo = ±5V. Ra (GS−R51212S) = 3.36kΩ Ra (GS−R51515S) = 2.3kΩ Example: Vo = ±10V. Ra (GS−R51212S) = 75.8kΩ Ra (GS−R51515S) = 41.3kΩ GS-R51212S/GS-R51515S Figure 3 - Typical Application. Inhibit/Enable Input The Inhibit/Enable function allows the ON/OFF logic control of the module. The converter is ON (Enable) when the voltage applied to pin 2 (EN.) and referred to pin 1 (GND IN) is lower than 0.8V (TTL, CMOS, open collector compatible level). The converter is OFF (Inhibit) when pin 2 is unconnected or the voltage applied is in the range of 1.2V to +Vin. Maximum sinking current is 1mA. Module Protection The module is protected against occasional and permanent short-circuits of the output pins to ground, as well as against output current overload. The main output (+5.1V) uses a foldback current limiting; the output current decreases with increasing overload, reaching a minimum at short-circuit condition. This solution minimizes internal power dissipation. The auxiliary outputs (±12V or ±15V) use a current limiting protection circuitry. Thermal characteristics Sometimes the GS-R51212S and GS-R51515Srequire an external heat-sink depending on both operating temperature conditions and power. Before entering into calculations details, some basic concepts will be explained to better understand the problem. The thermal resistance between two points is represented by their temperature difference in front of a specified dissipated power, and it is expressed in Degree Centigrade per Watt (°C/W). For the modules the thermal resistance case to ambient is 7.5°C/W. This means that an internal power dissipationof 1W will bring the case temperature at 7.5°C above the ambient temperature. The maximum case temperature is 85°C. Let’s suppose to have a GS-R51515S that delivers the maximum output power of 31.4W at an ambient temperature of 40°C. 7/8 GS-R51212S/GS-R51515S The dissipated power in this operating condition is about 7.4W (at typical efficiency of 81%), and the case temperature of the module will be: This value is the resulting value of the parallel connection of GS-R thermal resistance and of the additional heatsink thermal resistance. Tcase = Tamb + Pd × Rth = 40 + 7.4 × 7.5 = 95.5 °C Rth (GSR) × Rth (Heatsink) = 5.40°C / W R th (GSR) + Rth (Heatsink) This value exceeds the maximum allowed temperature and an external heat-sink must be added. To this purpose four holes (see mechanical drawing) are provided on the metal surface of the module. To calculate this heat-sink, let’s first determine what the total thermal resistance should be: Rth = Tcase(max) − Tamb = 85 − 40 = 5.40 °C ⁄ W Pd 7.4 To calculate the thermal resistance of the additional heat-sink the following equation may be used: Rth (Heatsink) = 5.40 × Rth (GSR) = 5.40× 7.5 = 19.3 °C / W Rth(GSR) − 5,40 7.5 − 5.40 In instead of or in addition to the external heatsink, a forced ventilation with an air speed of about 200 linear feet/minute can be used reducing the thermal resistance of the module at the specified value. Information furnished is believed to be accurate and reliable. However, SGS-THOMSON Microelectronics assumes no responsibility for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of SGS-THOMSON Microelectronics. Specification mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied. SGS-THOMSON Microelectronics products are not authorized for use as critical components in life support devices or systems without express written approval of SGS-THOMSON Microelectronics. 1994 SGS-THOMSON Microelectronics – All Rights Reserved SGS-THOMSON Microelectronics GROUP OF COMPANIES Australia - Brazil - China - France - Germany - Hong Kong - Italy - Japan - Korea - Malaysia - Malta - Morocco - The Netherlands Singapore - Spain - Sweden - Switzerland - Taiwan - Thailand - United Kingdom - U.S.A. 8/8