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GS-R51212S GS-R51515S
31W TRIPLE OUTPUT STEP-DOWN SWITCHING REGULATORS
Type GS-R51212S Vi 15 to 40 V Vo + 5,1 V Io 4,5 A 0,35 A 4,5 A 0,3 A
12 V
+ 5,1 V
GS-R51515S
15 to 40 V
15 V
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. ABSOLUTE MAXIMUM RATINGS
Symbol Vi Irs DC Input Voltage Reset Output Sink Current Parameter Value 44 20 Unit V mA
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.
June 1994
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GS-R51212S/GS-R51515S
ELECTRICAL CHARACTERISTICS (Tamb = 25C unless otherwise specified)
Symbol Vi Parameter Input Voltage GS-R51212S Input Voltage GS-R51515S Input Reflected Current Input Reflected Current Enable Input Voltage Enable Input Current Inhibit Input Voltage Output Voltage 1 Test Conditions Vo1 = +5.1V Vo2 = +12V Vo3 = - 12V Vo1 = +5.1V Vo2 = +15V Vo3 = - 15V Io1 = 4.5A Io2 = 0.35A Io3 = - 0.35A Io1 = 4.5A Io2 = 0.3A Io3 = - 0.3A Min 15 Typ Max 40 Unit V
Vi
15
40
V
lir lir Vien lien Viinh Vo1
Vi = 24V Io1,2,3 = Full Load No external input capacitor Vi = 24V Io1,2,3 = Full Load Ci (external) = 100F/50V Vi = 15 to 40V Vi = 15 to 40V Vi = 15 to 40V Vi = 15 to 40V Io1 = 0 to 4.5A Io2 = 0 to 0.35/0.3A Io3 = 0 to - 0.35/- 0.3A Vi = 15 to 40V Io2 = 0 to 0.35A Vi = 15 to 40V Io2 = 0 to 0.3A Vi = 15 to 40V Io2 = 0 to 0.35A Vi = 15 to 40V Io2 = 0 to 0.3A Vi = 24V Vi = 24V Io1 = 0 to 4.5A Io3 = 0 to - 0.35A Io1 = 0 to 4.5A Io3 = 0 to - 0.3A Io1 = 0 to 4.5A Io3 = 0 to - 0.35A Io1 = 0 to 4.5A Io3 = 0 to - 0.3A Io1 = 4.5A Io2,3 = 0.35/0.3A 1.2 +5 0
0.5 0.15 0.8 -1 +Vi +5.1 +5.2
App App V mA V V
Vo2 Vo2 Vo3 Vo3 Vor1 Vor2,3 VOL1 VOL2,3 VOO1 VOO2,3 Io1 Io2 Io2 Io2 Io2 Io3
Output Voltage 2 GS-R51212S Output Voltage 2 GS-R51515S Output Voltage 3 GS-R51212S Output Voltage 3 GS-R51515S Output Ripple Voltage 1 Output Ripple Voltage 2,3 Line Regulation 1 Line Regulation 2,3 Load Regulation 1 Load Regulation 2,3 Output Current 1 Output Current 2* GS-R51212S Output Current 2* GS-R51515S Output Current 2* GS-R51212S Output Current 2* GS-R51515S Output Current 3* GS-R51212S
+11.5 +14.5 - 11.5 - 14.5
+12 +15 - 12 - 15 30 50 0.5 1 2 500
+12.5 +15.5 - 12.5 - 15.5 50 100
V V V V mVpp mVpp mV/V mV/V mV/A mV/A
Vi = 15 to 40V Io1 = 2.5A Io2,3 = 0.35/0.3A Vi = 15 to 40V Io1 = 2.5A Io2,3 = 0.35/0.3A Vi = 24V Io1 = 0.5 to 4.5A Io2,3 = 0.35/0.3A Vi = 24V Io1 = 2.5A Io2,Io3 = 0.05 to 0.35/0.3A Vi = 15 to 40V Vo1 = 5.1V Io2,3 = 0 to 0.35/0.3A Vi = 15 to 40V Vo2 = +12V Vi = 15 to 40V Vo2 = +15V Vi = 15 to 40V Vo2 = +12V Vi = 15 to 40V Vo2 = +15V Vi = 15 to 40V Vo3 = - 12V Io1 = 0 to 4.5A Io3 = 0 to - 0.35A Io1 = 0 to 4.5A Io3 = 0 to - 0.3A Io1 = 0 to 4.5A Io3 = 0A Io1 = 0 to 4.5A Io3 = 0A Io1 = 0 to 4.5A Io2 = 0 to 0.35A 0 0 0 0 0 0
4.5 0.35 0.3 0.7 0.6 - 0.35
A A A A A A
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GS-R51212S/GS-R51515S
ELECTRICAL CHARACTERISTICS (Tamb = 25C unless otherwise specified) (cont'd)
Symbol Io3 Io3 Io3 Iosck1 Iosc1 Iosc2,3 tss tdr fs Parameter Output Current 3* GS-R51515S Output Current 3* GS-R51212S Output Current 3* GS-R51515S Output Current Limit 1 Output Short-circuit Current 1 Output Short-circuit Current 2,3 Soft-start time Reset Time Delay 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 Vi = 24V Io1,2,3 = Full Load 78 Test Conditions Vi = 15 to 40V Vo3 = - 15V Vi = 15 to 40V Vo3 = - 12V Vi = 15 to 40V Vo3 = - 15V Vi = 15 to 40V Vi = 15 to 40V Vi = 15 to 40V Io1 = 0 to 4.5A Io2 = 0 to 0.3A Io1 = 0 to 4.5A Io2 = 0A Io1 = 0 to 4.5A Io2 = 0A Overload Min 0 0 0 5.5 3 0.8 10 100 100 Typ Max - 0.3 - 0.7 - 0.6 Unit A A A A A A ms ms kHz
Rth Tcop Tstg
Efficiency Thermal Resistance Operating Case Temperature Range Storage Temperature Range
81 7.5
% C/W +85 +105 C C
0 - 40
* Note: when output current is less than 50mA, output ripple voltage increases due to discontinuous operation.
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GS-R51212S/GS-R51515S
CONNECTION DIAGRAM AND MECHANICAL DATA
Package R. Dimensions in mm (inches).
PIN DESCRIPTION
Pin 1 2 3 4 5 6 7 8 9 10 11 4/8 Function GND IN EN. P.F. + Vin RT Vo + 5V GND 1 Vo + 12/15V Vo - 12/15V ADJ. GND Aux. Description Return for input voltage source. Internally connected to pin 7. 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. Power Fail programmable input. If unconnected the Power Fail threshold voltage is 11V with 1V hysteresis (factory setting). DC input voltage. Recommended maximum voltage is 40V. 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. Regulated +5.1V output voltage. Return for output 1 current path. Internally connected to pin 1. Regulated +12 or +15V output. Regulated - 12 or - 15V output. External adjustment for output voltages 12 and 15V. Return for 12 and 15V output current path.
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 100F/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 output 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:
Rpf = 5.1 = (k) 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 = 14k 24 - 5.1 - 0.191 34
Figure 1 - Reset and Power Fail waveforms.
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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:
GS-R51212S GS-R51515S
Ra = 32.66 x Vo - 4.229 12.485 - Vo Ra = 38.66 x Vo - 4.39 15.252 - Vo
where Vo is the desired dual output voltage. Example: Vo = 5V.
Ra (GS-R51212S) = 3.36k Ra (GS-R51515S) = 2.3k
Example: Vo = 10V.
Ra (GS-R51212S) = 75.8k Ra (GS-R51515S) = 41.3k
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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-R51515S require 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 7.5C/W. This means that an internal power dissipation of 1W will bring the case temperature at 7.5C above the ambient temperature. The maximum case temperature is 85C. Let's suppose to have a GS-R51515S that delivers the maximum output power of 31.4W at an ambient temperature of 40C.
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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:
Tcase = Tamb + Pd x Rth = 40 + 7.4 x 7.5 = 95.5 C
This value is the resulting value of the parallel connection of GS-R thermal resistance and of the additional heatsink thermal resistance.
Rth (GSR) x Rth (Heatsink) = 5.40C / W Rth (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 x Rth (GSR) = 5.40 x 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. (c) 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.
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