GS-R24FP 1.8 A DC-DC converter modules Features ■ MTBF 1 000 000 hours (TA = 25 °C) ■ 1.8 A max output current ■ 35 V max input voltage ■ 1.5 V max drop-out voltage ■ Remote logic inhibit/enable ■ Synchronization ■ Not-latching overload and short circuit protection ■ Thermal shutdown ■ Fixed or adjustable output ■ No heatsink required ■ Operating temperature range -25 °C ÷ 85 °C Packing type: V = vertical PTH Description The GS-R24FP series is a family of high efficiency step down switching voltage regulator, designed to replace linear regulators. Based on ST L5973A device, this non isolated family of regulators are suitable for the full spectrum of applications including telecom, industry, computer and distributed power system applications having a widely ranging input voltage. Table 1. Packing type: S = horizontal SMD Device summary Output voltage Input voltage Output ripple Efficiency [V] [V] [mVpp] [%] GS-R24FP0181.8 1.8 ± 4% 16 ÷ 35 25 59 - 63 Fixed output voltage GS-R24FP0251.8 2.5 ± 4% 16 ÷ 35 30 66 - 70 Fixed output voltage GS-R24FP0331.8 3.3 ± 4% 16 ÷ 35 30 70 - 75 Fixed output voltage GS-R24FP0501.8 5.0 ± 4% 16 ÷ 35 40 79 - 83 Fixed output voltage GS-R24FP0001.8 1.235 ÷ 5.5% 16 ÷ 35 40 56 - 83 Progr. output voltage Order codes February 2008 Rev 2 Notes 1/15 www.st.com 15 Contents GS-R24FP Contents 1 2 Pin settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1 Pin connection and mechanical data (dimensions in mm) . . . . . . . . . . . . . 3 1.2 Pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2.1 Absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2.2 Thermal data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2.3 Thermal de-rating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 3 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 4 Application information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 5 4.1 Input voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 4.2 Reference voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 4.3 Inhibit function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 4.4 Multiple units synchronization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 4.5 Current limitation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 4.6 Thermal shutdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 4.7 Output voltage programming (GS-R24FP0001.8 only) . . . . . . . . . . . . . . . 9 4.8 Loop compensation (GS-R24FP0001.8 only) . . . . . . . . . . . . . . . . . . . . . . 9 4.9 Soldering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Additional features and protections . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 5.1 Output overvoltage protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 6 Ordering scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 7 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 2/15 GS-R24FP Pin settings 1 Pin settings 1.1 Pin connection and mechanical data (dimensions in mm) Figure 1. Pin connection GS-R24FVxxx1.8 Figure 2. Pin connection GS-R24FSxxx1.8 3/15 Pin settings 1.2 GS-R24FP Pin description Table 2. 4/15 Pin description Name Function Description 1 INH A logic high level disables the device. When the pin is open, an internal pull up disables the device 2 Sync Master/slave synchronization 3 Vref 4 Input + DC input voltage 5 Input + DC input voltage 6 Input/output GND Return for input/output voltage source 7 Input/output GND Return for input/output voltage source 8 Vout Regulated power output 9 Vout Regulated power output 10 FB Feedback input, available on adjustable device and on request for additional compensation 3.3 V reference voltage GS-R24FP Maximum ratings 2 Maximum ratings 2.1 Absolute maximum ratings Table 3. Absolute maximum ratings Symbol 2.2 Parameter Value Unit 36 V VI DC input voltage Iout Maximum output current int. limit V1 INH -0.3 to Vi V V2 Sync -0.3 to 4 V V10 FB 4 V Value Unit Thermal data Table 4. Symbol Thermal data Parameter TSTG Storage temperature range -40 ÷ 105 °C TOP Operating ambient temperature -25 ÷ 85 °C 5/15 Maximum ratings 2.3 Thermal de-rating Table 5. Symbol Io Io Io 6/15 GS-R24FP Thermal de-rating for free air condition (all versions) Parameter Output current Output c urrent Output current Test condition Value VI = 16 V, TA = 30 °C 1.80 VI = 16 V, TA = 40 °C 1.80 VI = 16 V, TA = 50 °C 1.75 VI = 16 V, TA = 55 °C 1.70 VI = 16 V, TA = 60 °C 1.65 VI = 16 V, TA = 65 °C 1.50 VI = 16 V, TA = 70 °C 1.35 VI = 16 V, TA = 75 °C 1.25 VI = 16 V, TA = 80 °C 1.10 VI = 16 V, TA = 85 °C 0.90 VI = 24 V, TA = 30 °C 1.80 VI = 24 V, TA = 40 °C 1.75 VI = 24 V, TA = 50 °C 1.70 VI = 24 V, TA = 55 °C 1.60 VI = 24 V, TA = 60 °C 1.45 VI = 24 V, TA = 65 °C 1.30 VI = 24 V, TA = 70 °C 1.20 VI = 24 V, TA = 75 °C 1.05 VI = 24 V, TA = 80 °C 0.85 VI = 24 V, TA = 85 °C 0.60 VI = 35 V, TA = 30 °C 1.75 VI = 35 V, TA = 40 °C 1.60 VI = 35 V, TA = 50 °C 1.45 VI = 35 V, TA = 55 °C 1.35 VI = 35 V, TA = 60 °C 1.20 VI = 35 V, TA = 65 °C 1.05 VI = 35 V , TA = 70 °C 0.90 VI = 35 V, TA = 75 °C 0.75 VI = 35 V, TA = 80 °C 0.50 VI = 35 V, TA = 85 °C 0.30 Unit A A A GS-R24FP 3 Electrical characteristics Electrical characteristics TA = 25 °C, unless otherwise specified Table 6. Symbol Electrical characteristics (all version) Parameter Test condition Min Typ Max Unit 30 60 mVpp Ripple voltage Vi =24 V Io = 1.8 A for GS-R24FPyyy1.8 Temperature stability Vi =Vo + 1.5 V Io = 1.8 A Io Output current Vi =16 ÷ 35 V for GS-R24FPyyy1.8 IoL Current limit Vi =16 ÷ 35 V Iq Quiescent current Vi =24 V Io = 0 A Iqst-by Total stand-by quiescent current Vinh > 2.2 V Vi = 35 V 80 Switching frequency Vi = 24 V Io = 1.8 A 500 Reference voltage Vi = 16 ÷ 35 V Iref = 0 ÷ 5 mA Vr fs Vref Short circuit current mV/°C 0 1.8 2.3 VFB A 2.7 mA 150 µA kHz 3.2 3.3 3.399 V 8 10 30 mA 0.8 V Device ON INH A INH threshold voltage Feedback voltage Device OFF 2.2 Vi =16 ÷ 35 V IO = 0 ÷ 1.8 A 1.22 V 1.235 1.25 V 7/15 Application information 4 Application information 4.1 Input voltage GS-R24FP The recommended maximum operating DC input voltage is 35 V including ripple voltage. 4.2 Reference voltage No capacitor is required for stability. 4.3 Inhibit function The inhibit feature allows to put the device in stand-by mode. With INH pin 1 is higher than 2.2 V the device is disabled and the current consumption is reduced to less than 150 µA for Vi = 35 V. With INH pin lower than 0.8 V, the device is enabled. If the INH pin is left floating, an internal pull up ensures that the voltage at the pin reaches the inhibit threshold and the device is disabled. The pin can be pulled to Vi to disable the device. 4.4 Multiple units synchronization Using more than one unit on the same circuit, it is possible to synchronize the switching frequency, connecting all pin 2 together (see Figure 6). The unit with higher frequency becomes the master. 4.5 Current limitation The device has two current limit protections, pulse by pulse and frequency fold back. The current is sensed through a resistor and if it reaches the threshold, the on time is reduced and consequently the output voltage, too. Since the minimum switch ON time (necessary to avoid false overcurrent signal) is not enough to obtain a sufficiently low duty cycle at 500 kHz, the output current could increase again, in strong overcurrent or short circuit conditions. For this reason the switching frequency is also reduced to keep the inductor current within its maximum threshold limit. The frequency depends on the feedback voltage. As the feedback voltage decreases (due to the reduced duty cycle), the switching frequency decrease too. 8/15 GS-R24FP 4.6 Application information Thermal shutdown The shutdown block generates a signal that turns OFF the power stage if the temperature of the internal chip goes higher than a fixed internal threshold (150 °C min). The sensing element of the chip is very close to the PDMOS area, so ensuring an accurate and fast temperature detection. An hysteresis of approximately 20 °C avoids that the devices turns ON and OFF continuously. 4.7 Output voltage programming (GS-R24FP0001.8 only) The GS-R24FP0001.8 output voltage is 5.54 V ± 4 %, to reduce this value connect a resistor between pin 10 (FB) and pin 9 (Vout). The resistor must be located very close to the proper pins, to minimize the injected noise (see Figure 4). The resistor value is calculated using the following formula: for GS-R24FP0001.8 Rv = [(Vout - 1.235) * 11.3] / 5.54 - Vout) --[kΩ] Vout can be adjusted between 1.235 V (Rv = 0 Ω) and 5.54V (Rv = open) 4.8 Loop compensation (GS-R24FP0001.8 only) If required by particular load conditions, it is possible to change the feedback loop compensation, adding an external capacitor between pin 10 (FB) and pin 9 (Vout), which will act as speed up (see Figure 5). 9/15 Application information 4.9 GS-R24FP Soldering Soldering phase has to be execute with care : in order to avoid undesired melting phenomenon, particular attention has to be take on the set up of the peak temperature. Here following some suggestions for the temperature profile based on IPC/JEDEC J-STD-020C ,July 2004 recommendations. Table 7. Soldering Profile feature Average ramp up rate ( TSMAX to TP) 3 °C / sec max Preheat: Temperature min ( TS MIN) Temperature max ( TS MAX) Time (TS MIN to TS MAX) ( tS ) 150 °C 200 °C 60 – 100 sec Time maintained above : Temperature TL Time tL 217 °C 40 – 70 sec Peak temperature (TP) 240 + 0 °C Time within 5 °C of actual peak temperature (tP) 10 – 20 sec Ramp down rate Time from 25 °C to peak temperature Figure 3. 10/15 PB free assembly Soldering 6 °C / sec 8 minutes max GS-R24FP Additional features and protections 5 Additional features and protections 5.1 Output overvoltage protection The overvoltage protection, OVP, is realized by using an internal comparator, whose input is connected to the feedback. It turns off the power stage when the OVP threshold is reached. This threshold is typically 30 % higher than the feedback voltage. Figure 4. Output voltage programming Figure 5. 10 4, 5 Loop compensation 4, 5 10 Rv Rv 8, 9 Vin GS-RxxFp000z.z Vin GS-RxxFp000z.z Rload Vout Vout Rload 6, 7 6, 7 Figure 6. Cc 8, 9 Multiple units synchronization 2 4, 5 4, 5 2 Rload 8, 9 Vin GS-RxxFpyyyz.z 6, 7 Vin Vout 8, 9 Rload GS-RxxFpyyyz.z Vout 6, 7 11/15 Additional features and protections Figure 7. 12/15 PCB footprint for GS-R24FSxxx1.8 (dimensions in mm) GS-R24FP GS-R24FP 6 Ordering scheme Ordering scheme Table 8. Ordering information scheme GS- R12 FV 018 1.8 Input voltage 24 = 24 V Package V = Vertical S = SMD Output voltage 018 = 1.8 V 025 = 2.5 V 033 = 3.3 V 050 = 5.0 V 000 = 1.235 ÷ 5.5 V Output current 1.8 = 1.8 A 13/15 Revision history 7 GS-R24FP Revision history Table 9. 14/15 Document revision history Date Revision Changes 13-Oct-2006 1 Initial release 27-Feb-2008 2 Added: Section 4.9: Soldering on page 10 GS-R24FP Please Read Carefully: Information in this document is provided solely in connection with ST products. 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