L5972

L5972D 2A SWITCH STEP DOWN SWITCHING REGULATOR s s s s s s s s s s 2A INTERNAL SWITCH OPERATING INPUT VOLTAGE FROM 4.4V TO 36V OUTPUT VOLTAGE ADJUSTABLE FROM 1.235V TO 35V LOW DROPOUT OPERATION: 100% DUTY CYCLE 250KHz INTERNALLY FIXED FREQUENCY VOLTAGE FEEDFORWARD ZERO LOAD CURRENT OPERATION INTERNAL CURRENT LIMITING PROTECTION AGAINST FEEDBACK DISCONNECTION THERMAL SHUTDOWN SO8 (4+2+2) ORDERING NUMBERS: L5972D (SO8) L5972D013TR (Tape & Reel) DESCRIPTION The L5972D is a step down monolithic power switching regulator with a minimum switch current limit of 2A so it is able to deliver more than 1.5A DC current to the load depending on the application conditions. The output voltage can be set from 1.235V to 35V. The device uses an internal P-Channel D-MOS transistor (with a typical Rdson of 250mΩ) as switching element to minimize the size of the external components. An internal oscillator fixes the switching frequency at 250KHz. Having a minimum input voltage of 4.4V only, it is particularly suitable for 5V bus, available in all computer related applications. Pulse by pulse current limit with the internal frequency modulation offers an effective constant current short circuit protection. APPLICATIONS: s CONSUMER: STB, DVD, TV, VCR,CAR RADIO, LCD MONITORS s NETWORKING: XDSL, MODEMS,DC-DC MODULES s COMPUTER: PRINTERS, AUDIO/GRAPHIC CARDS, OPTICAL STORAGE, HARD DISK DRIVE s INDUSTRIAL: CHARGERS, CAR BATTERY DC-DC CONVERTERS TEST APPLICATION CIRCUIT VIN = 4.4V to 35V VCC OUT L1 33µH D1 STPS2L40U 7 5 FB GND R3 4.7K R2 3.3K VOUT=3.3V 8 1 C1 10µF 35V CERAMIC COMP C4 22nF C3 220pF L5972D 4 6 2 3 R1 5.6K C2 100µF 10V D03IN1436 May 2003 1/10 L5972D PIN CONNECTION OUT GND GND COMP 1 2 3 4 D02IN1367 8 7 6 5 VCC GND GND FB PIN DESCRIPTION N° 1 2,3,6,7 4 5 8 Pin OUT GND COMP FB VCC Regulator Output. Ground. E/A output for frequency compensation. Feedback input. Connecting directly to this pin results in an output voltage of 1.23V. An external resistive divider is required for higher output voltages. Unregulated DC input voltage. Function THERMAL DATA Symbol Rth (j-amb) Parameter Thermal Resistance Junction to ambient (4cm2 ground-plane) Value Max. 65 (*) Unit °C/W (*) Package mounted on board ABSOLUTE MAXIMUM RATINGS Symbol V8 V1 I1 V4, V5 Ptot Tj Tstg Input Voltage Out pin DC voltage Out pin peak voltage at ∆t = 0.1µs Maximum output current Analog pins Power dissipation at Tamb ≤ 70°C Operating junction temperature range Storage temperature range Parameter Value 40 -1 to 40 -5 to 40 int. limit. 4 1.2 -40 to 150 -55 to 150 V W °C °C Unit V V V 2/10 L5972D ELECTRICAL CHARACTERISTICS (Tj = 25°C, VCC = 12V, unless otherwise specified.) (*) Specification Referred to Tj from -40 to 125°C. Symbol VCC Vd Il fs Parameter Operating input voltage range Dropout voltage Maximum limiting current Switching frequency Test Condition Vo = 1.235V; Io = 1.5A VCC = 4.4V; Io = 1.5A VCC = 4.4V to 36V * * * * 2 212 225 Duty cycle DYNAMIC CHARACTERISTICS (see test circuit ). V5 Voltage feedback 4.4V < VCC < 36V, 20mA < IO < 1.5A VO = 5V, VCC = 12V 1.220 * 1.198 1.235 1.235 90 1.25 1.272 V V % 0 Min. 4.4 0.375 2.5 250 250 Typ. Max. 36 0.75 3 280 275 100 Unit V V A KHz KHz % h Efficiency DC CHARACTERISTICS Iqop Iq Total operating quiescent current Quiescent current Duty Cycle = 0; VFB = 1.5V * 3 5 2.5 mA mA ERROR AMPLIFIER VOH VOL Io source Io sink Ib High level output voltage Low level output voltage Source output current Sink output current Source bias current DC open loop gain gm Transconductance RL = ∞ Icomp = -0.1mA to 0.1mA VCOMP = 1.9V 50 VFB = 1V VFB = 1.5V VCOMP = 1.9V; VFB = 1V VCOMP = 1.9V; VFB = 1.5V 200 1 300 1.5 2.5 65 2.3 4 3.5 0.4 V V µA mA µA dB mS 3/10 L5972D Figure 1. Output Voltage vs. Junction Temperature Vo (V) 3.312 3.308 3.304 3.3 3.296 3.292 3.288 3.284 3.28 3.276 0 0.5 Io (A) 1 1.5 Tj = 125°C 1.2 -50 0 50 Tj (°C) 100 150 1.4 Figure 4. Quiescent Current vs. Junction Iq (mA) 2 Vcc = 12V Vo = 3.3V Tj = 25°C 1.8 1.6 Vcc = 12V DC = 0% Figure 2. Line Regulation Vo (V) 3.312 3.308 3.304 3.3 3.296 3.292 3.288 3.284 3.28 3.276 0 10 20 Vcc (V) 30 40 Tj = 125°C Vcc = 12V Vo = 3.3V Tj = 25°C Figure 5. Shutdown Current vs.Junction Temperature Ishd ( µA) 70 60 Vcc = 12V 50 40 30 -50 0 50 Tj (°C) 100 150 Figure 3. Output Voltage vs. Junction Temperature Vo (V) 1.25 1.24 1.23 1.22 Vcc = 12V 1.21 1.2 -50 0 50 Tj (°C) 100 150 Vcc=12V Figure 6. Switching Frequency vs.Junction Temperature Iq (mA) 2 1.8 1.6 Vcc = 12V DC = 0% 1.4 1.2 -50 0 50 Tj (°C) 100 150 4/10 L5972D APPLICATION CIRCUIT In figure 7 is shown the demo board application circuit for the device in SMD version, where the input supply voltage, Vcc, can range from 4.4V to 25V due to the rated voltage of the input capacitor and the output voltage is adjustable from 1.235V to Vcc. Figure 7. Demo board Application Circuit VIN = 4.4V to 25V VCC 8 1 OUT L1 33µH D1 STPS2L25U VOUT=3.3V C1 10µF 25V CERAMIC COMP C4 22nF C3 220pF R3 4.7K L5972D 4 6 2 3 7 5 FB GND R1 5.6K C2 100µF 10V R2 3.3K D03IN1438 Table 1. Component List Reference C1 C2 C3 C4 R1 R2 R3 D1 L1 STPS2L25U DO3316P-333 POSCAP 10TPB100M C1206C221J5GAC C1206C223K5RAC Part Number Description 10µF, 25V 100µF, 10V 220pF, 5%, 50V 22nF, 10%, 50V 5.6K, 1%, 0.1W 0603 3.3K, 1%, 0.1W 0603 4.7K, 1%, 0.1W 0603 2A, 25V 33µH, 2.1A Manufacturer TOKIN Sanyo KEMET KEMET Neohm Neohm Neohm ST COILCRAFT 5/10 L5972D Figure 8. PCB layout (component side) 42mm 34mm Figure 9. PCB layout (bottom side) Figure 10. PCB layout (front side) Sideways two graphs show the Tj versus output current in different conditions of the input and output voltage. 6/10 L5972D Figure 11. Junction Temperature vs. Output Current TJ(°C) 100.0 90.0 80.0 70.0 60.0 50.0 40.0 30.0 20.0 0.2 0.4 0.6 0.8 1 1.2 Io(A) 1.4 1.6 1.8 2 Figure 13. Efficiency vs. Output Current 95 93 91 Vo=3.3V Vin=5V Tamb.=25 °C Vo=2.5V Vo=3.3V Efficiency (%) 89 87 85 83 81 79 77 75 73 71 69 67 0.1 0.3 0.5 0.7 0.9 1.1 1.3 1.5 1.7 Vo=2.5V Vo=1.8V Vo=1.8V Vcc=5V Io (A) Figure 12. Junction Temperature vs. Output Current TJ(°C) 100.0 90.0 80.0 70.0 60.0 50.0 40.0 30.0 20.0 0.2 0.4 0.6 0.8 1 1.2 Io(A) 1.4 1.6 1.8 2 Vo=2.5V V in=12V T amb= 25°C V o=5V V o=3.3V Figure 14. Efficiency vs. Output Current 96 94 92 90 88 Efficiency (%) 86 84 82 80 78 76 74 72 70 0.1 0.3 0.5 0.7 0.9 Io (A) 1.1 1.3 1.5 1.7 Vin=12V Vo=2.5V Vo=3.3V Vo=5V 7/10 L5972D APPLICATION IDEAS Figure 15. Positive Buck-Boost regulator L1 33uH VIN=5V Vcc OUT D2 STPS2L25U VOUT=12V/0.45A 8 COMP C1 10uF 10V Ceramic 1 L5972D FB D1 STPS2L25U 24k 4 2 C2 220pF C3 22nF R3 4.7k 6 GND 7 5 3 M1 STN4NE03L 2.7k C4 100uF 16V Figure 16. Buck-Boost regulator OUT VIN=5V Vcc L1 33uH 8 COMP C1 10uF 10V Ceramic 1 L5972D FB D1 STPS2L25U 2.7k C2 10uF C3 25V Ceramic 220pF 4 2 C4 22nF R3 4.7k VOUT=-12V/0.45A 6 GND 7 5 3 24k C5 100uF 16V Figure 17. Dual output voltage with auxiliary winding n=N1/N2=2 D2 N2 STPS2L25U VIN=12V Vcc OUT VOUT1=5V 50mA 8 COMP C1 10uF 25V 1 L5972D FB N1 D1 STPS2L25U VOUT=3.3V 4 2 C2 220pF C3 22nF R3 4.7k 6 GND 7 5 3 C4 100uF 10V C5 47uF 10V 8/10 L5972D DIM. MIN. A a1 a2 a3 b b1 C c1 D (1) E e e3 F (1) L M S 3.8 0.4 4.8 5.8 0.65 0.35 0.19 0.25 0.1 mm TYP. MAX. 1.75 0.25 1.65 0.85 0.48 0.25 0.5 0.026 0.014 0.007 0.010 0.004 MIN. inch TYP. MAX. 0.069 0.010 0.065 0.033 0.019 0.010 0.020 OUTLINE AND MECHANICAL DATA 45° (typ.) 5.0 6.2 1.27 3.81 4.0 1.27 0.6 8 ° (max.) 0.15 0.016 0.189 0.228 0.050 0.150 0.157 0.050 0.024 0.197 0.244 SO8 (1) D and F do not include mold flash or protrusions. Mold flash or potrusions shall not exceed 0.15mm (.006inch). 9/10 L5972D Information furnished is believed to be accurate and reliable. However, STMicroelectronics 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 STMicroelectronics. Specifications mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied. STMicroelectronics products are not authorized for use as critical components in life support devices or systems without express written approval of STMicroelectronics. The ST logo is a registered trademark of STMicroelectronics 2003 STMicroelectronics - All Rights Reserved STMicroelectronics GROUP OF COMPANIES Australia - Brazil - Canada - China - Finland - France - Germany - Hong Kong - India - Israel - Italy - Japan -Malaysia - Malta - Morocco Singapore - Spain - Sweden - Switzerland - United Kingdom - United States. http://www.st.com 10/10 ®