L5973D 2.5A SWITCH STEP DOWN SWITCHING REGULATOR ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ 2.5A INTERNAL SWITCH OPERATING INPUT VOLTAGE FROM 4.4V TO 36V 3.3V / (±2%) REFERENCE VOLTAGE 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 INHIBIT FOR ZERO CURRENT CONSUMPTION SYNCHRONIZATION PROTECTION AGAINST FEEDBACK DISCONNECTION THERMAL SHUTDOWN HSOP8 - EXPOSED PAD ORDERING NUMBER: L5973D DESCRIPTION The L5973D is a step down monolithic power switching regulator with a minimum switch current limit of 2.5A so it is able to deliver more than 2A DC current to the load depending on the application conditions. The output voltage can be set from 1.235V to 35V. The high current level is also achieved thanks to an SO8 package with exposed frame, that allows to reduce the Rth(j-amb) down to approximately 40°C/W 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: ■ CONSUMER: STB, DVD, TV, VCR,CAR RADIO, LCD MONITORS ■ NETWORKING: XDSL, MODEMS,DC-DC MODULES ■ COMPUTER: PRINTERS, AUDIO/GRAPHIC CARDS, OPTICAL STORAGE, HARD DISK DRIVE ■ INDUSTRIAL: CHARGERS, CAR BATTERY DC-DC CONVERTERS TEST APPLICATION CIRCUIT VREF 3.3V VIN = 4.4V to 35V VCC SYNC. C1 10µF 35V CERAMIC COMP C4 22nF C3 220pF 6 1 8 OUT D1 STPS340U L5973D 2 3 4 INH 7 L1 15µH VOUT=3.3V R1 5.6K 5 FB GND R3 4.7K C2 330µF 10V R2 3.3K D03IN1439 May 2003 1/10 L5973D PIN CONNECTION OUT 1 8 VCC SYNC 2 7 GND INH 3 6 VREF COMP 4 5 FB D98IN955 PIN DESCRIPTION N° Pin Function 1 OUT 2 SYNC 3 INH 4 COMP 5 FB 6 VREF 3.3V VREF. No cap is requested for stability. 7 GND Ground. 8 VCC Unregulated DC input voltage. Regulator Output. Master/slave synchronization. A logical signal (active high) disables the device. If INH not used the pin must be grounded. When it is open an internal pull-up disable the device. 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. THERMAL DATA Symbol Rth (j-amb) Parameter Thermal Resistance Junction to ambient Max. Value Unit 40 (*) °C/W Value Unit 40 V V V (*) Package mounted on board ABSOLUTE MAXIMUM RATINGS Symbol V8 Input Voltage V1 Output DC voltage Output peak voltage at t = 0.1µs -1 to 40 -5 to 40 I1 Maximum output current int. limit. V4, V5 Analog pins V3 INH V2 SYNC Ptot Power dissipation at Tamb ≤ 60°C Tj Tstg 2/10 Parameter 4 V -0.3V to VCC -0.3 to 4 V 2.25 W Operating junction temperature range -40 to 150 °C Storage temperature range -55 to 150 °C L5973D ELECTRICAL CHARACTERISTICS (Tj = 25°C, VCC = 12V, unless otherwise specified.) (*) Specification Referred to Tj from -40 to 125°C (1). Symbol VCC Parameter Operating input voltage range RDSON Mosfet on Resistance Il Maximum limiting current fs Switching frequency Test Condition Vo = 1.235V; Io = 2A η Efficiency Iqst-by Total stand-by quiescent current Min. 4.4 * VCC = 4.4V to 36V * Duty cycle DYNAMIC CHARACTERISTICS (see test circuit ). V5 Voltage feedback 4.4V < VCC < 36V, 20mA < IO < 2A DC CHARACTERISTICS Total Operating Quiescent Iqop Current Quiescent current Iq * * Typ. Max. 36 Unit V Ω 0.150 0.5 2.5 3 3.5 A 212 225 0 250 250 280 275 100 KHz KHz % 1.220 1.198 1.235 1.235 1.25 1.272 V V VO = 5V, VCC = 12V 90 % * 3 5 mA 2.5 mA Vinh > 2.2V * 50 100 µA VCC = 36V; Vinh > 2.2V * 80 150 µA 0.8 V V Duty Cycle = 0; VFB = 1.5V INHIBIT INH Threshold Voltage Device ON Device OFF 2.2 3.5 ERROR AMPLIFIER VOH High level output voltage VFB = 1V VOL Low level output voltage VFB = 1.5V Source output current VCOMP = 1.9V; VFB = 1V Io sink Sink output current VCOMP = 1.9V; VFB = 1.5V Ib Source bias current Io source gm V 0.4 200 1 1.5 2.5 DC open loop gain RL = ∞ Transconductance Icomp = -0.1mA to 0.1mA VCOMP = 1.9V SYNC FUNCTION High Input Voltage VCC = 4.4V to 36V Low Input Voltage VCC = 4.4V to 36V Slave Sink Current Vsync = 0.74V Vsync = 2.33V 50 V µA 300 mA 4 µA 57 dB 2.3 mS 2.5 0.11 0.21 VREF V 0.74 V 0.25 0.45 mA mA Master Output Amplitude Isource = 3mA 2.75 3 V Output Pulse Width no load, Vsync = 1.65V 0.20 0.35 µs 3.234 3.2 3.3 3.3 3.366 3.399 V V 5 10 mV REFERENCE SECTION Reference Voltage IREF = 0 to 5mA VCC = 4.4V to 36V Line Regulation IREF = 0mA VCC = 4.4V to 36V Load Regulation IREF = 0 to 5mA Short Circuit Current * 10 8 15 mV 8 30 mA Notes: 1. Specification over the -40 to +125 Tj Temperature range are assured by design, characterization and statistical correlation. 2. Guaranteed by design. 3/10 L5973D Figure 4. Shutdown Current vs.Junction Temperature Figure 1. Line Regulation Vo (V) Ishd (µA) 70 3.312 Vcc = 12V Vo = 3.3V 3.308 3.304 Tj = 25°C 3.3 60 Vcc = 12V 3.296 3.292 50 Tj = 125°C 3.288 3.284 40 3.28 3.276 0 10 20 Vcc (V) 30 40 30 -50 Figure 2. Output Voltage vs. Junction Temperature 0 50 Tj (°C) 100 150 Figure 5. Switching Frequency vs.Junction Temperature Vo (V) 1.25 Fsw (KHz) 260 1.24 250 1.23 240 1.22 Vcc = 12V 1.21 230 Vcc=12V 1.2 220 -50 0 50 Tj (°C) 100 150 Figure 3. Quiescent Current vs. Junction Temperature Iq (mA) 2 1.8 1.6 1.4 Vcc = 12V DC = 0% 1.2 -50 4/10 Vcc = 12V Vo = 3.3V 0 50 Tj (°C) 100 150 -50 0 50 Tj (°C) 100 150 L5973D APPLICATION CIRCUIT In figure 6 is shown the demo board application circuit, 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 6. Demo board Application Circuit VREF 3.3V VIN = 4.4V to 25V VCC SYNC. C1 10µF 25V CERAMIC COMP C4 22nF 6 8 3 4 INH C3 220pF 7 VOUT=3.3V D1 STPS2L25U L5973D 2 L1 15µH OUT 1 R1 5.6K 5 FB GND C2 330µF 6.3V R2 3.3K R3 4.7K D03IN1440 Table 1. Component List Reference Part Number C1 C2 POSCAP 6TPB330M Description Manufacturer 10µF, 25V TOKIN 330µF, 6.3V Sanyo C3 C1206C221J5GAC 220pF, 5%, 50V KEMET C4 C1206C223K5RAC 22nF, 10%, 50V KEMET R1 5.6K, 1%, 0.1W 0603 Neohm R2 3.3K, 1%, 0.1W 0603 Neohm R3 4.7K, 1%, 0.1W 0603 Neohm D1 STPS2L25U 2A, 25V ST L1 DO3316P-153 15µH, 3A COILCRAFT 5/10 L5973D Figure 7. PCB layout (component side) 42mm 34mm Figure 8. PCB layout (bottom side) Figure 9. PCB layout (front side) Below some graphs show the Tj versus output current in different conditions of the input and output voltage and some efficiency measurements. 6/10 L5973D Figure 10. Junction Temperature vs. Output Current (VCC = 5V) Vo=3.3V Vo=2.5V Vo=1.8V Efficiency (%) Tj(°C) 120 110 Vin=5V 100 Tamb=25°C 90 80 70 60 50 40 30 20 0.2 0.4 0.6 0.8 1 Figure 12. Efficiency vs. Output Current (VCC = 5V) 1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 95 93 91 89 87 85 83 81 79 77 75 73 71 69 67 Vo=2.5V Vo=1.8V Vcc=5V 0.1 0.3 0.5 0.7 0.9 1.1 1.3 1.5 1.7 1.9 2.1 2.3 Io (A) Io(A) Figure 11. Junction Temperature vs. Output Current (VCC = 12V) Vo=3.3V Figure 13. Efficiency vs. Output Current (VCC = 12V) Tj (°C) 120 100 Vo=5V Vin=12V Tamb=25°C Vo=3.3V 90 80 Vo=2.5V 70 60 50 40 30 20 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 Io (A) 2 2.2 2.4 2.6 Efficiency (%) 110 91 89 87 85 83 81 79 77 75 73 71 69 67 65 Vo=5V Vo=3.3V Vo=2.5V Vcc=12V 0.1 0.3 0.5 0.7 0.9 1.1 1.3 1.5 1.7 1.9 2.1 2.3 Io (A) 7/10 L5973D APPLICATION IDEAS Figure 14. Positive Buck-Boost regulator 8 C3 22nF R3 4.7k D1 STPS2L25U 4 2 C2 220pF D2 STPS2L25U VOUT=12V/0.6A 1 L5973D COMP C1 10uF 10V Ceramic L1 15uH OUT Vcc VIN=5V SYNC 6 VREF 7 24k FB 5 3 INH GND C4 100uF 16V M1 STN4NE03L 2.7k 3.3V Figure 15. Buck-Boost regulator VIN=5V 8 C2 10uF C3 25V Ceramic 220pF 1 L5973D COMP C1 10uF 10V Ceramic FB 4 2 C4 22nF R3 4.7k L1 15uH OUT Vcc 6 SYNC VREF 7 5 3 GND INH D1 STPS2L25U VOUT=-12V/0.6A 2.7k 24k C5 100uF 16V 3.3V Figure 16. Dual output voltage with auxiliary winding N1/N2=2 VIN=12V VCC COMP C1 10uF 25V Ceramic 8/10 1 L5973D C3 22nF R3 4.7k 6 SYNC VREF 7 GND 3.3V VOUT=3.3V 0.5A D1 STPS25L25U 4 2 C2 220pF VOUT1=5V 50mA Lp=22uH OUT 8 D2 1N4148 5 3 FB INH C4 100uF 10V C5 47uF 10V L5973D mm inch DIM. MIN. TYP. MAX. MIN. TYP. MAX. A 1.350 1.750 0.531 0.069 A1 0.100 0.250 0.004 0.010 A2 1.100 1.650 0.043 0.065 B 0.330 0.510 0.013 0.020 C 0.190 0.250 0.07 0.010 D 4.800 5.000 0.189 0.197 E 3.800 4.000 0.150 0.157 1.270 e 0.05 H 5.800 6.200 0.228 0.244 h 0.250 0.500 0.010 0.020 L 0.400 1.270 0.016 0.05 k OUTLINE AND MECHANICAL DATA 0˚ (min), 8˚ (max) ddd 0.100 0.010 (1) Dimension D does not include mold flash, protusions or gate burrs shall not exeed 0.15mm (both side). HSOP8 (Exposed Pad) Exposed Pad: D1 = 3.1mm E1 = 2.41mm 7195016 9/10 L5973D 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