L5970D UP TO 1A STEP DOWN SWITCHING REGULATOR ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ UP TO 1A OUTPUT CURRENT OPERATING INPUT VOLTAGE FROM 4.4V TO 36V 3.3V / (±2%) / REFERENCE VOLTAGE OUTPUT VOLTAGE ADJUSTABLE FROM 1.2V 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 SINCHRONIZATION PROTECTION AGAINST FEEDBACK DISCONNECTION THERMAL SHUTDOWN SO8 ORDERING NUMBERS: L5970D (SO8) L5970D013TR (T&R) DESCRIPTION The L5970D is a step down monolithic power switching regulator capable to deliver up to 1A at output voltages from 1.2V 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. 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 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. 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 STPS2L40U L5970D 2 3 4 INH. 7 L1 33µH 5 FB GND R3 4.7K VOUT=3.3V R1 5.6K C2 100µF 10V R2 3.3K D98IN954C May 2003 1/10 L5970D PINS CONNECTION (Top View) OUT 1 8 VCC SYNC 2 7 GND INH 3 6 VREF COMP 4 5 FB D98IN955 PINS FUNCTION N. Name 1 OUT 2 SYNC 3 INH 4 COMP 5 FB Description 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. 6 VREF 3.3V VREF. No cap is requested for stability. 7 GND Ground. 8 VCC Unregulated DC input voltage. THERMAL DATA Symbol Parameter Rth (j-amb) Thermal Resistance Junction to ambient Max. Value Unit 120 (*) °C/W Value Unit 40 V V V (*) Package mounted on board ABSOLUTE MAXIMUM RATINGS Symbol 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 V8 4 V -0.3V to VCC -0.3 to 4 V 0.75 W Operating junction temperature range -40 to 150 °C Storage temperature range -55 to 150 °C L5970D ELECTRICAL CHARACTERISTCS (Tj = 25°C, VCC = 12V, unless otherwise specified.) (*) Specification Referred to Tj from -40 to +125°C (1). Symbol Parameter Operating input voltage range Dropout voltage Test Condition Vo = 1.235V; Io = 1A * VCC = 4.4V; Io = 1A * Il Maximum limiting current VCC = 4.4V to 36V * 1.5 fs Switching frequency * VCC Vd Duty cycle DYNAMIC CHARACTERISTICS (see test circuit fig. xx note 1). V5 Voltage feedback 4.4V < VCC < 36V, 20mA < IO < 1A η Efficiency DC CHARACTERISTICS Total operating quiescent Iqop current Quiescent current Iq Iqst-by * Min. 4.4 Max. 36 Unit V 0.25 0.5 V 1.87 2.25 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 Typ. 90 * 3 Duty Cycle = 0; VFB = 1.5V Total stand-by quiescent current Vinh > 2.2V VCC = 36V; Vinh > 2.2V * * 50 80 INH Threshold voltage Device ON Device OFF 2.2 VFB = 1V 3.5 % 5 mA 2.5 mA 100 150 µA µA 0.8 V V 0.4 V INHIBIT ERROR AMPLIFIER High level output voltage VOH VOL V Low level output voltage VFB = 1.5V Source output current VCOMP = 1.9V; VFB = 1V 200 300 Io sink Sink output current Vcomp = 1.9V; VFB = 1.5V 1 1.5 Ib Source bias current Io source gm 2.5 DC open loop gain RL = ∞ Transconductance Icomp = -0.1mA to 0.1mA Vcomp = 1.9V 50 SYNC FUNCTION High Input Voltage VCC = 4.4V to 36V Low Input Voltage VCC = 4.4V to 36V µA mA µA 4 65 dB 2.3 mS 2.5 VREF V 0.74 V 0.11 0.21 0.25 0.45 mA mA Slave Sink Current Vsync = 0.74V Vsync = 2.33V 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 (2) REFERENCE SECTION Reference Voltage IREF = 0 to 5mA VCC = 4.4V to 36V * Line Regulation IREF = 0mA VCC = 4.4V to 36V 5 10 mV Load Regulation IREF = 0 to 5mA 8 15 mV 8 30 mA Short Circuit Current 10 Note (1): Specification over the -40 to +125 Tj Temperature range are assured by design, characterization and statistical correlation. Note (2): Guaranteed by design. 3/10 L5970D Figure 4. Load Regulation Figure 1. Junction Temperature vs. Output Current (SO8) *) Vo (V) 3.312 Tj(°C) 130 120 110 100 90 80 70 60 50 40 30 20 Vcc = 12V Vo = 3.3V 3.308 Vo=3.3V Vo=2.5V 3.304 Tj = 25°C 3.3 Vcc=5V Tamb=25°C Vo=1.8V 3.296 3.292 3.288 3.284 Tj = 125°C 3.28 3.276 0 0.2 0.4 0.6 0.8 1 1.2 1.4 0.5 1 1.5 Io (A) 1.6 Io(A) Figure 5. Line Regulation Figure 2. Junction Temperature vs. Output Current (SO8) *) Vo (V) 3.312 Tj(°C) Vcc = 12V Vo = 3.3V 3.308 130 120 110 100 90 80 70 60 50 40 30 20 Vo=3.3V Vo=5V Tj = 25°C 3.3 3.296 Vo=2.5V Vcc=12V Tamb=25°C 3.304 3.292 Tj = 125°C 3.288 3.284 3.28 3.276 0 0.2 0.4 0.6 0.8 1 1.2 1.4 10 20 Vcc (V) 30 40 1.6 Io(A) Figure 6. Output Voltage vs. Junction Temperature Figure 3. Junction Temperature vs. Output Current (SO8) *) Vo (V) 1.25 Tj(°C) 140 Vo=18V 1.24 Vo=12V 120 100 1.23 Vo=5V Vcc=24V Tamb=25°C 1.22 80 Vcc = 12V 1.21 60 40 1.2 20 0 0.2 -50 0.4 0.6 0.8 Io(A) 4/10 Vcc=12V 1 1.2 1.4 0 50 Tj (°C) 100 *) Package mounted on demoboard 150 L5970D Figure 9. Switching Frequency vs.Junction Temperature Figure 7. Quiescent Current vs. Junction Temperature 2 Fsw (KHz) 260 1.8 250 1.6 240 Iq (mA) 1.4 Vcc = 12V DC = 0% 230 1.2 -50 Vcc = 12V Vo = 3.3V 220 0 50 Tj (°C) 100 150 -50 0 50 Tj (C) 100 150 Figure 8. Shutdown Current vs.Junction Temperature Ishd (µA) 70 60 Vcc = 12V 50 40 30 -50 0 50 Tj (°C) 100 150 5/10 L5970D Figure 10. Demoboard schematic VREF 3.3V VIN = 4.4V to 25V 6 VCC 8 SYNC. C1 10µF 25V CERAMIC C4 22nF C3 220pF 3 4 R1 5.6K FB 5 7 INH. VOUT=3.3V D1 STPS2L25U L5970D 2 COMP L1 33µH OUT 1 GND C2 100µF 10V R2 3.3K R3 4.7K D03IN1437 Part list demoboard Reference Part Number Description C1 Manufacturer 10µF, 25V TOKIN C2 POSCAP 10TPB100M 100µF, 10V 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 STMicroelectronics L1 DO3316P-333 33µH, 2A COILCRAFT 94 92 90 88 86 84 82 80 78 76 74 72 70 0.1 6/10 Figure 12. Efficiency vs. Output Current Vo=3.3V Efficiency (%) Efficiency (%) Figure 11. Efficiency vs. Output Current Vo=2.5V Vo=1.8V Vcc=5V 0.2 0.3 0.4 0.5 0.6 Io (A) 0.7 0.8 0.9 1 92 90 88 86 84 82 80 78 76 74 72 70 Vo=5V Vo=3.3V Vo=2.5V Vcc=12V 0.1 0.2 0.3 0.4 0.5 0.6 Io (A) 0.7 0.8 0.9 1 L5970D Figure 13. PCB layout (component side) 42mm 34mm Figure 14. PCB layout (bottom side) Figure 15. PCB layout (front side) 7/10 L5970D APPLICATION IDEAS Figure 16. Dual output voltage with auxiliary winding N1/N2=2 VIN=12V VCC COMP C1 10uF 25V Ceramic 1 C2 220pF FB 4 6 5 3 7 SYNC VREF VOUT=3.3V 0.5A D1 STPS25L25U U1 L5970D 2 C3 22nF R3 4.7k VOUT1=5V 30mA Lp=22uH OUT 8 D2 1N4148 GND C4 100uF 10V C5 47uF 10V INH 3.3V Figure 17. Buck-Boost regulator VIN=12V VCC 8 1 U1 C2 10uF 35V C3 Ceramic 220pF Vin=12V Vout=-12V 4 2 C4 22nF R3 4.7k D1 STPS2L25U L5970 COMP C1 10uF 25V Ceramic L1 33uH OUT 6 5 3 7 SYNC VREF GND INH VOUT=-12V/0.3A 2.7k FB C5 100uF 16V 24k 3.3V Iout=0.5A Efficiency=81% Figure 18. Positive Buck-Boost regul L1 33uH VIN=5V VCC OUT 8 D1 STPS2L25U L5970 4 2 C2 220pF C3 22nF R3 4.7k 6 5 3 7 GND SYNC VREF VOUT=12V/0.3A 1 U1 COMP C1 10uF 25V Ceramic D2 STPS2L25U 24k FB C4 100uF 16V M1 STN4NE03L INH 2.7k 3.3V Vin=5V Vout=12V Iout=0.3A Efficiency=76% Figure 19. Synchronization example VIN OUT VCC 8 COMP L5970D 4 2 SYNC VREF 8/10 6 7 GND 5 3 OUT VCC 8 1 FB INH COMP 1 L5970D 4 2 SYNC VREF 6 7 GND 5 3 FB INH L5970D mm DIM. MIN. TYP. A a1 inch MAX. MIN. TYP. 1.75 0.1 0.25 a2 MAX. 0.069 0.004 0.010 1.65 0.065 a3 0.65 0.85 0.026 0.033 b 0.35 0.48 0.014 0.019 b1 0.19 0.25 0.007 0.010 C 0.25 0.5 0.010 0.020 c1 45° (typ.) D (1) 4.8 5.0 0.189 0.197 E 5.8 6.2 0.228 0.244 e 1.27 0.050 e3 3.81 0.150 F (1) 3.8 4.0 0.15 0.157 L 0.4 1.27 0.016 0.050 M S OUTLINE AND MECHANICAL DATA 0.6 0.024 SO8 8 ° (max.) (1) D and F do not include mold flash or protrusions. Mold flash or potrusions shall not exceed 0.15mm (.006inch). 9/10 L5970D 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. 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