L5970D Up to 1A step down switching regulator Features ■ 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 Description ■ Voltage feedforward ■ Zero load current operation ■ Internal current limiting The L5970D is a step down monolithic power switching regulator capable to deliver up to 1A at output voltages from 1.2V to 35V. ■ Inhibit for zero current consumption ■ Synchronization ■ Protection against feedback disconnection ■ Thermal shutdown SO8 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. Applications Having a minimum input voltage of 4.4V only, it is particularly suitable for 5V bus, available in all computer related 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: changers, car battery, DC-DC converters Figure 1. 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. L1 33µH 5 7 FB GND R3 4.7K VOUT=3.3V R1 5.6K C2 100µF 10V R2 3.3K D98IN954C October 2007 Rev 16 1/16 www.st.com 16 Contents L5970D Contents 1 2 Pin settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1 Pin connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.2 Pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Electrical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.1 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.2 Thermal data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 4 Typical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 5 Application circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 6 Application ideas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 7 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 8 Order code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 9 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 2/16 L5970D Pin settings 1 Pin settings 1.1 Pin connection Figure 2. Pin connection (top view) OUT 1 8 VCC SYNC 2 7 GND INH 3 6 VREF COMP 4 5 FB D98IN955 1.2 Pin description Table 1. Pin description N° Type Description 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. 3/16 Electrical data L5970D 2 Electrical data 2.1 Maximum ratings Table 2. Absolute maximum ratings Symbol Value Unit 40 V V V 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 TJ TSTG 2.2 Parameter 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 SO8 Unit 120 (1) °C/W Power dissipation at TA ≤ 60°C Thermal data Table 3. Thermal data Symbol RthJA Parameter Maximum thermal resistance junction-ambient 1. Package mounted on board 4/16 L5970D 3 Electrical characteristics Electrical characteristics Table 4. Electrical characteristics ( TJ = 25°C, VCC = 12V, unless otherwise specified) Symbol VCC RDS(on) Parameter Operating input voltage range Test condition Vo = 1.235V; Io = 2A Mosfet on Resistance Il Maximum limiting current fs Switching frequency Min (1) Max Unit 36 V 0.250 0.5 Ω 1.5 1.87 2.25 A 212 250 280 KHz 225 250 275 KHz 100 % 4.4 (1) VCC = 4.4V to 36V (1) Duty cycle Typ 0 Dynamic characteristics (see test circuit ). V5 Voltage feedback h Efficiency 4.4V < VCC < 36V, 20mA < IO < 2A (1) 1.220 1.235 1.25 V 1.198 1.235 1.272 V VO = 5V, VCC = 12V 90 % DC characteristics Iqop Total operating quiescent current Iq Quiescent current Iqst-by Total stand-by quiescent current (1) 3 Duty cycle = 0; VFB = 1.5V 5 mA 2.5 mA Vinh > 2.2V (1) 50 100 µA VCC = 36V; Vinh > 2.2V (1) 80 150 µA 0.8 V Inhibit INH threshold voltage Device ON Device OFF 2.2 V 3.5 V Error amplfier VOH High level output voltage VFB = 1V VOL Low level output voltage VFB = 1.5V Source output current VCOMP = 1.9V; VFB = 1V Io source 0.4 200 300 V µA 5/16 Electrical characteristics L5970D Table 4. Electrical characteristics (continued) ( TJ = 25°C, VCC = 12V, unless otherwise specified) Symbol Parameter Io sink Sink output current Ib Source bias current gm Test condition VCOMP = 1.9V; VFB = 1.5V Min Typ 1 1.5 2.5 DC open loop gain RL = ∞ Transconductance Icomp = -0.1mA to 0.1mA VCOMP = 1.9V High input voltage VCC = 4.4V to 36V Low input voltage VCC = 4.4V to 36V Slave sink current Vsync = 0.74V (2) Vsync = 2.33V Master output amplitude Isource = 3mA Output pulse width no load, Vsync = 1.65V 50 Max Unit mA 4 µA 65 dB 2.3 mS Sync function 2.5 0.11 0.21 VREF V 0.74 V 0.25 0.45 mA mA 2.75 3 V 0.20 0.35 µs 3.234 3.3 3.366 V 3.2 3.3 3.399 V Reference section Reference voltage IREF = 0 to 5mA VCC = 4.4V to 36V (1) Line regulation IREF = 0mA VCC = 4.4V to 36V 5 10 mV Load regulation IREF = 0 to 5mA 8 15 mV 18 30 mA Short circuit current 10 1. Specification Referred to TJ from -40 to 125°C. Specification over the -40 to +125 TJ Temperature range are assured by design, characterization and statistical correlation. 2. Guaranteed by design. 6/16 L5970D 4 Typical characteristics Typical characteristics Figure 3. Junction temperature vs output current Figure 4. Vo (V) 3.312 Tj(°C) 130 120 110 100 90 80 70 60 50 40 30 20 Vo=3.3V Vcc=5V Tamb=25°C Vo=2.5V Vo=1.8V Load regulator Vcc = 12V Vo = 3.3V 3.308 3.304 Tj = 25°C 3.3 3.296 3.292 3.288 3.284 Tj = 125°C 3.28 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 3.276 0 0.5 Figure 5. 1 1.5 Io (A) Io(A) Junction temperature vs output current Figure 6. Line regulator Vo (V) Tj(°C) 3.312 130 120 110 100 90 80 70 60 50 40 30 20 Vo=3.3V Vo=5V Vcc = 12V Vo = 3.3V 3.308 3.304 Vo=2.5V Vcc=12V Tamb=25°C Tj = 25°C 3.3 3.296 3.292 Tj = 125°C 3.288 3.284 3.28 3.276 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0 Io(A) Figure 7. Junction temperature vs output current Figure 8. 20 Vcc (V) 30 40 Output voltage vs junction temperature Vo (V) 1.25 Tj(°C) 140 Vo=18V Vo=12V 1.24 120 100 10 Vo=5V Vcc=24V Tamb=25°C 1.23 80 1.22 60 Vcc = 12V 40 1.21 Vcc=12V 20 0 0.2 1.2 0.4 0.6 0.8 Io(A) 1 1.2 1.4 -50 0 50 Tj (°C) 100 150 7/16 Typical characteristics L5970D Figure 9. Quiescent current vs junction temperature Figure 10. Switching frequency vs junction temperature Iq (mA) 2 Fsw (KHz) 260 1.8 250 1.6 240 Vcc = 12V DC = 0% 1.4 Vcc = 12V Vo = 3.3V 230 1.2 220 -50 0 50 Tj (°C) 100 150 -50 0 50 Tj (C) 100 150 Figure 11. Shutdown current vs junction Figure 12. Efficiency vs output current temperature Ishd (µA) 60 Efficiency (%) 70 Vcc = 12V 50 40 30 -50 50 Tj (°C) 0 100 150 Efficiency (%) Figure 13. Efficiency vs output current 8/16 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 94 92 90 88 86 84 82 80 78 76 74 72 70 0.1 Vo=3.3V 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 L5970D 5 Application circuit Application circuit Figure 14. Demo board application circuit VREF 3.3V VIN = 4.4V to 25V VCC SYNC. C1 10µF 25V CERAMIC COMP C4 22nF C3 220pF 6 1 8 D1 STPS2L25U L5970D 2 3 4 INH. 7 L1 33µH OUT 5 FB GND VOUT=3.3V R1 5.6K C2 100µF 10V R2 3.3K R3 4.7K D03IN1437 Table 5. Component list Reference Part number Description Manufacturer C1 GRM32DR61E106KA12L 10µF, 25V MURATA 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 9/16 Application circuit Figure 15. PCB layout (component side) Figure 16. PCB layout (bottom side) Figure 17. PCB layout (front side) 10/16 L5970D L5970D 6 Application ideas Application ideas Figure 18. Dual output voltage with auxiliary winding N1/N2=2 VIN=12V VCC COMP C1 10uF 25V Ceramic 1 C3 22nF R3 4.7k FB 4 6 5 3 7 SYNC VREF VOUT=3.3V 0.5A D1 STPS25L25U U1 L5970D 2 C2 220pF VOUT1=5V 30mA Lp=22uH OUT 8 D2 1N4148 GND C4 100uF 10V C5 47uF 10V INH 3.3V Figure 19. Buck-boost regulator VIN=12V VCC 8 1 U1 C2 10uF C3 35V 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 FB INH VOUT=-12V/0.3A 2.7k C5 100uF 16V 24k 3.3V Iout=0.5A Efficiency=81% Figure 20. Positive Buck-Boost regulator L1 33uH VIN=5V VCC 8 D1 STPS2L25U L5970 4 2 C2 220pF C3 22nF R3 4.7k 6 7 24k FB 5 3 GND SYNC VREF VOUT=12V/0.3A 1 U1 COMP C1 10uF 25V Ceramic D2 STPS2L25U OUT C4 100uF 16V M1 STN4NE03L INH 2.7k 3.3V Vin=5V Vout=12V Iout=0.3A Efficiency=76% Figure 21. Synchronization example VIN OUT VCC 8 COMP L5970D 4 2 SYNC VREF 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 11/16 Package mechanical data 7 L5970D Package mechanical data In order to meet environmental requirements, ST offers these devices in ECOPACK® packages. These packages have a Lead-free second level interconnect . The category of second level interconnect is marked on the package and on the inner box label, in compliance with JEDEC Standard JESD97. The maximum ratings related to soldering conditions are also marked on the inner box label. ECOPACK is an ST trademark. ECOPACK specifications are available at: www.st.com 12/16 L5970D Package mechanical data Table 6. SO-8 mechanical data mm. inch Dim. Min Typ Max Min Typ Max A 1.35 1.75 0.053 0.069 A1 0.10 0.25 0.004 0.010 A2 1.10 1.65 0.043 0.065 B 0.33 0.51 0.013 0.020 C 0.19 0.25 0.007 0.010 (1) 4.80 5.00 0.189 0.197 E 3.80 4.00 0.15 0.157 D e 1.27 0.050 H 5.80 6.20 0.228 0.244 h 0.25 0.50 0.010 0.020 L 0.40 1.27 0.016 0.050 k ddd 0° (min.), 8° (max.) 0.10 0.004 1. Dimensions D does not include mold flash, protru-sions or gate burrs. Mold flash, potrusions or gate burrs shall not exceed 0.15mm (.006inch) in total (both side). Figure 22. Package dimensions 13/16 Order codes 8 L5970D Order codes Table 7. Order codes 14/16 Part number Package Packaging L5970D SO8 Tube L5970D013TR SO8 Tape and reel L5970D 9 Revision history Revision history Table 8. Revision history Date Revision Changes 26-Jan-2007 14 Updated Table 5 on page 9 16-Mar-2007 15 Mechanical data typo 16-Oct-2007 16 Updated Section 5: Application circuit on page 9 15/16 L5970D Please Read Carefully: Information in this document is provided solely in connection with ST products. STMicroelectronics NV and its subsidiaries (“ST”) reserve the right to make changes, corrections, modifications or improvements, to this document, and the products and services described herein at any time, without notice. All ST products are sold pursuant to ST’s terms and conditions of sale. Purchasers are solely responsible for the choice, selection and use of the ST products and services described herein, and ST assumes no liability whatsoever relating to the choice, selection or use of the ST products and services described herein. No license, express or implied, by estoppel or otherwise, to any intellectual property rights is granted under this document. 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