L A step down switching regulator. Features. Description

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1 3.5 A step down switching regulator Features Up to 3.5 A step down converter Operating input voltage from 8 V to 55 V 3.3 V and 5. V (±%) fixed output, and adjustable outputs from: 0.5 V to 50 V (3.3 type) 5. V to 50 V (5. type) Frequency adjustable up to 300 khz Voltage feed forward Zero load current operation (min. ma) Internal current limiting (pulse by pulse and HICCUP mode) Precise 5. V (.5%) reference voltage externally available Input/output synchronization function Inhibit for zero current consumption (00 ma typ. at V CC = 24 V) Protection against feedback disconnection Thermal shutdown Output over voltage protection Soft-start function Figure. Internal schematic diagram DIP-8 (2+3+3) SO-20 (2+4+4) Description The is a step down monolithic power switching regulator delivering 3.5 A at fixed voltages of 3.3 V or 5. V and using a simple external divider output adjustable voltage up to 50V. Realized in BCD mixed technology, the device uses an internal power D-MOS transistor (with a typical R DS(on) of 0.5 Ω) to obtain very high efficiency and very fast switching times. Switching frequency up to 300 khz are achievable (the maximum power dissipation of the packages must be observed). A wide input voltage range between 8 V to 55 V and output voltages regulated from 3.3 V to 40 V cover the majority of the today applications. Features of this new generation of DC-DC converter includes pulse by pulse current limit, hiccup mode for output short circuit protection, voltage feed forward regulation, soft-start, input/output synchronization, protection against feedback loop disconnection, inhibit for zero current consumption and thermal shutdown. Packages available are in plastic dual in line, DIP- 8 (2+3+3) for standard assembly, and SO20 (2+4+4) for SMD assembly. V CC (8V to 55V) C BOOT C IN R OSC C2 4,5,6,0 3,4, L V O (3.3V or 5.V) R COMP C OSC C SS D C OUT C COMP D97IN554A February 2009 Rev 8 /

2 Contents Contents Block diagram Pin settings Pin connection Pin description Electrical data Maximum ratings Thermal data Electrical characteristics Evaluation board Application circuit Typical characteristics Application ideas Package mechanical data Order code Revision history /28

3 Block diagram Block diagram Figure 2. Block diagram INH V5. V CC V CC 0() 6(8) 7(8) 8(9) CBOOT CHARGE ZERO CURRENT INHIBIT VREF GOOD 5.V 3.3V INTERNAL REFERENCE INTERNAL SUPPLY 5.V SS 7(9) SOFT START HICCUP CURRENT LIMITING COMP VFB (2) 5.V 3.3V 2(3) + E/A - THERMAL SHUTDOWN - + PWM CURRENT LIMITING R S Q Q 9(0) BOOT SYNC 8(20) Pin x = Powerdip Pin (x) = S020 OSCILLATOR OSC DRIVER 4,5,6,3,4,5 () (4,5,6,7,4,5,6,7) 2(2) 3(3) OUT OUT D94IN6B 2 Pin settings 2. Pin connection Figure 3. Pin connection (top view) OSC OUT OUT V CC V CC BOOT 8 SYNC SS V5. VFB COMP INH D94IN62A OSC OUT OUT V CC V CC BOOT D94IN63A SYNC SS V5. VFB COMP INH DIP -8 (2+3+3) SO20 (2+4+4) 3/28

4 Pin settings 2.2 Pin description Table. Pin description N Pin DIP-8 SO-20 Name Description 2 COMP E/A output to be used for frequency compensation 0 INH A logic signal (active high) disables the device (sleep mode operation). If not used it must be connected to ; if floating the device is disabled. 9 0 BOOT A capacitor connected between this pin and the output allows to drive the internal D-MOS SYNC Input/Output synchronization. 7,8 8,9 V CC Unregulated DC input voltage 2,3 2,3 OUT Stepdown regulator output. 2 3 VFB Stepdown feedback input. Connecting the output directly to this pin results in an output voltage of 3.3 V for the V3.3 and 5. V for V5.. An external resistive divider is required for higher output voltages. For output voltage resistive divider is required for higher output voltages. For output voltage less than 3.3 V, see Note: and Figure V5. Reference voltage externally available. 4,5,6 3,4,5 4,5,6,7 4,5,6,7 OSC Signal ground An external resistor connected between the unregulated input voltage and Pin and a capacitor connected from Pin to ground fixes the switching frequency. (Line feed forward is automatically obtained) Note: The maximum power dissipation of the package must be observed. 4/28

5 Electrical data 3 Electrical data 3. Maximum ratings Table 2. Symbol DIP-8 S0-20 Absolute maximum ratings Parameter Value Unit V 7,V 8 V 9,V 8 Input voltage 58 V V 2,V 3 V 2,V 3 Output DC voltage Output peak voltage at t = 0. μs f = 200 khz I 2,I 3 I 2,I 3 Maximum output current int. limit. V 9 -V 8 V 0 -V 8 4 V V 9 V 0 Bootstrap voltage 70 V V V 2 Analogs input voltage (V CC = 24 V) 2 V V 7 V 9 Analogs input voltage (V CC = 24 V) 3 V V 2 V 3 (V CC = 20 V) V 8 V 20 (V CC = 20 V) V 0 V Inhibit P tot DIP Power dissipation a Tpins 90 C (T A = 70 C no copper area) (T A = 70 C 4 cm copper area on PCB) V CC SO-20 Power dissipation a T pins = 90 C 4 W T J,T STG Junction and storage temperature -40 to 50 C V V V V V V V V W W W 3.2 Thermal data Table 3. Thermal data Symbol Parameter DIP-8 SO-20 Unit R thjp Maximum thermal resistance junction-pin 2 5 C/W R thja Maximum thermal resistance junction-ambient 60 () 80 () C/W. Package mounted on board 5/28

6 Electrical characteristics 4 Electrical characteristics Table 4. Electrical characteristics (Refer to the test circuit,v CC = 24 V; T J = 25 C, C OSC = 2.7 nf; R OSC = 20 kω; unless otherwise specified) Symbol Parameter Test condition Min Typ Max Unit Dynamic characteristics η Δf sw Input voltage range () V O = V REF to 40 V; I O = 3.5A Output voltage V5. Output voltage V3.3 R DS(on ) Maximum limiting current (2) 8 55 V I O = A V I O = 0.5 A to 3.5 A V CC = 8 V to 55 V (2) V V I O = A V I O = 0.5 A to 3.5 A V CC = 8 V to 40 V V CC = 0.5 V I O = 3.5 A V CC = 8 V to 55 V (2) (2) (2) V V Ω 0.35 Ω A A V O = 5. V; I O = 3.5 A 90 % Efficiency V O = 3.3 V; I O = 3.5 A 85 % Switching frequency (2) khz Supply voltage ripple rejection Switching frequency stability vs., supply voltage V i = V CC +2 V RMS V O = V ref ; I O = A; f ripple = 00 Hz 60 db V CC = 8 V to 55 V 2 5 % Reference section Reference voltage I ref = 0 to 20 ma; V CC = 8 to 55 V V (2) V Line regulation Load regulation I ref = 0 ma; V CC = 8 to 55 V V ref = 0 to 5 ma; V CC = 0 to 20 ma 5 0 mv Short circuit current ma mv mv 6/28

7 Electrical characteristics Table 4. Soft-start Electrical characteristics (continued) (Refer to the test circuit,v CC = 24 V; T J = 25 C, C OSC = 2.7 nf; R OSC = 20 kω; unless otherwise specified) Symbol Parameter Test condition Min Typ Max Unit Soft-start charge current μa Inhibit Soft-start discharge current High level voltage (2) Low level voltage I source high level I source low level V INH = 3 V V INH = 0.8 V (2) (2) (2) μa 3.0 V 0.8 V μa μa DC characteristics Total operating quiescent current Duty cycle = 50 % 4 6 ma Quiescent current Duty cycle = ma Total stand-by quiescent current V CC = 24 V; V INH = 5 V μa V CC = 55 V; V INH = 5 V μa Error amplifier Oscillator section High level output voltage.0 V Low level output voltage 0.65 V Source bias current 2 3 μa Source output current μa Sink output current μa Supply voltage ripple rejection V COMP = VFB C REF = 4.7 μf -5 ma load current db DC open loop gain R L = db Transconductance I comp = -0. to 0. ma; V comp = 6 V 2.5 ms Ramp valley V Ramp peak V CC = 8 V V CC = 55 V Maximum duty cycle % V V 7/28

8 Electrical characteristics Table 4. Electrical characteristics (continued) (Refer to the test circuit,v CC = 24 V; T J = 25 C, C OSC = 2.7 nf; R OSC = 20 kω; unless otherwise specified) Symbol Parameter Test condition Min Typ Max Unit Sync function Maximum frequency Duty cycle = 0%; R OSC =3 kω; C OSC = 820 pf; 300 khz High input voltage V CC = 8 V to 55 V 3.5 V Low input voltage V CC = 8 V to 55 V 0.9 V Slave sink current ma Master output amplitude I source = 3 ma V Output pulse width No load, V sync = 4.5 V μs. Pulse testing with a low duty cycle 2. Specifications referred to T J from -40 C to 25 C. 8/28

9 Evaluation board 5 Evaluation board Figure 4. Evaluation board circuit SYNCH R6 NM JP Vin 3 2 C8 220n C0 470u 63v R 5k C9 220n U OSC 7 SS 6 V5. DIP 8 VCC 7 VCC 8 COMP INH 0 SYNC 8 VFB 2 9 BOOT OUT 2 OUT R7 NM Q2 C6 NM NM signal 2 L 68uH D STPS5L60 C7 NM C 50u 50v C2 50u 50v R3 2.7k C3 NM R4 4.99k Vout C4 NM C 2.7n C2 470n C3 NM C3A u R5 NM C4 22n R2 5k C5 50p signal plane Table 5. Component list (fsw = 50 khz, V OUT = 5 V) Reference Description Part number Manufacturer R Resistor 5 kω % R2 Resistor 5 kω % R3 Resistor 2.7 kω % R4 Resistor 4.99 kω % R5 Not mounted R6 Not mounted R7 Not mounted C Capacitor 2.7 nf 5% C2 Capacitor 470 nf 5% C3 Capacitor μf 5% C4 Capacitor 22 nf 5% C5 Capacitor 50 pf 5% C6 Not mounted C7 Not mounted C8 Capacitor 220 nf 5% C9 Capacitor 220 nf 5% C0 Capacitor 470 μf 63V EKY-630ELL47ML20S Nippon Chemi-con 9/28

10 Evaluation board Table 5. Component list (fsw = 50 khz, V OUT = 5 V) (continued) Reference Description Part number Manufacturer C Capacitor 50 μf 35 V EKY-350ELL5MHB5D Nippon Chemi-con C Capacitor 50 μf 35 V EKY-350ELL5MHB5D Nippon Chemi-con C3 Capacitor 00 nf 5 % C4 Not mounted L 68 μh I RMS = 3.4 A I SAT = 6.7 A DO5040H-683MLD Coilcraft U V3.3 STMicroelectronics Table 6. Resistor divider for V OUT = 2 V Reference Description Part number Manufacturer R3 Resistor 2.7 kω % R4 Resistor kω % Table 7. Resistor divider for V OUT = 3.3 V Reference Description Part number Manufacturer R3 Resistor 2.7 kω % R4 Not mounted 0/28

11 Evaluation board Figure 5. Evaluation board (components side) Figure 6. Evaluation board (solder side) /28

12 Application circuit 6 Application circuit Figure 7. Application circuit (see Figure 4 part list) V CC INH SYNC C R2 C2 C7 7, V5. 4,5,6 3,4,5 2 2,3 C8 L Vo C3 C4 C5 R D 3 x C0 C2 C6 D97IN665A Figure 8. Application circuit (see Figure 4 part list) V CC INH SYNC C R2 C2 C7 7, V3.3 4,5,6 3,4,5 2 2,3 C8 L Vo C3 C4 C5 R D 3 x C0 C2 C6 D97IN664A 2/28

13 Typical characteristics 7 Typical characteristics Figure 9. Quiescent drain current vs. input voltage (0% duty cycle) Figure 0. Quiescent drain current vs. junction temperature Ibias (ma) Tamb=25 C 0% DC 200KHz-R2=22K C7=.2nF D97IN633A Ibias (ma) KHz-R2=22K C7=.2nF D97IN KHz-R2=20K C7=2.7nF 3.5 0% DC V CC = 35V 00KHz-R2=20K C7=2.7nF Hz 3.0 0Hz V CC (V) Tj( C) Figure. Stand by drain current vs. input voltage Figure 2. Reference voltage vs. junction temperature (pin 6) Ibias (μa) D97IN635A V REF (V) D97IN V inh = 5V 5.5 Pin C 5. Vcc=35V 25 C V CC (V) Tj( C) 3/28

14 Typical characteristics Figure 3. Reference voltage vs. input voltage (pin 6) Figure 4. Reference voltage vs. reference input current V REF (V) D97IN636A V REF (V) D97IN Tj=25 C Pin Vcc=40V Vcc=0V Tj=25 C V CC (V) I REF (ma) Figure 5. Inhibit current vs. inhibit voltage (pin 0) Figure 6. Line regulation (see Figure 7) Iinh (μa) D97IN65 V O (V) D97IN639A 00 Vcc=35V Pin 0 Tj=0 C 5.2 Tj=25 C Tj=25 C Tj=25 C Tj=25 C I O = A Vinh(V) V CC (V) 4/28

15 Typical characteristics Figure 7. Load regulation (see Figure 7) Figure 8. Line regulation (see Figure 8) V O (V) D97IN640 V O (V) D97IN660A V CC = 35V Tj=25 C 5. Tj=25 C Tj=25 C 3.33 Tj=25 C I O = A I O (A) V CC (V) Figure 9. Load regulation (see Figure 4) Figure 20. Switching frequency vs. R2 and C7 (Figure 4) V O (V) D97IN66 fsw (KHz) D97IN V CC = 35V 500 Tamb=25 C Tj=25 C Tj=25 C nF.2nF 2.2nF 3.3nF 4.7nF 5.6nF I O (A) R2(KΩ) 5/28

16 Typical characteristics Figure 2. Switching frequency vs. input voltage Figure 22. Switching frequency vs. junction temperature (see Figure 4) fsw (KHz) D97IN63 fsw (KHz) D97IN Tamb=25 C V CC (V) Tj( C) Figure 23. Dropout voltage between pin 7,8 and 2,3 Figure 24. Efficiency vs. output voltage (see Figure 6) ΔV (V) D97IN643 η (%) D97IN Tj=25 C Tj=25 C KHz 0.4 Tj=0 C KHz I O = 3A V CC = 50V I O (A) V O (V) 6/28

17 Typical characteristics Figure 25. Dropout voltage between pin 7,8 and 2,3 Figure 26. Efficiency vs. output voltage (see Figure 4) ΔV (V) D97IN643 η (%) D97IN Tj=25 C Tj=25 C KHz 0.4 Tj=0 C KHz I O = 3A V CC = 50V I O (A) V O (V) Figure 27. Efficiency vs. output voltage (Diode STPS745D) Figure 28. Efficiency vs. output current (see Figure 7) η (%) D97IN642 η (%) D97IN KHz 95 Vcc=2V V O = 5.V f sw = 00KHz KHz Vcc=24V I O = 3A V CC = 35V 85 Vcc=48V V O (V) I O (A) 7/28

18 Typical characteristics Figure 29. Efficiency vs. output current (see Figure 7) Figure 30. Efficiency vs. output current (see Figure 8) η (%) D97IN646 η (%) D97IN Vcc=24V Vcc=2V 90 Vcc=2V V O = 3.3V f sw = 00KHz Vcc=24V Vcc=48V 80 V O = 5.V f sw = 200KHz 80 Vcc=48V I O (A) I O (A) Figure 3. Efficiency vs. output current (see Figure 8) Figure 32. Power dissipation vs. input voltage (device only) (see Figure 7) η (%) D97IN662 Pdiss (W) D97IN647A 90 Vcc=2V V O = 3.3V f sw = 200KHz.5 I O =3.5A V O = 5.V f sw = 00KHz 85 Vcc=24V.0 I O =3A 80 Vcc=48V I O =2.5A I O =2A I O (A) Vcc(V) 8/28

19 Typical characteristics Figure 33. Power dissipation vs. output voltage (device only) Figure 34. Pulse by pulse limiting current vs. junction temperature Pdiss (W) D97IN648 Ilim (A) D97IN V CC = 35V f sw = 00KHz I O =3.5A I O =3A I O =2.5A 4.8 Vcc=35.0 I O =2A I O =A V O (V) Tj( C) Figure 35. Load transient Figure 36. Line transient I O (A) D97IN649 V CC (V) D97IN T 200μs/DIV V O (mv) 00 0 I O = A f sw = 00KHz V O (mv) 00 T V CC = 35V f sw = 00KHz -00 ms/div -00 9/28

20 Typical characteristics Figure 37. Source current rise and fall time, pin 2, 3 (see Figure 4) Figure 38. Soft-start capacitor selection vs. inductor and V CC max (ref. AN938) Lomax (μh) 300 f sw = 00KHz Css=μF D97IN653 Css=820nF Css=680nF 50 Css=470nF 00 Css=220nF 50 Css=00nF Vi(V) Figure 39. Soft-start capacitor selection vs. inductor and V CC max (ref. AN938) Figure 40. Open loop frequency and phase of error amplifier Lomax (μh) f sw = 200KHz Css=68nF D97IN654 Css=56nF Css=47nF Css=33nF GAIN (db) GAIN D97IN663 Phase Css=22nF -50 Phase Vi(V) f(hz) 20/28

21 Application ideas 8 Application ideas Figure A at V O < 3.3 V (see part list Figure 4) V P R 5 R 3 3.6K 4.7K V CC INH SYNC.5 2K 2K 2 4.7K 3.6K V O = R 3 R 5 C R2 C2 C7 7, V3.3 2,3 6 4,5,6 3,4,5 2 C K 3.6K 3 5.K K L Vo C3 C5 R C6 R5 C4 D 3 x C0 R3 D97IN666A Figure V to 3.3 V high performance buck converter (fsw = 200 khz) INH SYNC V CC 2V±5% C 560uF-25V HFQ Panasonic C2 220nF R2 22k C7.2nF C3 33nF C4 uf C5 220pF 7, V3.3 R 9k C6 22nF 4,5,6 3,4,5 2,3 2 D C8 220nF L C9 470uF-25V HFQ Panasonic Vo=3.33V Io=3.5A η (%) L D KoolMm Turns- 0.9mm STPS025 D97IN668A Io(A) 2/28

22 Application ideas Figure 43. Synchronization example V CC2 V CC V CC 7,8 4,5,6 3,4, ,8 4,5,6 3,4,5 7,8 4,5,6 3,4, ,8 4,5,6 3,4,5 D97IN669 Figure 44. Multi output not isolated (pin out referred to DIP2+3+3) V CC INH SYNC C R2 C2 C7 7, ,5,6 3,4,5 2 2,3 C8 L n2 n D2 Vo2 Vo C3 C4 C5 R C6 D C9 C0 C V O2 = V O n + n 2 n D97IN667A P O2 < 20% P O 22/28

23 Package mechanical data 9 Package mechanical data In order to meet environmental requirements, ST offers these devices in different grades of ECOPACK packages, depending on their level of environmental compliance. ECOPACK specifications, grade definitions and product status are available at: ECOPACK is an ST trademark. 23/28

24 Package mechanical data Table 8. Dim. DIP-8 mechanical data mm. inch Min Typ Max Min Typ Max a B b b D E e e F I L Z Figure 45. Package dimensions 24/28

25 Package mechanical data Table 9. Dim. SO-20 mechanical data mm. inch Min Typ Max Min Typ Max A A B C D () E e H h L k 0 (min.), 8 (max.) ddd Figure 46. Package dimensions 25/28

26 Order code 0 Order code Table 0. Order code Part number Package Packaging D3.3, E-D3.3 SO-20 Tube D3.3-03TR, E-D3.3-TR SO-20 Tape and reel D5. SO-20 Tube D5.-03TR SO-20 Tape and reel V3.3, E-V3.3 DIP-8 Tube V5., E-V5. DIP-8 Tube 26/28

27 Revision history Revision history Table. Document revision history Date Revision Changes 2-Sep First Issue 07-May Updated the Layout look & feel. Changed name of the D on the fig Dec Added the ECOPACK part numbers in the Table. Order Codes. 06-Dec The document has been reformatted, and order codes updated 07-May New data on Table 4 26-Feb Updated Section 5: Evaluation board on page 9 27/28

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L A step down switching regulator. Features. Description L4976

L A step down switching regulator. Features. Description L4976 1A step down switching regulator Features Up to 1A step down converter Operating input voltage from 8v to 55v Precise 5.1V reference voltage Output voltage adjustable from 0.5V to 50V Switching frequency