L4962 ® 1.5A POWER SWITCHING REGULATOR 1.5A OUTPUT CURRENT 5.1V TO 40V OUTPUT VOLTAGE RANGE PRECISE (± 2%) ON-CHIP REFERENCE HIGH SWITCHING FREQUENCY VERY HIGH EFFICIENCY (UP TO 90%) VERY FEW EXTERNAL COMPONENTS SOFT START INTERNAL LIMITING CURRENT THERMAL SHUTDOWN DESCRIPTION The L4962 is a monolithic power switching regulator delivering 1.5A at a voltage variable from 5V to 40V in step down configuration. Features of the device include current limiting, soft start, thermal protection and 0 to 100% duty cycle for continuous operating mode. POWERDIP (12 + 2 + 2) HEPTAWATT ORDERING NUMBERS : L4962/A (12 + 2 + 2 Powerdip) L4962E/A (Heptawatt Vertical) L4962EH/A (Horizontal Heptawatt) The L4962 is mounted in a 16-lead Powerdip plastic package and Heptawatt package and requires very few external components. Efficient operation at switching frequencies up to 150KHz allows a reduction in the size and cost of external filter components. BLOCK DIAGRAM Pin X = Powerdip Pin (X) = Heptawatt June 2000 1/16 L4962 ABSOLUTE MAXIMUM RATINGS Symbol V7 V7 - V2 V2 V11, V15 Parameter Value Unit Input voltage 50 V Input to output voltage difference 50 V Negative output DC voltage -1 V Output peak voltage at t = 0.1µs; f = 100KHz -5 V Voltage at pin 11, 15 5.5 V V10 Voltage at pin 10 7 V I11 Pin 11 sink current 1 mA I14 Pin 14 source current 20 mA Ptot Power dissipation at Tpins ≤ 90°C (Powerdip) Tcase ≤ 90°C (Heptawatt) 4.3 15 W W -40 to 150 °C Tj, Tstg Junction and storage temperature PIN CONNECTION (Top view) THERMAL DATA Symbol Rth j-case Rth j-pins Rth j-amb Parameter Thermal resistance junction-case Thermal resistance junction-pins Thermal resistance junction-ambient max max max Heptawatt Powerdip 4°C/W 50°C/W 14°C/W 80°C/W* * Obtained with the GND pins soldered to printed circuit with minimized copper area. PIN FUNCTIONS HEPTAWATT POWERDIP NAME FUNCTION 1 7 SUPPLY VOLTAGE Unregulated voltage input. An internal regulator powers the internal logic. 2 10 FEEDBACK INPUT The feedback terminal of the regulation loop. The output is connected directly to this terminal for 5.1V operation; it is connected via a divider for higher voltages. 3 11 FREQUENCY COMPENSATION A series RC network connected between this terminal and ground determines the regulation loop gain characteristics. 2/16 L4962 PIN FUNCTIONS (cont’d) HEPTAWATT POWERDIP 4 4, 5, 12, 13 5 FUNCTION NAME GROUND Common ground terminal. 14 OSCILLATOR A parallel RC network connected to this terminal determines the switching frequency. This pin must be connected to pin 7 input when the internal oscillator is used. 6 15 SOFT START Soft start time constant. A capacitor is connected between this terminal and ground to define the soft start time constant. This capacitor also determines the average short circuit output current. 7 2 OUTPUT Regulator output. 1, 3, 6, 8, 9, 16 N.C. ELECTRICAL CHARACTERISTICS (Refer to the test circuit, Tj = 25 °C, Vi = 35V, unless otherwise specified) Symbol Parameter Test Conditions Min. Typ. Max. Unit Vref 40 V 9 46 V 15 50 mV 8 20 mV 5.1 5.2 V DYNAMIC CHARACTERISTICS Vo Output voltage range Vi = 46V Io = 1A Vi Input voltage range Vo = Vref to 36V Io = 1.5A ∆ Vo Line regulation Vi = 10V to 40V ∆ Vo Load regulation Vo = Vref Io = 0.5A to 1.5A Vref Internal reference voltage (pin 10) Vi = 9V to 46V Io = 1A ∆ Vref ∆T Average temperature coefficient of refer. voltage Tj = 0°C to 125°C Io = 1A 0.4 Vd Dropout voltage Io = 1.5A 1.5 Iom Maximum operating load current Vi = 9V to 46V Vo = Vref to 36V 1.5 I2L Current limiting threshold (pin 2) Vi = 9V to 46V Vo = Vref to 36V 2 ISH Input average current Vi = 46V; Efficiency η SVR Supply voltage ripple rejection Vo = Vref Io = 1A 5 mV/°C 2 V A 3.3 A 30 mA output short-circuit 15 f = 100KHz Vo = Vref 70 % Io = 1A Vo = 12V 80 % 56 dB ∆ Vi = 2Vrms fripple = 100Hz Vo = Vref 50 Io = 1A 3/16 L4962 ELECTRICAL CHARACTERISTICS (continued) Symbol Parameter Test Conditions Min. Typ. Max. Unit 85 100 115 KHz DYNAMIC CHARACTERISTICS (cont’d) f Switching frequency ∆f ∆ Vi Voltage stability of switching frequency Vi = 9V to 46V ∆f ∆ Tj Temperature stability of switching frequency Tj = 0°C to 125°C fmax Maximum operating switching frequency Vo = Vref Tsd Thermal shutdown junction temperature Io = 1A 120 0.5 % 1 % 150 KHz 150 °C DC CHARACTERISTICS I7Q Quiescent drain current 100% duty cycle pins 2 and 14 open 30 40 mA 15 20 mA 1 mA Vi = 46V 0% duty cycle -I2L Output leakage current 0% duty cycle SOFT START I15SO Source current 100 140 180 µA I15SI Sink current 50 70 120 µA ERROR AMPLIFIER V11H High level output voltage V10 = 4.7V I11 = 100µA V11L Low level output voltage V10 = 5.3V I11 = 100µA I11SI Sink output current V10 = 5.3V 100 150 µA Source output current V10 = 4.7V 100 150 µA I10 Input bias current V10 = 5.2V Gv DC open loop gain V11 = 1V to 3V -I11SO 3.5 V 0.5 2 46 55 10 V µA dB OSCILLATOR -I14 4/16 Oscillator source current 5 mA L4962 CIRCUIT OPERATION (refer to the block diagram) The L4962 is a monolithic stepdown switching regulator providing output voltages from 5.1V to 40V and delivering 1.5A. The regulation loop consists of a sawtooth oscillator, error amplifier, comparator and the output stage. An error signal is produced by comparing the output voltage with a precise 5.1V on-chip reference (zener zap trimmed to ± 2%). This error signal is then compared with the sawtooth signal to generate the fixed frequency pulse width modulated pulses which drive the output stage. The gain and frequency stability of the loop can be adjusted by an external RC network connected to pin 11. Closing the loop directly gives an output voltage of 5.1V. Higher voltages are obtained by inserting a voltage divider. Output overcurrents at switch on are prevented by the soft start function. The error amplifier output is initially clamped by the external capacitor Css and allowed to rise, linearly, as this capacitor is charged by a constant current source. Output overload protection is provided in the form of a current limiter. The load current is sensed by an internal metal resistor connected to a comparator. When the load current exceeds a preset threshold this comparator sets a flip flop which disables the output stage and discharges the soft start capacitor. A second comparator resets the flip flop when the voltage across the soft start capacitor has fallen to 0.4V. The output stage is thus re-enabled and the output voltage rises under control of the soft start network. If the overload condition is still present the limiter will trigger again when the threshold current is reached. The average short circuit current is limited to a safe value by the dead time introduced by the soft start network. The thermal overload circuit disables circuit operation when the junction temperature reaches about 150°C and has hysteresis to prevent unstable conditions. Figure 1. Soft start waveforms Figure 2. Current limiter waveforms 5/16 L4962 Figure 3. Test and application circuit (Powerdip) 1) D1: BYW98 or 3A Schottky diode, 45V of VRRM; 2) L1: CORE TYPE - MAGNETICS 58120 - A2 MPP N° TURNS 45, WIRE GAUGE: 0.8mm (20 AWG) 3) C6, C7: ROE, EKR 220µF 40V Figure 4. Quiescent drain current vs. supply voltage (0% duty cycle) 6/16 Figure 5. Quiescent drain current vs. supply voltage (100% duty cycle) Figure 6. Quiescent drain current vs. junction temperature (0% duty cycle) L4962 Figure 7. Quiescent drain current vs. junction temperature (100% duty cycle) Figure 8. Reference voltage (pin 10) vs. Vi rdip) vs. Vi Figure 9. Reference voltage (pin 10 ) vs. junction temperature Figure 10. Open loop frequency and phase re- sponse of error amplifier Figure 11. Switching frequency vs. input voltage Figure 12. Switching frequency vs. junction temperature Figure 13. Switching frequency vs. R2 (see test circuit) Figure 14. Line transient response Figure 15. Load transient response 7/16 L4962 Figure 16. Supply voltage ripple rejection vs. frequency Figure 17. Dropout voltage between pin 7 and pin 2 vs. current at pin 2 Figure 18. Dropout voltage between pin 7 and 2 vs. junction temperature Fig ure 19. Effi ciency vs. output current Fi gure 20. Effici ency vs. output current Fi gure 21 . Effi ciency vs. output current F igu re 22. Effi ciency vs. output voltage Fi gure 23. Effici ency vs. output voltage Figure 24. Maximum allowable power dissipation vs. ambient temperature (Powerdip) 8/16 L4962 APPLICATION INFORMATION Figure 25. Typical application circuit C1, C6, C7: EKR (ROE) D1: BYW98 OR VISK340 (SCHOTTKY) SUGGESTED INDUCTORS: (L1) = MAGNETICS 58120 - A2MPP - 45 TURNS - WIRE GAUGE 0.8mm (20AWG) COGEMA 946043 OR U15, GUP15, 60 TURNS 1mm, AIR GAP 0.8mm (20 AWG) - COGEMA 969051. Figure 26. P.C. board and component layout of the circuit of Fig. 25 (1 : 1 scale) Resistor values for standard output 7 voltages Vo R3 R4 12V 15V 18V 24V 4.7KΩ 4.7KΩ 4.7KΩ 4.7KΩ 6.2KΩ 9.1KΩ 12KΩ 18KΩ 9/16 L4962 APPLICATION INFORMATION (continued) Figure 27. - A minimal 5.1V fixed regulator; Very few component are required * COGEMA 946043 (TOROID CORE) 969051 (U15 CORE) ** EKR (ROE) Figure 28. Programmable power supply Vo = 5.1V to 15V Io = 1.5A max Load regulation (0.5A to 1.5A) = 10mV (Vo = 5.1V) Line regulation (220V ± 15% and to Io = 1A) = 15mV (Vo = 5.1V) 10/16 L4962 APPLICATION INFORMATION (continued) Figure 29. DC-DC converter 5.1V/4A, ± 12V/1A. A suggestion how to synchronize a negative output L1, L3 = COGEMA 946043 (969051) L2 = COGEMA 946044 (946045) Figure 30. In multiple supplies several L4962s can be synchronized as shown Figure 31. Preregulator for distributed supplies * L2 and C2 are necessary to reduce the switching frequency spikes when linear regulators are remote from L4962 11/16 L4962 MOUNTING INSTRUCTION The Rth-j-amb of the L4962 can be reduced by soldering the GND pins to a suitable copper area of the printed circuit board (Fig. 32). The diagram of figure 33 shows the Rth-j-amb as a function of the side "l" of two equal square copper areas having the thickness of 35µ (1.4 mils). During soldering the pins temperature must not exceed 260°C and the soldering time must not be longer than 12 seconds. The external heatsink or printed circuit copper are must be connected to electrical ground. Figure 32. Example of P.C. board copper area which is used as heatsink 12/16 Figure 33. Maximum dissipable power and junction to ambient thermal resistance vs. side "l" L4962 mm DIM. MIN. a1 0.51 B 0.85 b b1 TYP. inch MAX. MIN. TYP. MAX. 0.020 1.40 0.033 0.50 0.38 0.055 0.020 0.50 D 0.015 0.020 20.0 0.787 E 8.80 0.346 e 2.54 0.100 e3 17.78 0.700 F 7.10 0.280 I 5.10 0.201 L OUTLINE AND MECHANICAL DATA 3.30 0.130 Powerdip 16 Z 1.27 0.050 13/16 L4962 DIM. A C D D1 E E1 F F1 G G1 G2 H2 H3 L L1 L2 L3 L4 L5 L6 L7 L9 M M1 V4 Dia MIN. mm TYP. 2.4 1.2 0.35 0.7 0.6 2.34 4.88 7.42 10.05 16.7 21.24 22.27 2.6 15.1 6 2.55 4.83 2.54 5.08 7.62 16.9 14.92 21.54 22.52 2.8 15.5 6.35 0.2 2.8 5.08 3.65 MAX. 4.8 1.37 2.8 1.35 0.55 0.97 0.8 0.9 2.74 5.28 7.82 10.4 10.4 17.1 21.84 22.77 1.29 3 15.8 6.6 inch TYP. MIN. 0.094 0.047 0.014 0.028 0.024 0.095 0.193 0.295 0.396 0.657 0.386 0.877 0.102 0.594 0.236 3.05 0.100 5.33 0.190 40˚ (typ.) 3.85 0.144 0.100 0.200 0.300 0.668 0.587 0.848 0.891 0.110 0.610 0.250 0.008 0.110 0.200 OUTLINE AND MECHANICAL DATA MAX. 0.189 0.054 0.110 0.053 0.022 0.038 0.031 0.035 0.105 0.205 0.307 0.409 0.409 0.673 0.860 0.896 0.051 0.118 0.622 0.260 0.120 0.210 Heptawatt V 0.152 V L V E L1 M1 A M D C D1 H2 L2 L5 L3 F E E1 V4 L9 H3 G H1 G1 G2 Dia. F L4 L7 L6 14/16 H2 F1 HEPTAMEC L4962 mm DIM. MIN. TYP. inch MAX. A 4.8 C 1.37 MIN. TYP. MAX. 0.189 0.054 D 2.4 2.8 0.094 0.110 D1 1.2 1.35 0.047 0.053 E 0.35 0.55 0.014 0.022 F 0.6 0.8 0.024 0.031 F1 0.9 0.035 G 2.41 2.54 2.67 0.095 0.100 0.105 G1 4.91 5.08 5.21 0.193 0.200 0.205 G2 7.49 7.62 7.8 0.295 0.300 0.307 H2 H3 10.4 10.05 10.4 0.409 0.396 0.409 L 14.2 0.559 L1 4.4 0.173 L2 15.8 0.622 L3 5.1 0.201 L5 2.6 3 0.102 0.118 L6 15.1 15.8 0.594 0.622 L7 6 6.6 0.236 L9 Dia 4.44 3.65 0.260 Heptawatt H 0.175 3.85 OUTLINE AND MECHANICAL DATA 0.144 0.152 15/16 L4962 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. Specification mentioned in this publication are subject to change without notice. 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