L4962E

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 POWERDIP (12 + 2 + 2) HEPTAWATT ORDERING NUMBERS : L4962/A (12 + 2 + 2 Powerdip) L4962E/A (Heptawatt) L4962EH/A (Horizontal Heptawatt) 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. The L4962is mountedin 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 March 1996 1/15 L4962 ABSOLUTE MAXIMUM RATINGS Symbol V7 V7 - V2 V2 Input voltage Input to output voltage difference Negative output DC voltage Output peak voltage at t = 0.1µs; f = 100KHz V11, V15 V10 I11 I14 Ptot Tj, Tstg Voltage at pin 11, 15 Voltage at pin 10 Pin 11 sink current Pin 14 source current Power dissipation at Tpins ≤ 90°C (Powerdip) Tcase ≤ 90°C (Heptawatt) Junction and storage temperature Parameter Value 50 50 -1 -5 5.5 7 1 20 4.3 15 -40 to 150 Unit V V V V V V mA mA W W °C 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 4°C/W 50°C/W Powerdip 14°C/W 80°C/W* * Obtained with the GND pins soldered to printed circuit with minimized copper area. PIN FUNCTIONS HEPTAWATT 1 POWERDIP 7 NAME SUPPLY VOLTAGE FUNCTION Unregulated voltage input. An internal regulator powers the internal logic. 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. A series RC network connected between this terminal and ground determines the regulation loop gain characteristics. 2 10 FEEDBACK INPUT 3 11 FREQUENCY COMPENSATION 2/15 L4962 PIN FUNCTIONS (cont’d) HEPTAWATT 4 5 POWERDIP 4, 5, 12, 13 14 NAME GROUND OSCILLATOR FUNCTION Common ground terminal. 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. 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. Regulator output. N.C. 6 15 SOFT START 7 2 1, 3, 6, 8, 9, 16 OUTPUT ELECTRICAL CHARACTERISTICS (Refer to the test circuit, Tj = 25 °C, Vi = 35V, unless otherwise specified) Symbol Parameter Test Condition s Min. Typ. Max. Unit DYNAMIC CHARACTERISTICS Vo Vi ∆ Vo ∆ Vo Vref ∆ Vref ∆T Vd Iom Output voltage range Input voltage range Line regulation Load regulation Internal reference voltage (pin 10) Average temperature coefficient of refer. voltage Dropout voltage Maximum operating load current Current limiting threshold (pin 2) Input average current Efficiency Vi = 46V Vo = Vref to 36V Vi = 10V to 40V Vo = Vref Vi = 9V to 46V Tj = 0°C to 125°C Io = 1A Io = 1.5A Vi = 9V to 46V Vo = Vref to 36V Vi = 9V to 46V Vo = Vref to 36V Vi = 46V; f = 100KHz Io = 1A SVR Supply voltage ripple rejection ∆ Vi = 2Vrms fripple = 100Hz Vo = Vref output short-circuit Vo = Vref Vo = 12V 50 Io = 1A 1.5 Io = 1A Io = 1.5A Vo = Vref Io = 1A Vref 9 15 8 5 5.1 40 46 50 20 5.2 V V mV mV V mV/°C Io = 0.5A to 1.5A Io = 1A 0.4 1.5 2 V A I2L ISH η 2 3.3 A 15 70 80 56 30 mA % % dB 3/15 L4962 ELECTRICAL CHARACTERISTICS (continued) Symbol Parameter Test Conditions Min. Typ. Max. Unit DYNAMIC CHARACTERISTICS (cont’d) f ∆f ∆ Vi ∆f ∆ Tj fmax Switching frequency Voltage stability of switching frequency Temperature stability of switching frequency Maximum operating switching frequency Thermal shutdown junction temperature Vi = 9V to 46V Tj = 0°C to 125°C 85 100 0.5 115 KHz % 1 % Vo = Vref Io = 1A 120 150 KHz °C Tsd 150 DC CHARACTERISTICS I7Q Quiescent drain current 100% duty cycle pins 2 and 14 open Vi = 46V 0% duty cycle -I2L Output leakage current 0% duty cycle 15 20 1 mA mA 30 40 mA SOFT START I15SO I15SI Source current Sink current 100 50 140 70 180 120 µA µA ERROR AMPLIFIER V11H V11L I11SI -I11SO I10 Gv High level output voltage Low level output voltage Sink output current Source output current Input bias current DC open loop gain V10 = 4.7V V10 = 5.3V V10 = 5.3V V10 = 4.7V V10 = 5.2V V11 = 1V to 3V 46 I11 = 100µA I11 = 100µA 100 100 150 150 2 55 10 3.5 0.5 V V µA µA µA dB OSCILLATOR -I14 Oscillator source current 5 mA 4/15 L4962 CIRCUIT OPERATION (refer to the block diagram) The L4962 isa monolithic stepdownswitching 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 producedby comparing the output voltage with a precise 5.1V on-chip reference (zener zap trimmed to ± 2%). This error signal is then comparedwith 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 5/15 L4962 Figure 3. Test and application circuit (Powerdip) 1) D 1: 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) C 6, C7: ROE, EKR 220µF 40V Figure 4. Quiescent drain current vs. supply voltage (0% duty cycle) Figure 5. Quiescent drain current vs. supply voltage (100% duty cycle) Figure 6. Quiescent drain curr ent vs . junction temperature (0% duty cycle) 6/15 L4962 F igure 7. Quiescent drain cur rent vs. ju nc tion 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 Fi gure 11. Sw itchi ng frequency vs. input voltage Fi gure 1 2. Switchi ng freque nc y vs. ju ncti on temperature Figure 1 3. Switching frequency vs. R2 (see test circuit) Fi gure 1 4. L ine tr an si ent response Figure 15 . Load transient response 7/15 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 b etwe en pi n 7 a nd 2 v s. junction temperature Fi gu re 1 9. Effi c ien cy vs. output current Fi g ure 2 0. Effi ci ency v s. output current F ig ur e 2 1. Effic i en cy vs. output current Fi gur e 2 2 . Effi ci enc y vs. output voltage Fi g ure 2 3. Effi ci ency v s. output voltage Figure 24. Maximum allowable power dissipation vs. ambient temperature (Powerdip) 8/15 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 12V 15V 18V 24V R3 4.7KΩ 4.7KΩ 4.7KΩ 4.7KΩ R4 6.2KΩ 9.1KΩ 12KΩ 18KΩ 9/15 L4962 APPLICATION INFORMATION (continued) Figure 27. - A minimal 5.1V fixed regulator; Very few component are required * COGEMA 946043 969051 ** EKR (ROE) (TOROID CORE) (U15 CORE) 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) 10/15 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 11/15 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 Figure 33. Maximum dissipable power and junction to ambient thermal resistance vs. side ”l” 12/15 L4962 POWERDIP PACKAGE MECHANICAL DATA DIM. MIN. a1 B b b1 D E e e3 F I L Z 3.30 1.27 8.80 2.54 17.78 7.10 5.10 0.130 0.050 0.38 0.51 0.85 0.50 0.50 20.0 0.346 0.100 0.700 0.280 0.201 0.015 1.40 mm TYP. MAX. MIN. 0.020 0.033 0.020 0.020 0.787 0.055 inch TYP. MAX. 13/15 L4962 HEPTAWATT PACKAGE MECHANICAL DATA DIM. MIN. A C D D1 E F F1 G G1 G2 H2 H3 L L1 L2 L3 L5 L6 L7 M M1 Dia 3.65 2.6 15.1 6 2.8 5.08 3.85 0.144 10.05 16.97 14.92 21.54 22.62 3 15.8 6.6 0.102 0.594 0.236 0.110 0.200 0.152 2.41 4.91 7.49 2.54 5.08 7.62 2.4 1.2 0.35 0.6 mm TYP. MAX. 4.8 1.37 2.8 1.35 0.55 0.8 0.9 2.67 5.21 7.8 10.4 10.4 0.396 0.668 0.587 0.848 0.891 0.118 0.622 0.260 0.095 0.193 0.295 0.100 0.200 0.300 0.094 0.047 0.014 0.024 MIN. inch TYP. MAX. 0.189 0.054 0.110 0.053 0.022 0.031 0.035 0.105 0.205 0.307 0.409 0.409 14/15 L4962 Information furnished is believed to be accurate and reliable. However, SGS-THOMSON Microelectronics 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 SGS-THOMSON Microelectronics. Specifications mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied. SGS-THOMSON Microelectronics products are not authorized for use as critical components in life support devices or systems without express written approval of SGS-THOMSON Microelectronics. © 1996 SGS-THOMSON Microelectronics - All Rights Reserved SGS-THOMSON Microelectronics GROUP OF COMPANIES Australia - Brazil - France - Germany - Hong Kong - Italy - Japan - Korea - Malaysia - Malta - Morocco - The Netherlands - Singapore Spain - Sweden - Swit zerland - Taiwan - Thaliand - United Kingdom - U.S.A. 15/15