L296 L296P HIGH CURRENT SWITCHING REGULATORS .. .. .. .. .. .. . 4 A OUTPUT CURRENT 5.1 V TO 40 V OUTPUT VOLTAGE RANGE 0 TO 100 % DUTY CYCLE RANGE PRECISE (±2 %) ON-CHIP REFERENCE SWITCHING FREQUENCY UP TO 200 KHz VERY HIGH EFFICIENCY (UP TO 90 %) VERY FEW EXTERNAL COMPONENTS SOFT START RESET OUTPUT EXTERNAL PROGRAMMABLE LIMITING CURRENT (L296P) CONTROL CIRCUIT FOR CROWBAR SCR INPUT FOR REMOTE INHIBIT AND SYNCHRONUS PWM THERMAL SHUTDOWN DESCRIPTION The L296 andL296P are stepdownpowerswitching regulators delivering 4 A at a voltage variable from 5.1 V to 40 V. Featuresof the devices includesoft start, remoteinhibit, thermal protection, a reset output for microprocessors and a PWM comparator input for synchronization in multichip configurations. The L296P incudes external programmable limiting current. Multiwatt (15 lead) ORDERING NUMBERS : L296 (Vertical) L296HT (Horizontal) L296P (Vertical) L296PHT (Horizontal) The L296 and L296P are mounted in a 15-lead Multiwatt plasticpowerpackageand requiresvery few external components. Efficient operation at switching frequencies up to 200 KHz allows a reduction in the size and cost of external filter components. A voltage sense input and SCR drive output are provided for optional crowbar overvoltage protection with an external SCR. PIN CONNECTION (top view) June 2000 1/22 L296 - L296P PIN FUNCTIONS N° 1 Name CROWBAR INPUT 2 3 4 OUTPUT SUPPLY VOLTAGE CURRENT LIMIT 5 SOFT START 6 7 INHIBIT INPUT SYNC INPUT 8 9 10 GROUND FREQUENCY COMPENSATION FEEDBACK INPUT 11 OSCILLATOR 12 RESET INPUT 13 RESET DELAY 14 15 RESET OUTPUT CROWBAR OUTPUT BLOCK DIAGRAM 2/22 Function Voltage Sense Input for Crowbar Overvoltage Protection. Normally connected to the feedback input thus triggering the SCR when V out exceeds nominal by 20 %. May also monitor the input and a voltage divider can be added to increase the threshold. Connected to ground when SCR not used. Regulator Output Unrergulated Voltage Input. An internal Regulator Powers the L296s Internal Logic. A resistor connected between this terminal and ground sets the current limiter threshold. If this terminal is left unconnected the threshold is internally set (see electrical characteristics). 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. TTL – Level Remote Inhibit. A logic high level on this input disables the device. Multiple L296s are synchronized by connecting the pin 7 inputs together and omitting the oscillator RC network on all but one device. Common Ground Terminal A series RC network connected between this terminal and ground determines the regulation loop gain characteristics. The Feedback Terminal on 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 parallel RC networki connected to this terminal determines the switching frequency. This pin must be connected to pin 7 input when the internal oscillator is used. Input of the Reset Circuit. The threshold is roughly 5 V. It may be connected to the feedback point or via a divider to the input. A capacitor connected between this terminal and ground determines the reset signal delay time. Open collector reset signal output. This output is high when the supply is safe. SCR gate drive output of the crowbar circuit. L296 - L296P CIRCUIT OPERATION (refer to the block diagram) The L296 and L296P are monolithic stepdown switching regulators providing output voltages from 5.1V to 40V and delivering 4A. The regulationloop consists of a sawtoothoscillator, error amplifier, comparatorand the outputstage. An error signal is produced by comparing the output voltage with a precise 5.1V on-chipreference(zener zap trimmed to ± 2 %). This error signalis then compared with the sawtooth signal to generate the fixed frequencypulse width modulatedpulseswhich drive the output stage.The gain and frequencystability of the loop can be adjustedby an externalRC network connectedto pin9. Closing the loop directlygives an outputvoltageof 5.1V.Higher voltagesare 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. Outputoverloadprotection 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 outputstage 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 reset circuit generates an output signal when the supply voltage exceeds a threshold programmed by an external divider. The reset signal is generatedwith a delay time programmed by an external capacitor. When the supply falls below the threshold the reset output goes low immediately. The reset output is an open collector. The scrowbar circuit senses the output voltage and the crowbar output can provide a current of 100mA to switch on an externalSCR. This SCR is triggered when the output voltage exceeds the nominal by 20%. There is no internal connection between the outputand crowbar sense input thereforethe crowbar can monitor either the input or the output. A TTL - level inhibit input is providedfor applications such as remote on/offcontrol. This input is activated by high logic level and disables circuit operation.After an inhibit the L296 restarts under control of 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 : Reset Output Waveforms 3/22 L296 - L296P Figure 2 : Soft Start Waveforms Figure 3 : Current Limiter Waveforms ABSOLUTE MAXIMUM RATINGS Symbol Vi Vi – V2 V2 V1, V12 V15 V4, V5, V7, V9, V13 V10, V6 V14 4/22 Parameter Value Unit Input Voltage (pin 3) 50 V Input to Output Voltage Difference 50 V –1 –7 V V Output DC Voltage Output Peak Voltage at t = 0.1 µsec f = 200KHz Voltage at Pins 1, 12 10 V Voltage at Pin 15 15 V Voltage at Pins 4, 5, 7, 9 and 13 5.5 V Voltage at Pins 10 and 6 7 V Voltage at Pin 14 (I14 ≤ 1 mA) Vi I9 Pin 9 Sink Current 1 I11 Pin 11 Source Current 20 mA mA I14 Pin 14 Sink Current (V14 < 5 V) 50 mA Ptot Power Dissipation at Tcase ≤ 90 °C 20 W Tj, Tstg Junction and Storage Temperature – 40 to 150 °C L296 - L296P THERMAL DATA Symbol Parameter Value Unit Rth j-case Thermal Resistance Junction-case Max. 3 °C/W Rth j-amb Thermal Resistance Junction-ambient Max. 35 °C/W ELECTRICAL CHARACTERISTICS (refer to the test circuits Tj = 25oC, Vi = 35V, unless otherwise specified) Symbol Parameter Test Conditions Min. Typ. Max. Unit Fig. DYNAMIC CHARACTERISTICS (pin 6 to GND unless otherwise specified) Vo Output Voltage Range Vi = 46V, Io = 1A Vi Input Voltage Range Vo = Vref to 36V, Io ≤ 3A Vi Input Voltage Range Note (1), Vo = VREF to 36V Io = 4A ∆Vo Line Regulation Vi =10V to 40V, Vo = Vref, Io = 2A ∆Vo Load Regulation Vo = Vref Io = 2A to 4A Io = 0.5A to 4A Vref ∆ Vref ∆T Internal Reference Voltage (pin 10) Vi = 9V to 46V, Io = 2A Vref 40 V 4 9 46 V 4 46 V 4 15 5 10 15 30 45 5.1 5.2 Average Temperature Coefficient of Reference Voltage Tj = 0°C to 125°C, Io = 2A 0.4 Vd Dropout Voltage Between Pin 2 and Pin 3 Io = 4A Io = 2A 2 1.3 I2L Current Limiting Threshold (pin 2) L296 - Pin 4 Open, Vi = 9V to 40V, Vo = Vref to 36V L296P - Vi = 9V to 40V, Vo = Vref Pin 4 Open RIim = 22kΩ ISH η SVR f V 4 mV/°C 4 4 4.5 7.5 A 4 A 4 5 2.5 7 4.5 mA 4 % 4 dB 4 60 Efficiency Io = 3 A Vo = Vref Vo = 12V 75 85 Switching Frequency 4 4 V V Vi = 46V, Output Short-circuited ∆Vi = 2 Vrms, fripple = 100Hz Vo = Vref, Io = 2A mV mV 3.2 2.1 Input Average Current Supply Voltage Ripple Rejection 50 50 56 85 100 ∆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, Io = 1A 200 Tsd Thermal Shutdown Junction Temperature Note (2) 135 100 kHz 4 0.5 115 % 4 1 % 4 kHz – °C – 145 DC CHARACTERISTICS I3Q – I2L Note Quiescent Drain Current Output Leakage Current Vi = 46V, V7 = 0V, S1 : B, S2 : B V6 = 0V V6 = 3V Vi = 46V, V6 = 3V, S1 : B, S2 : A, V7 = 0V mA 66 30 85 40 2 mA (1) : Using min. 7 A schottky diode. (2) : Guaranteed by design, not 100 % tested in production. 5/22 L296 - L296P ELECTRICAL CHARACTERISTICS (continued) Symbol Parameter Test Conditions Min. Typ. Max. Unit Fig. SOFT START I5 so Source Current V6 = 0V, V5 = 3V 80 130 150 µA 6b I5 si Sink Current V6 = 3V, V5 = 3V 50 70 120 µA 6b Input Voltage Low Level High Level Vi = 9V to 46V, V7 = 0V, S1 : B, S2 : B V 6a V6L V6H Vi = 9V to 46V, V7 = 0V, S1 : B, S2 : B V6 = 0.8V V6 = 2V µA 6a – I6L – I6H Input Current with Input Voltage Low Level High Level V 6c V 6c INHIBIT – 0.3 2 0.8 5.5 10 3 ERROR AMPLIFIER V9H High Level Output Voltage V10 = 4.7V, I9 = 100µA, S1 : A, S2 : A V9L Low Level Output Voltage V10 = 5.3V, I9 = 100µA, S1 : A, S2 : E I9 si Sink Output Current V10 = 5.3V, S1 : A, S2 : B 100 150 µA 6c Source Output Current V10 = 4.7V, S1 : A, S2 : D 100 150 µA 6c I10 Input Bias Current V10 = 5.2V, S1 : B V10 = 6.4V, S1 : B, L296P µA µA 6c 6c Gv DC Open Loop Gain V9 = 1V to 3V, S1 : A, S2 : C dB 6c µA 6a – I9 so 3.5 0.5 2 2 46 10 10 55 OSCILLATOR AND PWM COMPARATOR – I7 Input Bias Current of PWM Comparator V7 = 0.5V to 3.5V – I11 Oscillator Source Current V11 = 2V, S1 : A, S2 : B 5 5 mA RESET V12 R Rising Threshold Voltage Vi = 9V to 46V, S1 : B, S2 : B V12 F Falling Threshold Voltage V13 D Delay Thershold Voltage V13 H Delay Threshold Voltage Hysteresis V14 S Output Saturation Voltage I14 = 16mA, V12 = 4.7V, S1, S2 : B Input Bias Current V12 = 0V to Vref, S1 : B, S2 : B Delay Source Current Delay Sink Current V13 = 3V, S1 : A, S2 : B V12 = 5.3V V12 = 4.7V Output Leakage Current Vi = 46V, V12 = 5.3V, S1 : B, S2 : A I12 – I13 so I13 si I14 Vref Vref -150mV -100mV 4.75 4.3 V12 = 5.3V, S1 : A, S2 : B Vref -50mV V 6d Vref Vref -150mV -100mV V 6d 4.5 4.7 100 70 10 V 6d mV 6d 0.4 V 6d 1 3 µA 6d 110 140 µA mA 100 µA 6d 6d CROWBAR V1 Input Threshold Voltage S1 : B V15 Output Saturation Voltage Vi = 9V to 46V, Vi = 5.4V, I15 = 5mA, S1 : A Input Bias Current V1 = 6V, S1 : B Output Source Current Vi = 9V to 46V, V1 = 6.5V, V15 = 2V, S1 : B I1 – I15 6/22 5.5 6 6.4 V 6b 0.2 0.4 V 6b 10 70 100 µA 6b mA 6b L296 - L296P Figure 4 : Dynamic Test Circuit C7, C8 : EKR (ROE) L1 : L = 300 µH at 8 A Core type : MAGNETICS 58930 - A2 MPP N° turns : 43 Wire Gauge : 1 mm (18 AWG) COGEMA 946044 (*) Minimum suggested value (10 µF) to avoid oscillations. Ripple consideration leads to typical value of 1000 µF or higher. Figure 5 : PC. Board and Component Layout of the Circuit of Figure 4 (1:1 scale) 7/22 L296 - L296P Figure 6 : DC Test Circuits. Figure 6a. Figure 6b. Figure 6c. 1 - Set V10 FOR V9 = 1 V 2 - Change V 10 to obtain V 9 = 3 V 3 - GV = DV9 ∆V10 Figure 6d. 8/22 = 2V ∆V10 L296 - L296P Figure 7 : QuienscentDrain Current vs. Supply Voltage (0 % Duty Cycle - see fig. 6a). Figure 8 : QuienscentDrain Current vs. Supply Voltage (100 % Duty Cycle see fig. 6a). Figure 9 : Quiescent Drain Current vs. Junction Temperature (0 % Duty Cycle see fig. 6a). Figure 10 : QuiescentDrain Current vs. Junction Temperature (100 % Duty Cycle see fig. 6a). Figure 11 : Reference Voltage (pin 10) vs. VI (see fig. 4). Figure 12 : ReferenceVoltage (pin 10) vs. Junction Temperature (see fig. 4). 9/22 L296 - L296P Figure 13 : Open Loop Frequency and Phase Response of Error Amplifier (see fig. 6c). Figure 14 : Switching Frequency vs. Input Voltage (see fig. 4). Figure 15 : Switching Frequency vs. Junction Temperature (see fig. 4). Figure 16 : Switching Frequency vs. R1 (see fig. 4). Figure 17 : Line Transient Response (see fig. 4). Figure 18 : Load Transient Response (see fig. 4). 10/22 L296 - L296P Figure 19 : SupplyVoltage Ripple Rejection vs. Frequency (see fig. 4). Figure 20 : Dropout Voltage Between Pin 3 and Pin 2 vs. Current at Pin 2. Figure 21 : Dropout Voltage Between Pin 3 and Pin 2 vs. Junction Temperature. Figure 22 : Power Dissipation Derating Curve. Figure 23 : Power Dissipation (device only) vs. Input Voltage. Figure 24 : Power Dissipation (device only) vs. Input voltage. 11/22 L296 - L296P Figure 25 : Power Dissipation (device only) vs. OutputVoltage (see fig. 4). Figure 26 : Power Dissipation (device only) vs. Output Voltage (see fig. 4). Figure27 : Voltageand Current Waveformsat Pin 2 (see fig. 4). Figure 28 : Efficiency vs. Output Current. Figure 29 : Efficiency vs. Output Voltage. Figure 30 : Efficiency vs. Output Voltage. 12/22 L296 - L296P Figure 31 : Current Limiting Threshold vs. Rpin 4 (L296P only). Figure 32 : Current Limiting Threshold vs. Junction Temperature. Figure 33 : Current Limiting Threshold vs. Supply Voltage. 13/22 L296 - L296P APPLICATION INFORMATION Figure 34 : Typical Application Circuit. (*) Minimum value (10 µF) to avoid oscillations ; ripple consideration leads to typical value of 1000 µF or higher L1 : 58930 - MPP COGEMA 946044 ; GUP 20 COGEMA 946045 SUGGESTED INDUCTOR (L1) Core Type Magnetics 58930 – A2MPP Thomson GUP 20 x 16 x 7 Siemens EC 35/17/10 (B6633& – G0500 – X127) VOGT 250 µH Toroidal Coil, Part Number 5730501800 V0 12 V 15 V 18 V 24 V 14/22 No Turns 43 65 40 Wire Gauge 1.0 mm 0.8 mm 2 x 0.8 mm Resistor Values for Standard Output Voltages R8 4.7 KΩ 4.7 KΩ 4.7 KΩ 4.7 KΩ Air Gap – 1 mm – R7 6.2 KΩ 9.1 KΩ 12 KΩ 18 KΩ L296 - L296P Figure 35 : P.C. Board and Component Layout of the Circuit of fig. 34 (1:1 scale) SELECTION OF COMPONENT VALUES (see fig. 34) Component Recommended Value R1 R2 – 100 kΩ Set Input Voltage Threshold for Reset. R3 R4 4.3 kΩ 10 kΩ Sets Switching Frequency Pull-down Resistor R5 R6 15 kΩ Frequency Compensation Collector Load For Reset Output R7 R8 – 4.7 kΩ R iim – C1 C2 C3 C4 Purpose Divider to Set Output Voltage Allowed Rage Notes Min. Max. – Vi min −1 220kΩ R1/R2 5 If output voltage is sensed R1 and R2 may be limited and pin 12 connected to pin 10. 1 kΩ 100kΩ 22kΩ May be omitted and pin 6 grounded if inhibit not used. 10kΩ VO Omitted if reset function not used. 0.05A – – – 1kΩ Sets Current Limit Level 7.5kΩ 10 µF 2.2 µF 2.2 nF 2.2 µF Stability Sets Reset Delay Sets Switching Frequency Soft Start 2.2µF – 1 nF 1 µF – 3.3nF – C5 C6 33 nF 390 pF – – C7, C8 L1 Q1 100 µF 300 µH Frequency Compensation High Frequency Compensation Output Filter – 100µH – D1 Crowbar Protection Recirculation Diode R7/R8 = VO − VREF VREF If Riim is omitted and pin 4 left open the current limit is internally fixed. Omitted if reset function not used. Also determines average short circuit current. Not required for 5 V operation. The SCR must be able to withstand the peak discharge current of the output capacitor and the short circuit current of the device. 7A Schottky or 35 ns trr Diode. 15/22 L296 - L296P Figure 36 : A Minimal 5.1 V Fixed Regulator. Very Few Components are Required. Figure 37 : 12 V/10 A Power Supply. 16/22 L296 - L296P Figure 38 : Programmable Power Supply. V o = 5.1 to 15 V I o = 4 A max. (min. load current = 100 mA) ripple ≤ 20 mV load regulation (1 A to 4 A) = 10 mV (V o = 5.1 V) line regulation (220 V ± 15 % and to I o = 3 A) = 15 mV (V o = 5.1 V) Figure 39 : Preregulator for Distributed Supplies. (*) L2 and C2 are necessary to reduce the switching frequency spikes. 17/22 L296 - L296P Figure 40 : In Multiple Supplies Several L296s can be Synchronized As Shown. Figure 41 : Voltage Sensing for Remote Load. Figure 42 : A 5.1 V/15 V/24 V Multiple Supply. Note the Synchronization of the Three L296s. 18/22 L296 - L296P Figure 43 : 5.1V/2A Power Supply using External Limiting Current Resistor and Crowbar Protection on the Supply Voltage (L296P only) sistor may be added, as shown in Figure 45 ; with this circuit discharge times of a few microseconds may be obtained. Figure 45 SOFT-START AND REPETITIVE POWER-ON When the device is repetitivelypowered-on,the softstart capacitor, CSS, must be discharged rapidly to ensurethat each start is ”soft”. This can be achieved economicallyusing the reset circuit, as shownin Figure 44. In this circuit the divider R1, R2 connectedto pin 12 determines the minimum supply voltage, below which the open collector transistor at the pin 14 output discharges CSS. Figure 44 HOW TO OBTAIN BOTH RESET AND POWER FAIL Figure 46 illustrateshowit is possibleto obtainat the same time both the power fail and reset functions simply by adding one diode(D) and one resistor (R). In this case the Reset delay time (pin 13) can only start when the output voltage is VO ≥ VREF - 100mV and the voltage accross R2 is higher than 4.5V. With the hysteresis resistor it is possible to fix the input pin 12 hysteresis in order to increase immunity to the 100Hz ripple present on the supply voltage. Moreover, the power fail and reset delay time are automatically locked to the soft-start. Soft-start and delayed reset are thus two sequential functions. The hysteresis resistor should be In the range of aboit 100kΩ and the pull-up resistor of 1 to 2.2kΩ. Figure 46 The approximate discharge times obtainedwith this circuit are : CSS (µF) tDIS (µs) 2.2 4.7 10 200 300 600 If thesetimes are still too long,an externalPNPtran- 19/22 L296 - L296P mm DIM. MIN. TYP. inch MAX. MIN. TYP. MAX. A 5 0.197 B 2.65 0.104 C 1.6 D E F 0.66 G G1 1.02 17.53 H1 19.6 0.039 0.55 1.27 17.78 0.019 0.75 0.026 1.52 18.03 0.040 0.690 0.022 0.030 0.050 0.700 0.060 0.710 0.772 H2 L 0.063 1 0.49 20.2 0.795 21.9 22.2 22.5 0.862 0.874 0.886 L1 21.7 22.1 22.5 0.854 0.870 0.886 L2 17.65 18.1 0.695 L3 17.25 17.5 17.75 0.679 0.689 0.699 L4 10.3 10.7 10.9 0.406 0.421 0.429 L7 2.65 2.9 0.104 M 4.25 4.55 4.85 0.167 0.179 0.191 M1 4.63 5.08 5.53 0.182 0.200 0.218 S S1 1.9 1.9 2.6 2.6 0.075 0.075 0.102 0.102 Dia1 3.65 3.85 0.144 0.152 20/22 OUTLINE AND MECHANICAL DATA 0.713 0.114 Multiwatt15 V L296 - L296P mm DIM. MIN. TYP. inch MAX. MIN. TYP. MAX. A 5 0.197 B 2.65 0.104 C 1.6 E 0.49 OUTLINE AND MECHANICAL DATA 0.063 0.55 0.019 0.022 F 0.66 0.75 0.026 G 1.14 1.27 1.4 0.045 0.050 0.030 0.055 G1 17.57 17.78 17.91 0.692 0.700 0.705 H1 19.6 0.772 H2 20.2 0.795 L 20.57 0.810 L1 18.03 0.710 L2 2.54 0.100 L3 17.25 17.5 17.75 0.679 0.689 0.699 L4 10.3 10.7 10.9 0.406 0.421 0.429 L5 5.28 0.208 L6 2.38 0.094 L7 2.65 2.9 0.104 0.114 S 1.9 2.6 0.075 0.102 S1 1.9 2.6 0.075 0.102 Dia1 3.65 3.85 0.144 0.152 Multiwatt15 H 21/22 L296 - L296P 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. This publication supersedes and replaces all information previously supplied. STMicroelectronics products are not authorized for use as critical components in life support devices or systems without express written approval of STMicroelectronics. The ST logo is a registered trademark of STMicroelectronics 2000 STMicroelectronics – Printed in Italy – All Rights Reserved STMicroelectronics GROUP OF COMPANIES Australia - Brazil - China - Finland - France - Germany - Hong Kong - India - Italy - Japan - Malaysia - Malta - Morocco Singapore - Spain - Sweden - Switzerland - United Kingdom - U.S.A. http://www.st.com 22/22