L6598 HIGH VOLTAGE RESONANT CONTROLLER ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ HIGH VOLTAGE RAIL UP TO 600V dV/dt IMMUNITY ±50V/ns IN FULL TEMPERATURE RANGE DRIVER CURRENT CAPABILITY: 250mA SOURCE 450mA SINK SWITCHING TIMES 80/40ns RISE/FALL WITH 1nF LOAD CMOS SHUT DOWN INPUT UNDER VOLTAGE LOCK OUT SOFT START FREQUENCY SHIFTING TIMING SENSE OP AMP FOR CLOSED LOOP CONTROL OR PROTECTION FEATURES HIGH ACCURACY CURRENT CONTROLLED OSCILLATOR INTEGRATED BOOTSTRAP DIODE CLAMPING ON Vs SO16, DIP16 PACKAGES DIP16 SO16N ORDERING NUMBERS: L6598 L6598D technology, able to ensure voltage ratings up to 600V, making it perfectly suited for AC/DC Adapters and wherever a Resonant Topology can be beneficial. The device is intended to drive two Power MOS, in the classical Half Bridge Topology. A dedicated Timing Section allows the designer to set Soft Start Time, Soft Start and Minimum Frequency. An Error Amplifier, together with the two Enable inputs, are made available. In addition, the integrated Bootstrap Diode and the Zener Clamping on low voltage supply, reduces to a minimum the external parts needed in the applications. DESCRIPTION The L6598 is manufactured with the BCD OFF LINE BLOCK DIAGRAM VS OPOUT OPINOPIN+ OP AMP 5 H.V. 12 + - 6 UV DETECTION 7 BOOTSTRAP DRIVER HVG DRIVER 16 V BOOT 15 HVG 14 OUT Ifmin V REF DEAD TIME DRIVING LOGIC LEVEL SHIFTER 11 LVG DRIVER Ifstart V REF + Rfstart + CONTROL LOGIC LVG 10 GND Vthe1 8 - 2 LOAD Vs 4 Rfmin CBOOT EN1 Vthe2 9 - EN2 Iss 3 Cf VCO 1 Css February 2000 D98IN887A 1/16 L6598 PIN CONNECTION Css 1 16 VBOOT Rfstart 2 15 HVG Cf 3 14 OUT Rfmin 4 13 N.C. OPOUT 5 12 VS OPIN- 6 11 LVG OPIN+ 7 10 GND EN1 8 9 EN2 D98IN888 THERMAL DATA Symbol Rth j-amb Parameter Thermal Resistance Junction to Ambient SO16N DIP16 Unit 120 80 °C/W PIN FUNCTION N. Name 1 C SS 2 R fstart 3 Cf 4 R fmin Minimum Oscillation Frequency Setting - Low Impedance Voltage Source - See also Cf 5 OPout Sense OP AMP Output - Low Impedance 6 OPon- Sense Op Amp Inverting Input - High Impedance 7 OPon+ Sense Op Amp Non Inverting Input - High Impedance 8 EN1 Half Bridge Latched Enable 9 EN2 Half Bridge Unlatched Enable 10 GND Ground 11 LVG Low Side Driver Output 12 Vs 13 N.C. Not Connected 14 OUT High Side Driver Reference 15 HVG High Side Driver Output 16 Vboot Bootstrapped Supply Voltage 2/16 Function Soft Start Timing Capacitor Soft Start Frequency Setting - Low Impedance Voltage Source - See also Cf Oscillator Frequency Setting - see also Rfmin, Rfstart Supply Volatge with Internal Zener Clamp L6598 ABSOLUTE MAXIMUM RATINGS Symbol IS Parameter Supply Current at Vcl (*) Value Unit 25 mA 14.6 V -1 to VBOOT -18 V -1 to VBOOT V V LVG Low Side Output VOUT High Side Reference V HVG High Side Output VBOOT Floating Supply Voltage 618 V VBOOT pin Slew Rate (repetitive) ±50 V/ns OUT pin Slew Rate (repetitive) ±50 V/ns dV BOOT/dt dVOUT/dt Vir Forced Input Voltage (pins Rfmin, Rfstart) -0.3 to 5 V V ic Forced Input Volatge (pins Css, Cf) -0.3 to 5 V -0.3 to 5 V ±3 mA -0.3 to 5 V V EN1, VEN2 Enable Input Voltage IEN1, IEN2 Enable Input Current Vopc Sense Op Amp Common Mode Range Vopd Sense Op Amp Differential Mode Range -5 to 5 V Vopo Sense Op Amp Output Voltage (forced) 4.6 V Tstg Storage Temperature -40 to +150 °C Tj Junction Temperature -40 to +150 °C Tamb Ambient Temperature -40 to +125 °C (*) The device is provided of an internal Clamping Zener between GND and the Vs pin, It must not be supplied by a low impedance voltage source. Note : ESD immunity for pins 14, 15 and 16 is guaranteed up to 900 (Human Body Model). RECOMMENDED OPERATING CONDITIONS Symbol VS Parameter Supply Voltage Value Unit 10 to Vcl V Vout (*) High Side Reference -1 to Vboot-Vcl V Vboot (*) Floating Supply Rail 500 V Maximum Switching Frequency 400 kHz fmax (*) If the condition Vboot - Vout < 18 is guaranteed, Vout can range from -3 to 580V. 3/16 L6598 ELECTRICAL CHARACTERISTCS (VS = 12V; VBOOT - VOUT = 12V; Tamb = 25°C) Symbol Pin Parameter Test Condition Min. Typ. Max. Unit VS Turn On Threshold 10 10.7 11.4 V Vsuvn VS Turn Off Threshold 7.3 8 8.7 V Vsuvh Supply Voltage Under Voltage hysteresis SUPPLY VOLTAGE Vsuvp 12 2.7 Vcl Supply Voltage Clamping 14.6 Isu Start Up Current Vs < Vsuvn Iq Quiescent Current, fout = 60kHz, no load Vs > Vsuvp 15.6 V 16.6 V 250 µA 2 mA HIGH VOLTAGE SECTION Ibootleak 16 BOOT pin Leakage Current VBOOT = 580V 5 mA Ioutleak 14 OUT pin Leakage Current VOUT = 562V 5 mA Rdon 16 Bootstrap Driver On Resistance 150 Ω HIGH/LOW SIDE DRIVERS Ihvgso 15 Ihvgsi Ilvgso 11 Ilvgsi trise 15,11 High Side Driver Source Current VHVG-VOUT = 0 170 250 mA High Side Driver Sink Current VHVG-VBOOT = 0 300 450 mA Low Side Driver Source Current VLVG-GND = 0 170 250 mA Low Side Driver Sink Current VLVG - VS = 0 300 450 mA Low/High Side Output Rise Time Cload = 1nF 80 120 ns C load = 1nF 40 80 ns 48 50 52 % tfall OSCILL ATOR DC 14 Output Duty Cycle fmin Minimum Output Oscillation Frequency C f = 470pF; Rfmin = 50k 58.2 60 61.8 kHz fstart Soft Start Output Oscillation Frequency C f = 470pF; Rfmin = 50k; R fstart = 47k 114 120 126 kHz V ref 2, 4 Voltage to Current Converters Threshold td 14 Dead Time between Low and High Side Conduction 2 2 0.2 0.27 0.35 µs 0.115 0.15 0.185 s/µF TIMING SECTION kss 4/16 1 Soft Start Timing constant C ss = 330nF L6598 ELECTRICAL CHARACTERISTCS (continued) Symbol Pin Parameter Test Condition Min. Typ. Max. Unit 0.1 µA SENSE OP AMP lIB 6, 7 Vio Rout 5 Input Bias Current Input Offset Voltage -10 10 mV Output Resistance 200 300 Ω Iout- Source Output Current Vout = 4.5V 1 mA Iout+ Sink Output Current Vout = 0.2V 1 mA Vic 6,7 GBW Gdc OP AMP input common mode range -0.2 3 V Sense Op Amp Gain Band Width Product 1 MHz DC Open Loop Gain 80 dB COMPARATORS Vthe1 8 Enabling Comparator Threshold 0.56 0.6 0.64 V Vthe2 9 Enabling Comparator Threshold 1.05 1.2 1.35 V tpulse 8,9 Minimum Pulse lenght 200 ns Figure 1. EN2 Timing Diagrams VS fOUT fstart fmin EN2 VCss TSS TSS D98IN889 5/16 L6598 Figure 2. EN1 Timing Diagrams HVG LVG EN1 EN2 D98IN890 Figure 3. Oscillator/Output Timing Diagram Cf HVG LVG D98IN897 High/Low Side driving section An High and Low Side driving Section provide the proper driving to the external Power MOS or IGBT. An high sink/source driving current (450/250 mA typ) ensure fast switching times also when size4 Power MOS are used. The internal logic ensures a minimum dead time to avoid cross-conduction of the power devices. Timing and Oscillator Section The L6598 is provided of a soft start function. It consists in a period of time, TSS, in which the switching frequency shifts from fstart to fmin. This feature is explained in the following description (ref. fig.4 and fig.5). 6/16 L6598 Figure 4. Soft Start and frequency shifting block Iss Ifstart Ifmin Iosc gm OSC Css During the soft start time the current ISS charges the capacitor CSS, generating a voltage ramp which is delivered to a transconductance amplifier, as shown in fig. 4. Thus this voltage signal is converted in a growing current which is subtracted to Ifstart. Therefore the current which drives the oscillator to set the frequency during the soft start is equal to: g m I ss ------- t I osc = I fmin + ( I fstart – g m V Css ( t )) = I fmin + I fstart – ------ C ss V R EF V REF R fmin R fstart [1] where I fmin = --------------, Ifsart = ---------------- , V R EF = 2V [2] At the start-up (t=0) the L6598 oscillates at fstart, set by: 1 1 I osc ( 0 ) = I fmin + I fstart = V R EF -------------- + ---------------- [3] R R fm in fstart At the end of soft start (t = TSS) the second term of eq.1 decreases to zero and the switching frequency is set only by Imin (i.e. Rfmin): V I osc ( T ss ) = I fm in = -----REF --------- [4] R fmin Since the second term of eq.1 is equal to zero, we have: g m I ss C Ifstart - T SS = 0 → T SS = -----ss ------------------- [5] I fstart – ------------C ss g m I ss Note that there is not a fixed threshold of the voltage across CSS in which the soft start finishes (i.e. the end of the frequency shifting), and TSS depends on CSS, Ifstart, gm, and ISS (eq. 5). Making TSS independent of Ifstart, the ISS current has been designed to be a fraction of Ifstart, so: I fstart C ss Ifstart C ss ---------- → T SS = ------------------------- → T SS = ---------- → T SS – k SS C SS [6] I SS = ---K g m I fstart K gmK In this way the soft start time depends only on the capacitor CSS. The typical value of the kSS constant (Soft 7/16 L6598 Start Timing Constant) is 0.15 s/µF. The current Iosc is fed to the oscillator as shown in fig. 5. It is twice mirrored (x4 and x8) generating the triangular wave on the oscillator capacitor Cf. Referring to the internal structure of the oscillator (fig.5), a good relationship to compute an approximate value of the oscillator frequency in normal operation is: 1.41 f min = -------------------- [7] R fminC f The degree of approximation depends on the frequency value, but it remains very good in the range from 30kHz to 100kHz (figg.6-10) Figure 5. Oscillator Block Iosc Vth+ X4 + S Cf R Vth- + X8 8/16 L6598 Figure 6. Typ. fmin vs. Rfmin @ Cf = 470pF fmin (KHz) Figure 9. Typ. (fstart-fmin) vs. Rfstar @ Cf = 470pF D98IN891 ∆f (KHz) D98IN894 100 100 Rfmin=100KΩ 80 80 60 60 40 40 20 20 40 60 80 100 Rfmin(KΩ) 20 20 Figure 7. Typ. (fstart-fmin) vs. Rfstar @ Cf = 470pF ∆f (KHz) D98IN892 40 60 80 100 Rfstart(KΩ) Figure 10. fmin @ different Rf vs Cf fmin (KHz) 80 400 Rf=19.9Kohm - calc. Rf=19.9Kohm - meas. Rfmin=33KΩ 60 200 Rf=90Kohm - meas. 40 Rf=90Kohm - calc. 0 20 20 40 60 80 100 Rfstart(KΩ) 0 200 400 Cf (pF) Figure 8. Typ. (fstart-fmin) vs. Rfstar @ Cf = 470pF ∆f (KHz) D98IN893 100 Rfmin=50KΩ 80 60 40 20 20 40 60 80 100 Rfstart(KΩ) 9/16 L6598 Bootstrap Section The supply of the high voltage section is obtained by means of a bootstrap circuitry. This solution normally requires an high voltage fast recovery diode for charging the bootstrap capacitor (fig. 11a). In the L6568 a patented integrated structure, replaces this external diode. It is realised by means of a high voltage DMOS, driven synchronously with the low side driver (LVG), with in series a diode, as shown in fig. 11b. Figure 11. ootstrap driver D BOOT VS VS VBOOT VBOOT C BOOT C BOOT VOUT VOUT LVG a b To drive the synchronised DMOS it is necessary a voltage higher than the supply voltage Vs. This voltage is obtained by means of an internal charge pump (fig. 11b). The diode connected in series to the DMOS has been added to avoid undesirable turn on of it. The introduction of the diode prevents any current can flow from the Vboot pin to the VS one in case that the supply is quickly turned off when the internal capacitor of the pump is not fully discharged. The bootstrap driver introduces a voltage drop during the recharging of the capacitor Cboot (i.e. when the low side driver is on), which increases with the frequency and with the size of the external power MOS. It is the sum of the drop across the RDSON and of the diode threshold voltage. At low frequency this drop is very small and can be neglected. Anyway increasing the frequency it must be taken in to account. In fact the drop, reducing the amplitude of the driving signal, can significantly increase the RDSON of the external power MOS (and so the dissipation). To be considered that in resonant power supplies the current which flows in the power MOS decreases increasing the switching frequency and generally the increases of RDSON is not a problem because power dissipation is negligible. The following equation is useful to compute the drop on the bootstrap driver: Qg -----R V drop = I ch arg e R dson + V diode → V drop = -------------+ V diode [8] T ch arg e dson where Qg is the gate charge of the external power MOS, Rdson is the on resistance of the bootstrap DMOS, and Tcharge is the time in which the bootstrap driver remains on (about the semiperiod of the switching frequency minus the dead time). The typical resistance value of the bootstrap DMOS is 150 Ohm. For example using a power MOS with a total gate charge of 30nC the drop on the bootstrap driver is about 3V, at a switching frequency of 200kHz. In fact: 30nC V drop = ------------------ 150Ω + 0.6V~2.6V 2.23µs To summarise, if a significant drop on the bootstrap driver (at high switching frequency when large power MOS are used) represents a problem, an external diode can be used, avoiding the drop on the RDSON of the DMOS. 10/16 L6598 OP AMP Section The integrated OP AMP is designed to offer Low Output Impedance, wide band, High input Impedance and wide Common Mode Range. It can be readily used to implement protection features or a closed loop control. For this purpose the OP AMP Output can be properly connected to Rfmin pin to adjust the oscillation frequency. Comparators Two CMOS comparators are available to perform protection schemes. Short pulses (>= 200ns) on Comparators Input are recognised. The EN1 input (active High), has a threshold of 0.6V (typical value) forces the L6598 in a latched shut down state (e.g. LVG Low, HVG low, Oscillator stopped), as in the Under Voltage Conditions. Normal Operating conditions are resumed after a power-off power-on sequence. The EN2 input (active high), with a threshold of 1.2V (typical value) restarts a Soft Start sequence (see Timing Diagrams). In addition the EN2 Comparator, when activated, removes a latched shutdown caused by EN1. Figure 12. Switching Time Waveform Definitions 90% HVG 90% 10% 10% tr 90% LVG tf 90% 10% 10% tr tf D98IN898 Figure 13. Dead Time and Duty Cycle Waveform Definition T1 td td Dc = 50% T1 Tperiod 50% HVG 50% 50% 50% LVG Tperiod D98IN899 11/16 L6598 Figure 17. Start Up Current vs Temperature Figure 14. Typ. fmin vs. Temperature fmin (KHz) D98IN895 Isu (µA) 200 70 150 60 50 100 50 40 -50 0 50 100 0 50 T (°C) 100 Figure 18. Quiescent Current vs Temperature Figure 15. Typ. fstart vs. Temperature ffstart (KHz) -50 T(°C) D98IN896 Iq (mA) 2.3 130 Iq @ Vclamp 2.1 Iq @ 12V 120 1.9 110 1.7 100 1.5 -50 0 50 100 T(°C) Figure 16. Vs thresholds and clamp vs temp. Vs (V) -50 0 50 100 T (°C) Figure 19. HVG Source and Sink Current vs. Temperature Ihvg (mA) Vclamp 14 500 12 400 Vsuvp 10 Ihvg sink curr. 300 8 Vsuvn Ihvg source curr. 200 6 -50 0 50 100 T (°C) 100 -50 12/16 0 50 100 T (°C) L6598 Figure 20. LVG Source and Sink Current vs. Temperature Figure 21. Soft Start Timing Constant vs. Temperature Ilvg (mA) kss (s/µF) 500 0.16 400 Ilvg sink curr. 300 0.14 Ilvg source curr. 200 100 -50 0 50 100 T (°C) 0.12 -50 0 50 100 T (°C) Figure 22. Wide Range AC/DC Adapter Application 85 to 270 Vac L6561 Vo L6598 DRIVER VCO & CONTROL TL431 ENABLE D98IN874A 13/16 L6598 mm DIM. MIN. a1 0.51 B 0.77 TYP. inch MAX. MIN. TYP. MAX. 0.020 1.65 0.030 0.065 b 0.5 0.020 b1 0.25 0.010 D 20 0.787 E 8.5 0.335 e 2.54 0.100 e3 17.78 0.700 F 7.1 0.280 I 5.1 0.201 L Z 14/16 OUTLINE AND MECHANICAL DATA 3.3 0.130 1.27 DIP16 0.050 L6598 mm DIM. MIN. TYP. A a1 inch MAX. MIN. TYP. 1.75 0.1 0.25 a2 MAX. 0.069 0.009 0.004 1.6 0.063 b 0.35 0.46 0.014 0.018 b1 0.19 0.25 0.007 0.010 C 0.5 c1 0.020 45° (typ.) D (1) 9.8 10 0.386 0.394 E 5.8 6.2 0.228 0.244 e 1.27 0.050 e3 8.89 0.350 F (1) 3.8 4 0.150 0.157 G 4.6 5.3 0.181 0.209 L 0.4 1.27 0.016 0.050 M S OUTLINE AND MECHANICAL DATA 0.62 0.024 SO16 Narrow 8°(max.) (1) D and F do not include mold flash or protrusions. Mold flash or potrusions shall not exceed 0.15mm (.006inch). 15/16 L6598 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. N o license is granted by implication or otherwise under any patent or patent rights of STMicroelectronics. Specifications 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 - 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 16/16