L6599 High-voltage resonant controller Not for new design Features ■ 50 % duty cycle, variable frequency control of resonant half-bridge ■ High-accuracy oscillator ■ Up to 500 kHz operating frequency ■ Two-level OCP: frequency-shift and latched shutdown ■ Interface with PFC controller ■ Latched disable input ■ Burst-mode operation at light load ■ Input for power-ON/OFF sequencing or brownout protection DIP-16 ■ Non-linear soft-start for monotonic output voltage rise ■ 600 V-rail compati
Contents L6599 Contents 1 Device description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2 Pin settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.1 Connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.2 Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
L6599 1 Device description Device description The L6599 is a double-ended controller specific for the resonant half-bridge topology. It provides 50 % complementary duty cycle: the high-side switch and the low-side switch are driven ON\OFF 180° out-of-phase for exactly the same time. Output voltage regulation is obtained by modulating the operating frequency.
Pin settings L6599 2 Pin settings 2.1 Connection Figure 2. Pin connection (top view) 2.2 Functions Table 2. Pin functions N. Css 1 16 VBOOT DELAY 2 15 HVG CF 3 14 OUT RFmin 4 13 N.C. STBY 5 12 Vcc ISEN 6 11 LVG LINE 7 10 GND DIS 8 9 PFC_STOP Name Function CSS Soft start.
L6599 Table 2. N. 4 5 6 7 8 9 10 Pin settings Pin functions (continued) Name Function RFmin Minimum oscillator frequency setting. This pin provides a precise 2 V reference and a resistor connected from this pin to GND defines a current that is used to set the minimum oscillator frequency. To close the feedback loop that regulates the converter output voltage by modulating the oscillator frequency, the phototransistor of an optocoupler will be connected to this pin through a resistor.
Typical system block diagram Table 2. L6599 Pin functions (continued) N. Name 11 LVG Low-side gate-drive output. The driver is capable of 0.3 A min. source and 0.8 A min. sink peak current to drive the lower MOSFET of the half-bridge leg. The pin is actively pulled to GND during UVLO. 12 VCC Supply Voltage of both the signal part of the IC and the low-side gate driver. Sometimes a small bypass capacitor (0.1 µF typ.) to GND might be useful to get a clean bias voltage for the signal part of the IC.
L6599 Electrical data 4 Electrical data 4.1 Maximum ratings Table 3. Absolute maximum ratings Symbol Pin VBOOT 16 VOUT Parameter Value Unit Floating supply voltage -1 to 618 V 14 Floating ground voltage -3 to VBOOT -18 V dVOUT /dt 14 Floating ground max. slew rate 50 V/ns VCC 12 IC Supply voltage (ICC ≤ 25 mA) Self-limited V VPFC_STOP 9 Maximum voltage (pin open) -0.
Electrical characteristics 5 L6599 Electrical characteristics TJ = 0 to 105 °C, VCC = 15 V, VBOOT = 15 V, CHVG = CLVG = 1 nF; CF = 470 pF; RRFmin = 12 kΩ; unless otherwise specified. Table 5. Electrical characteristics Symbol Parameter Test condition Min Operating range After device turn-on 8.85 VCC(ON) Turn-ON threshold Voltage rising 10 VCC(OFF) Turn-OFF threshold Voltage falling 7.45 Typ Max Unit 16 V 10.7 11.4 V 8.15 8.
L6599 Electrical characteristics Table 5. Electrical characteristics (continued) Symbol Parameter Test condition Min Typ Max Unit 1.2 1.25 1.3 V 15 18 µA 8 V -1 µA Line sensing Voltage rising or falling Vth Threshold voltage IHyst Current hysteresis VCC > 5 V, VLINE = 0.3 V 12 Clamp level ILINE = 1mA 6 IDIS Input bias current VDIS = 0 to Vth Vth Disable threshold Voltage rising (1) Output duty cycle Both HVG and LVG Vclamp (1) DIS function 1.77 1.85 1.
Electrical characteristics Table 5. Symbol L6599 Electrical characteristics (continued) Parameter Test condition Min Typ Max Unit 0.5 µA Delayed shutdown function Ileak ICHARGE Open-state current V(DELAY) = 0 Charge current VDELAY = 1 V, VISEN = 0.85 V 100 150 200 µA Vth1 Threshold for forced operation at max. frequency Voltage rising (1) 1.92 2 2.08 V Vth2 Shutdown threshold Voltage rising (1) 3.3 3.5 3.7 V Vth3 Restart threshold Voltage falling (1) 0.25 0.3 0.
L6599 Typical electrical performance 6 Typical electrical performance Figure 4. Device consumption vs supply voltage Figure 5. IC consumption vs junction temperature Figure 6. VCC clamp voltage vs junction temperature Figure 7.
Typical electrical performance Figure 8. Oscillator frequency vs junction temperature Figure 10. Oscillator frequency vs timing components 12/36 L6599 Figure 9. Dead-time vs junction temperature Figure 11.
L6599 Typical electrical performance Figure 12. Reference voltage vs junction temperature Figure 13. Current mirroring ratio vs junction temperature Figure 14. OCP delay source current vs junction temperature Figure 15.
Typical electrical performance L6599 Figure 16. Standby thresholds vs junction temperature Figure 17. Current sense thresholds vs junction temperature Figure 18. Line thresholds vs junction temperature Figure 19. Line source current vs junction temperature Figure 20.
L6599 7 Application information Application information The L6599 is an advanced double-ended controller specific for resonant half-bridge topology. In these converters the switches (MOSFETs) of the half-bridge leg are alternately switched on and OFF (180° out-of-phase) for exactly the same time. This is commonly referred to as operation at "50 % duty cycle", although the real duty cycle, that is the ratio of the ON-time of either switch to the switching period, is actually less than 50 %.
Application information 7.1 L6599 Oscillator The oscillator is programmed externally by means of a capacitor (CF), connected from pin 3 (CF) to ground, that will be alternately charged and discharged by the current defined with the network connected to pin 4 (RFmin). The pin provides an accurate 2 V reference with about 2 mA source capability and the higher the current sourced by the pin is, the higher the oscillator frequency will be.
L6599 Application information After fixing CF in the hundred pF or in the nF (consistently with the maximum source capability of the RFmin pin and trading this off against the total consumption of the device), the value of RFmin and RFmax will be selected so that the oscillator frequency is able to cover the entire range needed for regulation, from the minimum value fmin (at minimum input voltage and maximum load) to the maximum value fmax (at maximum input voltage and minimum load): 1 RF min = -----------
Application information 7.2 L6599 Operation at no load or very light load When the resonant half-bridge is lightly loaded or unloaded at all, its switching frequency will be at its maximum value. To keep the output voltage under control in these conditions and to avoid losing soft-switching, there must be some significant residual current flowing through the transformer's magnetizing inductance.
L6599 Application information Essentially, RFmax will define the switching frequency fmax above which the L6599 will enter burst-mode operation. Once fixed fmax, RFmax will be found from the relationship: 3 RF min RF max = --- ⋅ --------------------8 f max ----------- – 1 f min Note that, unlike the fmax considered in the previous section ("Chapter 7.1: Oscillator"), here fmax is associated to some load PoutB greater than the minimum one.
Application information L6599 Figure 26. Load-dependent operating modes: timing diagram STBY 50 mV hyster. 1.25V t fosc t LVG HVG t PFC_STOP PFC GATE-DRIVE Resonant Mode Burst-mode Resonant Mode Figure 27.
L6599 7.3 Application information Soft-start Generally speaking, purpose of soft-start is to progressively increase converter's power capability when it is started up, so as to avoid excessive inrush current. In resonant converters the deliverable power depends inversely on frequency, then soft- start is done by sweeping the operating frequency from an initial high value until the control loop takes over.
Application information L6599 Figure 29. Power vs frequency curve in an resonant half-bridge |Z(f)| -1 RESONANCE FREQUENCY f Steady-state frequency Initial frequency As a result, the average input current will smoothly increase, without the peaking that occurs with linear frequency sweep, and the output voltage will reach the regulated value with almost no overshoot.
L6599 7.4 Application information Current sense, OCP and OLP The resonant half-bridge is essentially voltage-mode controlled; hence a current sense input will only serve as an overcurrent protection (OCP). Unlike PWM-controlled converters, where energy flow is controlled by the duty cycle of the primary switch (or switches), in a resonant half-bridge the duty cycle is fixed and energy flow is controlled by its switching frequency. This impacts on the way current limitation can be realized.
Application information L6599 Figure 31. Lossless current sensing technique, with capacitive shunt τ≈ L6599 6 ISEN pk CB 10 fmin 1N4148 RB VCrpk CA RA 1N4148 ICr Cr The device is equipped with a current sensing input (pin 6, ISEN) and a sophisticated overcurrent management system. The ISEN pin is internally connected to the input of a first comparator, referenced to 0.8 V, and to that of a second comparator referenced to 1.5 V.
L6599 Application information The circuit shown in Figure 31 can be operated in two different ways. If the resistor RA in series to CA is small (not above some hundred Ω, just to limit current spiking) the circuit operates like a capacitive current divider; CA will be typically selected equal to CR/100 or less and will be a low-loss type, the sense resistor RB will be selected as: C 0.8π R B = --------------- ⎛⎝ 1 + ------r-⎞⎠ I Crpkx CA and CB will be such that RB·CB is in the range of 10 /fmin.
Application information L6599 Figure 32. Soft-start and delayed shutdown upon overcurrent timing diagram Vcc TSH Css Primary Current ISEN DELAY 2V TMP TSTOP t Tss t 0A 0.8V t 3.5V t 2V 0.3V t Vout t PFC_STOP START-UP SOFT-START NORMAL OPERATION OVER LOAD NORMAL OPERATION OVERLOAD SHUTDOWN SOFT-START t MIN. POWER This function is realized with pin 2 (DELAY), by means of a capacitor CDelay and a parallel resistor RDelay connected to ground.
L6599 Application information The timing diagram of Figure 32 shows this operation. Note that if during TSTOP the supply voltage of the L6599 (Vcc) falls below the UVLO threshold the IC keeps memory of the event and will not restart immediately after VCC exceeds the start-up threshold if V(DELAY) is still higher than 0.3 V. Also the PFC_STOP pin will stay low as long as V(DELAY) is greater than 0.3 V.
Application information L6599 Figure 33. Line sensing function: internal block diagram and timing diagram With reference to Figure 33 the following relationships can be established for the ON (VinON) and OFF (VinOFF) thresholds of the input voltage: Vin ON – 1.25 –6 ---------------------------------- = 15 ⋅ 10 + 1.25 ----------RH RH Vin OFF – 1.25 1.
L6599 Application information voltage on the pin exceeds 7 V the device is shutdown. If its supply voltage is always above the UVLO threshold, the IC will restart as the voltage falls below 7 V. The LINE pin, while the device is operating, is a high impedance input connected to high value resistors, thus it is prone to pick up noise, which might alter the OFF threshold or give origin to undesired switch-off of the IC during ESD tests.
Application information L6599 This concern applies to converters designed with a high resonance frequency (indicatively, > 150 kHz), so that they run at high frequency also at full load. Otherwise, the converter will run at high frequency only at light load, where the current flowing in the MOSFETs of the half-bridge leg is lower, so that, generally, an RDS(on) rise is not an issue.
L6599 7.8 Application information Application example Figure 35.
Application information Table 6. L6599 EVAL6599-90W demo board, 90W adapter with L6563 & L6599: evaluation data Vin = 115 Vac 32/36 Vin = 230 Vac Vout Iout Pout Pin Eff. Vout Iout Pout Pin Eff. [V] [A] [W] [W] % [V] [A] [W] [W] % 18.95 4.71 89.25 99.13 90.04 18.95 4.71 89.25 97.23 91.80 18.95 3.72 70.49 78.00 90.38 18.96 3.72 70.53 76.74 91.91 18.97 2.7 51.22 56.55 90.57 18.97 2.7 51.22 55.85 91.71 18.98 1.71 32.46 36.00 90.16 18.98 1.71 32.
L6599 8 Package mechanical data 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: www.st.com. ECOPACK® is an ST trademark. Table 7. Plastic DIP-16 mechanical data mm. inch Dim. Min a1 0.51 B 0.77 Typ Max Min Typ Max 0.020 1.65 0.030 0.065 b 0.5 0.020 b1 0.25 0.
Package mechanical data Table 8. L6599 SO16N mechanical data mm. inch Dim. Min Typ A a1 Min Typ 1.75 0.1 Max 0.069 0.25 a2 0.004 0.009 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 0.150 0.157 G 4.60 5.30 0.181 0.208 L 0.4 1.27 0.150 0.050 M S Figure 37. Package dimensions 34/36 Max 0.62 0.024 8°(max.
L6599 9 Revision history Revision history Table 9.
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