L6591 PWM controller for ZVS half bridge Datasheet − production data Features ■ Complementary PWM control for soft-switched half bridge with programmable deadtime ■ Up to 500 kHz operating frequency ■ Onboard high-voltage startup ■ Advanced light load management ■ Adaptive UVLO ■ Pulse-by-pulse OCP ■ OLP (latched or autorestart) ■ Transformer saturation detection ■ Interface with PFC controller Applications ■ Latched disable input ■ High power AC-DC adapter/charger ■ Input for power
Contents L6591 Contents 1 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2 Pin settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3 2.1 Connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.2 Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Electrical data .
L6591 1 Description Description The L6591 is a double-ended PWM controller specific to the soft-switched half bridge topology. It provides complementary PWM control, where the high-side switch is driven ON for a duty cycle D and the low-side switch for a duty cycle 1-D, with D < 50%. An externally programmable deadtime inserted between the turn-off of one switch and the turn-on of the other one guarantees soft-switching and enables high-frequency operation.
Pin settings L6591 2 Pin settings 2.1 Connection Figure 3. Pin connection (top view) LINE 1 16 HVSTART DIS 2 15 BOOT ISEN 3 14 HVG SS 4 13 FGND OSC 5 12 N.C. VREF 6 11 GND COMP 7 10 LVG PFC_STOP 8 9 Vcc AM13254v1 2.2 Functions Table 1. Pin N. 1 2 4/41 Pin functions Name Function LINE Line sensing input. The pin is to be connected to the high-voltage input bus with a resistor divider. A voltage below 1.
L6591 Pin settings Table 1. Pin N. 3 4 5 6 7 8 Pin functions (continued) Name Function ISEN Current sense (PWM comparator) input.
Pin settings L6591 Table 1. Pin N. Name Function 9 Vcc Supply voltage of both the signal part of the IC and the low-side gate driver. The internal high-voltage generator charges an electrolytic capacitor connected between this pin and GND (#11) as long as the voltage on the pin is below the startup threshold of the IC, after that, it is disabled and the chip turns on. Sometimes a small bypass capacitor (0.1 µF typ.) to GND may be useful to get a clean bias voltage for the signal part of the IC.
L6591 Electrical data 3 Electrical data 3.1 Maximum ratings Table 2. Absolute maximum ratings Symbol Pin VHVSTART 16 IHVS Value Unit Voltage range (referred to ground) -0.
Electrical characteristics 4 L6591 Electrical characteristics TJ = 0 to 105 °C, Vcc = 15 V, VBOOT = 12 V, CHVG = CLVG = 1 nF; RT = 22 kΩ, CT = 330 pF; unless otherwise specified. Table 4. Electrical characteristics Symbol Parameter Test condition Min. Typ. Max. Unit IC supply voltage Vcc VccOn VccOff Operating range after turn-on VCOMP > VCOMPL 11.3 22 VCOMP = VCOMPL 9.2 22 Turn-on threshold (1) 13 14 15 VCOMPL 9.7 10.5 11.3 = VCOMPL 8.2 8.7 9.
L6591 Electrical characteristics Table 4. Electrical characteristics (continued) Symbol IHV, ON IHV, OFF Parameter Test condition ON-state current Min. Typ. VHV > VHvstart, Vcc > 3 V 1.6 VHV > VHvstart, Vcc = 0 0.8 (1) (1) After DIS tripping Unit mA Leakage current (OFF-state) VHV = 400 V VCCrestart HV generator restart voltage Max. 40 µA 4.4 5 5.6 V 12.2 13.2 14.2 V 5 5.1 V Reference voltage (1) VREF Output voltage TJ = 25 °C; IREF = 1 mA 4.
Electrical characteristics Table 4. L6591 Electrical characteristics (continued) Symbol Parameter Test condition Min. Typ. Max. Unit -1 µA DIS function IOTP Input bias current Vth Disable threshold VDIS = 0 to Vth 4.275 4.5 4.725 V TJ = 25 °C 170 180 190 kHz Vcc = 9.2 to 22 V 168 180 192 kHz Oscillator peak voltage (1) 2.85 3 3.15 V Oscillator valley voltage (1) 0.75 0.9 1.
L6591 Electrical characteristics Table 4. Electrical characteristics (continued) Symbol Parameter Test condition Min. Typ. Max. Unit tf Fall time 40 ns tr Rise time 80 ns Vcc = 0 to VccOn, Isink = 1 mA UVLO saturation 1.1 V 1.5 V High-side gate driver (voltages referred to FGND) VHVGL Output low-voltage Isink = 200 mA VHVGH Output high-voltage Isource = 5 mA Isourcepk Peak source current (2) Isinkpk Peak sink current (2) 11 11.9 V -0.3 A 0.
Typical characteristics L6591 5 Typical characteristics Figure 4. High-voltage generator ON-state sink current vs. Tj Figure 5. ϭ͘Ϯ High-voltage generator output (Vcc charge current) vs. Tj ϭϭϬй ϭ ϭϬϱй sĐĐ ш ϯs Ϭ͘ϴ ϭϬϬй / , Z' й /,s ŵ sĐĐ ш ϯs sĐĐ с Ϭs Ϭ͘ϲ ϵϱй Ϭ͘ϰ ϵϬй Ϭ͘Ϯ ϴϱй Ϭ ϴϬй ͲϱϬ Ϭ ϱϬ ϭϬϬ ϭϱϬ ͲϱϬ Ϭ dũ Σ ϱϬ ϭϬϬ ". W Figure 6. ϭϱϬ dũ Σ High-voltage generator start voltage vs. Tj ". W Figure 7. High-voltage generator Vcc restart voltage vs.
L6591 Typical characteristics Figure 8. IC consumption during normal operation vs. Tj Figure 9. IC consumption under protection and before turn-on vs. Tj Ϭ͘ϯϱ ϲ Ϭ͘ϯ ϱ KƉĞƌĂƚŝŶŐ Ϭ͘Ϯϱ YƵŝĞƐĐĞŶƚ ϰ /ĐĐ ŵ /ĐĐ ŵ ƵƌƐƚ ŵŽĚĞ ϯ Ϭ͘Ϯ Ϭ͘ϭϱ >/E ф ϭ͘ϰϰs Ϯ /^ х ϰ͘ϱs Ϭ͘ϭ /^ E х ϭ͘ϱs ϭ ĞĨŽƌĞ ƚƵƌŶ ŽŶ ;sĐĐсϭϮ͘ϱsͿ Ϭ͘Ϭϱ Ϭ Ϭ ͲϱϬ Ϭ ϱϬ ϭϬϬ ͲϱϬ ϭϱϬ Ϭ ϱϬ ϭϬϬ ϭϱϬ dũ Σ dũ Σ ". W Figure 10. Startup & UVLO vs. Tj ". W Figure 11. Vcc Zener voltage vs.
Typical characteristics L6591 Figure 12. COMP voltage upper clamp level vs. Figure 13. COMP source current vs. Tj Tj ϭϮϬй ϳ ϭϬϬй ϲ͘ϱ / KDW й s KDW s ϴϬй ϲ ϲϬй s KDW с Ϯ s / KDW с Ϭ ϰϬй ϱ͘ϱ ϮϬй sĂůƵĞƐ ŶŽƌŵĂůŝnjĞĚ ƚŽ / KDW Λ ϮϱΣ Ϭй ϱ ͲϱϬ Ϭ ϱϬ ϭϬϬ ͲϱϬ ϭϱϬ Ϭ ϱϬ ϭϬϬ ϭϱϬ dũ Σ dũ Σ ". W Figure 14. COMP dynamic resistance vs. Tj ". W Figure 15. Oscillator frequency vs.
L6591 Typical characteristics Figure 16. Oscillator ramp vs. Tj Figure 17. Max. duty cycle vs. Tj ϱϬй ϯ͘ϱ ϯ s KDW с ϱ s ϰϵй ϰϴй sƉŬ Ϯ ŵĂdž й sK^ s Ϯ͘ϱ sǀLJ ϭ͘ϱ ϰϳй ϭ ϰϲй Ϭ͘ϱ ϰϱй Ϭ ͲϱϬ Ϭ ϱϬ ϭϬϬ ͲϱϬ ϭϱϬ Ϭ ϱϬ ϭϬϬ ϭϱϬ dũ Σ dũ Σ ". W Figure 18. Current sense clamp vs. Tj ". W Figure 19. Disable level on current sense vs.
Typical characteristics L6591 Figure 20. Reference voltage vs. Tj Figure 21. DIS threshold vs. Tj ϱ͘ϭ ϱ ϱ͘Ϭϴ ϰ͘ϵ ϰ͘ϴ ϱ͘Ϭϲ s с ϭϱ s /Z & с ϭ ŵ ϱ͘Ϭϰ ϰ͘ϳ ϰ͘ϲ s /^ s sZ & s ϱ͘ϬϮ ϱ ϰ͘ϱ ϰ͘ϵϴ ϰ͘ϰ ϰ͘ϵϲ ϰ͘ϯ ϰ͘ϵϰ ϰ͘Ϯ ϰ͘ϵϮ ϰ͘ϭ ϰ ϰ͘ϵ ͲϱϬ Ϭ ϱϬ ϭϬϬ ͲϱϬ ϭϱϬ Ϭ ϱϬ ϭϬϬ ϭϱϬ dũ Σ dũ Σ ". W Figure 22. Soft-start charge current vs. Tj ". W Figure 23. Soft-start discharge current vs.
L6591 Typical characteristics Figure 24. UVLO saturation vs. Tj Figure 25. Soft-start clamp voltage vs. Tj Ϭ͘ϵ Ϯ͘ϱ Ϭ͘ϴ Ϯ͘ϰ Ϯ͘ϯ Ϭ͘ϳ Ϯ͘Ϯ Ϭ͘ϲ s KDW с ϰ s s^^ s s>s' s Ϯ͘ϭ Ϭ͘ϱ s с Ϭ s /^/E< с ϭ ŵ Ϭ͘ϰ Ϯ ϭ͘ϵ Ϭ͘ϯ ϭ͘ϴ Ϭ͘Ϯ ϭ͘ϳ Ϭ͘ϭ ϭ͘ϲ ϭ͘ϱ Ϭ ͲϱϬ Ϭ ϱϬ ϭϬϬ ͲϱϬ ϭϱϬ Ϭ ϱϬ ϭϬϬ ". W Figure 26. UVLO saturation vs. Tj ". W Figure 27. Soft-start clamp voltage vs.
Typical characteristics L6591 Figure 28. Low-side gate drive output low saturation Figure 29. Gate drive output low-voltage vs. Tj Ϭ͘ϱ ϭ͘ϴ Ϭ͘ϰϱ ϭ͘ϲ Ϭ͘ϰ ϭ͘ϰ Ϭ͘ϯϱ s>s' Θ s,s' s ϭ͘Ϯ Ϭ͘ϯ s>s' s / с ϮϬϬ ŵ ,ŝŐŚ ƐŝĚĞ ƌĞĨĞƌƌĞĚ ƚŽ &'E Ϭ͘Ϯϱ Ϭ͘Ϯ ϭ ,ŝŐŚ ƐŝĚĞ Ϭ͘ϴ >Žǁ ƐŝĚĞ Ϭ͘ϲ Ϭ͘ϭϱ Ϭ͘ϰ Ϭ͘ϭ Ϭ͘Ϯ Ϭ͘Ϭϱ Ϭ Ϭ Ϭ ϱϬ ϭϬϬ ϭϱϬ ϮϬϬ ͲϱϬ ϮϱϬ Ϭ ϱϬ ϭϬϬ ϭϱϬ dũ Σ />s' ŵ ". W Figure 30. Gate drive output high-voltage vs. Tj ". W Figure 31. High-side pull-down resistor vs.
L6591 Typical characteristics Figure 32. Burst mode thresholds vs. Tj Figure 33. Burst mode hysteresis vs. Tj ϵϬ ϭ͘ϵ ϭ͘ϴϱ KĨĨ ƚŚƌĞƐŚŽůĚ ;s KDW ƌĂŝƐŝŶŐͿ ϴϱ ϭ͘ϴ ϴϬ s KDW ƌĂŝƐŝŶŐ ϭ͘ϳ s KDW ŵs s KDW s ϭ͘ϳϱ KŶ ƚŚƌĞƐŚŽůĚ ;s KDW ĨĂůůŝŶŐͿ ϭ͘ϲϱ ϳϱ ϳϬ ϭ͘ϲ ϲϱ ϭ͘ϱϱ ϲϬ ϭ͘ϱ ͲϱϬ Ϭ ϱϬ ϭϬϬ ϭϱϬ ͲϱϬ Ϭ dũ Σ ϱϬ ϭϬϬ ϭϱϬ dũ Σ ". W Figure 34. Line sensing threshold vs. Tj ". W Figure 35. Line sensing current hysteresis vs.
Typical characteristics L6591 Figure 36. Deadtime vs. Tj Figure 37. Oscillator frequency vs. RT, CT ϱϬϬ ϭ͘Ϯ ϰϱϬ ϭ d с ϭϬϬƉ& ϰϬϬ Zd с ϮϮ< Ͳ d с ϭŶ& d с ϮϮϬƉ& ϯϱϬ d с ϯϯϬƉ& Ϭ͘ϴ d с ϰϳϬƉ& ĨK^ <,nj d ŵƐ ϯϬϬ Ϭ͘ϲ d с ϲϴϬƉ& ϮϱϬ d с ϭŶ& ϮϬϬ Ϭ͘ϰ ϭϱϬ Zd с ϮϮ< Ͳ d с ϯϯϬƉ& ϭϬϬ Ϭ͘Ϯ ϱϬ Ϭ Ϭ ͲϱϬ Ϭ ϱϬ ϭϬϬ ϭϱϬ Ϭ ". W Figure 38. Deadtime vs.
L6591 6 Application information Application information The L6591 is an advanced current-mode PWM controller specific for fixed-frequency, peakcurrent-mode-controlled ZVS half bridge converters. In these converters the switches (MOSFET) are controlled with complementary duty cycle: the high-side MOSFET is driven ON for a duty cycle D and the low-side MOSFET for a duty cycle 1-D. For a proper operation the maximum allowed duty cycle must be limited below 50%.
Application information 6.1 L6591 High-voltage startup generator Figure 40 shows the internal schematic of the high-voltage startup generator (HV generator). It is made up of a high-voltage N-channel FET, whose gate is biased by a 15 MW resistor, with a temperature-compensated current generator connected to its source.
L6591 Application information Figure 41. Timing diagram: normal power-up and power-down sequences Vin VHstart Vcc Vccon t regulation is lost here Vccoff Vcc restart t PFC_STOP HVG , LVG t HV_EN t Vcc_OK Ich arg e t 0.75 mA t P ower-on Normal operation P ower- off AM13257v1 At converter power-down the system loses regulation as soon as the input voltage is so low that either peak current or maximum duty cycle limitation is tripped.
Application information L6591 Figure 42. Timing diagram showing short-circuit behavior (SS pin clamped below 5 V) Vcc LVG,HVG Vcc_OK AM13258v1 6.2 Operation at no load or very light load When the PWM control voltage at the COMP pin falls below a threshold located at 1.75 V, the IC is disabled with both the high-side and the low-side MOSFET kept in OFF-state, the oscillator stopped and the quiescent consumption very much reduced to minimize Vcc capacitor discharge.
L6591 Application information Figure 43. Load-dependent operating modes: timing diagram COMP 1.82V 1.75V t fosc t L VG, HVG t PF C_STOP PFC GATE-DR IVE F i x. Fr eq . M od e Bu rst -mo d e Fi x. Freq . Mo de AM13259v1 Figure 44.
Application information L6591 Figure 45. How the L6591 can switch off a PFC controller at light load ZCD Vref 5.6 k 6 47 k L6591 L6591 8 PFC_STOP L6562 B C547 B C547 8 PFC_STOP L6563 PFC_OK (AC_OK) AM13261v1 6.3 PWM control block The device is specific to secondary feedback. Typically, there is a TL431 at the secondary side and an optocoupler that transfers output voltage information to the PWM control at the primary side, crossing the isolation barrier.
L6591 Application information Figure 46. Hiccup mode OCP: timing diagram (device self-supplied) Sec on da ry di od e i s s ho rted he re Vc c Vcc on Vcc off Vccr esta rt VC S t 1.5 V t LVG, HV G OC P la tc h t Vc c_ OK t PFC _S top t t AM13262v1 6.5 Latched shutdown The L6591 is equipped with a comparator having the non-inverting input externally available at the DIS pin (#2) and with the inverting input internally referenced to 4.5 V.
Application information L6591 Figure 47. Operation after latched disable activation: timing diagram DIS 4 .
L6591 Application information During the negative-going ramp of the sawtooth, a clock pulse is released. A T-flip-flop, along with a logic circuit, separates the odd and the even clock pulses. The even ones turn off the low-side MOSFET first and, after a dead time Td, turn on the high-side MOSFET.
Application information L6591 Figure 48. Oscillator waveforms and their relationship with gate-driving signals O SC Cl ock t HVG t t LVG Td Td T on Td t Tsw AM13264v1 6.7 Adaptive UVLO A major problem when optimizing a converter for minimum no load consumption is that the voltage generated by the self-supply system under these conditions falls considerably as compared even to a few mA load.
L6591 6.8 Application information Line sensing function This function basically stops the IC as the input voltage to the converter falls below the specified range and lets it restart as the voltage goes back within the range.
Application information L6591 Equation 6 Vin ON − 1.25 1.25 = 15 ⋅ 10 − 6 + RH RL Vin OFF − 1.25 1.25 = RH RL which, solved for RH and RL, yields: Equation 7 RH = Vin ON − Vin OFF 15 ⋅ 10 −6 ; RL = RH 1.25 Vin OFF − 1.25 While the line undervoltage is active the startup generator keeps on working but there is no PWM activity, therefore the Vcc voltage continuously oscillates between the startup and the UVLO thresholds, as shown in the timing diagram of Figure 52.
L6591 Application information Figure 51. Soft-start pin operation under different operating conditions AM13267v1 While, in the case of feedback loop failure, the system must be stopped quickly to prevent the output voltage from reaching too high values, an overload or a short-circuit does not generally need such fast intervention. The L6591 makes it easier to handle such conditions: the 2 V clamp on the SS pin is removed and a second internal current generator ISS2 = ISS1 /4 keeps on charging Css.
Summary of L6591 power management functions 7 L6591 Summary of L6591 power management functions It has been shown that the device is provided with a number of power management functions: different operating mode upon loading conditions, protection functions, as well as interaction with the PFC pre-regulator.
L6591 Table 6. Summary of L6591 power management functions Protection (continued) Protection Description Caused by Vcc IC Iq VREF IC restart behavior [mA] [V] [V] SS VCOMP [V] OSC [V] PFC_STOP Protection Description Caused by Vcc IC Iq VREF IC restart [mA] [V] behavior [V] SS VCOMP [V] OSC [V] PFC_STOP 2nd OCP Transformer VISEN > saturation or 1.
/41 NTC1 10 Vin = 88 to 264 V ac F1 T4A LF1-B CX1 0.47 F LF1-A C15 TBD 8 2 Doc ID 14821 Rev 6 C10 10n 1 LI NE CX2 0. 68 F NTC1 TBD OC2B 4 1/ 2 PC817A R20 TBD 3 DIS PFC_STOP LF2-B LF2-A 6 BD1 FBI 6K5F1 IC2 C16 100 nF R21 TB D V REF 5 L659 1 16 HVSTART 9 C17 TBD 4 C18 TBD SS R13 47 C4 3. 3nF R2 68k Vcc D5 1N4148 (optional) OSC C11 220n R2 33k 0.
ECOPACK® L6591 8 ECOPACK® 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. SO16 narrow mechanical data mm Dim. Min. Typ. A Max. 1.75 A1 0.1 A2 1.25 b 0.31 0.51 c 0.17 0.25 D 9.8 9.9 10 E 5.8 6 6.2 E1 3.8 3.9 4 e 0.25 1.27 h 0.25 0.
ECOPACK® L6591 Figure 53.
L6591 9 Order codes Order codes Table 8.
Revision history 10 L6591 Revision history Table 9. Document revision history Date Revision Changes 19-Jun-2008 1 Initial release 17-Oct-2008 2 Updated: Section 1: Description on page 3 24-Mar-2009 3 Updated: Table 4 on page 8 19-May-2009 4 Updated: Table 4 on page 8, Section 6.
L6591 Please Read Carefully: Information in this document is provided solely in connection with ST products. STMicroelectronics NV and its subsidiaries (“ST”) reserve the right to make changes, corrections, modifications or improvements, to this document, and the products and services described herein at any time, without notice. All ST products are sold pursuant to ST’s terms and conditions of sale.
