L6566B STMicroelectronics, L6566B Datasheet
L6566B
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L6566B Summary of contents
Page 1
... BURST-MODE + S MODE SELECTION & TURN-ON LOGIC TIME ZERO CURRENT OUT OVPL - DETECTOR + OVP OVERVOLTAGE LATCH PROTECTION IC_LATCH - AC_FAIL DISABLE 0.450V + UVLO 0.485V Rev 3 L6566B SO16N 6.4V - OVPL OVP LEB 7 1 OCP V CC Hiccup-mode 14V OCP logic OCP2 4 GD ...
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... PWM comparator, PWM latch and voltage feedforward blocks . . . . . . . . 27 5.7 Hiccup-mode OCP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 5.8 Frequency modulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 5.9 Latched disable function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 5.10 Soft-start and delayed latched shutdown upon overcurrent . . . . . . . . . . . 33 5.11 OVP block . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 5.12 Brownout protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 5.13 Slope compensation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 5.14 Summary of L6566B power management functions . . . . . . . . . . . . . . . . 41 2/51 L6566B ...
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... L6566B 6 Application examples and ideas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 7 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 8 Order codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 9 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 Contents 3/51 ...
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... Table 2. Pin functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Table 3. Absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Table 4. Thermal data Table 5. Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Table 6. L6566B light load management features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 Table 7. L6566B protections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 Table 8. External circuits that determine IC behavior upon OVP and OCP . . . . . . . . . . . . . . . . . . . 45 Table 9. SO16N mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 Table 10. Order codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 Table 11. ...
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... Addition of an offset to the current sense lowers the burst-mode operation threshold . . . . 25 Figure 13. Adaptive UVLO block Figure 14. Possible feedback configurations that can be used with the L6566B . . . . . . . . . . . . . . . . . 26 Figure 15. Externally controlled burst-mode operation by driving pin COMP: timing diagram Figure 16. Typical power capability change vs. input voltage in QR flyback converters . . . . . . . . . . . 28 Figure 17. Left: Overcurrent setpoint vs. VFF voltage ...
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... Description 1 Description The L6566B is an extremely versatile current-mode primary controller ICs, specifically designed for high-performance offline flyback converters also suited for single-stage single-switch input-current-shaping converters (single-stage PFC) for applications supposed to comply with EN61000-3-2 or JEITA-MITI regulations. Both fixed-frequency (FF) and quasi-resonant (QR) operation are supported. The user can pick either of the two depending on application needs. The device features an externally programmable oscillator: it defines converter’ ...
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... L6566B Figure 2. Typical system block diagram Rectified & Filtered Mains Voltage FLYBACK DC-DC CONVERTER L6566B Description V outdc 7/51 ...
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... Gate driver output. The totem pole output stage is able to drive power MOSFET’ and IGBT’s with a peak current capability of 800 mA source/sink. 8/51 HVS GND Vcc 6 11 FMOD DIS 8 9 Function L6566B AC_OK VFF SS OSC MODE/SC ZCD VREF COMP ...
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... L6566B Table 1. Pin functions (continued) N° Pin Supply voltage of both the signal part of the IC and the gate driver. The internal high voltage generator charges an electrolytic capacitor connected between this pin and GND (pin 3) as long as the voltage on the pin is below the turn-on threshold of the IC, after that it is disabled and the chip is turned on ...
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... OSC the oscillator frequency that defines the maximum allowed switching frequency of the L6566B, if working in QR mode, or the operating switching frequency if working in FF mode. Soft-start current source. At start-up a capacitor Css between this pin and GND (pin 3) is charged with an internal current generator. During the ramp, the internal ...
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... L6566B 3 Electrical data 3.1 Maximum rating Table 2. Absolute maximum ratings Symbol Pin V HVS I HVS FMOD 10, 14 max V 9, 15, 16 max I 11 ZCD V 12 MODE/ OSC P TOT T STG T J 3.2 Thermal data Table 3. Thermal data Symbol R Thermal resistance junction to ambient thJA Parameter ...
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... OSC to GND, REF T Min Typ Max 10 9.4 10 10.6 7.2 7.6 8 200 250 = 1 V 2.6 2 4.6 330 2500 440 500 700 65 80 100 0.55 0.85 1 1.6 0.8 40 4.4 5 5.6 12.5 13.5 14.5 9.4 10 10.6 L6566B Unit µ µ µA V ...
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... L6566B Table 4. Electrical characteristics (continued) Symbol Parameter Reference voltage V Output voltage REF V Total variation REF I Short circuit current REF Sink capability in UVLO V Overvoltage threshold OV Internal oscillator f Oscillation frequency sw V Voltage reference OSC D Maximum duty cycle max Brownout protection Vth Threshold voltage ...
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... COMP SOURCE ( VFF V = 3.3 V COMP V = 2.6 to 4.8 V COMP (1) (1) MODE/SC = open COMP Voltage falling (3) (3) MODE/SC = open (3) (3) MODE/SC = open L6566B Min Typ Max Unit -1 µA 150 250 300 ns 100 ns 0.92 1 1.08 0.45 0.5 0. 0.1 1.4 1.5 1.6 V 5 ...
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... L6566B Table 4. Electrical characteristics (continued) Symbol Parameter Zero current detector/ overvoltage protection V Upper clamp voltage ZCDH V Lower clamp voltage ZCDL V Arming voltage ZCDA V Triggering voltage ZCDT I Internal pull-up ZCD I Source current capability ZCDsrc I Sink current capability ZCDsnk T Turn-on inhibit time BLANK1 ...
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... V > COMP ( COMP COMPHi COMP COMPHi mA, Vcc = 12 V GDsource I = 100 mA GDsink mA; Vcc = 20 V GDsource Vcc = ccon sink ( ) = − − COMP FF L6566B Min. Typ. Max. Unit µA 3.5 5 6.5 3.5 5 6.5 µ 4.85 5 5.15 V 6 0.75 V -0 0.9 1.1 V VFF ...
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... Valley-skipping mode at medium/ light load. The externally programmable oscillator of the L6566B, synchronized to MOSFET’s turn-on, enables the designer to define the maximum operating frequency of the converter. As the load is reduced MOSFET’s turn- on will not any more occur on the first valley but on the second one, the third one and so on ...
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... Burst-mode with no or very light load. This kind of operation is activated in the same way and results in the same behavior as previously described for QR operation. The L6566B is specifically designed for applications with no PFC front-end; pin 6 (FMOD) features an auxiliary oscillator that can modulate the switching frequency (when FF operation is selected) in order to mitigate EMI emissions by a spread-spectrum action ...
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... L6566B With reference to the timing diagram of the voltage on the bulk capacitor (Vin) builds up and, at about 80 V, the HV generator is enabled to operate (HV_EN is pulled high) so that it draws about 1 mA. This current, minus the device’s consumption, charges the bypass capacitor connected from pin Vcc (5) to ground and makes its voltage rise almost linearly ...
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... Short circuit occurs here COMP 9 L6566B 11 BLANKING 5.7V TIME TURN-ON - MONO LOGIC STABLE + 100 OSCILLATOR Strobe Reset + FAULT 4:1 S/H Counter - 5V T rep < 0.03T rep VFF 15 line FFWD PWM blanking START DRIVER S AUXILIARY OSCILLATOR 6 13 FMOD OSC R MOD MOD L6566B +Vin Q Rs ...
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... This feature is typically used to detect transformer demagnetization for QR operation, where the signal for the ZCD input is obtained from the transformer’s auxiliary winding used also to supply the L6566B. The triggering block is blanked for T turn-off to prevent any negative-going edge that follows leakage inductance demagnetization from triggering the ZCD circuit erroneously ...
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... BLANK T ≤ − BLANK consequence, the maximum switching frequency will be a little and valley-skipping mode may take place slightly osc for further implications of T BLANK osc < in''' in'' after MOSFET’s BLANK osc = 150 kHz, the osc Section 5.11: OVP . L6566B t osc ...
Page 23
... L6566B start-up, at the end of the soft-start phase the output voltage of the converter must meet the condition: Equation 4 where Ns is the turn number of the secondary winding, Naux the turn number of the auxiliary winding and I The operation described so far under different operating conditions for the converter is ...
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... Burst-mode operation at no load or very light load When the voltage at the COMP pin (9) falls 20 mV below a threshold fixed internally at a value depending on the selected operating mode, the L6566B is disabled with COMPBM the MOSFET kept in OFF state and its consumption reduced at a lower value to minimize Vcc capacitor discharge ...
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... Vref o Vref 10 4 L6566B 7 3 and Vcc has exceeded the normal UVLO threshold (see Vcc UVLO Vcc Vcc OFF2 OFF1 (*) L6566B Application information internally fixed have more COMPO Figure 13 VCOMP (pin 9) V COMPL V COMPO Vcc (pin 5) Vcc OFF1 Vcc OFF2 Q ). The ...
Page 26
... The dynamics of the pin is in the 2 range. The voltage at the pin is clamped downwards at about the clamp is externally overridden and the voltage on the pin is pulled below 1.4 V the L6566B will shut down. This condition is latched as long as the device is supplied. While the device is disabled, however, no energy is coming from the self- supply circuit, thus the voltage on the Vcc capacitor will decay and cross the UVLO threshold after some time, which clears the latch and lets the HV generator restart ...
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... L6566B Figure 15. Externally controlled burst-mode operation by driving pin COMP: timing diagram Vcc (pin 5) Vcc Vcc OFF Vcc restart COMP (pin 9) GD (pin 4) Vcc_OK I charge 0.85 mA Vout 5.6 PWM comparator, PWM latch and voltage feedforward blocks The PWM comparator senses the voltage across the current sense resistor Rs and, by comparing it to the programming signal delivered by the feedforward block, determines the exact time when the external MOSFET switched off ...
Page 28
... Figure 17 on page 29 shows also how the function is included , which minimizes the power capability variation over the input opt V = ⋅ opt ⋅ min in max in min Figure 17 on page 29 (with the error amplifier csx k Vin opt 3 3.5 4 can be found: opt ) + ⋅ max R L6566B : it ...
Page 29
... Rs I PKp Rectif ied Line Voltage COMP 9 2.5 3 3.5 L6566B > Pout @ Vin the system is still undercompensated and k needs lim min @ Vin < Pout @ Vin lim max lim min in this way possible that Pout opt ”). The overcurrent setpoint will be then fixed at the maximum value of ...
Page 30
... If in the next switching cycle the comparator is not tripped, a temporary disturbance is assumed and the protection logic will be reset in its idle state; if the comparator will be tripped again a real malfunction is assumed and the L6566B will be stopped. Depending on the time relationship 30/51 = ...
Page 31
... This is what naturally occurs with QR operation, due to the twice-mains- frequency ripple appearing on the input bulk capacitor, which translates into different DCM- CCM boundary frequencies. The L6566B is provided with a dedicated pin, FMOD (6), to perform this function if FF mode is selected. Figure 19. Frequency modulation circuit ...
Page 32
... HV generator in this way cuts its power dissipation approximately by three (as compared to the case of continuous conduction) and keeps peak silicon temperature close to the average value. To let the L6566B restart it is then necessary to disconnect the converter from the input source. Pulling pin 16 (AC_OK) below the disable threshold (see protection on page 37 latch can be cleared and a quicker restart is allowed as the input source is removed ...
Page 33
... L6566B This function is useful to implement a latched overtemperature protection very easily by biasing the pin with a divider from VREF, where the upper resistor is an NTC physically located close to a heating element like the MOSFET, or the transformer. The DIS pin is a high impedance input, thus it is prone to pick up noise, which might give origin to undesired latch-off of the device ...
Page 34
... A control loop failure results in an output overvoltage that is handled by the OVP function of the L6566B (see next section). In case of QR operation, a short circuit causes the converter to run at a very low frequency, then with very low power capability ...
Page 35
... An internal current generator is activated that sources 1 mA out of the VFF pin (15). If the VFF voltage is allowed to reach 2 Vbe over 5 V, the L6566B will be latched off. See disable function on page 32 impedance externally connected to pin low that the 5+2 V reached or if some means is provided to prevent that, the device will be able to restart after the Vcc has dropped below 5 V. Refer to the “ ...
Page 36
... OVP comparator is active only for a small time window (typically, 0.5 µs) starting 2 µs after MOSFET’s turn-off, to reject the voltage spike associated to the positive-going edges of the voltage across the auxiliary winding Vaux; second, to stop the L6566B the OVP comparator must be triggered for four consecutive switching cycles. A counter, which is reset every time the OVP comparator is not triggered in one switching cycle, is provided to this purpose ...
Page 37
... RMS current. Secondly, spurious restarts may occur during converter power down, hence causing the output voltage not to decay to zero monotonically. L6566B shutdown upon brownout is accomplished by means of an internal comparator, as shown in the block diagram of inverting input of the comparator, available on the AC_OK pin (16), is supposed to sense a voltage proportional to the RMS (peak) mains voltage ...
Page 38
... OFF − 485 . 0 485 − = ⋅ and R , yield − ⋅ Vsen . 1 078 Vsen = ON OFF ; − ⋅ Vsen ON Vsen OFF VAC_OK 0.485V (pin 16) AC_FAIL I HYS 15 µA Vcc (pin 5) GD (pin 4) Vout − Vsen . OFF − Vsen . 0 45 OFF L6566B t 0.45V ...
Page 39
... L 2 opt L H π the peak mains voltage, while in the second case it π the peak mains voltage will be discharged after some ten ms then this F Application information AC mains (L/ AC_OK L6566B VFF Optionalfor OVP settings b) have been found as suggested above, L will be split as − ...
Page 40
... Note also that the burst-mode threshold (in terms of power) will be slightly changed. If slope compensation is not required with FF operation, the pin shall be left floating. 40/51 GD (pin 4) Figure external component other than the L6566B ...
Page 41
... L6566B 5.14 Summary of L6566B power management functions It has been seen that the device is provided with a number of power management functions: multiple operating mode upon loading conditions and protection functions. To help the designer familiarize with these functions, in the following tables all of theme are summarized with their respective activation mechanism and the resulting status of the most important pins ...
Page 42
... Application information Table 6. L6566B protections Protection Description Caused by V >V ZCD for 4 h consecutive Output switching OVP overvoltage cycles protection VFF > VFFlatch V COMP =V COMPHi V > SS Output V SSDIS OLP overload V protection COMP =V COMPHi V > SSLAT V COMP =V COMPHi V > SS Output short (4) V Short circuit ...
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... L6566B Table 6. L6566B protections (continued) Protection Description Caused by Shutdown V COMP Shutdown2 by V COMP V COMPOFF low Shutdown V < 9. going ( cc VCOMP V below V COMPL ccoff ADAPTIVE (lowering of UVLO V < 7. ccoff ( threshold at VCOMP V light load) COMPO 1. Use One external diode from Use one external diode from SS (#14 ...
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... R14 IC1 VFF 15 L6566B DIS VREF MODE/SC OSC R13 NTC2 R12 44/ HVS Vcc ZCD COMP GND Optional operation 1N4148 HVS Vcc R3 ZCD 1N4148 R18 SS COMP GND C8A IC3 TL431 C8A IC3 PC817A TL431 L6566B Vout R10 Vout R10 ...
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... VREF AC_OK L6566B VFF R ≈ 1N4148 SS VREF AC_OK L6566B VFF Application examples and ideas Vout C8A IC3 PC817A TL431 OVP auto-restart SS VREF R H AC_OK L6566B VFF R L2 − ⋅ Diode needed 1N4148 SS VREF R H AC_OK L6566B VFF R L2 − ⋅ ...
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... Application examples and ideas Figure 31. Frequency foldback at light load (FF operation) Figure 32. Latched shutdown upon mains overvoltage L6566B 46/51 MODE/SC Vref L6566B 13 OSC R T Vin Vcc BC847 5 DIS 8 15 VFF > COMP BC857C Vin BC857 Vref DIS 10 8 L6566B 15 VFF L6566B Rq ...
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... L6566B 7 Package mechanical data In order to meet environmental requirements, ST offers these devices in ECOPACK packages. These packages have a lead-free second level interconnect. The category of second Level Interconnect is marked on the package and on the inner box label, in compliance with JEDEC Standard JESD97. The maximum ratings related to soldering conditions are also marked on the inner box label ...
Page 48
... Min Typ 0.004 0.014 0.007 0.020 (typ.) 0.386 0.228 0.050 0.350 0.150 0.181 0.150 8°(max.) L6566B Max 0.069 0.009 0.063 0.018 0.010 0.394 0.244 0.157 0.208 0.050 0.024 ...
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... L6566B 8 Order codes Table 9. Order codes Order codes L6566B L6566BTR Package Packaging SO16N SO16N Tape and reel Order codes Tube 49/51 ...
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... Revision history 9 Revision history Table 10. Document revision history Date 20-Aug-2007 29-May-2008 02-Dec-2008 50/51 Revision 1 First release 2 Updated Figure 29 on page 3 Updated Figure 1 on page 1 L6566B Changes 44, Table 2 on page 11 and Section 5.6 on page 27 ...
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... L6566B 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. ...