Cosemitech. Industry Product Group

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1 Cosemitech subject to change without notice and Cosemitech product. Contact Cosemitech for the latest status FEATURES PACKAGE High Performance Transition-mode PFC controller Guaranteed for extreme temperature range (outdoor) -40 o C to 150 o C Superior temperature operation Wide VCC voltage range 10V to 32V Patented multiplier design for minimum THD Internal input voltage feedforward for fast input voltage response Over temperature protection Very accurate adjustable output overvoltage protection Ultra-low (15uA) start-up current Low (2mA) quiescent current Digital leading-edge blanking on current sense Disable function on E/A input 1% (@ TJ = 25 C) internal reference voltage -600/+800 ma Totem pole gate driver with high level clamp and active pull-down when UVLO Cycle by cycle protection Inductor saturation protection Light load mode to improve the efficient at light load SO-8 Package SO-8 APPLICATIONS PFC Pre-regulators for: - Street lighting - IEC compliant SMPS - Flat TVs and monitors - PC and Games - Electronic ballast Block Diagram INV COMP MULT CS VCC 8 Disable VFF V 0.45V Mult iplier and + 2.5V 0.2V + THD opt imizer Leading-edge Error AMP 1V Blanking - + PWM comparator Voltage Regulator Internal Supply Over voltasge Detection DYN OVP STA OVP R S SET CLR Q Q + - Driver &Cl amp Disable VCC 7 GD 12.5V 10V - + UVLO Disable Frequency limit 6 GND Lower & Upper Cl amps 1.4V 0.7V ZCD comp Starter ZCD Page 1/16

2 Description Cosemitech subject to change without notice and Cosemi-tech product. Contact Cosemi-tech for the latest status The is a current-mode PFC controller operating in transition mode (TM). The patented linear multiplier incorporating in-chip feedforward function is able to reduce the THD performance and improves the line transient response. It also optimizes the stability of the loop. The output voltage is controlled by a voltage-mode error amplifier and an accurate = 25 C) internal voltage reference. The device consumes low current (30μA max before start-up and < 4.5 ma at operating) and includes a disable function at INV pin, suitable for IC remote ON/OFF control, which makes it easier to comply with energy saving requirements (Blue Angel, EnergyStar, Energy2000, etc.). An effective two-step OVP enables afely handle over-voltages either occurring at startup or resulting from load disconnection. The totem-pole output stage, capable of 600 ma source and 800 ma sink current, is suitable to drive high current MOSFETs or IGBTs. This combined with the other features makes the device an excellent low-cost solution for EN compliant SMPS. add internal frequency limit at light load, which increase the efficiency of the whole system at light load. Typical Application Page 2/16

3 Cosemitech Table of Contents in development or undergoing evaluation. Details are subject to change without notice and Cosemi-tech assumes no obligation for future manufacture of this product. Contact Cosemi-tech for the latest status 1. PIN DEFINITIONS AND DESCRIPTIONS ABSOLUTE MAXIMUM RATINGS, THERMAL PROTECTION AND ESD PROTECTION ELECTRICAL CHARACTERISTIC TYPICAL ELECTRICAL PERFORMANCE APPLICATION INFORMATION PACKAGE INFORMATION Page 3/16

4 Cosemitech subject to change without notice and Cosemi-tech product. Contact Cosemi-tech for the latest status 1. Pin Definitions and Descriptions Table 1: Pin description Pin Name Type Function Inverting input of the error amplifier. The information on the 1 INV Input output voltage of the PFC pre-regulator is fed into this pin through a resistor divider. The pin doubles as an ON/OFF control input. Output of the error amplifier. A compensation network is placed 2 COMP Output between this pin and INV to achieve stability of the voltage control loop and ensure high power factor and low THD. Main input to the multiplier. This pin is connected to the rectified 3 MULT Input mains voltage via a resistor divider and provides the sinusoidal reference to the current loop. Input to the PWM comparator. The current flowing in the MOSFET is sensed through a resistor, the resulting voltage is 4 CS Input applied to this pin and compared with an internal sinusoidalshaped reference, generated by the multiplier, to determine MOSFET s turn-off. The pin is equipped with 200 ns leadingedge blanking for improved noise immunity. Boost inductor s demagnetization sensing input for transitionmode 5 ZCD Input operation. A negative-going edge triggers MOSFET s turn-on. 6 GND Ground Ground pin. Gate driver output. The totem pole output stage is able to drive power MOSFET s and IGBT s with a peak current of 600 ma 7 GD Output source and 800 ma sink. The high-level voltage of this pin is clamped at about 12 V to avoid excessive gate voltages in case the pin is supplied with a high Vcc. Supply voltage of both the signal part of the IC and the gate 8 Vcc Supply driver. The supply voltage upper limit is extended to 32 V min. to provide more headroom for supply voltage changes. Pin connections (top view) Page 4/16

5 Cosemitech in development or undergoing evaluation. Details are subject to change without notice and Cosemi-tech assumes no obligation for future manufacture of this product. Contact Cosemi-tech for the latest status 2. Absolute Maximum Ratings, Thermal Protection and ESD Protection 2.1 Absolute Maximum Ratings Parameter Symbol Min Max Units Supply Voltage Vcc Self-limited V Analog input and output INV, MULT, CS V COMP Output totem pole Current I_GD Self-limited ma Zero current detect sink and source current I_ZCD ma Operating Ambient temperature TA C Storage Temperature TS C Junction temperature TJ 165 C Note: Exceeding the absolute maximum ratings may cause permanent damage. Exposure to absolutemaximum- rated conditions for extended periods may affect device reliability & ESD Protection 2.2 Temperature Warning and Thermal Shutdown Parameter Symbol Min. Typ. Max. Unit Thermal shut-down junction temperature T SDOFF T j, 1) C T SDhys Hysteresis 55 C 1) non-overlapping 2.3 ESD protection Parameter Value Unit All pins (1) +/-4 kv All pins (2) +/-200 V 1) HBM (human body model, 100pF, 1.5 kohm ) according to MIL 883C, Method or EIA/JESD22A114-A 2) acc. Machine Model: C=200pF; R= 0 Ω Page 5/16

6 Cosemitech subject to change without notice and Cosemi-tech product. Contact Cosemi-tech for the latest status 3. Electrical Characteristic The voltages are referred to GND. VCC =12V, TJ =-40 to 150 C, C O = 1 nf; unless otherwise specified. Symbol Parameter Test Condition Min Typ Max Units VCC Operating range After turn on V VCC on Turn on threshold V VCC off Turn off threshold V Hys Hysteresis V Vz Zener voltage Icc=20mA V Supply current Istart-up Start up current Before turn on, VCC=11V ua Iq Quiescent current After turn off ma Icc Operating supply current At 70 khz ma Iqovp Quiescent current During OVP (either static or dynamic) ma Iqdis Quiescent current Vinv <=150mV ma Multiplier I MULT Input bias current VMULT = 0 to 3 V -1 ua V MULT Linear operation range 0 to 3 V V V cs/ V MULT Output max slope MULT=0 to 1V, V/V V COMP=Upper clamp K Gain (1) V MULT=1V, /V V COMP=4V Error amplifier V INV Voltage feedback input threshold Tj= V 10.5V<Vcc<32V V Line regulation V CC=10.5 V to 32V 2 5 mv I INV Input bias current V INV=0 to 3-1 ua Gv Voltage gain Open loop db GB Gain bandwidth product 1 MHz Source current V COMP=4V, V INV=2.4V ma Sink current V COMP=4V, V INV=2.6V ma Upper clamp voltage Isource=0.5mA V I COMP V COMP Lower clamp voltage Isink=0.5mA V V INVdis Disable threshold mv V INVen Restart threshold mv Output overvoltage I OVP Dynamic OVP triggering ua Hys Hysteresis (2) 20 ua Static OVP threshold V Current sense comparator I CS Input bias current V CS=0-1 ua Page 6/16

7 Cosemitech in development or undergoing evaluation. Details are subject to change without notice and Cosemi-tech assumes no obligation for future manufacture of this product. Contact Cosemi-tech for the latest status t LEB Leading edge blanking ns Td (H-L) Delay to output 175 ns V CS Current sense clamp V COMP=Upper clamp, Vmult=1.5V V Vcs offset Current sense offset Vmult=0,VFF=3V 40 mv Vmult=3V,VFF=3V 20 mv Vcs_oc Threshold of over current V Zero current detector VZCDH Upper clamp voltage IZCD=2.5mA V VZCDL Lower clamp voltage IZCD=-2.5mA V VZCDA Arming voltage (positivegoing edge) (2) 1.4 V VZCDT Triggering voltage (2) (negative-going edge) 0.7 V IZCDsrc Source current capability -2.5 ma IZCDsink Sink current capability 2.5 ma Starter tstart Gate driver Start time period us Restart after Vcs>Vcs_oc us VOL Output low voltage Isink=100mA V VOH Output high voltage Isource=5mA V Isrcpk Peak source current -0.6 A Isnkpk Peak sink current 0.8 A Tf Voltage fall time ns Tr Voltage rise time ns Voclamp Output clamp voltage Isource=5mA; Vcc=20V V UVLO saturation Vcc=0 to Vccon, Isink=2mA 1.1 V (1) The multiplier output is given by : VVFF means the peak voltage value of VMULT. (2) Parameters guaranteed by design, functionality tested in production. Page 7/16

8 4. Typical Electrical Performance Cosemitech subject to change without notice and Cosemi-tech product. Contact Cosemi-tech for the latest status Page 8/16

9 Cosemitech in development or undergoing evaluation. Details are subject to change without notice and Cosemi-tech assumes no obligation for future manufacture of this product. Contact Cosemi-tech for the latest status Page 9/16

10 Cosemitech subject to change without notice and Cosemi-tech product. Contact Cosemi-tech for the latest status Figure 13 Multiplier Characteristic Page 10/16

11 5. Application information Cosemitech in development or undergoing evaluation. Details are subject to change without notice and Cosemi-tech assumes no obligation for future manufacture of this product. Contact Cosemi-tech for the latest status 5.1 Voltage feedforward The power stage gain of PFC pre-regulators varies with the square of the RMS input voltage. So does the crossover frequency fc of the overall open-loop gain because the gain has a single pole characteristic. This leads to large trade-offs in the design. For example, setting the gain of the error amplifier to get fc = Vac means having fc 4 88 Vac, resulting in a sluggish control dynamics. Additionally, the slow control loop causes large transient current flow during rapid line or load changes that are limited by the dynamics of the multiplier output. This limit is considered when selecting the sense resistor to let the full load power pass under minimum line voltage conditions, with some margin. But a fixed current limit allows excessive power input at high line, whereas a fixed power limit requires the current limit to vary inversely with the line voltage. Voltage Feedforward can compensate for the gain variation with the line voltage and allow minimizing all of the above-mentioned issues. It consists of deriving a voltage proportional to the input RMS voltage, feeding this voltage into a squarer/divider circuit (1/V 2 corrector) and providing the resulting signal to the multiplier that generates the current reference for the inner current control loop (see Figure 14). Figure 14 Voltage feedforward: squarer-divider (1/V2) block diagram and transfer characteristic In this way a change of the line voltage causes an inversely proportional change of the half sine amplitude at the output of the multiplier (if the line voltage doubles the amplitude of the multiplier output is halved and vice versa) so that the current reference is adapted to the new operating conditions with (ideally) no need for invoking the slow dynamics of the error amplifier. Additionally, the loop gain is constant throughout the input voltage range, which improves significantly dynamic behavior at low line and simplifies loop design. The realizes a NEW voltage feed forward circuit that, with a technique that makes not use of any additional external parts, and have a very good VMULT peak track ability, the VFF output voltage is perfect flat Page 11/16

12 Cosemitech subject to change without notice and Cosemi-tech product. Contact Cosemi-tech for the latest status 5.2 Overvoltage protection Under steady-state conditions, the voltage control loop keeps the output voltage Vo of a PFC preregulator close to its nominal value, set by the resistors R1 and R2 of the output divider. Neglecting ripple components, the current through R1, IR1, equals that through R2, IR2. Considering that the non-inverting input of the error amplifier is internally referenced at 2.5 V, also the voltage at pin INV will be 2.5 V, then: Equation 1 If the output voltage experiences an abrupt change ΔVo > 0 due to a load drop, the voltage at pin INV will be kept at 2.5 V by the local feedback of the error amplifier, a network connected between pins INV and COMP that introduces a long time constant to achieve high PF (this is why ΔVo can be large). As a result, the current through R2 will remain equal to 2.5/R2 but that through R1 will become: Equation 2 The difference current ΔIR1=I'R1-IR2=I'R1-IR1= ΔVo/R1 will flow through the compensation network and enter the error amplifier output (pin COMP). This current is monitored inside the device As the current exceeds 27 μa, the OVP is triggered (Dynamic OVP): the gate-drive is forced low to switch off the external power transistor and the IC put in an idle state. This condition is maintained until the current falls below approximately 7 μa, which re-enables the internal starter and allows switching to restart. The output ΔVo that is able to trigger the Dynamic OVP function is then: Equation 3 ΔV O = R An important advantage of this technique is that the OV level can be set independently of the regulated output voltage: the latter depends on the ratio of R1 to R2, the former on the individual value of R1. Another advantage is the precision: the tolerance of the detection current is 13%, i.e. 13% tolerance on ΔVo. Since ΔVo << Vo, the tolerance on the absolute value will be proportionally reduced. Example: Vo = 400 V, ΔVo = 40 V. Then: R1 = 40 V/27 μa 1.5 MΩ; R2 = 1.5 MΩ 2.5/( ) = 9.43 kω. The tolerance on the OVP level due to the will be = 5.3 V, that is ± 1.2 % When the load of a PFC pre-regulator is very low, the output voltage tends to stay steadily above the nominal value, which cannot be handled by the Dynamic OVP. If this occurs, however, the error amplifier output will saturate low; hence, when this is detected the external power transistor is switched off and the IC put in an idle state (static OVP). Normal operation is resumed as the error amplifier goes back into its linear region. As a result, the device will work in burst-mode, with a repetition rate that can be very low. When either OVP is activated the quiescent consumption of the IC is reduced to minimize the discharge of the Vcc capacitor and increase the hold-up capability of the IC supply system. 5.3 Disable function The INV pin doubles its function as a not-latched IC disable: a voltage below 0.2 V shuts down the IC and reduces its consumption at a lower value. To restart the IC, the voltage on the pin must exceed 0.45 V. The main usage of this function is a remote ON/OFF control input that can be driven by a PWM controller for power management purposes. However it also offers a certain degree of additional safety since it will cause the IC to shutdown in case the lower resistor of the output divider is shorted to ground or if the upper resistor is missing or fails open. 5.4 THD optimizer circuit Page 12/16

13 Cosemitech in development or undergoing evaluation. Details are subject to change without notice and Cosemi-tech assumes no obligation for future manufacture of this product. Contact Cosemi-tech for the latest status The provided with a special circuit that reduces the conduction dead-angle occurring to the AC input current near the zero-crossings of the line voltage (crossover distortion). In this way the THD (total harmonic distortion) of the current is considerably reduced. 5.5 Inductor saturation protection Boost inductor's hard saturation may be a fatal event for a PFC pre-regulator: the current upslope becomes so large ( times steeper) that during the current sense propagation delay the current may reach abnormally high values. The voltage drop caused by this abnormal current on the sense resistor reduces the gate-to-source voltage, so that the MOSFET may work in the active region and dissipate a huge amount of power, which leads to a catastrophic failure after few switching cycles. However, in some applications such as ac-dc adapters, where the PFC pre-regulator is turned off at light load for energy saving reasons, even a well-designed boost inductor may occasionally slightly saturate when the PFC stage is restarted because of a larger load demand. This happens when the restart occurs at an unfavorable line voltage phase, i.e. when the output voltage is significantly below the rectified peak voltage. As a result, in the boost inductor the inrush current coming from the bridge rectifier adds up to the switched current and, furthermore, there is little or no voltage available for demagnetization. To cope with a saturated inductor, the is provided with a second comparator on the current sense pin (CS, pin 4) that stops the IC if the voltage, normally limited within 1.1 V, exceeds 1.7 V. After that, the IC attempts to restart by the internal starter circuitry; the starter repetition time is twice the nominal value to guarantee lower stress for the inductor and boost diode. Hence, the system safety is considerably increased. 5.6 Frequency limit Near the zero crossing node of rectified line voltage, the frequency of regulator would become much high especially at light load. It decreases the efficiency of the whole system. To solve this problem, add frequency limit block to limit the max frequency of the operation to get better efficiency at light load condition. 5.7 Operating with no auxiliary winding on the boost inductor To generate the synchronization signal on the ZCD pin, the typical approach requires the connection between the pin and an auxiliary winding of the boost inductor through a limiting resistor. When the device is supplied by the cascaded DC-DC converter, it is necessary to introduce a supplementary winding to the PFC choke just to operate the ZCD pin. Another solution could be implemented by simply connecting the ZCD pin to the drain of the power MOSFET through an R-C network as shown in figure 15: in this way the high frequency edges experienced by the drain will be transferred to the ZCD pin, hence arming and triggering the ZCD comparator. Also in this case the resistance value must be properly chosen to limit the current sourced/sunk by the ZCD pin. In typical applications with output voltages around 400 V, recommended values for these components are 22 pf (or 33 pf) for CZCD and 330 kω for RZCD. With these values proper operation is guaranteed even with few volts difference between the regulated output voltage and the peak input voltage Page 13/16

14 Cosemitech Figure 15. ZCD pin synchronization without auxiliary winding subject to change without notice and Cosemi-tech product. Contact Cosemi-tech for the latest status 5.8 Other Protections This device ensures good protection includes OTP (Over temperature protection); UVLO (VCC under voltage lockout), cycle-by-cycle current limiting, Gate driver output clamp and over current protection (. Page 14/16

15 Cosemitech in development or undergoing evaluation. Details are subject to change without notice and Cosemi-tech assumes no obligation for future manufacture of this product. Contact Cosemi-tech for the latest status 7. Package Information Symbol Parameter Test Condition Min Typ Max Units RTH SO-8 Package Thermal Resistance 150 C/W Package dimensions: Page 15/16

16 Cosemitech subject to change without notice and Cosemi-tech product. Contact Cosemi-tech for the latest status Information furnished is believed to be accurate and reliable. However, Cosemitech 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 Cosemitech. Specification mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied. Cosemi-tech products are not authorized for use as critical components in life support devices or systems without express written approval of Cosemi-tech. The Cosemitech logo is a registered trademark of Cosemitech Page 16/16