STMicroelectronics

The EVL-SRK2001-HVS evaluation board for the SRK2001 synchronous rectification controller is suitable for LLC converter applications with higher output voltage (up to 48 V), thanks to the use of external sensing MOSFETs in series with DVS1,2 pins. An external VCCvoltage (12 V, max. 20 V) is required to supply the IC. The SRK2001 implements a control scheme for secondary-side synchronous rectification in LLC resonant converters, using a transformer with a center-tap secondary winding for full-wave rectification. It provides two high-current gate-drive outputs (for driving N-channel power MOSFETs). Each gate-driver is controlled separately and an interlock logic circuit prevents the two synchronous rectifier (SR) MOSFETs from conducting simultaneously. Device operation is based on adaptive algorithms for both turn-on and turn-off of SR MOSFETs. During fast load transitions or during the above resonance operation, a further turn-off mechanism based on a ZCD_OFF comparator is provided, which triggers the gate-drive circuit for a very fast MOSFET turn-off. The board includes two SR MOSFETs (TO220 package) and can be easily implemented in an existing converter to substitute rectifier diodes. Refer to the AN4674 for circuit implementation.

The EVL012LED is an LED driver board. This architecture is based on a two-stage approach: a front-end PFC preregulator and a downstream resonant half-bridge converter, using the new STNRG012 IC that embeds the controllers of both sections in the same device. Thanks to the STNRG012, the main features of this design are high efficiency, low power consumption at no load without an auxiliary supply, good power factor with low harmonic content, and reduced part count. The board also has a full set of protection features including output overload, short-circuit, and overvoltage; all of which can be easily defined as latched or auto-restart, simply changing a value in the non-volatile memory of the controller.

The EVL4984-350W demonstration board, based on the new L4984D continuous conduction mode PFC controller, implements a 350 W wide-range input PFC pre-conditioner. It is suitable for all SMPS from 150 W to several kWs, and is compliant with IEC61000-3-2 and JEITA-MITI standards.

The EVL62XX-MAIN is an expansion board that can host small EVL62XX-PLUG plug-in boards for quick and easy evaluation of brush DC and stepper motor drivers of the L62xx family. These boards provide an affordable and easy-to-use solution to drive dual brush DC and bipolar stepper motors in association with the evaluation software STSPIN Studio. The EVL62XX-MAIN is compatible with the Arduino UNO R3 connector.

The EVL62XX-MAIN is an expansion board that can host small EVL62XX-PLUG plug-in boards for quick and easy evaluation of brush DC and stepper motor drivers of the L62xx family. These boards provide an affordable and easy-to-use solution to drive dual brush DC and bipolar stepper motors in association with the evaluation software STSPIN Studio. The EVL62XX-MAIN is compatible with the Arduino UNO R3 connector.

The L6564H is a current-mode PFC controller operating in transition mode (TM) which embeds the same features existing in the L6564 with the addition of a high voltage startup source. These functions make the IC especially suitable for applications that must be compliant with energy saving regulations and where the PFC preregulator works as the master stage. The highly linear multiplier, along with a special correction circuit that reduces crossover distortion of the mains current, allows wide-range-mains operation with an extremely low THD even over a large load range. The output voltage is controlled by means of a voltage-mode error amplifier and an accurate (1% @TJ= 25 °C) internal voltage reference. The loop stability is optimized by the voltage feedforward function (1/V2 correction), which, in this IC, uses a proprietary technique that also considerably improves line transient response in the case of both mains drops and surges ("bi-directional"). In addition to overvoltage protection able to control the output voltage during transient conditions, the IC also provides protection against feedback loop failures or erroneous settings. Other onboard protection functions allow brownout conditions and boost inductor saturation to be safely handled. The totem pole output stage, capable of a 600 mA source and 800 mA sink current, is suitable for a high power MOSFET or IGBT drive. This, combined with the other features and the possibility to operate with ST's proprietary fixed-off-time control, makes the device an excellent solution for SMPS up to 400 W that requires compliance with EN61000-3-2 and JEITA-MITI standards.

The board implements a reference design of a 40W Switch Mode Power Supply dedicated to Set-Top Box, DVD and Auxiliary SMPS for Flat TV or small size Flat screen equipment. The board accepts wide range input voltage (90 to 265Vrms) and delivers 4 voltages. It is based on the L6566B, a new current mode fixed frequency or QR controller. High efficiency and low standby consumption are the main characteristics of this board. This joined to minimal part count required and low cost approach of the global solution makes it a very interesting solution for powering Digital Consumer Equipment, capable of meeting worldwide standby rules. The topology of this converter is the classical Flyback, working in continuous and discontinuous conduction mode with fixed frequency, capable of achieving the best trade-off between the peak/rms current ratio and output capacitors size. The nominal switching frequency, 62 KHz, has been chosen to get a compromise between the transformer size and the harmonics of the switching frequency, optimizing the input filter size and its cost. The input EMI filter is a classical Pi-filter, 1-cell for differential mode noise. The MOSFET is a standard and inexpensive 600V-2Ωmax, TO-220FP, needing a just small heat sink. The transformer is a layer type, using a standard ferrite type EER28L. It has been designed according to the EN60065. The reflected voltage is 70V, providing enough room for the leakage inductance voltage spike with still margin for reliability of the MOSFET. The output rectifiers have been selected according to the maximum reverse voltage, forward voltage drop and power dissipation. The rectifiers for 5V and 12V outputs are Schottky, low forward voltage drop type, hence dissipating less power with respect to standard types. They are housed in TO-220 package. A small heat sink for both devices is required. The other two output rectifiers are Schottky too but with a smaller package. The snubber R2 and C7 damps the oscillation produced by the diode D2 at MOSFET turn-on. A small LC filter has been added on all output in order to filter the high frequency ripple without increasing the output capacitors and a capacitor (100nF) has been placed on each output, to limit the spike amplitude. The output voltage regulation is performed by secondary feedback sensing the 12V, 5V and 3.3V outputs, while for 1.8V output the regulation is achieved by the transformer coupling. The feedback network uses a TS2431 as error amplifier which drives an optocoupler SFH617A-4, insuring the required insulation between primary and secondary. The opto-transistor modulates directly the voltage on COMP pin of the L6566B. The controller, the new L6566B, is an extremely versatile current mode primary controller embedding all functions needed to get very high performances power supplies. It integrates also all protections are needed by a power supply offering a very high degree of flexibility to the designer.

The EVL80WLED-STCH03 demonstration board implements a wide range 80 W - LED driver for street lighting applications with a primary current sensing control loop. The LED driver is a fixed current source with a very fast start-up time, protections to short-circuit and to open load. The board is optimized to supply an LED string load in the range from 40 V to 80V with a fixed 1 A current source with a very low current ripple. Due to current primary side STCH03 control loop, the output stage is composed of a simple diode rectification and the output capacitor. Form factor is compatible with street lighting application. At full load the efficiency is above the 90% at nominal voltages and remains very close to this value till half the load. Output short-circuit and no-load protections are auto-restart for a safe operation in lighting environment. Low input power is there at no-load conditions.