COMPMIN CS CCLIM Oscillator CC Amplifier Limits …

1 RED2511. LED Controller for LLC converters Features Advanced LED Controller IC for high efficiency low-cost LLC converters with bipolar transistors and integrated PFC. PSR - +/-5% Primary Side Regulation of LED current and voltage with no Flicker SO8. 50% duty cycle, variable frequency control of resonant half-bridge Automatic dead-time control and Applications capacitive mode protection Single stage PFC LED drivers without flicker Protection modes: CC LED drivers 5-100W. Overload No-Load Internal Over-temperature Order code External Over-temperature (NTC).

2 Control Loop Fault protection Part Number Package Packaging Low output capacitance allows live LED RED2511AD-TR13 SO8 Tape and reel connection Very low output current ripple <5%. Small SO8 IC package RC VDD. VDD. VREF ISTART. CV Amplifier TX1. - SLEEP. VFB Analog + VCOMPMAX +. Primary Control CLK Driver Side Logic Limits - Sensing Oscillator CS - VCOMPMIN RC RESET. VCCLIM +. SHUTDOWN. VFB VFB CC Amplifier VCOMPMIN=>Max Frequency ISTART. High Low CS Voltage Low TX2. FAULTS. Fault Logic NTC Shutdown VDD. INTC IOTP. NTC - STARTUP. VNTC + Internal SLEEP.

3 Over Temperature Shunt Startup RUN. Protection Regulator POR. GND. Figure 1: Block diagram 1/13 September 2015. RED2511 Datasheet Rev02. Preliminary RED2511 LED LLC Controller Device Pins VFB 1 8 CS. NTC 2 7 GND. TX2 3 6 VDD. TX1 4 5 RC. Figure 2: SO8 pin connections (top view). Pin Functions Pin # Name Function 1 VFB PSR Feedback input for output voltage regulation. Connect to primary sense winding. Shutdown pin that can be used for over-temperature protection with an external NTC resistor. A. 2 NTC. voltage of <VNTC will shut the IC down. Pin also includes a current source.

4 3 TX2 Output to control transformer. 4 TX1 Output to control transformer. 5 RC External RC network sets the minimum [full power] switching frequency. 6 VDD IC Power Supply pin nominally 7 GND Chip ground. PSR Current Sense input provides output current regulation and cycle-by-cycle over-current 8 CS. protection. The CS pin is connected to the half-bridge current sense resistor 2/13 September 2015. RED2511 Datasheet Rev02. Preliminary RED2511 LED LLC Controller Typical Application HT+. Q1 VOUT. T1. T2. +. T1a D1 Cout T1d Ls Output Lm _. D2. Q2. Daux Cr T1b Rcs Caux HT- Raux Rfb1.

5 RNTC. T1c 4 3 2 1. TX1 TX2 NTC VFB. U1 Rcs2 Rfb2. Rrc RED2511. RC VDD GND CS. 5 6 7 8. Crc Cdd Figure 3: Typical Application Schematic: LLC converter with RED2511 PSR controller Features RED2511 is an advanced CMOS control IC for disconnected, the RED2511 controls the resonant LLC converters. The RED2511 Primary maximum output voltage and enters fault-mode Side Regulation (PSR) control scheme accurately operation to keep the output voltage from rising controls the LED current and removes the need and to keep the power consumption low. for secondary side opto-coupler feedback, reducing cost and complexity.

6 Protection Features RED2511 uses the CSOC (Controlled Self- There are 5 faults that can cause the IC to enter Oscillating Converter) scheme to drive two low- fault mode: cost bipolar transistors in a half-bridge VFB pin voltage rises too high (no LED. configuration. RED2511 is optimized to work with connected). RediSem's LLC converter topology with VFB pin voltage falls too low (feedback integrated Power Factor Correction. resistor Rfb1 disconnected). Please contact RediSem for application design CS pin voltage is low (CS pin shorted to information for LED drivers with PFC.)

7 GND). Overtemperature fault (discussed later). Accurate Primary Side Regulation Operating frequency rises too high The RED2511 PSR scheme regulates the LED During these fault conditions, the IC will drive current by modulating the converter continually attempt re-starts. Between each re- frequency. Primary side current control enables start attempt there will be 8 dummy re-starts +/-5% LED current regulation. With the LED when the IC re-starts while the converter is off. 3/13 September 2015. RED2511 Datasheet Rev02. Preliminary RED2511 LED LLC Controller Additionally, if the output is short-circuit, the 125 C.

8 The IC will restart the converter when the auxiliary power to the IC fails and the IC shuts IC temperature drops by 15 C. down. From this condition the IC automatically cyclically re-starts until the short-circuit has been Automatic Dead-Time Control removed. An important feature of the Controlled Self The IC also has an instantaneous cycle-by-cycle Oscillating Converter is that the dead-time is over-current protection (OCP) level that will controlled naturally. Unlike MOSFET half-bridge terminate any cycle instantaneously should the converters, it is not necessary to program the current exceed a pre-set level.

9 Dead-time on RED2511. The bipolar switching transistors are turned on correctly through the Over-temperature Protection & Shutdown self-oscillation of the converter and turned off by RED2511 has an NTC shutdown pin that can be RED2511. This greatly simplifies the design used either in conjunction with a thermistor or process and improves the robustness of the LLC. with a logic signal. A high voltage on the NTC converter. pin will allow the converter to run and a low voltage will turn it off. 40uA is sourced from the Capacitive Mode Protection NTC pin to allow simple connection to a RED2511 includes a capacitive mode protection thermistor.

10 A small amount of hysteresis is also feature which prevents the converter from applied to this pin. entering capacitive switching mode on a cycle-by- An internal over-temperature protection shuts cycle basis by limiting the minimum frequency. down the controller if the IC temperature exceeds This always ensures the Controlled Self Oscillating Converter continues to oscillate correctly. 4/13 September 2015. RED2511 Datasheet Rev02. Preliminary RED2511 LED LLC Controller IC Operation clamp inside the IC regulates the VDD voltage to Startup, Shutdown and re-start (VDDREG).