TEA2262 SWITCH MODE POWER SUPPLY CONTROLLER . .. . .. .. . . POSITIVE AND NEGATIVE OUTPUT CURRENT UP TO 1A LOW START-UP CURRENT DIRECT DRIVE OF THE MOS POWER TRANSISTOR TWO LEVELS TRANSISTOR CURRENT LIMITATION DOUBLE PULSE SUPPRESSION SOFT-STARTING UNDER AND OVERVOLTAGE LOCK-OUT AUTOMATIC STAND-BY MODE LARGE POWER RANGE CAPABILITY IN STAND-BY (Burst mode) INTERNAL PWM SIGNAL GENERATOR DESCRIPTION DIP16 (Plastic Package) The TEA2262 is a monolithic integrated circuit for the use in primary part of an off-line switching mode power supply using a MOS power transistor. All functions required for SMPS control under normal operating,transient or abnormal conditions are provided. The capability of working according to the ”masterslave” concept, or according to the ”primary regulation” mode makes the TEA2262 very flexible and easy to use. This is particularly true for TV receivers wherethe IC provides an attractive and low cost solution (no need of stand-by auxiliary power supply). ORDER CODE : TEA2262 TRANSFORMER DEMAGNETIZATION SENSING INPUT IS 1 16 V CC POWER SUPPLY IN 2 15 V POSITIVE OUTPUT STAGE SUPPLY SECONDARY PULSES INPUT POWER TRANSISTOR CURRENT LIMITATION INPUT GROUND I max. 3 14 OUT POWER OUTPUT GND 4 13 GND GROUND GROUND GND 5 12 GND GROUND ERROR AMPLIFIER INPUT (INVERTING) E 6 11 R0 OSCILLATOR RESISTOR ERROR AMPLIFIER OUTPUT S 7 10 C0 OSCILLATOR CAPACITOR OVERLOAD INTEGRATION CAPACITOR C2 8 9 C1 SOFT-START CAPACITOR April 1996 2262-01.EPS PIN CONNECTIONS 1/9 2/9 6 2262-02.EPS E 11 R0 9 C0 10 Primary Pulses 0.15V Demagnetization Sensing AUTOMATIC BURST GENERATION MODULATOR LOGIC OSCILLATOR f/4 Modulators Error Amplifier C1 TON (Max.) (60%) SOFT-START -1 VREF 2.49V TEA2262 S 7 IS 1 IN 2 IS LOGIC VREF (2.49V) INTERNAL BIAS Secondary Pulse 10 µA 45 µA Overvoltage Protection 8 C2 2.55V IMAX 3 0.84V Current Limitation 0.6V LOGIC PROCESSOR Repetitive Overload Protection 8.5V 11.8V Regulation Pulses 15.7V POSITIVE OUTPUT STAGE 4 NEGATIVE OUTPUT STAGE VCC 5 GND 12 13 -1A (Max.) +1A (Max.) 15 16 VCC MONITORING V+ VCC 14 OUT TEA2262 BLOCK DIAGRAM TEA2262 ABSOLUTE MAXIMUM RATINGS Parameter Value Unit V VCC Power Supply V16-V4, 5, 12, 13 20 V+ Output Stage Power Supply V15-V4, 5, 12, 13 20 V 1.5 A IOUT+ Positive Output Current (source current) IOUT- Negative Output Current (sink current) 1.5 A Operating Junction Temperature 150 o -40, +150 o Tj Storage Temperature Tstg 2262-01.TBL Symbol C C Symbol Parameter Value Junction-case Thermal Resistance Rth (j-c) R th (j-a)* Junction-ambient Thermal Resistance Unit 15 o 50 o C/W C/W 2262-02.TBL THERMAL DATA * Soldered on a 35µm, 40cm 2 board copper area Figure 1 : Maximum Power Dissipation 4 P tot (W) 3 50 o C/W 2 TAMB ( oC) 0 50 100 150 2262-03.EPS 1 RECOMMENDED OPERATING CONDITIONS Symbol VCC Parameter Power Supply IOUT+ Positive Output Current (source current) Min. Typ. Max. Unit VCC stop 12 VCC max V 1 A 1 A IOUT- Negative Output Current (sink current) IOUT+ Average Positive Output Current 0.3 A IOUT- Average Negative Output Current 0.3 A foper Operating Frequency 10 150 kHz VIN Input Pulses Amplitude (Pin 2) 1.5 ROSC Oscillator Resistor Range 10 COSC 4.5 V 100 kΩ Oscillator Capacitor Range 0.33 C1 Soft-starting Capacitor Range 0.047 1 4.7 µF C2 Overload Integration Capacitor 0.047 1 µF C2/C1 Ratio C2/C1 (C2 must be ≥ C1) 1 Tamb Operating Ambient Temperature -20 70 nF 2262-03.TBL 2.5 o C 3/9 TEA2262 ELECTRICAL CHARACTERISTICS (Tamb = 25oC, VCC =12V, unless otherwise specified) Symbol Parameter Min. Typ. Max. Unit 9.5 7 11.8 13 V 8.5 9.5 V 2.7 3.3 3.7 POWER SUPPLY VCC(start) Starting Voltage (VCC increasing) VCC(stop) Stopping Voltage (VCC decreasing) Hyst VCC Hysteresis (VCC(start) - VCC(Stop)) V ICC(start) Starting Current (VCC = 9V) 0.5 mA ICC Supply Current (VCC = 12V) 6.5 mA VCC(max) Overvoltage Threshold on V CC ICC(over) Supply Current after Overvoltage Detection (VCC = 17V) 15 15.7 V 35 mA 10 % OSCILLATOR / PWM SECTION ∆F F tON max Accuracy (ROSC = 68kΩ, COSC = 1nF) Maximum Duty Cycle in Primary Regulation Mode 50 60 70 % ERROR AMPLIFIER SECTION AVO Open Loop Gain 75 dB Fug Unity Gain Frequency 550 kHz ISC Short Circuit Output Current (Pin 7 connected to ground) 2 mA IBE E Input Bias Current (Pin 6) VREF Internal Voltage Reference (connected to error amplifier input and not directly accessible) µA 0.08 2.34 2.49 2.64 V 0.85 1.2 V INPUT SECTION VIN IN Input Threshold (Pin 2) VIS IS Input Threshold (Pin 1) 0.6 0.15 V IBIN IN Input Bias Current 0.3 µA IBIS IS Input Bias Current 0.4 µA CURRENT LIMITATION SECTION First Current Limitation Threshold 600 650 mV VIM2 Second Current Limitation Threshold 780 840 900 mV ∆VIM Thresholds Difference VIM2 - VIM1 190 240 280 mV VC2 Lock-out Threshold on Pin C2 2.25 2.55 2.85 V IDC2 Capacitor C2 Discharge Current 10 µA ICC2 Capacitor C2 Charge Current 45 µA Maximum Input Bias Current (Pin 3) 0.2 µA IBI(max) 4/9 550 2262-04.TBL VIM1 TEA2262 SIMPLIFIED APPLICATION DIAGRAMS Figure 1 : Master-slave Concept AUDIO OUTPUT STAGE Muting Control R P1 MAINS INPUT Synchronization SCANNING DEVICE Remote Stand-by P2 C VOLTAGE REGULATOR Remote Stand-by V CC TEA2262 SLAVE TEA5170 MASTER µP V CC INFRA-RED RECEIVER 2262-04.EPS PWM Power primary ground Secondary ground (isolated from mains) P 1 : Output voltage adjusteme nt in normal mode P 2 : Output voltage adjustement in stand- by Figure 2 : Secondary Regulation (with optocoupler) AUDIO OUTPUT STAGE Muting Control R P MAINS INPUT SCANNING DEVICE Remote Stand-by C VOLTAGE REGULATOR V CC TEA2262 µP V CC P : Output voltage adjustement 2262-05.EPS INFRA-RED RECEIVER Power primary ground Secondary ground (isolated from mains) 5/9 TEA2262 GENERAL DESCRIPTION The TEA2262 is an off-line switch mode power supply controller. The synchronization function and the specific operationin stand-by mode make it well adapted to video applications such as TV sets, VCRs, monitors, etc... The TEA2262 can be used in two types of architectures : - Master/slave architecture. In this case, the TEA2262drives the power transistor according to the pulse width modulated signals generated by the secondary located master circuit. A pulse transformer provides the feedback(see Figure 1). - Conventional architecture with linear feedback signal (feedback sources : optocoupler or transformer winding) (see Figure 2). Using the TEA2262, the stand-by auxiliary power supply, often realized with a small but costly 50Hz transformer, is no longer necessary. The burst mode operation of the TEA2262 makes possible the control of very low output power (down to less than 1W) with the main power transformer. When used in a master/slave architecture, the TEA2262 and also the power transistor turn-off can be easily synchronized with the line transformer. The switching noise cannot disturb the picture in this case. As an S.M.P.S. controller, the TEA2262 features the following functions : - Power supply start-up (with soft-start) - PWM generator - Direct power transistor drive (±1A) - Safety functions : pulse by pulse current limitation, output power limitation, over and under voltage lock-out. S.M.P.S. OPERATING DESCRIPTION Starting Mode - Stand By Mode Power for circuit supply is taken from the mains through a high value resistor before starting. As long as VCC of the TEA2262 is below VCC start, the quiescent current is very low (typically 0.5mA) and the electrolytic capacitor across VCC is linearly charged. When VCC reaches VCC start (typically 11.8V), the circuit starts, generating output pulses with a soft-starting. Then the SMPS goes into the stand-by mode and the output voltage is a percentage of the nominal output voltage (eg. 80%). During starting phase, in order to avoid transformer 6/9 magnetization (specially at high frequency), the frequency oscillator is divided by four. At switch-on, C0 charging current is divided by four. It recover its normal value when the voltage on soft-start capacitor reach 2.5V. The current also recover its standard value when the soft-start capacitor is discharged because of a burst operating mode (starting in stand-by). In other words, the charging current will become and stay at its normal value, as soon as one of the following events occurs : - VC1 rearch 2.5V - C1 is discharged by burst operating mode For this the TEA2262 contains all the functions required for primary mode regulation : a fixed frequency oscillator, a voltage reference, an error amplifier and a pulse width modulator (PWM). For transmission of low power with a good efficiency in stand-by, an automatic burst generation system is used, in order to avoid audible noise. Normal Mode (secondary regulation) The normal operating of the TV set is obtained by sending to the TEA2262 regulation pulses generated by a regulator located in the secondary side of the power supply (TEA5170 for example). This architecture uses the ”Master-slave Concept”, advantages of which are now well-known especially the very high efficiency in stand-bymode, and the accurate regulation in normal mode. Stand-by mode or normal mode are obtained by supplying or not the secondary regulator. This can be ordonnered for exemple by a microprocessor in relation with the remote control unit. Regulation pulses are applied to the TEA2262 through a small pulse-transformer to the IN input (pin 2). This input is sensitive to positive square pulses. The typical threshold of this input is 0.85V. The frequency of pulses coming from the secondary regulator can be lower or higher than the frequency of the starting oscillator. The TEA2262 has no soft-starting system when it receives pulses from the secondary. The soft-starting has to be located in the secondary regulator. Due to the principle of the primary regulation, pulses generated by the starting system automatically disappear when the voltage delivered by the SMPS increases. TEA2262 Stand-by Mode - Normal Mode Transition During the transition there are simultaneously pulses coming from the primary and secondary regulators. These signals are not synchronized and some care has to be taken to ensure the safety of the switching power transistor. A very sure and simple way consist in checking the transformer demagnetization state. - A primary pulse is taken in account only if the transformer is demagnetized after a conduction of the power transistor required by the secondary regulator. - A secondary pulse is taken in account only if the transformer is demagnetized after a conduction of the power transistor required by the primary regulator. With this arrangement the switching safety area of the power transistor is respected and there is no risk of transformer magnetization. The magnetization state of the transformer is checked by sensing the voltage across a winding of the transformer (generally the same which supplies the TEA2262). This is made by connecting a resistor between this winding and the demagnetization sensing input of the circuit (pin 1). SECURITY FUNCTIONS (see flow-chart below) - Undervoltage detection. This protection works in association with the starting device ”VCC switch” (see paragraph Starting-mode - standby mode). If VCC is lower than VCCstop (typically 8.5V) output pulses are inhibited, in order to avoid wrong operation of the power supply or bad power transistor drive. - Overvoltage detection. If VCC exceeds VCCmax (typically 15.7V) output pulses are inhibited and the external capacitor C 2 is charged as long as VCC is higher than VCC stop. Restarting of the power supply is obtained by reducing VCC below VCCstop except if the voltage across C 2 reaches VC2 (typically 2.55V) (refer to ”Restart of the power supply” paragraph).In this last case, the circuit is definitively stopped. - Current limitation of the power transistor. The current is measured by a shunt resistor. A double threshold system is used : - When the first threshold (VIM1) is reached, the conduction of the power transistor is stopped until the end of the period : a new conduction signal is needed to obtain conduction again. - Furthermore as long as the first threshold is reached (it means during several periods), an external capacitor C2 is charged. When the voltage across the capacitor reaches VC2 (typically 2.55V) the output is inhibited. This is called the ”repetitive overload protection”. If the overload diseappears before VC2 is reached, C2 is discharged, so transient overloads are tolerated. - Second current limitation threshold (VIM2). When this threshold is reached the output of the circuit is immediatly inhibited. This protection is helpfull in case of hard overload for example to avoid the magnetization of the transformer. - Restart of the power supply. After stopping due to VIM2, VCCMax or VCCstop triggering, restart of the power supply can be obtained by the normal operating of the ”VCC switch” VCC switch sequency from VCCstop to VCCstart . After stopping due to VC2 threshold reaching, the circuit is definitively stopped. In this case it is necessary to reduce VCC below approximately 5V to reset the circuit. From a practical point of view, it means that the power supply has to be temporarily disconnected from any power source to get the restart. 7/9 TEA2262 SECURITY FLOW-CHART S.M.P.S. starting First threshold reached VIM1 Y Second threshold reached VIM2 N VCC max reached N Y N Pulse by pulse current limiting C2 charged Y C2 charged S.M.P.S. stopped Normal operating C 2 discharged VC2 < 2.6V VC2 < 2.6V Y Y N N Definitive stopping Y 8/9 N 2262-06.EPS Reset C2 discharged TEA2262 PM-DIP16.EPS PACKAGE MECHANICAL DATA 16 PINS - PLASTIC DIP a1 B b b1 D E e e3 F I L Z Min. 0.51 0.77 Millimeters Typ. Max. 1.65 Min. 0.020 0.030 0.5 0.25 Inches Typ. Max. 0.065 0.020 0.010 20 8.5 2.54 17.78 0.787 0.335 0.100 0.700 7.1 5.1 3.3 0.280 0.201 DIP16.TBL Dimensions 0.130 1.27 0.050 Information furnished is believed to be accurate and reliable. However, SGS-THOMSON Microelectronics 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 licence is granted by implication or otherwise under any patent or patent rights of SGS-THOMSON Microelectronics. Specifications mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied. SGS-THOMSON Microelectronics products are not authorized for use as critical components in life support devices or systems without express written approval of SGS-THOMSON Microelectronics. 199 SGS-THOMSON Microelectronics - All Rights Reserved Purchase of I2C Components of SGS-THOMSON Microelectronics, conveys a license under the Philips I2C Patent. Rights to use these components in a I2C system, is granted provided that the system conforms to the I2C Standard Specifications as defined by Philips. SGS-THOMSON Microelectronics GROUP OF COMPANIES Australia - Brazil - Canada - China - France - Germany - Hong Kong - Italy - Japan - Korea - Malaysia - Malta - Morocco The Netherlands - Singapore - Spain - Sweden - Switzerland - Taiwan - Thailand - United Kingdom - U.S.A. 9/9