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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 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). PIN CONNECTIONS
TRANSFORMER DEMAGNETIZATION SENSING INPUT SECONDARY PULSES INPUT POWER TRANSISTOR CURRENT LIMITATION INPUT GROUND GROUND ERROR AMPLIFIER INPUT (INVERTING) ERROR AMPLIFIER OUTPUT OVERLOAD INTEGRATION CAPACITOR IS IN I max. GND GND E S C2 1 2 3 4 5 6 7 8 16 15 14 13 12 11 10 9 V CC V OUT GND GND R0 C0 C1
DIP16 (Plastic Package) ORDER CODE : TEA2262
POWER SUPPLY POSITIVE OUTPUT STAGE SUPPLY POWER OUTPUT GROUND GROUND OSCILLATOR RESISTOR OSCILLATOR CAPACITOR SOFT-START CAPACITOR
2262-01.EPS
April 1996
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VCC V+ 15 16
TEA2262
S 7
BLOCK DIAGRAM
TEA2262
INTERNAL BIAS VCC MONITORING 15.7V VREF (2.49V) 8.5V 11.8V Overvoltage Protection
Error Amplifier
E
6
VREF 2.49V
-1 Primary Pulses IS LOGIC Regulation Pulses LOGIC PROCESSOR
MODULATOR LOGIC
POSITIVE OUTPUT STAGE VCC
+1A (Max.)
Modulators
14 OUT NEGATIVE OUTPUT STAGE -1A (Max.)
AUTOMATIC BURST GENERATION
Repetitive Overload Protection Current Limitation Demagnetization Sensing 0.15V 2.55V 0.6V 0.84V 45 µA
TON (Max.) (60%) SOFT-START
OSCILLATOR f/4
Secondary Pulse 10 C0 IS 1 2 IN
10 µA 8 C2 3 IMAX 4 5 12 GND 13
9
11
C1
R0
2262-02.EPS
TEA2262
ABSOLUTE MAXIMUM RATINGS
Symbol VCC V+ IOUT+ IOUTTj Tstg Power Supply Output Stage Power Supply Parameter V16-V4, 5, 12, 13 V15-V4, 5, 12, 13 Value 20 20 1.5 1.5 150 -40, +150 Unit V V A A
o o
Positive Output Current (source current) Negative Output Current (sink current) Operating Junction Temperature Storage Temperature
C C
THERMAL DATA
Rth (j-c) R th (j-a)* Junction-case Thermal Resistance Junction-ambient Thermal Resistance 15 50
o o
C/W C/W
* Soldered on a 35µm, 40cm 2 board copper area
Figure 1 : Maximum Power Dissipation
4 3 50 o C/W 2 1
o T AMB ( C)
2262-03.EPS
P tot (W)
0
50
100
150
RECOMMENDED OPERATING CONDITIONS
Symbol VCC IOUT+ IOUTIOUT+ IOUTfoper VIN ROSC COSC C1 C2 C2/C1 Tamb Power Supply Positive Output Current (source current) Negative Output Current (sink current) Average Positive Output Current Average Negative Output Current Operating Frequency Input Pulses Amplitude (Pin 2) Oscillator Resistor Range Oscillator Capacitor Range Soft-starting Capacitor Range Overload Integration Capacitor Ratio C2/C1 (C2 must be C1) Operating Ambient Temperature 10 1.5 10 0.33 0.047 0.047 1 -20 70
o
Parameter
Min. VCC stop
Typ. 12
Max. VCC max 1 1 0.3 0.3 150
Unit V A A A A kHz V k nF µF
2262-03.TBL
2.5
4.5 100 4.7
1 1
µF C
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2262-02.TBL
Symbol
Parameter
Value
Unit
2262-01.TBL
TEA2262
ELECTRICAL CHARACTERISTICS (Tamb = 25oC, VCC =12V, unless otherwise specified)
Symbol POWER SUPPLY VCC(start) VCC(stop) Hyst VCC ICC(start) ICC VCC(max) ICC(over) F F tON max Starting Voltage (VCC increasing) Stopping Voltage (VCC decreasing) Hysteresis (VCC(start) - VCC(Stop)) Starting Current (VCC = 9V) Supply Current (VCC = 12V) Overvoltage Threshold on V CC Supply Current after Overvoltage Detection (VCC = 17V) 15 9.5 7 2.7 11.8 8.5 3.3 0.5 6.5 15.7 35 13 9.5 3.7 V V V mA mA V mA Parameter Min. Typ. Max. Unit
OSCILLATOR / PWM SECTION Accuracy (ROSC = 68k, COSC = 1nF) Maximum Duty Cycle in Primary Regulation Mode 50 10 60 70 % %
ERROR AMPLIFIER SECTION AVO Fug ISC IBE VREF Open Loop Gain Unity Gain Frequency Short Circuit Output Current (Pin 7 connected to ground) E Input Bias Current (Pin 6) Internal Voltage Reference (connected to error amplifier input and not directly accessible) 2.34 75 550 2 0.08 2.49 2.64 dB kHz mA µA V
INPUT SECTION VIN VIS IBIN IBIS IN Input Threshold (Pin 2) IS Input Threshold (Pin 1) IN Input Bias Current IS Input Bias Current 0.6 0.85 0.15 0.3 0.4 1.2 V V µA µA
CURRENT LIMITATION SECTION VIM1 VIM2 VIM VC2 IDC2 ICC2 IBI(max) First Current Limitation Threshold Second Current Limitation Threshold Thresholds Difference VIM2 - VIM1 Lock-out Threshold on Pin C2 Capacitor C2 Discharge Current Capacitor C2 Charge Current Maximum Input Bias Current (Pin 3) 550 780 190 2.25 600 840 240 2.55 10 45 0.2 650 900 280 2.85 mV mV mV V µA µA
2262-04.TBL
µA
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TEA2262
SIMPLIFIED APPLICATION DIAGRAMS Figure 1 : Master-slave Concept
AUDIO OUTPUT STAGE Muting Control
R P1 Remote Stand-by
MAINS INPUT
Synchronization
SCANNING DEVICE
P2 C VOLTAGE REGULATOR Remote Stand-by V CC
TEA2262 SLAVE
TEA5170 MASTER
V CC
µP
INFRA-RED RECEIVER PWM
P 1 : Output voltage adjusteme nt in normal mode P 2 : Output voltage adjustement in stand- by
Power primary ground Secondary ground (isolated from mains)
Figure 2 : Secondary Regulation (with optocoupler)
AUDIO OUTPUT STAGE Muting Control
R P SCANNING DEVICE Remote Stand-by
MAINS INPUT
C VOLTAGE REGULATOR
V CC
TEA2262
µP
V CC INFRA-RED RECEIVER
2262-05.EPS
P : Output voltage adjustement
Power primary ground Secondary ground (isolated from mains)
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2262-04.EPS
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 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.
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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.
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TEA2262
SECURITY FLOW-CHART
S.M.P.S. starting
First threshold reached VIM1 N
Y
Second threshold reached VIM2 Y Y C2 charged S.M.P.S. stopped
N
VCC max reached N Normal operating C 2 discharged
Pulse by pulse current limiting C2 charged
VC2 < 2.6V VC2 < 2.6V Y N
Y
N Definitive stopping
Y
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2262-06.EPS
Reset C2 discharged
N
TEA2262
PACKAGE MECHANICAL DATA 16 PINS - PLASTIC DIP
Dimensions 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
Inches Typ.
Max. 0.065
0.5 0.25 20 8.5 2.54 17.78 7.1 5.1 3.3 1.27
0.020 0.010 0.787 0.335 0.100 0.700 0.280 0.201 0.130 0.050
DIP16.TBL
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.
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