TEA2018A STMICROELECTRONICS | Alldatasheet
Document overview
- Manufacturer or author: Provided By ALLDATASHEET.COM(FREE DATASHEET DOWNLOAD SITE)
- PDF pages: 7
Technical content
POWER SUPPLY CONTROL CIRCUIT May 1993 OSCILLATOR GROUND COLLECTOR CURRENT SENSING NEGATIVE SUPPLY VOLTAGE ERROR AMPLIFIER NON-INVERTING INPUT DEMAGNETIZATION SENSING POSITIVE SUPPLY VOLTAGE OUTPUT 2018A-01.EPS PIN CONNECTIONS DIP8 (Plastic Package) ORDER CODE : TEA2018A .DIRECT DRIVE OF THE EXTERNAL SWITCHING TRANSISTOR .POSITIVE AND NEGATIVE OUTPUT CUR- RENTS UP TO 0.5 A .CURRENT LIMITATION .TRANSFORMER DEMAGNETIZATION SENSING .FULL OVERLOAD AND SHORT-CIRCUIT PROTECTION .PROPORTIONAL BASE CURRENT DRIVING .LOW STANDBY CURRENT BEFORE START- ING (< 1.6 mA) .THERMAL PROTECTION
DESCRIPTION
The TEA2018Ais an 8-pin DIP low-cost integrated circuit designed for the control of switch mode power supplies. Due to its current mode regulation, the TEA2018A facilitates design of power supplies with following features : .High stability regulation loop .Automatic input voltage feed-forward in dis- continuous mode fly-back .Automatic pulse-by-pulse current limitation Typical applications : Video Display Units, TV sets, typewriters, microcomputersand industrialapplica- tions Where synchronization is required, use the TEA2019. For more details, see application note AN406/0591
-1V VOLTAGE LIMITATION OSCILLATOR1 2.4V COMPARATOR INTERNAL BIAS V CC ”Good” V REF 2.4V DEMAGNETIZATION SENSING Undervoltage0.1V OUTPUT GROUNDISENSE V CC RC tt IS V CC G ≅ 50 MAXIMUM DUTY CYCLE 70% TEA2018A 2018A-02.EPS BLOCK DIAGRAM ABSOLUTE MAXIMUM RATINGS Symbol Parameter Value Unit VCC + Positive Supply Voltage 15 V VCC - Negative Supply Voltage -5 V IO (peak) Peak Output Current (duty cycle < 5%) ±1A II Input Current (Pin 3) ±5m A Tj Junction Temperature +150 oC Toper Operating Ambient Temperature Range -20, +70 oC Tstg Storage Temperature Range -40, +150 oC 2018A-01.TBL THERMAL DATA Symbol Parameter Value Unit R th (j-a) Junction-ambient Thermal Resistance 80 oC/W 2018A-02.TBL ELECTRICAL OPERATING CHARACTERISTICS Tamb =2 5oC, potentials referenced to ground (unless otherwise specified) (see test circuit) Symbol Parameter Min. Typ. Max. Unit VCC + Positive Supply Voltage 6.6 8 15 V VCC - Negative Supply Voltage -1 -3 -5 V VCC(start) Minimum Positive Supply Voltage required for starting (VCC + rising) 6 6.6 V VCC(stop) Minimum Positive Voltage below wich device stops operating (VCC + falling) 4.2 4.9 5.6 V 2018A-03.TBL TEA2018A
ELECTRICAL OPERATING CHARACTERISTICS Tamb =2 5oC, potentials referenced to ground (unless otherwise specified) (see test circuit) Symbol Parameter Min. Typ. Max. Unit Δ VCC + Hysteresis on VCC + Threshold 0.7 1.1 1.6 V ICC(sb) Stand-by Supply Current before starting (VCC +<V CC(start)) 1 1.6 mA Vth(IC) Current Limitation Threshold Voltage (Pin 3) -1100 -1000 -880 mV R (IC) Collector Current Sensing Input Resistance 1000 Ω V7(th) Demagnetization Sensing Threshold 75 100 125 mV IS Demagnetization Sensing Input Current (Pin 7 = 0V) 1 µA τmax Maximum Duty Cycle 60 70 % AV Error Amplifier Gain 50 II+ Error Amplifier Input Current (non-inverting input) 2 µA VREF Internal Reference Voltage 2.3 2.4 2.5 V Δ VREF Δ T Reference Voltage Temperature Drift 10 -4 V/oC tOSC Oscillator Free-running Period ( R = 59kΩ , C = 1.2nF) 44 48 52 µs Δ fOSC Δ T Oscillator Frequency Drift with Temperature (VCC + = +8V) 0.05 %/ oC Δ fOSC ΔVCC Oscillator Frequency Drift with VCC + (+8V < VCC + < +14V) 0.5 %/V ton(min) Minimum Conducting Time (Ct = 1nF) 2 µs 2018A-04.TBL RECOMMENDED OPERATING CONDITIONS Symbol Parameter Min. Typ. Max. Unit VCC + Positive Supply Voltage 8 V VCC - Negative Supply Voltage -3 V IO Output Current 0.5 A foper Operating Frequency 30 kHz 2018A-05.TBL 8765 4321 TEA2018A 22nF 1.2nF 4.7nF V8 V7 V6 V1 V3 V4 470nF 22nF 22nF 10Ω470Ω 100Ω 59kΩ 2018A-03.EPS TEST CIRCUIT TEA2018A
(see application note AN-086) Operating Principles(Figure 1) On every period, the beginning of the conduction time of the transistor is triggered by the fall of the oscillator sawtooth which acts as clock signal. The period T osc is given by : Tosc ≅ 0.66 Ct (Rt + 200) (Tosc in seconds, Ctin Farad, RtinΩ ) The end of the conduction time is determinedby a signal issued from comparing the following sig- nals : a) the sawtooth waveform representing the collector current of the switching transistor, sampled across the emitter shunt resistor, b) the output of the error amplifier. Base Drive - Fast turn-on : On each period, a current pulse ensures fast transistor switch-on. This pulse performs also the t on(min)function at the beginning of the conduction. - Proportional base drive : In order to save power, the positive base current after the starting pulse becomes an image of the collector current. The ratioI C IB is programmed as follows Figure 2) : IC IB = R B R e - Efficient and fast switch-off : When the positive base drive is removed, 1ms (typically) will elapse before the application of negative current there- fore allowing a safe and rapid collector current fall. Safety Functions - Overload & short-circuit protection : When the voltage applied to pin 3 exceeds the current limitation threshold voltage [V th(Ic)], the output flip-flop is reset and the transistor is turned off. The shunt resistor Re must be calculated so as to obtain the current limitation threshold on pin 3 at the maximum allowable collector current. - Demagnetizationsensing : This functiondisables any new conductioncycle of thetransistor as long as the core is not completely demagnetized. When not used, pin 7 must be grounded. on(max) : Outside the regulation area and in the absence of current limitation, the maximum con- duction time is set at about 70 % of the period. on(min): A minimum conducting time is ensured during each period (see Figure 2) - Supply voltage monitoring : The TEA2018A will stop operating if VCC + on pin 6 falls below the threshold level VCC(stop) OSCILLATOR SAW-TOOTH Errorsignal I (sample)C t FLIP-FLOP OUTPUT t t 2018A-04.EPS - 2018A-05.EPS TEST CIRCUIT CI SENSE OSCILLATOR ERROR SIGNAL ERROR AMPLIFIER COMPARATO R S R Q FLIP-FLOP VREF IC V i OUTPUT FILTER LOAD Re TEA2018A
t t IC IB COLLECTOR CURRENT BIAS CURRENT IC IB R e R B IC ton(min) 2018A-06.EPS Figure 2 E + V CC + VoIs V CC 1kΩ 50µA 7.5kΩ V ref DISCH. OSC. 2kΩ GND Ic V CC 1kΩ V L = 0.33 V CCth V H = 0.66 V CCth 1kΩ 15kΩ V CC Vd + 0.1V 7.5kΩ15kΩ 2018A-07.EPS SCHEMATICS OF INPUTS AND OUTPUTS TEA2018A
Starting Process(Figure 3) Prior to starting, a low current is drawn from the high voltage source through a high value resistor. This current charges the power supply voltage capacitor of the device. No output pulses are available before the voltage on pin 6 has reached the threshold level [VCC(start), VCC rising]. During this time the TEA2018A draws only 1mA (typically). When the voltage on pin 6 reaches this threshold, base drive pulses appear. The energy drawn by these pulses tends to dis- charge the power supply storage capacitor. How- ever a hysteresis of about 1.1V (typically) (Δ V CC ) is implemented to avoid the device from stopping. t V (stop)CC V (start)CC V CC V CC 4.9V 2018A-08.EPS Figure 3 :Normal Start-up Sequence 12 3 4567 8 91 0 t (µs)on (min.) C (nF)t 2018A-09.EPS Figure 4 :tON (min.)versus Ct 47µF 385V 0.1µF 0.1µF 4 x 1N4007 RF Filter 2 x 12mH 0.5A
220 VAC
47kΩ 1kΩ 1.2nF 3.9V100Ω 22kΩ 4.7kΩ 10µF1 5 0 Ω 8.2Ω R B 4.7µF4.7kΩ 1N414815Ω 1N4148 68 Ω 47µF R e BUV 46A BA 159 BA 159 2.2kΩ 1kΩ 3W 1nF 1kV +12V +5V 4700µF 1000µF BYW98-50 BYW98-50 220µF 16V Primary Ground Second ary Ground Maximum Power ≅ 30W TEA2018A Operating Frequency≅ 30kHz 2018A-10.EPS TYPICAL APPLICATION TEA2018A
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 anypatent 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. 1994 SGS-THOMSON Microelectronics - All Rights Reserve d Purchase of I 2C 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 - China - France - Germany - Hong Kong - Italy - Japan - Korea - Malaysia - Malta - Morocco The Netherlands - Singapore - Spain - Sweden - Switzerland - Taiwan - Thailand - United Kingdom - U.S.A. Dimensions Millimeters Inches A 3.32 0.131 a1 0.51 0.020 B 1.15 1.65 0.045 0.065 b 0.356 0.55 0.014 0.022 b1 0.204 0.304 0.008 0.012 D 10.92 0.430 E 7.95 9.75 0.313 0.384 e 2.54 0.100 e3 7.62 0.300 e4 7.62 0.300 F 6.6 0260 i 5.08 0.200 L 3.18 3.81 0.125 0.150 Z 1.52 0.060 DIP8.TBL I L B e D b Z F E Z A PM-DIP8.EPS PACKAGE MECHANICAL DATA