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TDA4605
CONTROL CIRCUIT FOR SWITCH MODE POWER SUPPLIES USING MOS TRANSISTORS
. . . . . . . . .
FOLD-BACK CHARACTERISTIC PROVIDES OVERLOAD PROTECTION FOR EXTERNAL DIODES BURST OPERATION UNDER SHORT-CIRCUIT AND NO LOAD CONDITIONS LOOP ERROR PROTECTION SWITCH-OFF IN CASE OF TOO LOW LINE VOLTAGE (under voltage switch-off) LINE VOLTAGE COMPENSATION OF OVERLOAD POINT SOFT-START FOR SMOOTH START-UP CHIP OVER-TEMPERATURE PROTECTION (thermal shutdown) ON-CHIP PARASITIC TRANSFORMER OSCILLATION SUPPRESSION CIRCUITRY DECREASE OF REGULATED VOLTAGE FOR LOW POWER CONSUMPTION
DIP8 (Plastic Package) ORDER CODE : TDA4605
DESCRIPTION The IC TDA4605 controls the MOS Power Transistor and performs all necessary regulation and monitoring functions in free running flyback converters. Since good load regulation over a wide load range is attained, this IC is particularly suitable for Consumer as well as Industrial Power Supplies. Alternative source of the TDA4605 is also available from SIEMENS Semiconductors Consumer Electronics A.G. PIN CONNECTIONS
SO8 (Plastic Micropackage) ORDER CODE : TDA4605D
REGULATION INPUT PRIMARY CURRENT SIMULATION PRIMARY VOLTAGE MONITORING GROUND
1 2 3 4
8 7 6 5
ZERO CROSSING DETECTOR INPUT SOFT-START SUPPLY VOLTAGE OUTPUT
4605-01.EPS
April 1996
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TDA4605
PIN CONFIGURATION
Pin Number 1 Description Regulating voltage : information input concerning secondary voltage. By comparing the regulating voltage obtained from the regulating winding of the transformer with the internal reference voltage, the output pulse width on Pin 5 is adapted to the load of the secondary side (normal, overload, short circuit, no load) Primary current simulation : information input regarding the primary current. The primary current rise in the primary winding is simulated at Pin 2 as a voltage rise by means of external RC element. When a value is reached that is derived from the regulating voltage at Pin 1, the output pulse at Pin 5 is terminated. The RC element serves to set the maximum power at the overload point. Primary voltage detector : input for primary voltage monitoring. When the line voltage is too low the IC is switched-off by comparing V 3 with an internal reference. Voltage at Pin 3 is used for overload point compensation. Ground Output : push-pull output for charge and discharge of the gate capacitance of the power MOS transistor. Supply voltage : Supply voltage input. From it are derived a stable internal reference voltage (VREF) and the switching threshold V6A, V6E, V6 max and V6 min for the supply voltage detector. if V6 > V6E the VREF is switched on and switched off when V6 < V6A. In addition the logic is only enable for V6 min < V6 < V6 max. Soft-start : input for soft-start and integration network. Start-up will begin with short pulses by connecting a capacitor between Pin 7 to ground. This capacitor together with a resistor connected between Pin 7 and error amplifier output also as acts an integrator network for regulation. Zero detector : Input for the oscillator feedback. After starting oscillator, every zero transit of the feedback voltage (falling edge) triggers an output pulse at Pin 5. The trigger threshold is at typically - 50mV
2
3
4 5 6
7
8
BLOCK DIAGRAM
6 2 5
TDA4605
Re fere nce Voltage (typ. 3V) S upply Voltage Monitor
V2B
P rima ry Current Recopy
Output S ta ge a nd Current Limit
VREF
4
V6min V6A V6E V 6ma x
Vs t
S ta rting Impulse Genera tor
Logic
Current S ource
1
VR
Regulating & Ove rload Amplifier
S top Comp. Zero Cros s ing De te ctor
4605-02.EPS
Ove rloa d Point Corre ction
Vu
Low Volta ge P rote ction Monitoring
7
3
8
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4605-01.TBL
TDA4605
ABSOLUTE MAXIMUM RATINGS
Symbol V1 V2 V3 V4 V6 V7 I1 I2 I3 I4 I5 I6 I7 I8 Tj Tstg Parameter Pin 1 2 3 4 6 7 1 2 3 4 5 6 7 8 Value -0.3, +3 -0.3 -0.3 -0.3 -0.3, +20 -0.3 3 3 3 - 1.5 -0.5, +1.5 0.5 3 -3, +3 +125 -40, +125 Unit V V V V V V mA mA mA A A A mA mA o C o C
Supply Voltage
Supply Current
tp 50s, V 0.1 tp 50s, V 0.1 tp 50s, V 0.1
Junction Temperature (autom. thermal disjunction) Storage Temperature
THERMAL DATA
Symbol R th(j-a) Rth(j-c) Tamb Parameter Junction-ambient Thermal Resistance Junction-case Thermal Resistance Ambient Temperature Value 80 45 -20, +85 Unit C/W o C/W o C
o
ELECTRICAL CHARACTERISTICS (VCC = 10V, Tamb = 25oC, unless otherwise specified)
Symbol START-UP HYSTERESIS I6E0 V6E V6A I6E1 I6A1 V2(Max.) V3(Max.) V1R -VR Start-up Current Drain Switch-on Voltage Switch-off Voltage Switch-on Current Switch-off Current At Pin 2 (V6 < V6E) At Pin 3 (V6 < V6E) Control Input Voltage Voltage Gain of the Control Circuit in the Control Range Basic Value Peak Value in the Range of Secondary Overload Maximum Ramp Amplitude Peak Value in the Range of Secondary Short Circuit Operation Foldback Point Correction Current V1 = V1R - 10mV V2O - V2B V1 = 0 V6 = V6E 11 4.5 V6 = V6E V6 = V6A I2 = 1mA I3 = 1mA 5.6 5.6 400 VR = d(V2S - V 2B)/dV1 f = 1kHz 0.955 2.8 1.82 2.3 0.6 12 5 11 10 6.6 6.6 410 43 0.8 13 5.5 mA V V mA mA V V mV dB Parameter Test Conditions Min. Typ. Max. Unit
VOLTAGE CLAMP (V6 = 10V, IC Switched off) 9 9 420
CONTROL RANGE
PRIMARY CURRENT SIMULATION VOLTAGE V2B V2O DV 2 V2S 1.00 2.95 1.95 2.5 1.03 3.1 2.08 2.7 V V V V
4605-04.TBL
OVERLOAD RANGE AND SHORT CIRCUIT OPERATION
FOLDBACK POINT CORRECTION -I2 V3 = 3.7V 300 500 650 A 3/6
4605-03.TBL
4605-02.TBL
TDA4605
ELECTRICAL CHARACTERISTICS (VCC = 10V, Tamb = 25oC, unless otherwise specified) (continued)
Symbol Parameter Test Conditions Min. Typ. Max. Unit GENERALLY VALID DATA (V6 = 10V) VOLTAGE OF THE ZERO Transition DETECTOR V8P V8N V8S TUL -I8 Positive Clamping Voltage Negative Clamping Voltage Threshold Value Suppression of Transformer Ringing Input Current I8 = 1mA I8 = -1mA 40 3 0 0.75 -0.2 50 3.8 V V mV s V
V8 = 0
4.5 4
PUSH-PULL OUTPUT STAGE SATURATION VOLTAGES VSatU VSatU VSatU +dV5/dt -dV5/dt -I1 V6(Min.) V6(Max.) V3A Oj V3Sat I6 Pin 5 Sourcing Pin 5 Sinking Pin 5 Sinking Rising Edge Falling Edge Current to reduce the Control Voltage Undervoltage Protection for V6 : Voltage at Pin 5 = V5(Min.) if V6 < V6(Min.) Overvoltage Protection for V6 : Voltage at Pin 5 = V5(Min.) if V6 > V6(Max.) Undervoltage Protection for VAC : Voltage at Pin 5 = V5(Min.) if V3 < V3A Over Temperature : at the given chip temperature the IC will switch V5 to V5(Min.) Voltage at Pin 3 if one of the protection functions was triggered ; (V3 will be clamped until V6 < V6A) Current Drain during Burst Operation V7 = 1V 7.0 15 V2 = 0V 970 I5 = -0.1A I5 = +0.1A I5 = +0.5A 1.5 1.0 1.4 70 100 50 7.25 16 1005 150 I3 = 750A V3 = V2 = 0V 0.4 8 0.8 7.5 16.5 1040 2.0 1.2 1.8 V V V V/s V/s A V V mV
o
OUTPUT SLOW RATE
REDUCTION OF CONTROL VOLTAGE PROTECTION CIRCUIT
C
4605-05.TBL
V mA
FUNCTIONAL DESCRIPTION In free running fly-back converters, the TDA4605 assumes control of a MOS power transistor and all necessary regulation and monitoring functions. The serial circuit of power transistor and primary winding of the flyback transformer is connected to the input voltage. During the switch-on period of the transistor, energy is stored in the transformer and during the switch-off period it is fed to te load via the secondary winding. By varing the switch-on time of the power transistor, the IC controls each portion of energy transferred to the secondary side such that the output voltage remains nearly independent of load variations. The required control information is taken from the input voltage during the switch-on period and from a regulation winding during the switch-off period. A new cycle begins as soon as the energy stored in the transformer has been totally delivered to the
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secondary side. In different load ranges, the SMPS will behave as follows : - No-Load Operation : The power supply unit oscillates in non continuous mode at a typical frequency of 20 to 40kHz. Depending upon the transformer winding and the regulated voltage divider, the output voltage can be slightly above the nominal value. - Normal Operation : Starting from typ. 200kHz, the switching frequency falls with increasing load and decreasing AC voltage. The duty cycle depends primarily on the AC voltage. The output voltage is only slightly load-dependen t. - OverloadPoint : Maximum output power is available at this point of the output characteristics - Overload : The energy transferred per operation cycle is limited at the top. Therefore, the output voltage will fall with secondary oveloading.
TDA4605
PACKAGE MECHANICAL DATA 8 PINS - PLASTIC DIP
Dimensions A a1 B b b1 D E e e3 e4 F I L Z
Min. 0.51 1.15 0.356 0.204 7.95
Millimeters Typ. 3.32
Max.
Min. 0.020 0.045 0.014 0.008 0.313
Inches Typ. 0.131
Max.
1.65 0.55 0.304 10.92 9.75 2.54 7.62 7.62 6.6 5.08 3.81 1.52
0.065 0.022 0.012 0.430 0.384 0.100 0.300 0.300 0260 0.200 0.150 0.060
3.18
0.125
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DIP8.TBL
PM-DIP8.EPS
TDA4605
PACKAGE MECHANICAL DATA 8 PINS - PLASTIC MICROPACKAGE (SO)
Dimensions A a1 a2 a3 b b1 C c1 D E e e3 F L M S
Min. 0.1 0.65 0.35 0.19 0.25 4.8 5.8
Millimeters Typ.
Max. 1.75 0.25 1.65 0.85 0.48 0.25 0.5 45o (Typ.) 5.0 6.2
Min. 0.004 0.026 0.014 0.007 0.010 0.189 0.228
Inches Typ.
Max. 0.069 0.010 0.065 0.033 0.019 0.010 0.020 0.197 0.244
1.27 3.81 3.8 0.4 4.0 1.27 0.6 8 (Max.)
o
0.050 0.150 0.15 0.016 0.157 0.050 0.024
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. (c) 1996 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 - 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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SO8.TBL
PM-SO8.EPS

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