From: Jaap van Ganswijk To: Wolfgang Subject: Re: Siemens TDA 4605 IC Hi Wolfgang, At 08:10 AM 9/29/95 -0400, you wrote: >We are Looking for Information about the SIEMENS TDA 4605 IC > >there is no Information about in your Database - please send a Note to my >Compuserv Adress Hi it's on the Siemens CD-ROM (in some graphics format). I have OCR'ed two pages for you: (OCR=Optical Character Recognision) I haven't corrected any errors... Greetings, Jaap SIEMENS Control IC for Switched-Mode Power Supplies TDA 4605 using MOS-Transistors Bipolar IC Features · Fold-back characteristic provides overload protection for external components · Burst operation under short-circuit conditions · Looperrorprotection · Switch-off if line voltage is too low (undervoltage switch-off) · Line voltage compensation of overload point · Sof t-start for quiet start-up · Chip-over temperature protection (thermal shutdown) P-DIP-8 ·On-chip parasitic transformer oscillation suppression circuitry Type Ordering Code Package TDA4605 Q67000-A8078 F-DIF-8 The IC TDA 4605-1 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 applicable tor consumer and industrial power supplies The serial circuit of power transistor and primary winding of the flyback transf ormer 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 the load via the secondary winding By varying 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 ot 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. Semiconductor Group 33 0694 SIEMENS TDA 4605 Pin Definitions and Functions Pin No. Function 1 Regulating Voltage: Information input concerning secondary voltage. By comparing the regulating voltage - obtained from the regulating winding ot the transf ormer - with the internal ref erence voltage. the output impulse width on pin 5 is adapted to the load ot the secondary side (normal, overload, short-circuit, no load). 2 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 ot external RC-element, When a value is reached that is derived from the regulating voltage at pin I,the output impulse at pin 5 is terminated. The RC-element serves to set the maximum power at the overload point set 3 Input for Primary Voltage Monitoring: In the normal operation V3 is moving between the thresholds V3H and V3L(V3H > ~j > ~j~)· ~j < ~j~: SMPS is switched OFF (line voltage too low). V3 > V3H : Compensation of the overload point regulation (controlled by pin 2) starts at V3H: V3L = 1 7 4 Ground 5 Output: Push-pull-output provides i 1 A for rapid charge and discharge of the gate capacitance ot the power MOS-transistor. 6 Supply Voltage Input: A stable internal reference voltage VREF is derived from the supply voltage also the switching thresholds VsA. VsE. V~,,, and Vs,, for the supply voltage detector. If ~ > V~E then VREF is switched on and swiched off when V, < V,A. In addition the logic is only enable for v,,,, < v,< v,,,. 7 Soft-Start: Input for soft-start Start-up will begin with short pulses by connecting a capacitor from pin 7 to ground 8 Zero Detector: Input tor the oscillation feedback. After starting oscillation, every zero transit of the feedback voltage (falling edge) triggers an output impulse at pin 5 The trigger threshold is at + 50 mV typical Semiconductor Group 35