TEA2262

SWITCH MODE POWER SUPPLY CONTROLLER

April 1996

1

2

3

4

5

6

7

8

16

15

14

13

12

11

10

9

IS

IN

GND

GND

E

S

SECONDARY PULSES INPUT

GROUND

GROUND

ERROR AMPLIFIER INPUT (INVERTING)

ERROR AMPLIFIER OUTPUT

OVERLOAD INTEGRATION CAPACITOR

POWER SUPPLY

POSITIVE OUTPUT STAGE SUPPLY

POWER OUTPUT

GROUND

GROUND

OSCILLATOR RESISTOR

OSCILLATOR CAPACITOR

SOFT-START CAPACITOR

V

V

OUT

GND

GND

C0

C1

R0

CC

max.I

C2

TRANSFORMER DEMAGNETIZATIONSENSING INPUT

POWER TRANSISTORCURRENT LIMITATION INPUT

2262

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EP

S

PIN CONNECTIONS

DIP16(Plastic Package)

ORDER CODE : TEA2262

.POSITIVE AND NEGATIVE OUTPUT CUR-RENT UP TO 1A.LOW START-UP CURRENT.DIRECT DRIVE OF THE MOS POWERTRANSISTOR.TWO LEVELS TRANSISTOR CURRENT LIMI-TATION.DOUBLE PULSE SUPPRESSION.SOFT-STARTING.UNDER AND OVERVOLTAGE LOCK-OUT.AUTOMATIC STAND-BY MODE.LARGE POWER RANGE CAPABILITY INSTAND-BY (Burst mode). INTERNAL PWM SIGNAL GENERATOR

DESCRIPTION

The TEA2262 is a monolithic integrated circuit forthe use in primarypart of anoff-lineswitching modepower supply using a MOS power transistor.All functions required for SMPS control under nor-mal operating,transient or abnormal conditionsareprovided.The capability of working according to the ”master-slave” concept, or according to the ”primary regu-lation” mode makes the TEA2262 very flexible andeasy to use. This is particularly true for TV receiv-ers wherethe IC providesanattractive and low costsolution (no need of stand-by auxiliary power sup-ply).

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INT

ER

NA

LB

IAS

VR

EF

(2.4

9V)

AU

TO

MA

TIC

BU

RS

TG

EN

ER

AT

ION

12

34

5

6

7

89

10

16

1112

13

14

PO

SIT

IVE

OU

TP

UT

ST

AG

E

NE

GA

TIV

EO

UT

PU

TS

TA

GE

VC

C

+1A

(Max

.)

-1A

(Max

.)

OU

T

45µA

10µA

Sec

onda

ryP

ulse

2.55

V0.

6V0.

84V

Cur

rent

Lim

itatio

n

Rep

etiti

veO

verlo

adP

rote

ctio

n

LOG

ICP

RO

CE

SS

OR

15.7

V

15V+

Ove

rvol

tage

Pro

tect

ion

ISLO

GIC

0.15

V

GN

DI M

AX

C2

INIS

Reg

ulat

ion

Pul

ses

Prim

ary

Pul

ses

VC

CM

ON

ITO

RIN

G

8.5V

11.8

V

VC

C

MO

DU

LAT

OR

LOG

IC

Dem

agne

tizat

ion

Sen

sing

Mod

ulat

ors

-1

OS

CIL

LAT

OR

f/4T

ON

(Max

.)(6

0%)

SO

FT

-ST

AR

T

C0

R0

C1

VR

EF

2.49

V

Err

orA

mpl

ifier

S

E

TE

A22

62

2262

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EP

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BLOCK DIAGRAM

TEA2262

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ABSOLUTE MAXIMUM RATINGS

Symbol Parameter Value Unit

VCC Power Supply V16-V4, 5, 12, 13 20 V

V+ Output Stage Power Supply V15-V4, 5, 12, 13 20 V

IOUT+ Positive Output Current (source current) 1.5 A

IOUT- Negative Output Current (sink current) 1.5 A

Tj Operating Junction Temperature 150 oC

Tstg Storage Temperature -40, +150 oC

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L

THERMAL DATA

Symbol Parameter Value Unit

Rth (j-c) Junction-case Thermal Resistance 15 oC/W

Rth (j-a)* Junction-ambient Thermal Resistance 50 oC/W

* Soldered on a 35µm, 40cm2 board copper area

2262

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TB

L

50 100 1500

3

2

1

P (W)tot4

T ( C)AMBo

o50 C/W

2262

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S

Figure 1 : Maximum Power Dissipation

RECOMMENDED OPERATING CONDITIONS

Symbol Parameter Min. Typ. Max. Unit

VCC Power Supply VCC stop 12 VCC max V

IOUT+ Positive Output Current (source current) 1 A

IOUT- Negative Output Current (sink current) 1 A

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 2.5 4.5 V

ROSC Oscillator Resistor Range 10 100 kΩCOSC Oscillator Capacitor Range 0.33 4.7 nF

C1 Soft-starting Capacitor Range 0.047 1 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 oC

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L

TEA2262

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ELECTRICAL CHARACTERISTICS (Tamb = 25oC, VCC =12V, unless otherwise specified)

Symbol Parameter Min. Typ. Max. Unit

POWER SUPPLY

VCC(start) Starting Voltage (VCC increasing) 9.5 11.8 13 V

VCC(stop) Stopping Voltage (VCC decreasing) 7 8.5 9.5 V

Hyst VCC Hysteresis (VCC(start) - VCC(Stop)) 2.7 3.3 3.7 V

ICC(start) Starting Current (VCC = 9V) 0.5 mA

ICC Supply Current (VCC = 12V) 6.5 mA

VCC(max) Overvoltage Threshold on VCC 15 15.7 V

ICC(over) Supply Current after Overvoltage Detection (VCC = 17V) 35 mA

OSCILLATOR / PWM SECTION

∆FF

Accuracy (ROSC = 68kΩ, COSC = 1nF) 10 %

tON max 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) 0.08 µA

VREF Internal Voltage Reference(connected to error amplifier input and not directly accessible)

2.34 2.49 2.64 V

INPUT SECTION

VIN IN Input Threshold (Pin 2) 0.6 0.85 1.2 V

VIS IS Input Threshold (Pin 1) 0.15 V

IBIN IN Input Bias Current 0.3 µA

IBIS IS Input Bias Current 0.4 µA

CURRENT LIMITATION SECTION

VIM1 First Current Limitation Threshold 550 600 650 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

IBI(max) Maximum Input Bias Current (Pin 3) 0.2 µA

2262

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TEA2262

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AUDIOOUTPUTSTAGE

SCANNINGDEVICE

MAINSINPUT

R

C

VOLTAGEREGULATOR

µ P

INFRA-REDRECEIVER

MutingControl

RemoteStand-by

RemoteStand-by

Synchronization

VCC

2P

P1

VCC

2

1P : Output voltage adjustement in normal mode

P : Output voltage adjustement in stand-by

Power primary groundSecondary ground (isolated from mains)

PWM

TEA5170MASTER

TEA2262SLAVE

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Figure 1 : Master-slave Concept

AUDIOOUTPUTSTAGE

SCANNINGDEVICE

MAINSINPUT

R

C

VOLTAGEREGULATOR

µ P

INFRA-REDRECEIVER

MutingControl

RemoteStand-by

VCC

P

VCC

P : Output voltage adjustement Power primary groundSecondary ground (isolated from mains)

TEA2262

2262

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Figure 2 : SecondaryRegulation (with optocoupler)

SIMPLIFIED APPLICATION DIAGRAMS

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GENERAL DESCRIPTION

The TEA2262 is an off-line switch mode powersupply controller. The synchronization functionandthe specificoperationin stand-bymodemake itwelladapted to video applications such as TV sets,VCRs, monitors, etc...The TEA2262 can be used in two types of architec-tures :- Master/slave architecture. In this case, the

TEA2262drives the power transistor according tothe pulse width modulated signals generated bythe secondary located master circuit. A pulsetransformerprovides the feedback(see Figure 1).

- Conventional architecture with linear feedbacksignal (feedback sources : optocoupler or trans-former winding) (see Figure 2).

Using the TEA2262, the stand-by auxiliary powersupply, often realized with a small but costly 50Hztransformer, is no longer necessary. The burstmode operation of the TEA2262 makes possiblethe control of very low output power (down to lessthan 1W) with the main power transformer.When used in a master/slave architecture, theTEA2262and also the power transistor turn-off canbe easily synchronized with the line transformer.The switching noise cannot disturb the picture inthis case.As an S.M.P.S. controller, the TEA2262 featuresthe following functions :- Power supply start-up (with soft-start)- PWM generator- Direct power transistor drive (±1A)- Safety functions : pulse by pulse current limita-

tion, output power limitation, over and undervolt-age lock-out.

S.M.P.S. OPERATING DESCRIPTIONStarting Mode - Stand By Mode

Power for circuit supply is taken from the mainsthrough a high value resistor before starting. Aslong as VCC of the TEA2262 is below VCC start, thequiescent current is very low (typically 0.5mA) andthe electrolytic capacitor across VCC is linearlycharged. When VCC reaches VCC start (typically11.8V), the circuit starts, generating output pulseswith a soft-starting. Then the SMPS goes into thestand-by mode and the output voltage is a percen-tage of the nominal output voltage (eg. 80%).During startingphase, in order to avoid transformer

magnetization (specially at high frequency), thefrequency oscillator is divided by four.At switch-on, C0 charging current is divided by four.It recover its normal value when the voltage onsoft-start capacitor reach 2.5V.

The current also recover its standard value whenthe soft-start capacitor is discharged because of aburst operating mode (starting in stand-by).In other words, the charging current will becomeand stay at its normal value, as soon as one of thefollowing events occurs :- VC1 rearch 2.5V- C1 is discharged by burst operating modeFor this the TEA2262 contains all the functionsrequired for primary mode regulation : a fixed fre-quency oscillator, a voltage reference, an erroramplifier and a pulse width modulator (PWM).For transmission of low power with a good effi-ciency in stand-by, an automatic burst generationsystem is used, in order to avoid audible noise.

Normal Mode (secondary regulation)The normal operating of the TV set is obtained bysending to the TEA2262 regulation pulses gener-ated by a regulator located in the secondary sideof the power supply (TEA5170 for example).This architectureuses the ”Master-slave Concept”,advantages of which are now well-known espe-cially the very high efficiency in stand-bymode, andthe accurate regulation in normal mode.

Stand-by mode or normal mode are obtained bysupplying or not the secondary regulator. This canbe ordonnered for exemple by a microprocessor inrelation with the remote control unit.Regulation pulses are applied to the TEA2262through a small pulse-transformer to the IN input(pin 2). This input is sensitive to positive squarepulses. The typical threshold of this input is 0.85V.

The frequency of pulses coming from the secon-dary regulator can be lower or higher than thefrequency of the starting oscillator.The TEA2262 has no soft-starting system when itreceives pulses from the secondary. The soft-start-ing has to be located in the secondary regulator.Due to the principle of the primary regulation,pulses generated by the starting system automat-ically disappear when the voltage delivered by theSMPS increases.

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Stand-by Mode - Normal Mode TransitionDuring the transition there are simultaneouslypulses coming from the primary and secondaryregulators.These signals are not synchronizedand somecarehas to be taken to ensurethe safetyof the switchingpower transistor.A very sure and simple way consist in checking thetransformer demagnetization state.- A primary pulse is taken in account only if the

transformer is demagnetized after a conductionof the power transistor required by the secondaryregulator.

- A secondary pulse is taken in account only if thetransformer is demagnetized after a conductionof the power transistor required by the primaryregulator.

With this arrangement the switching safety area ofthe power transistor is respected and there is norisk of transformer magnetization.The magnetization state of the transformer ischecked by sensing the voltage across a windingof the transformer (generally the same which sup-plies the TEA2262). This is made by connecting aresistor between this winding and the demagneti-zation sensing input of the circuit (pin 1).

SECURITY FUNCTIONS (see flow-chart below)

- Undervoltage detection. This protection worksin association with the starting device ”VCCswitch” (see paragraph Starting-mode - standbymode). If VCC is lower than VCCstop (typically8.5V) output pulses are inhibited, in order to avoidwrong operation of the power supply or badpower transistor drive.

- Overvoltagedetection. If VCC exceeds VCCmax(typically 15.7V) output pulses are inhibited andthe external capacitor C2 is charged as long as

VCC is higher than VCC stop. Restarting of thepower supply is obtained by reducing VCC belowVCCstop except if the voltage across C2 reachesVC2 (typically 2.55V) (refer to ”Restart of thepower supply” paragraph).In this last case, thecircuit is definitively stopped.

- Current limitation of the power transistor. Thecurrent is measured by a shunt resistor. A doublethreshold system is used :

- When the first threshold (VIM1) is reached, theconduction of the power transistor is stoppeduntil the end of the period : a new conductionsignal is needed to obtain conduction again.

- Furthermore as long as the first threshold isreached (it means during several periods), anexternal capacitor C2 is charged. When thevoltage across the capacitor reaches VC2 (typi-cally 2.55V) the output is inhibited. This is calledthe ”repetitive overload protection”. If the over-load diseappears before VC2 is reached, C2 isdischarged, so transient overloads are toler-ated.

- Second current limitation threshold (VIM2).When this threshold is reached the output of thecircuit is immediatly inhibited. This protection ishelpfull in case of hard overload for example toavoid the magnetization of the transformer.

- Restart of the power supply . After stopping dueto VIM2, VCCMax or VCCstop triggering, restart ofthe power supply can be obtained by the normaloperating of the ”VCC switch” VCC switch se-quency from VCCstop to VCCstart . After stoppingdue to VC2 threshold reaching, the circuit is de-finitively stopped. In this case it is necessary toreduce VCC below approximately 5V to reset thecircuit. From a practical point of view, it meansthat the power supply has to be temporarily dis-connected from any power source to get therestart.

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S.M.P.S.starting

Firstthreshold reached

VIM1

2

V < 2.6VC2

CCV maxreached

2

Normal operatingC discharged

Definitivestopping

N

N

Y

N

N

YY

Y

N

Y

Pulse by pulse currentlimiting C charged2

C chargedS.M.P.S. stopped

V < 2.6VC2Y

Reset Cdischarged

2

N

Secondthreshold reached

VIM2

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SECURITY FLOW-CHART

TEA2262

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PM

-DIP

16.E

PS

PACKAGE MECHANICAL DATA16 PINS - PLASTIC DIP

Information furnished is believed to be accurate and reliable. However, SGS-THOMSON Microelectronics assumes no responsibilityfor the consequences of use of such information nor for any infringement of patents or other rights of third parties which may resultfrom 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 allinformation previously supplied. SGS-THOMSON Microelectronics products are not authorized for use as critical components in lifesupport devices or systems without express written approval of SGS-THOMSON Microelectronics.

199 SGS-THOMSON Microelectronics - All Rights Reserved

Purchase of I 2C Components of SGS-THOMSON Microelectronics, conveys a license under the PhilipsI2C Patent. Rights to use these components in a I 2C system, is granted provided that the system conforms to

the I2C Standard Specifications as defined by Philips.

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DimensionsMillimeters Inches

Min. Typ. Max. Min. Typ. Max.a1 0.51 0.020B 0.77 1.65 0.030 0.065

b 0.5 0.020b1 0.25 0.010

D 20 0.787E 8.5 0.335e 2.54 0.100

e3 17.78 0.700F 7.1 0.280

I 5.1 0.201L 3.3 0.130Z 1.27 0.050

DIP

16.T

BL

TEA2262

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