STMicroelectronics TDA4605, TDA4605D Schematic [ru]

CONTROL CIRCUIT FOR SWITCH MODE

1
2
3
4

8
7
6
5

REGULATION INPUT

PRIMARY CURRENT SIMULATION

PRIMARY VOLTAGE MONITORING

GROUND OUTPUT

SUPPLY VOLTAGE

SOFT-START

ZERO CROSSING DETECTOR INPUT

Obsolete Product(s) - Obsolete Product(s)

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 Overlo ad Point

■ Soft-Start for smooth Start-up

■ Chip Over-Temperature Protection (Thermal

Shutdown)

■ On-Chip Parasitic Transformer Oscillation

Suppression Circuitry

■ Decrease of Regulated Vol tage for low Power

Consumption

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 TDA 4605 is als o availa­ble from SIEMENS Semiconductors Consumer
Electronics A.G.

TDA4605

DIP28

(Plastic Package)

ORDER CODE: TDA4605

SO8

(Plastic Micropackage)

ORDER CODE: TDA4605D

Figure 1. Pin Connections

4605-01.eps

September 2003 1/7

1

Obsolete Product(s) - Obsolete Product(s)

TDA4605

PIN CONFIGURATION

Pin

Number

Regulating voltage : information input concerning secondary voltage.
By comparing the regulating voltage obtained from the regulating winding of the transformer with the

1

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

2

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

3

switched-off by comparing V

compensation.
4 Ground
5 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 (V

switching threshold V
6

if V

> V6E the V

6

min < V6 < V6 max.

V

6

Soft-start : input for soft-start and integration network. Start-up will begin with short pulses by connecting a
7

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
8

voltage (falling edge) triggers an output pulse at Pin 5. The trigger threshold is at typically - 50mV

6A

is switched on and switched off when V6 < V6A. In addition the logic is only enable for

REF

with an internal reference. Voltage at Pin 3 is used for overload point

3

, V6E, V6 max and V6 min for the supply voltage detector.

Description

) and the

REF

Figure 2. Block Diagram

2

56

TDA4605

4

1

Reference

Voltage

(typ. 3V)

V

Current

Source

Overload

Point

Correction

REF

V

R

V

u

V

6min

Regulating

& Overload

Amplifier

Low Voltage

Protection

Monitoring

Supply
Voltage
Monitor

V

V

6A

6E

V

6max

V

2B

Primary

Current
Recopy

V

st

Starting

Impulse

Generator

Output Stage

and

Current Limit

Logic

Stop
Comp.

Zero

Crossing

Detector

3

7 8

4605-02.eps

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Obsolete Product(s) - Obsolete Product(s)

TDA4605

ABSOLUTE MAXIMUM RATINGS

Symbol Parameter Pin Value Unit

V

1

V

2

V

3

V
V
V

I
I
I
I

I
I
I
I
T

T

stg

Supply Voltage

4
6

7
1
2
3

t

50µs, V ≤ 0.1 4 - 1.5 A

4

Supply Current

5
6
7
8

Junction Temperature (autom. thermal disjunction) +125

j

≤

p

tp ≤ 50µs, V ≤ 0.1 5 -0.5, +1.5 A
tp ≤ 50µs, V ≤ 0.1 6 0.5 A

Storage Temperature -40, +125

THERMA L D ATA

Symbol Parameter Value Unit

R

(j-a) Junction-ambient Thermal Resistance 80

th

(j-c) Junction-case Thermal Resistance 45

R

th

T

amb

Ambient Temperature -20, +85

1 -0.3, +3 V
2 -0.3 V
3 -0.3 V
4 -0.3 V
6 -0.3, +20 V
7 -0.3 V
13mA
23mA
33mA

73mA
8 -3, +3 mA

o

C/W

o

C/W

o

o

C

o

C

C

ELECTRICAL CHARACTERISTICS

(V

= 10V, T

CC

= 25oC, unless otherwise specified)

amb

Symbol Parameter Test Conditions Min. Typ. Max. Unit

START-UP HYSTERESIS

I

6E0

V
V
I

6E1

I

6A1

VOLTAGE CLAMP (V

(Max.) At Pin 2 (V6 < V6E)I

V

2

V

(Max.) At Pin 3 (V6 < V6E)I

3

Start-up Current Drain V6 = V
Switch-on Voltage 11 12 13 V

6E

Switch-off Voltage 4.5 5 5.5 V

6A

Switch-on Current V6 = V
Switch-off Current V6 = V

= 10V, IC Switched off)

6

6E

6E
6A

= 1mA 5.6 6.6 9 V

2

= 1mA 5.6 6.6 9 V

3

0.6 0.8 mA

11 mA
10 mA

CONTROL RANGE

V

-V

Control Input Voltage 400 410 420 mV

1R

= d(V2S - V2B)/dV

V

Voltage Gain of the Control Circuit in the Control Range

R

R

f = 1kHz

1

43 dB

PRIMARY CURRENT SIMULATION VOLTAGE

V

Basic Value 0.955 1.00 1.03 V

2B

OVERLOAD RANGE AND SHORT CIRCUIT OPERATION

V

2O

DV
V

Peak Value in the Range of Secondary Overload V1 = V1R - 10mV 2.8 2.95 3.1 V
Maximum Ramp Amplitude V2O - V

2

Peak Value in the Range of Secondary Short

2S

Circuit Operation

2B

= 0 2.3 2.5 2.7 V

V

1

1.82 1.95 2.08 V

FOLDBACK POINT CORRECTION

-I

Foldback Point Correction Curre nt V3 = 3.7V 300 500 650 µA

2

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Obsolete Product(s) - Obsolete Product(s)

TDA4605

ELECTRICAL CHARACTERISTICS (V

= 10V, T

CC

= 25oC, unless otherwise specified) - Continued

amb

Symbol Parameter Test Conditions Min. Typ. Max. Unit

GENERALLY VALID DATA (V
VOLTAGE OF THE ZERO Transition DETECTOR

V
V
V

Positive Clamping Voltage I8 = 1mA 0.75 V

8P

Negative Clamping Voltage I8 = -1mA -0.2 V

8N

Threshold Value 40 50 mV

8S

= 10V)

6

TUL Suppression of Transformer Ringing 3 3.8 4.5 µs

-I

Input Current V8 = 0 0 4 µV

8

PUSH-PULL OUTPUT STAGE
SATURATION VOLTAGES

V
V
V

SatU
SatU
SatU

Pin 5 Sourcing I5 = -0.1A 1.5 2.0 V
Pin 5 Sinking I5 = 0.1A 1.0 1.2 V
Pin 5 Sinking I5 = 0.5A 1.4 1.8 V

OUTPUT SLOW RATE

/dt Rising Edge 70 V/µs

dV

5

/dt Falling Edge 100 V/µs

-dV

5

REDUCTION OF CONTROL VOLTAGE

-I

Current to reduce the Control Voltage V7 = 1V 50 µA

1

PROTECTION CIRCUIT

V

6

V

6

V

(Min.)

(Max.)

V

3A

Oj

3Sat

I

6

Undervoltage Protection for V
Voltage at Pin 5 = V

(Min.) if V6 < V6(Min.)

5

Overvoltage Protection for V
Voltage at Pin 5 = V

(Min.) if V6 > V6(Max.)

5

Undervoltage Protection for VAC :
Voltage at Pin 5 = V

(Min.) if V3 < V

5

Over Temperature : at the given chip temperature the
IC will switch V

to V5(Min.)

5

Voltage at Pin 3 if one of the protection functions was
triggered ; (V

will be clamped until V6 < V6A)

3

Current Drain during Burst Operation V3 = V2 = 0V 8 mA

:

6

:

6

3A

V2 = 0V 970 1005 1040 mV

7.0 7.25 7.5 V

15 16 16.5 V

150

= 750µA 0.4 0.8 V

I

3

o

C

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FUNCTIONAL DESCRIPTION

In free running fly-back converters, the TDA460 5
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 co nnecte d to
the input voltage. During the switch-on period of
the transistor, energy is s tored in the tran sformer
and during the switch-off period it is fed to t he l oad
via the secondary winding. By varying the switch­on time of the power transistor, the IC controls
each portion of energy transferred to the second­ary side such that the output v oltage remains near­ly independent of load variations.

The required control information is taken from th e
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
secondary side.

TDA4605

In different load ranges, the SMPS will behave as
follows:

– No-Load Operation: The power supply unit os-

cillates 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: S tarting 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-dependent.

– Overload Point: Maximum output po w er 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 overloading.

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TDA4605

PACKAGE MECHANICAL DATA

8-PINS - PLASTIC DIP

Figure 3. 8-Pin Package

8-PINS - PLAS TI C SO

Figure 4. 8-Pin Plastic Micropackage

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TDA4605

Information furnished is believed to be accurate and reliable. However, STMicroelectronics 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 license is granted
by implic ation or otherwise under any patent or patent r i ght s of STMi croelectr oni cs. Spec i fications mentione d i n this publicatio n are subj ect
to change without notice. This publication supersedes and replaces all information previously supplied. STMicroelectronics product s are not
authorized for use as cri tical comp onents in lif e support devi ces or systems without the express written appr oval of STMic roelectronics.

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