SGS-THOMSON TEA2018A Technical data

POWER SUPPLY CONTROLCIRCUIT

.

DIRECT DRIVE OF THE EXTERNAL
SWITCHING TRANSISTOR

.

POSITIVE AND NEGATIVE OUTPUT CUR­RENTSUP TO 0.5 A

.

CURRENT LIMITATION

.

TRANSFORMER DEMAGNETIZATION
SENSING

.

FULL OVERLOAD AND SHORT-CIRCUIT
PROTECTION

.

PROPORTIONALBASECURRENT DRIVING

.

LOW STANDBY CURRENT BEFORE START­ING (< 1.6 mA)

.

THERMAL PROTECTION

DESCRIPTION

The TEA2018Aisan 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 regulationloop

.

Automatic input voltage feed-forward in dis­continuousmode fly-back

.

Automaticpulse-by-pulsecurrent limitation
Typical applications: VideoDisplayUnits, TVsets,
typewriters,microcomputersandindustrialapplica­tions

Where synchronization is required, use the
TEA2019. For more details, see application
note AN406/0591

TEA2018A

CURRENT MODE SWITCHING

DIP8

(Plastic Package)

ORDER CODE : TEA2018A

PINCONNECTIONS

OSCILLATOR

COLLECTOR CURRENT SENSING

NEGATIVE SUPPLY VOLTAGE

May 1993

GROUND

1
2
3
4

8

ERROR AMPLIFIER NON-INVERTING INPUT

7

DEMAGNETIZATION SENSING

6

POSITIVE SUPPLY VOLTAGE

5

OUTPUT

2018A-01.EPS

1/7

TEA2018A

BLOCK DIAGRAM

TEA2018A

7

I

S

DEMAGNETIZATION

SENSING

INTERNAL

BIAS

V

CC

”Good”

V

CC

6

V

CC

MONITORING

V

REF

2.4V

Undervoltage0.1V

2.4V

OSCILLATOR1

MAXIMUM

DUTYCYCLE

70%

COMPARATOR

G ≅ 50

-1V

VOLTAGE

LIMITATION

I

SENSE

&

FLIP-FLOP

&

1

THERMAL

SHUTDOWN

3

GROUND

Ic

RECOPY

DELAY

500ns

5

OUTPUT

1

42

V

CC

RC

tt

8

ABSOLUTE MAXIMUM RATINGS

Symbol Parameter Value Unit

V

+ Positive Supply Voltage 15 V

CC

V

- Negative Supply Voltage -5 V

CC

I

(peak) Peak Output Current (duty cycle < 5%) ±1A

O

I

I

T

T

oper

T

stg

Input Current (Pin 3) ±5mA
Junction Temperature +150

j

Operating Ambient Temperature Range -20, +70
Storage Temperature Range -40, +150

o

C

o

C

o

C

2018A-02.EPS

2018A-01.TBL

THERMALDATA

Symbol Parameter Value Unit

R

th (j-a)

Junction-ambient Thermal Resistance 80

o

ELECTRICAL OPERATINGCHARACTERISTICS

=25oC, potentials referenced to ground (unless otherwise specified) (see testcircuit)

T

amb

Symbol Parameter Min. Typ. Max. Unit

V

+ Positive Supply Voltage 6.6 8 15 V

CC

V

- Negative Supply Voltage -1 -3 -5 V

CC

2/7

V

CC(start)

V

CC(stop)

Minimum Positive Supply Voltage required for starting (VCC+ rising) 6 6.6 V
Minimum Positive Voltage below wich device stopsoperating (VCC+ falling) 4.2 4.9 5.6 V

C/W

2018A-02.TBL

2018A-03.TBL

TEA2018A

ELECTRICAL OPERATINGCHARACTERISTICS

=25oC, potentials referenced to ground (unless otherwise specified) (see testcircuit)

T

amb

Symbol Parameter Min. Typ. Max. Unit

∆V

+ Hysteresis on VCC+ Threshold 0.7 1.1 1.6 V

CC

I

CC(sb)

V

th(IC)

R

V

τ

max

A
I

V

∆V

∆T

t

OSC

∆f

∆T

∆f

∆V

t

on(min)

Stand-by Supply Current before starting (VCC+<V

) 1 1.6 mA

CC(start)

Current Limitation Threshold Voltage (Pin 3) -1100 -1000 -880 mV
Collector Current Sensing Input Resistance 1000 Ω

(IC)

Demagnetization Sensing Threshold 75 100 125 mV

7(th)

I

Demagnetization Sensing Input Current (Pin7 = 0V) 1 µA

S

Maximum Duty Cycle 60 70 %
ErrorAmplifier Gain 50

V

+ Error Amplifier Input Current (non-inverting input) 2 µA

I

Internal Reference Voltage 2.3 2.4 2.5 V

REF

REF

ReferenceVoltage Temperature Drift 10

-4

Oscillator Free-running Period ( R = 59kΩ, C = 1.2nF) 44 48 52 µs

OSC

Oscillator Frequency Drift with Temperature (V

OSC

Oscillator Frequency Drift with VCC+ (+8V < VCC+ < +14V) 0.5 %/V

CC

+ = +8V) 0.05 %/oC

CC

Minimum Conducting Time (Ct= 1nF) 2 µs

V/oC

2018A-04.TBL

RECOMMENDEDOPERATINGCONDITIONS

Symbol Parameter Min. Typ. Max. Unit

V

+ Positive Supply Voltage 8 V

CC

V

- Negative Supply Voltage -3 V

CC

I

Output Current 0.5 A

O

f

oper

Operating Frequency 30 kHz

TEST CIRCUIT

V8 V7 V6

10

Ω

4321

470nF

22nF

59k

1%

1.2nF
1%

470

22nF

22nF

8765

Ω

TEA2018A

4.7nF

Ω

2018A-05.TBL

100Ω

V1 V3 V4

2018A-03.EPS

3/7