Datasheet TDA8380 Specification

INTEGRATED CIRCUITS

DATA SH EET

TDA8380A

Control circuit for switched mode
power supplies

Product specification
Supersedes data of October 1993
File under Integrated Circuits, IC02

November 1993

Philips Semiconductors Product specification

Control circuit for switched mode power supplies TDA8380A

GENERAL DESCRIPTION

The TDA8380A is an integrated circuit intended for use as a control circuit in low-cost switched mode power supplies for
television, monitors and small industrial equipment. The TDA8380A operates using duty factor regulation in the fixed
frequency mode.

Features

• A low-current initialization circuit (maximum 150 µA) which can be switched off

• A bandgap reference generator

• Circuitry for slow-start combined with an accurate setting of the maximum duty factor (D

• Programmable low supply voltage protection with one default value

• High supply protection circuitry

• Error amplifier with a transfer characteristic generator (TCG)

• Protection against open- and short-circuited feedback loop

• An overload voltage foldback

• Primary current protection circuitry for both cycle-by-cycle and trip mode

• Protection against transformer saturation

• A direct drive output stage (sink current 2.5 A, source current 0.75 A)

• Anti-double pulse logic

• Protected against damage as a result of a short-circuited high-voltage transistor

• RC oscillator with synchronization input

max

)

QUICK REFERENCE DATA

PARAMETER SYMBOL MIN. TYP. MAX. UNIT

Supply voltage V
Supply current I
Output pulse repetition frequency range f
Operating ambient temperature range T

CC
CC
o

amb

PACKAGE OUTLINE

16-lead DIL; plastic (SOT38); SOT38-1 ; 1996 November 18.

− 14 − V

−−15 mA
10 − 100 kHz

−25 −+70 °C

November 1993 2

Philips Semiconductors Product specification

Control circuit for switched mode power
supplies

TDA8380A

November 1993 3

Fig.1 Block diagram.

Philips Semiconductors Product specification

Control circuit for switched mode power supplies TDA8380A

PINNING

Fig.2 Pinning diagram.

1 E2 Emitter of output source transistor
2 C2 Collector of output source transistor
3 DEM Demagnetization sense input
4V
5V
6I

ref

Minimum VCC threshold setting

CCmin

Supply voltage

CC

Reference current setting
7 FB Feedback input
8 STAB Output error amplifier
9 DUTY Pulse width modulator input
10 C

Oscillator capacitor

OSC

11 SYNC Synchronization input
12 SS Maximum duty factor (D

) setting plus slow-start

max

13 CURR Input current protection
14 V

EE

Ground
15 E1 Emitter of output sink transistor
16 C1 Collector of output sink transistor

November 1993 4

Philips Semiconductors Product specification

Control circuit for switched mode power supplies TDA8380A

FUNCTIONAL DESCRIPTION

The TDA8380A is a control circuit which generates the pulses required to drive the switching transistor in a switched
mode power supply (SMPS).

Supply

This device is intended to be used on the primary side of the power supply and can be supplied via a take-over (auxiliary)
winding on the transformer.

The device is initialized via a high value resistor connected between the rectified mains voltage and the device’s supply
pin (pin 5), which causes the capacitor connected to this pin to charge slowly. When the voltage exceeds the initialization
level (typically 17 V) the device will start up and the duty cycle will be slowly increased by the slow-start circuit. After a
short period the take-over winding will supply the device. The value of the resistor is normally defined by the time taken
to charge the capacitor.
A one second delay between switching on and operation of the power supply is acceptable in most cases.

The operating voltage range is from 9 to 20 V. The supply pin is protected by a 23 V Zener diode. The supply protection
circuit is activated once the Zener diode is conducting. The slow-start procedure begins after initialization, until then the
output is off. The current drawn by the device during the initialization period is less than 150 µA.

When the supply voltage falls below the minimum trip level, the device switches off and the start-up procedure is
repeated. The minimum voltage supply threshold setting (V
the V

pin (pin 4) and ground (pin 14) (see Fig.3).

CCmin

) can be set externally with a resistor connected between

CCmin

Fig.3 Trip level setting of minimum VCC protection level.

V

can be set between 8.4 V (an internally fixed overriding protection level) and 17 V by means of an external resistor

CCmin

connected to pin 4.
When choosing the initialization and minimum supply voltages the following should be taken into account:

• The difference between the two voltages should be large enough to enable a supply voltage dip during start-up.

• The value of the minimum supply voltage should be high enough to ensure that the high-voltage transistor is correctly

driven. A high protection level makes it possible to have a large resistor value in series with the base drive.

For battery line input operation, the V

pin is connected to VCC, the start-up circuit is then inhibited and the device

CCmin

starts operating when VCC exceeds the 8.4 V protection level (this level has a hysteresis of approximately 50 mV). The
device draws current continuously under these conditions.

November 1993 5

Philips Semiconductors Product specification

Control circuit for switched mode power supplies TDA8380A

Reference block

A bandgap based reference generates a stabilized voltage of 7 V to supply most of the device’s internal circuits, this
decreases chip size and increases reliability. The only circuits connected to VCC are:

• The initialization circuit

• The output circuitry

• The series transistor of the stabilized voltage

By means of a resistor (R6) connected to the I

input a reference current is defined which determines six other device

ref

settings.
Part of the reference current is used to charge the oscillator capacitor (C10), therefore, the charging time is proportional

to R6× C10. The maximum duty factor (D
R6/R12. The minimum supply voltage (pin 5) set by the resistor (R4) at input V

) is set by the resistor connected to pin 12 (R12) and is defined by the ratio

max

is defined by: 4/6 × V6× R4/R6.

CCmin

Oscillator

The oscillator capacitor is charged and discharged between the high and low voltage levels as defined by the bandgap
reference (high voltage typically 5 V and low voltage typically 1.4 V). The charge current is 1/6 of the reference current,
the discharge current having the same value as the reference current. The period is therefore defined by 10 × R

× C10.

6

The oscillator flyback pulse is used to set the bistable in the output logic, however the output remains low until the positive
ramp starts (see Fig.4). The oscillator can be synchronized by means of the SYNC pin. When this pin is connected to
VCC, the oscillator is free running. When it is between 0.85 and 5.6 V, the oscillator stops at the low voltage level prior to
the next positive ramp.

Fig.4 Oscillator levels.

November 1993 6

Philips Semiconductors Product specification

Control circuit for switched mode power supplies TDA8380A

Synchronization
The synchronisation input (pin 11) can be driven by either an optocoupler or a loosely coupled pulse transformer.
Figure 5 illustrates synchronization using the 0.85 V threshold and a digital signal connected to the SYNC input (for

example, an optocoupler between pin 11 and VCC); the duty factor of the pulse is not very important. The oscillator starts
at the first negative going edge of the sync. signal after the low voltage level has been reached. The synchronization
frequency must be lower than the free running frequency. Synchronization must never affect the period time as this will
corrupt the setting of the maximum duty factor.

Fig.5 DC coupled synchronization using the 0.85 V level.

In Fig.6 the disabling threshold (5.6 V) is used for synchronization. In this case the oscillator starts at the positive going
edge of the sync. signal.

Fig.6 DC coupled synchronization using the 5.6 V level.

November 1993 7

Philips Semiconductors Product specification

Control circuit for switched mode power supplies TDA8380A

Figure 7 illustrates synchronization using a pulse transformer. Internal circuitry causes a DC shift which informs the
device that synchronization pulses are present (spikes around 0 V at the output of the pulse transformer) or not present
(DC 0 V at the output of the pulse transformer). When synchronization is not used the SYNC pin must be connected to
VCC, it must not be connected directly to ground or left open.

Synchronization pulses present. Synchronization pulses not present.

Fig.7 Synchronization using a pulse transformer.

November 1993 8

Philips Semiconductors Product specification

Control circuit for switched mode power supplies TDA8380A

Error amplifier

The error amplifier compares the feedback voltage of the SMPS with a reference voltage (nominally 2.5 V). The amplifier
output at pin 8 enables gain setting. The amplifier is stable for a gain greater than 20 dB.

The output of the error amplifier is not internally connected to the Pulse Width Modulator (PWM). One input to the PWM
is available at the DUTY input (pin 9) via the Control Slicing Level (CSL) circuit. Normally the STAB and DUTY pins are
connected together, but direct driving of pin 9 via an optocoupler from the secondary side is also possible. A type of
current mode control can be achieved by mixing the STAB signal with the primary current signal before applying it to the
DUTY input.

The feedback (FB) input (pin 7) is used as the input to the Transfer Characteristic Generator (TCG) circuit which ensures
well defined duty factors at low FB voltages; a voltage foldback is an inherent characteristic. In Fig.8, the duty factor is
shown as a function of the voltages at the FB, DUTY and SS inputs. The input which gives the lowest duty factor overrides
the others.

The left hand curve is passed through during a slow-start (via the slow-start input pin 12) when the duty cycle slowly
increases linearly with respect to V12. The right-hand curve is passed through at start-up. The FB voltage slowly
increases from zero and the duty factor, starting at 12%, increases until the maximum duty factor (D
few hundred millivolts later, the FB voltage reaches the start of the regulation curve which is at approximately 2.5 V. The
plateau area between reaching D

and starting the regulation curve is kept as small as possible (typically 200 mV).

max

) is reached. A

max

Fig.8 The duty factor as a function of the FB, SS and DUTY voltages.

Due to the characteristics of the TCG, and the fact that an open FB input results in a low voltage at the FB input, open­and short-circuit feedback loops will result in low duty factors. When DC feedback is used across the error amplifier, the
current capability of the error amplifier must be considered when determining the feedback resistor value.

When the input to the PWM (pin 9) is driven by an optocoupler, the TCG can be used when a rough primary voltage is
applied to the FB input. In this situation an open feedback loop will cause an increase in the FB voltage as the duty factor
rises to its maximum. As soon as the FB voltage exceeds the reference by 0.7 V, the slow-start is triggered.

November 1993 9

Philips Semiconductors Product specification

Control circuit for switched mode power supplies TDA8380A

Demagnetization sense circuit

To enable the SMPS to be kept in the non-continuous mode, an input is available which delays switch-on of the
high-voltage transistor until the transformer currents have decayed to zero. This is an effective way of avoiding
transformer saturation. The waveforms illustrated by Fig.9 show demagnetization with respect to the application diagram
of Fig.13.

Fig.9 Demagnetization function.

As long as the voltage of the take-over (auxiliary) winding (also used for supplying the device) is above 0.6 V (V

) the

3

output will be prevented from switching on.

Over-current protection

The over-current protection circuit (pin 13) senses the voltage across resistor R

(see Fig.13), which reflects the primary

s

current. This generated voltage is negative-going as the emitter of the high-voltage power transistor is grounded (this
circuit arrangement provides the IC with the best safeguard against a possible collector-emitter short-circuit in the power
transistor). At pin 13, the negative voltage signal is shifted to a positive level by a voltage across resistor R13. This voltage
is set by the reference current at pin 13 and is defined by resistor R6 at the I
Therefore V

shift(VR 13

) = V

/6 × R13/R6 or nominal 0.416 × R13/R6 (V).

ref

input (pin 6) and = 1/6 × V

ref

ref/R6

.

The positive current monitor voltage at pin 13 is compared with two voltage levels: the first level = 0.2 V and the second
level = 0 V (see Fig.10).

The first trip level only switches off the high-voltage transistor for a cycle and puts the SMPS in a continuous
cycle-by-cycle current protection mode.

The second trip level is only activated when the primary current rise is very fast which can occur during a short-circuited
output. In this mode the high-voltage transistor is quickly switched off and the slow-start procedure is activated.

The difference between the first and second primary current peak levels is set by Rs:
I2− I1 = 0.2/Rs.
The absolute peak values are set by R6 and R13:
I2× Rs = 0.416 × R13/R6 or

I1× Rs = (0.416 × R13/R6) − 0.2

November 1993 10

Philips Semiconductors Product specification

Control circuit for switched mode power supplies TDA8380A

Fig.10 Current protection.

Slow-start circuit

A slow-start occurs:

• At Switch-on of the SMPS

• After a current trip as described in the section Over-current protection

• After a low or high VCC trip.

The capacitor at the SS input is discharged and the slow-start bistable is reset when the voltage at the SS input falls
below 0.5 V after which the circuit is ready for a slow-start. The dead time (during which the capacitor at the SS input is
being charged to the 1.4 V lower level of the sawtooth) before duty cycle regulation starts is minimal. The SS input can
also be used for D
1/6 × V

× R12/R6.

ref

setting by connecting a resistor to ground. The voltage across this resistor is then limited to

max

Output stages

The output stage consists of two NPN darlington transistors, their collector and emitter connected to separate pins (see
Fig.13). The top transistor is capable of sourcing a maximum of 0.75 A to the high-voltage transistor while the bottom
transistor can sink peak currents up to 2.5 A.

For low currents up to 10 mA, the saturation voltage of the sink darlington transistor is similar to that of a single transistor
(see Fig.11). During switching of this transistor dV/dt is internally limited to reduce interference.

Care should be taken with the external wiring of the output pins to avoid oscillation or interference due to parasitic
inductance and wire resistance.

During start-up a small current flows from V

to E2 to precharge the series capacitor at the output (see Fig.13).

CC

November 1993 11

Philips Semiconductors Product specification

Control circuit for switched mode power supplies TDA8380A

Fig.11 Saturation curve.

November 1993 12

Philips Semiconductors Product specification

Control circuit for switched mode power supplies TDA8380A

RATINGS

Limiting values in accordance with the Absolute Maximum System (IEC 134)

PARAMETER SYMBOL MIN. TYP. MAX. UNIT

Voltage

pin 5 (VCC) −0.5 − 20 V
pins 1, 2, 4 and 16 −0.5 − V

CC

pins 3 and 13 −0.5 − 0.5 V
pins 7 and 9 −0.5 − 6.5 V
pin 11 0.6 − V

CC

Currents

pins 5 (V

)0−20 mA

CC

pin 1 −0.75 − 0A
pin 2 0 − 0.75 A
pins 3, 4, 6 to 8 and 10 to 12 −10 − 10 mA
pin 13 −200 − 10 mA
pin 15 −2.5 − 0A
pin 16 0 − 2.5 A

Total power dissipation P

tot

see Fig.12

Operating ambient temperature range

(for dissipation ≤ 1W) T

Storage temperature range T

amb
stg

−25 −+70 °C

−55 −+150 °C

V

V

THERMAL RESISTANCE

From junction to ambient (in free air) R

Fig.12 Power derating curve.

th j−a(max)

= 55 K/W

November 1993 13

Philips Semiconductors Product specification

Control circuit for switched mode power supplies TDA8380A

CHARACTERISTICS

= 14 V; T

V

CC

Supply

Supply voltage V
Supply initialization level V
High voltage protection V
Internal fixed minimum

protection level V
Hysteresis dV
Supply current

operational I

before initialization I
Reference current (pin 4) note 1 I
Trigger level V
Clamp voltage at 20 mA 21.5 23.5 25.5 V

= 25 °C; reference resistor = 5 kΩ unless otherwise specified

amb

PARAMETER CONDITIONS SYMBOL MIN. TYP. MAX. UNIT

9 − 20 V
15 17 18 V
21 23 25 V

7.9 8.4 8.9 V

− 50 − mV

−−15 mA

− 100 150 µA

I6/5.7 I6/6 I6/6.4 mA

3.6V

3.8V

4

4.2V

4

V

4

setting V

CCmin

CC
5
5

5

CC

CC
CC
4

5

Reference (pin 6)
Reference voltage V

Current range I

ref

ref

2.4 2.5 2.6 V
200 − 800 µA

Reference voltage over

I

range dV

6

ref

−20 −+20 mV

Error amplifier

Error amplifier threshold VCC = 8.5 to 20 V V
Input current I
Sink current output at 1.2 V I
Source current output at 5.5 V I

7
7
8
8

2.4 2.5 2.6 V
0 − 5 µA
1 −−mA

80 100 130 µA
Open loop gain A0 − 100 − dB
Unity gain bandwidth BW − 5 − MHz
Input DUTY current note 1 I
High FB protection level V

9

7

I6/5.7 I6/6 I6/6.3 mA

2.95 3.1 3.25 V

Temperature coefficient of

error amplifier threshold dV

/dT − 100 − 10−6/K

7

TCG function (see Fig.8)
Transfer characteristics dD/dV

Minimum duty factor D
Plateau width V

min
7

7

− 32 − %/V

− 12 − %

− 200 − mV

November 1993 14

Philips Semiconductors Product specification

Control circuit for switched mode power supplies TDA8380A

PARAMETER CONDITIONS SYMBOL MIN. TYP. MAX. UNIT

Slow-start function

Transfer characteristics dD/dV
Input current note 1 I
Sink current during faults at 0.5 V I

12
12
12

Internally fixed maximum

duty factor D

Clamp current at V

= 0.5 V I

12

max

12

Output stage

Source transistor

Voltage drop with respect

to V

CC

Pull-up current V
Operating current range −I

Sink transistor

(see Fig.11)

at 0.75 A VCC−V

− V1 = 15 V −I

CC

1
1

1

Saturation voltage

at 2.5 A V16− V
at 1 A V
at 10 mA V

Leakage current V

− V15 = 20 V I

16

Falling edge dV

15

− V

16

15

− V

16

15

16

/dt − 0.2 − V/ns

16−15

Operating current range

Peak I
Average I

16
16

Oscillator

High level voltage V
Low level voltage V
Charge current note 1 I
Frequency range f
Frequency R

= 5 kΩ

6

C10= 680 pF f

10

10
10
o

o

Temperature coefficient of

the frequency df/dT − 100 − 10

− 23.8 − %/V
I6/5.7 I6/6 I6/6.3 mA
8 −−mA

75 80 85 %

−−2−mA

− 2 − V

25 − 100 µA
0 − 0.75 A

− 2 − V

− 1.5 − V

− 0.3 − V

−−1µA

0 − 2.5 A

−−250 mA

− 5 − V

− 1.4 − V

I6/5.7 I6/6 I6/6.3 mA
10 − 100 kHz

27 28.5 30 kHz

−6

/K

November 1993 15

Philips Semiconductors Product specification

Control circuit for switched mode power supplies TDA8380A

PARAMETER CONDITIONS SYMBOL MIN. TYP. MAX. UNIT

Synchronization

Minimum synchronization

pulse width t
Switching threshold V
Input current I
Disabling threshold V
Input voltage at −700 µAV

11

11

11

11
11

Demagnetization input

Switching voltage level V
Switching current level I

3

3

Current range of clamp

circuits I
Clamp level positive at 10 mA V
Clamp level negative at −10 mA V

3

3
3

Temperature coefficient TC −−1.9 − mV/K

−−0.5 µs

0.7 0.85 0.9 V

2.5 5.0 7.5 µA

4.2 5.6 6.0 V
390 − 550 mV

615 645 675 mV

−23 −−39 µA

−10 −+10 mA

− 950 − mV

−−800 − mV

Current protection

Input current note 1 I
First threshold V
Second threshold V
Delay to switch output via pulse at pin 13

level 1 from 300 mV to

100 mV;
I

= 500 mA −−350 − ns

O

Delay to switch output via pulse at pin 13

level 2 from 300 mV to

−200 mV;
IO= 500 mA −−300 500 ns

First threshold including

R

(12 kΩ)R

13

= 5 kΩ− −−800 − mV

6

Threshold for open pin

detection V

Note to the characteristics

1. Over the current range of I6; 200 to 800 µA.

13

13
13

13

I6/5.7 I6/6 I6/6.3 mA
190 200 210 mV

−10 0 10 mV

− 3.5 − V

November 1993 16

Philips Semiconductors Product specification

Control circuit for switched mode power
supplies

TDA8380A

November 1993 17

Fig.13 Simplified application diagram.

Philips Semiconductors Product specification

Control circuit for switched mode power supplies TDA8380A

Fig.14 Input and output loading diagram.

November 1993 18

Philips Semiconductors Product specification

Control circuit for switched mode power supplies TDA8380A

PACKAGE OUTLINE

DIP16: plastic dual in-line package; 16 leads (300 mil); long body

D

seating plane

L

Z

16

pin 1 index

e

b

b

1

9

A

w M

SOT38-1

M

E

A

2

A

1

c

(e )

1

M

H

E

1

0 5 10 mm

scale

DIMENSIONS (inch dimensions are derived from the original mm dimensions)

A

UNIT

mm

inches

Note

1. Plastic or metal protrusions of 0.25 mm maximum per side are not included.

A

max.

4.7 0.51 3.7

OUTLINE
VERSION

SOT38-1

min.

A

1 2

max.

0.15

IEC JEDEC EIAJ

050G09 MO-001AE

b

1.40

1.14

0.055

0.045

b

1

0.53

0.38

0.021

0.015

REFERENCES

cEe M

0.32

0.23

0.013

0.009

(1) (1)

D

21.8

21.4

0.86

0.84

November 1993 19

6.48

6.20

0.26

0.24

8

(1)

Z

e

0.30

1

0.15

0.13

M

L

3.9

3.4

E

8.25

7.80

0.32

0.31

EUROPEAN

PROJECTION

9.5

8.3

0.37

0.33

w

H

0.2542.54 7.62

0.010.100.0200.19

ISSUE DATE

92-10-02
95-01-19

max.

2.2

0.087

Philips Semiconductors Product specification

Control circuit for switched mode power supplies TDA8380A

SOLDERING
Introduction

There is no soldering method that is ideal for all IC packages. Wave soldering is often preferred when through-hole and
surface mounted components are mixed on one printed-circuit board. However, wave soldering is not always suitable for
surface mounted ICs, or for printed-circuits with high population densities. In these situations reflow soldering is often
used.

This text gives a very brief insight to a complex technology. A more in-depth account of soldering ICs can be found in our

“IC Package Databook”

Soldering by dipping or by wave

The maximum permissible temperature of the solder is 260 °C; solder at this temperature must not be in contact with the
joint for more than 5 seconds. The total contact time of successive solder waves must not exceed 5 seconds.

The device may be mounted up to the seating plane, but the temperature of the plastic body must not exceed the
specified maximum storage temperature (T
be necessary immediately after soldering to keep the temperature within the permissible limit.

(order code 9398 652 90011).

). If the printed-circuit board has been pre-heated, forced cooling may

stg max

Repairing soldered joints

Apply a low voltage soldering iron (less than 24 V) to the lead(s) of the package, below the seating plane or not more
than 2 mm above it. If the temperature of the soldering iron bit is less than 300 °C it may remain in contact for up to
10 seconds. If the bit temperature is between 300 and 400 °C, contact may be up to 5 seconds.

DEFINITIONS

Data sheet status

Objective specification This data sheet contains target or goal specifications for product development.
Preliminary specification This data sheet contains preliminary data; supplementary data may be published later.
Product specification This data sheet contains final product specifications.

Limiting values

Limiting values given are in accordance with the Absolute Maximum Rating System (IEC 134). Stress above one or
more of the limiting values may cause permanent damage to the device. These are stress ratings only and operation
of the device at these or at any other conditions above those given in the Characteristics sections of the specification
is not implied. Exposure to limiting values for extended periods may affect device reliability.

Application information

Where application information is given, it is advisory and does not form part of the specification.

LIFE SUPPORT APPLICATIONS

These products are not designed for use in life support appliances, devices, or systems where malfunction of these
products can reasonably be expected to result in personal injury. Philips customers using or selling these products for
use in such applications do so at their own risk and agree to fully indemnify Philips for any damages resulting from such
improper use or sale.

November 1993 20