Datasheet TDA8385 Datasheet (Philips)

INTEGRATED CIRCUITS

DATA SH EET

TDA8385

Control circuit for a Self-Oscillating
Power Supply (SOPS)

Preliminary specification
Supersedes data of September 1991
File under Integrated Circuits, IC02

Philips Semiconductors

March 1994

Philips Semiconductors Preliminary specification

Control circuit for a Self-Oscillating
Power Supply (SOPS)

FEATURES

• Bandgap reference generator

• Slow-start circuitry

• Low-loss peak current sensing

• Over-voltage protection

• Hysteresis controlled stand-by

function

• Error amplifier with gain setting

• Programmable transfer character

generator

• Protection against open- and
short-circuited feedback loop

ORDERING INFORMATION

EXTENDED TYPE

NUMBER

TDA8385 16 DIL plastic SOT38WBE

PINS PIN POSITION MATERIAL CODE

• Over-load current fold back
characteristic

• LED driver

• Demagnetization protection

• Programmable determination of

switch-on moment of switching
transistor for low-switching losses

• Feed-forward input

• Regulation-indicator output

• Programmable minimum on-time of

switching transistor

• Accurate peak-current setting.

TDA8385

GENERAL DESCRIPTION

The TDA8385 is intended to be used
in combination with the opto-coupler
(CNR50) as a control unit for a
self-oscillating power supply.

PACKAGE

March 1994 2

Philips Semiconductors Preliminary specification

Control circuit for a Self-Oscillating
Power Supply (SOPS)

BLOCK DIAGRAMS

handbook, full pagewidth

current reference

setting

feed forward

input

regulation indicator

output

differential amplifier

output

I

ref

3

V

fo

13

1 RIO

11Vdiff

REFERENCE

BLOCK

I

ref

REGULATION

INDICATOR

V

DIFFERENTIAL AMPLIFIER

TDA8385

V

P GND

16 14

latch

V

diff

V

P (min)

DETECTOR

7

V

reset

2812

(28, 27, 23)

mv

V

ts

I

STABILIZED

SUPPLY

V

ref

29

stab

SUPPLY REFERENCES

V

ts

X

V

ref

(2.5 V)

3

feedback voltage

input

transistor-on
setting input

slow start voltage

input

V

9

T

on(min)

4

7Vss

fb

50 µA

5

CLAMP

TCG

2.5 V
4

+

T

V

on (min)

ss

reset (28)

quick

discharge

Fig.1 Block diagram; part A (continued in Fig.2; part B).

V

TCG

CONTROL PART

27

SLOW START

MINIMUM

VOLTAGE

CLAMP

50 µA

charge

19

6

III

VII

MCD417

March 1994 3

Philips Semiconductors Preliminary specification

Control circuit for a Self-Oscillating
Power Supply (SOPS)

handbook, full pagewidth

stand-by voltage input

V

10

sb

latch

2.5 V

V

r

V

sim

(28)18

2.5 V

25

STAND-BY

8

2 V

PWM

IV

S

IX

comparator

latch

OUTPUT

STAGE

17

LED DRIVER

TDA8385

LED

15

VI

Q (23)

2

TDA8385

LED driver output

26

demagnetization

100 mV

100 µA

slow

discharge

OVER-VOLTAGE PROTECTION

10

(17) (28)

21

FF

Q

R

13

V

c

DELAY

12

SAWTOOTH GENERATOR

QR

FF

23

S

Q

16

demagnetization

LED CONTROL

I

sim

0.2 I

11

24

22

14

12

I

I

12

9

peak

DEM

115 mV

II

115 mV

over voltage

2.5 V

VIII

V

12

current simulation

input

5

peak-current

setting input

15

demagnetization

input

6

delay setting

8

over-voltage

protection

Fig.2 Block diagram; part B (continued from Fig.1; part A).

March 1994 4

MCD418

Philips Semiconductors Preliminary specification

Control circuit for a Self-Oscillating
Power Supply (SOPS)

PINNING

SYMBOL PIN DESCRIPTION

RIO 1 regulation indicator output
LED 2 LED driver output
I

ref

T

on(min)

I

peak

DELAY 6 delay setting
V

ss

OVP 8 over-voltage protection
V

fb

V

sb

V

diff

I

sim

V

fo

GND 14 ground (0 V)
DEM 15 demagnetization input
V

P

3 current reference setting
4 transistor-on setting input
5 peak current setting input

7 slow start voltage input

9 feedback voltage input
10 stand-by voltage input
11 differential amplifier output
12 current simulation input
13 feed forward input

16 positive supply voltage

handbook, 2 columns

T

on(min)

DELAY

I

peak

OVP

RIO

LED

I

V

ref

1
2
3
4
5
6
7

ss

8

Fig.3 Pinning diagram.

TDA8385

TDA8385

MCD402

V

16

P

DEM

15

GND

14

V

13

fo

I

12

sim

V

11

diff

V

10

sb

V

9

fb

FUNCTIONAL DESCRIPTION

The TDA8385 can be divided into
10 functional blocks as shown in Fig.1
and Fig.2.

Block for Figs 1 and 2

BLOCK

NO.

DESCRIPTION

I supply references
II sawtooth generator
III control part
IV pulse width modulator

(PWM)
V LED control
VI LED driver
VII slow-start circuitry
VIII over-voltage protection
IX stand-by circuit
X regulation-indicator

output

These 10 functional blocks of Fig.1
and Fig.2 contain sub-sections
numbered 1 to 28 which are

cross-referenced in the following
description.

Supply references (Block I)

The TDA8385 is intended to be used
on the secondary side of the
self-oscillating power supply. It can be
supplied either by an auxiliary winding
of the transformer or an external
supply e.g. 50 Hz transformer.
Charging of the capacitor C

(see

P

Fig.16) takes place during transistor
on-time (Ton; see Fig.17). During
stand-by the IC is supplied by the
stand-by voltage Vsb (pin 10). The
operating voltage range is from 7.5 to
20 V. The supply current, inclusive
drive current for the LED, is less than
20 mA. A bandgap based reference
(2.5 V) generates a stabilized voltage
V

of 3.9 V to supply all internal

stab

circuits of the IC except the LED
driver. The LED driver is directly
supplied by VP. The reference block
generates all the reference voltages
in the circuit. By means of a resistor
connected to pin 3, a reference
current (I

) is defined.

ref

This current is reflected several times
and is used to obtain IC-independent
settings e.g. T

setting, delay

on(min)

setting, charging and discharging of
slow-start capacitor Css on pin 7
(see Fig.16).

The power supply is released by the
opto-coupler IC at an input voltage
level, which is high enough to
guarantee correct operation of the
TDA8385 e.g. VP = 10 V by sensing
the mains voltage VI. As soon as the
SOPS switching transistor (T1, see
Fig.16) is conductive the capacitor C
is charged. As long as the IC supply
voltage is below 7.5 V the LED driver
is blocked (see latch output;
sub-section 28) in order to guarantee
start-up of SOPS.

During the initialization phase the
quick-discharge-switch
(sub-section 27), set input of
flip-flop (13) and reset input of
flip-flop (23) are also activated.
As soon as the voltage of 7.5 V is
reached the control functions of the IC
are operative. Hysteresis on the
initialization level is 2.3 V.

P

March 1994 5

Philips Semiconductors Preliminary specification

Control circuit for a Self-Oscillating
Power Supply (SOPS)

Sawtooth generator (Block II)

URRENT SIMULATION

C
(SEE FIGS 5 AND 16)

The current of the power supply
switching transistor is detected on the
secondary side by an indirect method
of current sensing.

Information of the collector current (Ic)
is obtained by integrating the voltage
of an auxiliary winding of the
transformer during transistor on-time
(Ton). An external capacitor C on pin 5
is charged during Ton by the current
source I
reflection of the current which flows
into pin 12. This current is obtained by
connecting an external resistor R12 to
the auxiliary transformer winding.
During transistor on-time this current
is related to the input voltage VI.
During transistor off time (T
capacitor C is discharged by switch
sw1. This switch is active during the
total T
voltage Vc is formed across C. This
sawtooth is a measure for the
collector current of the switching
transistor T1.

For the voltage Vc yields:

V

c

. The current I

sim

time. In this way a sawtooth

off

I

×

simTon

=

------------------------ ­C

sim

is the

) the

off

(1)

TDA8385

latch

initialization

operation

5.2 7.5 20

Fig.4 Latch initialization as a function of supply voltage VP.

L

n

n

p

h

V

I

T1

I

c

V

c

R12

C

I

12

VP(V)

12

5

I

sw1

MCD403

sim

I

sim

---------- -

----- ­n

R12

p

×

p

Where: p = reflection factor;

I

sim

--------­I

12

0.2==

p

(2)

V

c

V

n

h

I

×=

(2) → (1) gives:

V

n

p

h

V

c

×

----- -

--- ­C

n

× T

---------- ­R12

p

I

×=

on

(3)

March 1994 6

t

T

on

T

off

MCD404

Fig.5 Determination of the peak current Ic.

Philips Semiconductors Preliminary specification

Control circuit for a Self-Oscillating
Power Supply (SOPS)

For ‘Ton’ yields:

VcC× np× R12×

T

=

---------------------------------------------- -

on

pn

× V

×

h

I

For the primary current Ic yields:

V

I

T

I

×=

-----

c

on

L

Substitution (4) into (5):

C

I

--- -

c

L

n

1

p

×

× R12× V

-- -

----- -

p

n

h

×=

c

Equation (6) shows that by limiting the
voltage V

the collector peak current

c

can be limited. The peak current is
limited by means of the clamping
circuit in the transfer character
generator (TCG); see Fig.1
sub-section 4.

D

ELAY SETTING (PIN 6)

The output of sub-section 11 is

(4)

extended by the delay circuit of
sub-section 12. The starting
(reference) point of the delay circuit is
the falling edge of the output of
demagnetizing comparator (11) The

(5)

delay can be determined externally by
capacitor (C

The switch-on moment of the
switching transistor can be

(6)

determined by capacitor C
A minimum delay time is required to

prevent transistor T1 from switching
during demagnetization of the
transformer because of oscillations
caused by the leakage inductance.

delay

) on pin 6.

delay

TDA8385

Control part (Block III)

The differential amplifier,
sub-section 3, compares the
feedback voltage (Vfb) with the
reference voltage V
the differential amplifier is available
on pin 11 to allow gain setting. The
differential amplifier is internally
compensated for 0 dB feedback
stability.

The feedback input (pin 9) is also

.

used as the input for the TCG
(see Fig.6) with which a current
foldback characteristic can be
obtained as shown in Fig.7.

. The output of

ref

The clamping level can be externally
influenced by means of a resistor
on pin 7.

The collector peak current can be
influenced in several ways:

• Resistor R12 on pin 12

• Capacitor C on pin 5

• Capacitor on pin 7

• Transfer ratio nh/n

p

• Inductance L
Before comparing the sawtooth

voltage Vc with the control voltage V
in the pulse width modulator, a
voltage of 100 mV is added to Vc. In
this way it will be possible for Vr to
become smaller than V

, which is

sim

important for a stabilized no-load
operation (see Fig.6 area 3).

D

EMAGNETIZATION INPUT (PIN 15)

This input prevents the switching
transistor from conducting during
demagnetization of the transformer in
order to prevent the transformer from
going into saturation. The output of
comparator (11) is HIGH as soon as
the voltage of the transformer winding
exceeds 115 mV.

(3)

V

mv

(4)

(2)

r

(1)

(5)

V

fb

(1), (2), (3) = V
(4), (5) = V

.

TCG

.

diff

V

clamp

V

Ton(min)

MCD405

Fig.6 Reference voltage (Vmv) as a function of feedback voltage (Vfb).

March 1994 7

Philips Semiconductors Preliminary specification

Control circuit for a Self-Oscillating
Power Supply (SOPS)

V

O

(5)

(1)

(1), (2), (3) = V
(4), (5) = V

.

TCG

.

diff

Fig.7 Current foldback characteristic; stabilized output voltage (VO)

as function of load current (IO).

(4)

(2)

(3)

I

O

MCD406

TDA8385

The voltage V
minimum on-time of the switching
transistor. This voltage can be
determined externally with a resistor
on pin 4. With this resistor the current
foldback characteristic can be
influenced (see dotted line in Figs 6
and 7).

The minimum on-time is of
importance for the following.

• Stand-by operation

• Starting-up of power supply

• Overload and short-circuit

conditions.

The output of the differential amplifier
(V

), the output of the TCG (V

diff

and the voltage Vss + V
compared in a minimum voltage
clamping circuit (see Fig.1
sub-section 6). The output voltage is
equal to the lowest input voltage.

Some relevant characteristics of the
control part are depicted in Fig.8.

Ton(min)

determines the

TCG

are

Ton(min)

)

I

V

c

handbook, full pagewidth

The voltage Vmv determines the collector peak current Ic of transistor T1. The right-hand curve is passed through at start-up. When the feedback voltage
slowly increases from zero, the peak current starts at I
the regulation slope is reached, which is approximately V

The plateau of the top between the points x and y has to be kept as small as possible.
The voltage V
Due to the characteristic of the TCG open- and short-circuit feedback loop will result in low peak current.
An additional signal on pin 13 can be supplied which is subtracted from the signal Vmv. This input can be used for feed forward information.
If no feed forward information is used, pin 13 should be connected to ground.

I

c (max)

I

c (min)

V

+

V

Ton(min)

ss

decreases with the decreasing load. For good no-load operation the peak current has to be made zero with V

diff

mv

xy

and rises along the straight line until I

c(min)

.

ref

V

TCG

V

diff

V

mv

external peak-current
setting (pin 7)

V

ref

V

fb

MCD407

is reached. At a slightly higher feedback voltage

c(max)

.

diff

Fig.8 Characteristics of the control part.

March 1994 8

Philips Semiconductors Preliminary specification

Control circuit for a Self-Oscillating
Power Supply (SOPS)

Pulse width modulator (Block IV)

The pulse width modulator compares
the control voltage Vr with the
sawtooth voltage V

sim

. If V

sim

> V

r

output sub-section 8 is HIGH the LED
is switched on and then the switching
transistor is switched off. In this way
the output voltage is controlled.

XAMPLE

E
If the load decreases, VO increases

and therefore Vr decreases. This
causes the LED to start conducting
prematurely, which implies that the
switching transistor is turned off
sooner. The consequence is that the
collector peak current decreases and
hence less energy is stored in the
transformer and VO will decrease.

LED control (Block V)

If either output of sub-section 8 or
output of sub-section 16 are HIGH the
LED is conductive. In order to
improve the start-up behaviour of the
power supply, the demagnetization
signal of sub-section 12 will only
activate the LED driver if flip-flop (13)
has previously been set. The set
signal is generated in the following
three ways.

1. Pulse width modulator
(sub-section 8)

2. Comparator (18)

P(min)

detector

3. V

Set signal (2.) and (3.) are added as
extra security to guarantee a
demagnetization pulse in the event of
the switching transistor not having
enough base current. In that situation
e.g. at start-up, no comparator signal,
set signal (3.) is generated by
sub-section 8.

LED driver (Block VI)

The LED driver (pin 2) is blocked if the
supply voltage VP is in the
initialization phase (see Fig.4). The
output stage is a push-pull stage,
which can sink 5 mA and source
10 mA.

Slow-start circuit (Block VII)

The slow-start circuit is active at
start-up, over voltage protection or
after an overload (short-circuited),
and stand-by mode. The voltage V
and therefore the voltage Vmv and the
peak current Ic slowly increase at
start-up.

By means of sub-section 27 the slow
start voltage Vss is clamped to the
voltage Vfb. If the feedback voltage is
reduced, e.g. as overload, the
slow-start capacitor is discharged to
the level of Vfb. In this way a slow
start-up is also guaranteed after an
overload, short-circuit situation or
after a stand-by mode. The circuit of
sub-section 27 is not active during an
over voltage protection.

When the supply voltage VP is below
the reset-level of 5.2 V
(sub-section 28) the slow-start
capacitor is quickly discharged.

The slow-start input (pin 7) can also
be used for I
connecting a resistor to this pin.

Over voltage protection (Block VIII)

The operation of the over voltage
protection circuit is, in the event of the
IC being SOPS-supplied, quite
different from when the IC is
externally supplied.

c(max)

setting by

TDA8385

O

PERATION WHEN THE IC IS

EXTERNALLY SUPPLIED

When the voltage on pin 8 exceeds

2.5 V the slow-start capacitor is
slowly discharged. During discharge
the LED is permanently conducting.
Discharge is stopped when Vss is
below 115 mV. Flip-flop (23) will then
be reset and the circuit is ready again
for a new slow-start procedure.

During an over voltage sub-section 27
is not active so that the output voltage
VO cannot influence the slow-start

ss

discharge procedure.

PERATION WHEN IC IS

O
SOPS-SUPPLIED (SEE FIGS 9 AND 10)

When the voltage on pin 8 exceeds

2.5 V the slow-start capacitor is
slowly discharged. During discharge
of Css the supply capacitor CP is also
discharged. Because the capacitors
CP and Css have almost the same
value and the supply current I
(≈15 mA) is much larger than the slow
discharge current (≈50 µA), the LED
will be switched off by means of the
V

detection circuit (5.2 V). At that

P(min)

moment the switching transistor will
be switched on again until the 7.5 V
level is reached. During this
hysteresis interval the slow-charge
capacitor is quickly discharged. At the

7.5 V level the LED will be switched
on again because flip-flop (23) output
is still HIGH.

The same procedure will be repeated
several times until the slow-start
capacitor reaches the 115 mV reset
level. At that moment the slow-start
procedure is started again.

If there is still an over voltage the
procedure will be repeated.

Figure 10 is a detailed exposure of
Fig.11.

P

March 1994 9

Philips Semiconductors Preliminary specification

Control circuit for a Self-Oscillating
Power Supply (SOPS)

handbook, full pagewidth

(1) For detail see Fig.10.

I

c

V

ss

Fig.9 Over voltage protection.

(1)

TDA8385

t

MCD408

t

Q

V
(V)

V

ss

(V)

I

FF23

P

7.5 V

5.2 V

0

t

slow discharge

quick discharge

0

c

delay

t

t

t

Fig.10 Detailed over voltage protection of Fig.9.

March 1994 10

t

MCD409

Philips Semiconductors Preliminary specification

Control circuit for a Self-Oscillating

TDA8385

Power Supply (SOPS)

Stand-by circuit (Block IX)

During stand-by operation the voltage Vsb is supplied from the SOPS via thyristor TH1 (see Fig.16). In the stand-by state,
SOPS operates in a burst mode. When the voltage on pin 10 exceeds 2.5 V the LED driver is permanently activated. The
LED driver is released again if the voltage is below 2 V (see Fig.11).

handbook, full pagewidth

V

sb

(V)

0

2.5 V

2 V

t

output sub-section 25

I

LED

(mA)

0

0

Fig.11 Stand-by operation; burst mode.

t

5 mA

t

MCD410

March 1994 11

Philips Semiconductors Preliminary specification

Control circuit for a Self-Oscillating

TDA8385

Power Supply (SOPS)

Regulation indicator output (Block X)

Pin 1 can be used to reset the logic circuit in the TV receiver at power on and off. Sub-section 29 has an open-collector
output. The output of this block is LOW during the regulation mode (V

handbook, full pagewidth

V

2.5

0

V

diff

< Vts; see Fig.12).

diff

V

fb

V

ts

t

V

P

0

V

RIO

0

A desired delay at power-on reset can be made externally.

Fig.12 Regulation indicator output; pin 1.

t

V

: open-collector output

RIO

t

MCD411

March 1994 12

Philips Semiconductors Preliminary specification

Control circuit for a Self-Oscillating

TDA8385

Power Supply (SOPS)

LIMITING VALUES

In accordance with the Absolute Maximum Rating System (IEC 134).
All voltages are measured with respect to ground; positive current flow into the IC; all pins not mentioned in the voltage
list are not allowed to be voltage driven. The voltage ratings are valid provided other ratings are not violated; current
ratings are valid provided the power rating is not violated.

SYMBOL PARAMETER CONDITIONS MIN. MAX. UNIT

Voltages

V

P

V

n

V

3

V

8,10

V

12

V

15

Currents

I

1

I

n

I

3

I

5, 6

I

7

I

11

I

16

Temperatures

T

amb

T

stg

Power dissipation

P

tot

supply voltage pin 2 connected −0.5 20 V

pin 2 open-circuit −0.5 18 V
voltage on pins 1, 2, 4, 7, 9 and 13 −0.5 +18 V
voltage on pin 3 −0.5 +6 V
voltage on pins 8 and 10 −0.5 +3.9 V
voltage on pin 12 −0.1 +0.5 V
voltage on pin 15 −0.5 +0.5 V

current on pin 1 0 2 mA
current on pins 2, 12 and 15 −10 +10 mA
current on pin 3 −10mA
current on pins 5 and 6 −1+1mA
current on pin 7 −1 +25 mA
current on pin 11 −10 +0.5 mA
current on pin 16 0 20 mA

operating ambient temperature −25 +70 °C
storage temperature −55 +150 °C

total power dissipation − 500 mW

THERMAL RESISTANCE

SYMBOL PARAMETER THERMAL RESISTANCE

R

th j-a

from junction to ambient in free air 55 K/W

March 1994 13

Philips Semiconductors Preliminary specification

Control circuit for a Self-Oscillating

TDA8385

Power Supply (SOPS)

CHARACTERISTICS

= 15 V; I3 = 200 µA; T

V

P

SYMBOL PARAMETER CONDITIONS MIN. TYP. MAX. UNIT
Supply

V

P

V

16

V

16(hys)

I

16

V

11

supply voltage (pin 16) 7.9 − 20 V
supply initialization level 7.1 7.5 7.9 V
internal fixed hysteresis 2.5 − 2.55 V
supply current active LED output −− 20 mA
supply voltage ripple rejection see Figs 13 and 14 − 60 − mV

Reference voltage

V

3

reference voltage at pin 3 0.52 0.55 0.58 V

Error amplifier

V

9

I

9

I

11

I

11

G

o

threshold voltage error amplitude 2.4 2.5 2.6 V
input current feedback input −− 0.5 µA
sink current output V11 = 80 mV 400 −−µA
source current output V11 = 2.5 V 500 −−µA
open loop gain − 100 − dB

B unity gain bandwidth − 600 − kHz

/∆T temperature coefficient −±300 × 10−6− K

∆V

9

V

5

threshold for switching output V

= 25 °C; unless otherwise specified.

amb

= 1.25 V;

diff

V4 = 2 V; V13 = 0 V;
V7> V9; I2 = 2 mA

− V

diff

− V

(1)

− V

os

−1

Transfer characteristic generator

I4/I
V

3

5

current ratio V4 = 0.5 V 0.23 0.25 0.27
threshold for switching output V4 = 0.5 V; V13 = 0 V;

T

on(min)

= 20% V9 = 0.4 V − 0.9 − V

V

fb

= 50% V9 = 1 V 1.4 − V

V

fb

= 80% V9 = 1.6 V − 2.1 − V

V

fb

clamp V

t

PLH

response time pulse width
modulation pin 5 to pin 2
LOW-to-HIGH

t

PHL

response time pulse width
modulation pin 5 to pin 2
HIGH-to-LOW

Feed forward

V

5

threshold for switching output
(Vfo)

I

13

input bias current V13 = 0 V −−1µA

V7> V9; I2 = 2 mA

V9 = 0 V 0.4 − V

= 2.25 V 2.4 − V

9

0.5 − V

os

1.5 − V

os

− 2.6 − V

os

0.6 − V

os

− V

os

1.6 − V

os

− V

os

V

os

V

os

V

os

note 2 −− 700 ns

note 2 −− 1µs

V4 = 0.5 V; V13 = 0 V;

0.6 − V

0.7 − V

os

0.8 − V

os

V

os

V7 = V9 = 3 V;
I2 = 2 mA; V11 = 1 V

March 1994 14

Philips Semiconductors Preliminary specification

Control circuit for a Self-Oscillating

TDA8385

Power Supply (SOPS)

SYMBOL PARAMETER CONDITIONS MIN. TYP. MAX. UNIT
Slow-start

I

7/I3

I

7

V

7

V

5

Output stage

V

2(sat)

I

2

V

2

Current simulation

I5/I

12

V

12

V

5(sat)

∆V threshold for switching output;

Demagnetization input

t

demLH

t

demHL

V

15

V

15

C

15

I

15

charge current ratio V7 = 0.5 V 0.22 0.24 0.26
quick discharge current V7 = 1 V 20 −−mA

= 100 mV 50 −−µA

V

7

clamping level I7 = 100 µA 2.8 3.0 3.2 V
threshold for switching output

(Vss)

V4 = 0.5 V; V13 = 0 V;
V7 = 1 V; I2 = 2 mA;

1.4 − V

1.5 − V

os

1.6 − V

os

V

os

V9 = 2 V

saturation voltage I2 = 2 mA −−300 mV
source current V2 = 2 V

operating 4.8 5.3 6.3 mA
initialization phase −−50 µA

open output voltage HIGH I2 = 5 mA 12 −−V

current ratio V5 = 1 V; I12 = 0.5 mA 0.19 0.2 0.21
simulation input voltage I12 = 0.5 mA −− 1.1 V
saturation voltage V15 = V6 = 0 V;

−− 300 mV

I5 = 1 mA

= V6 = 0 V;

V

15

−− 200 mV

I5 = 200 µA

voltage difference between pins 5
and 11; offset simulation voltage

)

(V

os

delay from pin 15 to pin 5
LOW-to-HIGH

delay from pin 15 to pin 5

V4 = 0.5 V; V13 = 0 V;
V7 = V9 = 3 V;
I2 = 2 mA;
V11 = 0.5 V

see Fig.15;
pin 6 not connected

see Fig.15 −− 1µs

60 100 140 mV

−− 500 ns

HIGH-to-LOW
clamping level I15 = 10 mA

positive −− 1.2 V
negative −− −1V

demagnetization threshold

90 115 140 mV

voltage
input capacitance −− 10 pF
input bias current V15 = 60 mV −− 0.5 µA

March 1994 15

Philips Semiconductors Preliminary specification

Control circuit for a Self-Oscillating

TDA8385

Power Supply (SOPS)

SYMBOL PARAMETER CONDITIONS MIN. TYP. MAX. UNIT
Delay setting

I

6/I3

I

6

V

6

V

6(sat)

t

dLH

t/c delay setting (t = C

Stand-by

V

10H

V

10(hys)

t

dLH

t

dHL

I

10

Over voltage protection

V

8

t

dLH

t

dHL

V

7

I

7/I3

I

8

Regulation indicator output

V

1

I

1

Notes

1. Vos = V

2. V5 pulse = 1 V; V4 = 0.5 V; V9 = V7= 3 V; V11 = 0.5 V; V13 = 0 V; I2 = 2 mA.

charge current ratio V6 = 1 V 1.1 1.2 1.3
charge current initialization phase V6 = 1 V; V16 = 5 V 2 −−mA
clamping level 2.8 − 3.2 V
saturation voltage V15 = 140 mV − 50 100 mV
delay from pin 6 to pin 2;

V6 crossing the 2.5 V level;
LOW-to-HIGH

C6 = 470 pF;
V5 = 0 V; I2 = 2 mA;
V15 see Fig.15;

−− 1.2 µs

excluding capacitive
tolerances

× V/I) V6 = 2.5 V;

6

− 10 − ns/pF

I3 = 250 µA

threshold level HIGH 2.4 2.5 2.6 V
hysteresis 450 500 550 mV
delay to output pin 10 to pin 2

−− 1µs

LOW-to-HIGH
delay to output pin 10 to pin 2

−− 1µs

HIGH-to-LOW
input current V10 = 2.3 V −− 5µA

threshold level 2.4 2.5 2.6 V
delay to output pin 8 to pin 2

−− 1µs

LOW-to-HIGH
delay to output pin 8 to pin 2

−− 1µs

HIGH-to-LOW
reset level 90 − 140 mV
slow discharge current ratio V7 = 1 V 0.12 0.23 0.31
input current V8 = 3 V −− 1µA

saturation voltage I1 = 1 mA −−300 mV
leakage current V1 = V

offset.

16

−− 1µA

March 1994 16

Philips Semiconductors Preliminary specification

Control circuit for a Self-Oscillating
Power Supply (SOPS)

V

P

2 V15 V

t

Frequency = 50 kHz.
Slew rate = 0.2 µs.

Fig.13 Supply voltage ripple rejection;

VP as a function of time.

MCD412

V

diff

(pin 11)

Frequency = 50 kHz.
Slew rate = 0.2 µs.

Fig.14 Supply voltage ripple rejection;

V

as a function of time.

diff

TDA8385

~

3 V

~

MCD413

t

Table 1 Condition of test circuit used for Figs 13 and 14.

PINS STATUS

1, 2, 4 to 6, 12, 13 not connected
8 to 10, 14, 15 ground
3R
7C
16 V
11 V

= 2.7 kΩ

ref

= 4.7 µF

ss

; see Fig.13

P

; see Fig.14

diff

March 1994 17

Philips Semiconductors Preliminary specification

Control circuit for a Self-Oscillating
Power Supply (SOPS)

handbook, full pagewidth

demagnetization input

peak-current setting input

(pin 15)

(pin 5)

115 mV

90%

t

demLH demHL

TDA8385

~

+ 0.8 V

~

0 V

~

– 0.8 V

~

1 V

10%

t

0 V

MCD414

Fig.15 Timing diagram; demagnetization delay time.

March 1994 18

Philips Semiconductors Preliminary specification

Control circuit for a Self-Oscillating
Power Supply (SOPS)

APPLICATION INFORMATION

O

V

9118

R15

2

1

TDA8385

151016

1/2 CNR50

13

ss

C

delay

C

C

1456 473

12

TDA8385

MCD415

ref

R

Ton(min)

R

o

C

stab

V

f

V

s

n

TH1

p

n

c

I

A

RC

T1

1/2 CNR50

P

V

A

n

P

C

R12

h

handbook, full pagewidth

Fig.16 Application circuit of SOPS with stand-by facility.

I

V

(mains)

March 1994 19

Philips Semiconductors Preliminary specification

Control circuit for a Self-Oscillating
Power Supply (SOPS)

V

handbook, full pagewidth

V

f

I

c

O

n

s

V

I

n

p

TDA8385

T

on

storage time and delay

T

off

(SOPS)

output sub-section 11

output sub-section 12

DEMAGNETIZATION

V

c

V

sim

output sub-section 8

COMPARATOR

output sub-section 13

output sub-section 16

DEMAGNETIZATION

output sub-section 14

Q

LED driver

Vr(output sub-section 7)

(output sub-section 10)V

sim

(sub-section 13)

delay

SET

(sub-section 13)

RESET

comparator (18)
level = 1 V

t

MCD416

Fig.17 Application timing diagram.

March 1994 20

Philips Semiconductors Preliminary specification

Control circuit for a Self-Oscillating
Power Supply (SOPS)

PACKAGE OUTLINE

22.00

21.35

seating plane

3.9

3.4

2.2

max

2.54

(14x)

1.4 max

0.53
max

1.2 min

0.254

TDA8385

8.25

7.80

5.1

max

M

0.32 max

7.62

9.5

8.3

MSA349

Dimensions in mm.

Fig.18 16-lead dual in-line; plastic with internal heat spreader; opposite bent leads (SOT38WBE).

16

1

9

6.48

6.14

8

March 1994 21

Philips Semiconductors Preliminary specification

Control circuit for a Self-Oscillating

TDA8385

Power Supply (SOPS)

SOLDERING
Plastic dual in-line packages

Y DIP OR WAVE

B
The maximum permissible

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

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.

The device may be mounted up to the
seating plane, but the temperature of
the plastic body must not exceed the
specified storage maximum. If the
printed-circuit board has been
pre-heated, forced cooling may be
necessary immediately after
soldering to keep the temperature
within the permissible limit.

R

EPAIRING SOLDERED JOINTS

Apply a low voltage soldering iron
below the seating plane (or not more
than 2 mm above it). If its temperature
is below 300 °C, it must not be in
contact for more than 10 s; if
between 300 and 400 °C, for not
more than 5 s.

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.

March 1994 22

Philips Semiconductors Preliminary specification

Control circuit for a Self-Oscillating
Power Supply (SOPS)

TDA8385

NOTES

March 1994 23

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SCD29 © Philips Electronics N.V. 1994

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Philips Semiconductors