PHILIPS TDA8385

Philips Semiconductors
Preliminary specification
Control circuit for a Self-Oscillating
Power Supply (SOPS)
TDA8385
• Over-load current fold back
characteristic
FEATURES
• Bandgap reference generator
GENERAL DESCRIPTION
• LED driver
• 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
• Demagnetization protection
• Programmable determination of
switch-on moment of switching
transistor for low-switching losses
The TDA8385 is intended to be used
in combination with the opto-coupler
(CNR50) as a control unit for a
self-oscillating power supply.
• Feed-forward input
• Regulation-indicator output
• Programmable minimum on-time of
switching transistor
• Accurate peak-current setting.
ORDERING INFORMATION
PACKAGE
EXTENDED TYPE
NUMBER
PINS
PIN POSITION
MATERIAL
CODE
TDA8385
16
DIL
plastic
SOT38WBE
March 1994
2
Philips Semiconductors
Preliminary specification
Control circuit for a Self-Oscillating
Power Supply (SOPS)
TDA8385
BLOCK DIAGRAMS
VP
GND
handbook, full pagewidth
16
14
latch
current reference
setting
3 I ref
REFERENCE
BLOCK
V P (min)
DETECTOR
STABILIZED
SUPPLY
2
1
28
reset
(28, 27, 23)
I ref
feed forward
input
Vstab
Vref
I
SUPPLY REFERENCES
13 V fo
V ts
regulation indicator
output
differential amplifier
output
1
RIO
29
REGULATION
INDICATOR
7
X
Vmv
11 V diff
DIFFERENTIAL AMPLIFIER
Vref
(2.5 V)
V diff
V ts
3
feedback voltage
input
9
V TCG
CLAMP
Vfb
MINIMUM
VOLTAGE
CLAMP
TCG
50 µA
2.5 V
CONTROL PART
4
transistor-on
setting input
III
T
4 on(min)
50 µA
charge
5
Vss + Ton (min)
slow start voltage
input
6
7
19
Vss
reset (28)
quick
discharge
27
SLOW START
VII
MCD417
Fig.1 Block diagram; part A (continued in Fig.2; part B).
March 1994
3
Philips Semiconductors
Preliminary specification
Control circuit for a Self-Oscillating
Power Supply (SOPS)
handbook, full pagewidth
TDA8385
stand-by voltage input
Vsb
10
TDA8385
latch
latch
2.5 V
2V
LED
OUTPUT
STAGE
25
2
LED driver output
15
2.5 V
STAND-BY
Vr
IX
17
PWM
8
Vsim
VI
LED DRIVER
IV
Q (23)
comparator
18
(28)
S
FF
14
16
demagnetization
R
26
Q
13
V
LED CONTROL
demagnetization
I sim
0.2 I 12
Vc
I12
9
12
5
I peak
DEM
15
11
DELAY
6
10
demagnetization
input
delay setting
II
SAWTOOTH GENERATOR
(17)
100 µA
slow
discharge
peak-current
setting input
115 mV
12
100 mV
current simulation
input
(28)
Q
R
24
115 mV
21
FF
23
S
Q
over voltage
8
22
2.5 V
VIII
OVER-VOLTAGE PROTECTION
MCD418
Fig.2 Block diagram; part B (continued from Fig.1; part A).
March 1994
4
over-voltage
protection
Philips Semiconductors
Preliminary specification
Control circuit for a Self-Oscillating
Power Supply (SOPS)
TDA8385
PINNING
SYMBOL
PIN
DESCRIPTION
RIO
1
regulation indicator output
LED
2
LED driver output
Iref
3
current reference setting
Ton(min)
4
transistor-on setting input
Ipeak
5
peak current setting input
DELAY
6
delay setting
Vss
7
slow start voltage input
OVP
8
over-voltage protection
Vfb
9
feedback voltage input
Vsb
10
stand-by voltage input
Vdiff
11
differential amplifier output
Isim
12
current simulation input
Vfo
13
feed forward input
GND
14
ground (0 V)
DEM
15
demagnetization input
VP
16
positive supply voltage
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
March 1994
handbook, 2 columns
1
16 V P
LED
2
15 DEM
I ref
3
14 GND
Ton(min)
4
RIO
13 Vfo
TDA8385
I peak
5
12 I sim
DELAY
6
11 Vdiff
Vss
7
10 Vsb
OVP
8
9
V fb
MCD402
Fig.3 Pinning diagram.
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 CP (see
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
Vstab of 3.9 V to supply all internal
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 (Iref) is defined.
5
This current is reflected several times
and is used to obtain IC-independent
settings e.g. Ton(min) setting, delay
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 CP
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.
Philips Semiconductors
Preliminary specification
Control circuit for a Self-Oscillating
Power Supply (SOPS)
TDA8385
Sawtooth generator (Block II)
CURRENT SIMULATION
(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 Isim. The current Isim is the
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 (Toff) the
capacitor C is discharged by switch
handbook, full pagewidth
sw1. This switch is active
during the
total Toff time. In this way a sawtooth
voltage Vc is formed across C. This
sawtooth is a measure for the
collector current of the switching
transistor T1.
latch
initialization
operation
5.2
VI
nh
I sim = p × ------ × ----------n p R12
(2)
I sim
R12
12
L
np
I 12
nh
5
Ic
sw1
T1
Where: p = reflection factor;
I sim
p = -------- = 0.2
I 12
MCD403
Fig.4 Latch initialization as a function of supply voltage VP.
VI
(1)
20
V P (V)
For the voltage Vc yields:
I sim × T on
V c = -----------------------C
7.5
Vc
C
Vc
(2) → (1) gives:
t
VI
p nh
V c = ---- × ------ × ----------- × T on
C n p R12
Ton
(3)
Toff
MCD404
Fig.5 Determination of the peak current Ic.
March 1994
6
Philips Semiconductors
Preliminary specification
Control circuit for a Self-Oscillating
Power Supply (SOPS)
For ‘Ton’ yields:
V c × C × n p × R12
T on = ---------------------------------------------p × nh × VI
(4)
For the primary current Ic yields:
VI
I c = ----- × T on
L
(5)
Substitution (4) into (5):
C 1 np
I c = ---- × --- × ------ × R12 × V c
L p nh
(6)
Equation (6) shows that by limiting the
voltage Vc the collector peak current
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.
TDA8385
DELAY SETTING (PIN 6)
Control part (Block III)
The output of sub-section 11 is
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
delay can be determined externally by
capacitor (Cdelay) on pin 6.
The differential amplifier,
sub-section 3, compares the
feedback voltage (Vfb) with the
reference voltage Vref. The output of
the differential amplifier is available
on pin 11 to allow gain setting. The
differential amplifier is internally
compensated for 0 dB feedback
stability.
The switch-on moment of the
switching transistor can be
determined by capacitor Cdelay.
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.
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 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
(3)
V clamp
Vmv
• Transfer ratio nh/np
• Inductance L
Before comparing the sawtooth
voltage Vc with the control voltage Vr
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 Vsim, which is
important for a stabilized no-load
operation (see Fig.6 area 3).
(4)
(2)
V Ton(min)
(1)
(5)
Vfb
MCD405
DEMAGNETIZATION 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.
March 1994
(1), (2), (3) = VTCG.
(4), (5) = Vdiff.
Fig.6 Reference voltage (Vmv) as a function of feedback voltage (Vfb).
7
Philips Semiconductors
Preliminary specification
Control circuit for a Self-Oscillating
Power Supply (SOPS)
TDA8385
The voltage VTon(min) determines the
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).
VO
(5)
(4)
(3)
The minimum on-time is of
importance for the following.
• Stand-by operation
• Starting-up of power supply
(2)
• Overload and short-circuit
conditions.
The output of the differential amplifier
(Vdiff), the output of the TCG (VTCG)
and the voltage Vss + VTon(min) are
compared in a minimum voltage
clamping circuit (see Fig.1
sub-section 6). The output voltage is
equal to the lowest input voltage.
(1)
IO
MCD406
(1), (2), (3) = VTCG.
(4), (5) = Vdiff.
Fig.7
Current foldback characteristic; stabilized output voltage (VO)
as function of load current (IO).
handbook, full pagewidth
Ic
Some relevant characteristics of the
control part are depicted in Fig.8.
Vmv
Ic (max)
x
y
VTCG
Vdiff
Vmv
external peak-current
setting (pin 7)
I c (min)
V ref
Vss + V Ton(min)
V fb
MCD407
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 Ic(min) and rises along the straight line until Ic(max) is reached. At a slightly higher feedback voltage
the regulation slope is reached, which is approximately Vref.
The plateau of the top between the points x and y has to be kept as small as possible.
The voltage Vdiff decreases with the decreasing load. For good no-load operation the peak current has to be made zero with Vdiff.
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.
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 Vsim. If Vsim > Vr
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.
TDA8385
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)
EXAMPLE
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)
The slow-start circuit is active at
start-up, over voltage protection or
after an overload (short-circuited),
and stand-by mode. The voltage Vss
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 Ic(max) setting by
connecting a resistor to this pin.
3. VP(min) detector
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.
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.
OPERATION 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
discharge procedure.
OPERATION WHEN IC IS
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 IP
(≈15 mA) is much larger than the slow
discharge current (≈50 µA), the LED
will be switched off by means of the
VP(min) detection circuit (5.2 V). At that
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.
March 1994
9
Philips Semiconductors
Preliminary specification
Control circuit for a Self-Oscillating
Power Supply (SOPS)
TDA8385
handbook, full pagewidth
Ic
(1)
t
Vss
t
(1) For detail see Fig.10.
MCD408
Fig.9 Over voltage protection.
VP
(V)
7.5 V
5.2 V
0
t
t delay
slow discharge
Vss
(V)
quick discharge
0
t
Ic
t
Q FF23
t
MCD409
Fig.10 Detailed over voltage protection of Fig.9.
March 1994
10
Philips Semiconductors
Preliminary specification
Control circuit for a Self-Oscillating
Power Supply (SOPS)
TDA8385
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
Vsb
(V)
2.5 V
2V
0
t
output sub-section 25
0
t
I LED
(mA)
5 mA
0
t
MCD410
Fig.11 Stand-by operation; burst mode.
March 1994
11
Philips Semiconductors
Preliminary specification
Control circuit for a Self-Oscillating
Power Supply (SOPS)
TDA8385
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 (Vdiff < Vts; see Fig.12).
handbook, full pagewidth
V
Vfb
Vts
2.5
0
t
Vdiff
VP
0
t
V
VRIO : open-collector output
RIO
0
t
MCD411
A desired delay at power-on reset can be made externally.
Fig.12 Regulation indicator output; pin 1.
March 1994
12
Philips Semiconductors
Preliminary specification
Control circuit for a Self-Oscillating
Power Supply (SOPS)
TDA8385
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
VP
supply voltage
pin 2 connected
−0.5
20
V
pin 2 open-circuit
−0.5
18
V
V
Vn
voltage on pins 1, 2, 4, 7, 9 and 13
−0.5
+18
V3
voltage on pin 3
−0.5
+6
V
V8,10
voltage on pins 8 and 10
−0.5
+3.9
V
V12
voltage on pin 12
−0.1
+0.5
V
V15
voltage on pin 15
−0.5
+0.5
V
I1
current on pin 1
0
2
mA
In
current on pins 2, 12 and 15
−10
+10
mA
I3
current on pin 3
−1
0
mA
I5, 6
current on pins 5 and 6
−1
+1
mA
I7
current on pin 7
−1
+25
mA
I11
current on pin 11
−10
+0.5
mA
I16
current on pin 16
0
20
mA
Tamb
operating ambient temperature
−25
+70
°C
Tstg
storage temperature
−55
+150
°C
−
500
mW
Currents
Temperatures
Power dissipation
Ptot
total power dissipation
THERMAL RESISTANCE
SYMBOL
Rth j-a
March 1994
PARAMETER
THERMAL RESISTANCE
from junction to ambient in free air
55 K/W
13
Philips Semiconductors
Preliminary specification
Control circuit for a Self-Oscillating
Power Supply (SOPS)
TDA8385
CHARACTERISTICS
VP = 15 V; I3 = 200 µA; Tamb = 25 °C; unless otherwise specified.
SYMBOL
PARAMETER
CONDITIONS
MIN.
TYP.
MAX.
UNIT
Supply
VP
supply voltage (pin 16)
7.9
−
20
V
V16
supply initialization level
7.1
7.5
7.9
V
V16(hys)
internal fixed hysteresis
2.5
−
2.55
V
I16
supply current
active LED output
−
−
20
mA
V11
supply voltage ripple rejection
see Figs 13 and 14
−
60
−
mV
0.52
0.55
0.58
V
Reference voltage
V3
reference voltage at pin 3
Error amplifier
V9
threshold voltage error amplitude
2.4
2.5
2.6
V
I9
input current feedback input
−
−
0.5
µA
I11
sink current output
V11 = 80 mV
400
−
−
µA
I11
source current output
V11 = 2.5 V
500
−
−
µA
Go
open loop gain
−
100
−
dB
B
unity gain bandwidth
−
600
−
kHz
10−6
−
K−1
Vos(1)
−
V
∆V9/∆T
V5
temperature coefficient
−
±300 ×
threshold for switching output
Vdiff = 1.25 V;
V4 = 2 V; V13 = 0 V;
V7 > V9; I2 = 2 mA
−
Vdiff −
0.23
0.25
0.27
Transfer characteristic generator
I4/I3
current ratio
V4 = 0.5 V
V5
threshold for switching output
V4 = 0.5 V; V13 = 0 V;
V7 > V9; I2 = 2 mA
Ton(min)
V9 = 0 V
0.4 − Vos
0.5 − Vos
0.6 − Vos
V
Vfb = 20%
V9 = 0.4 V
−
0.9 − Vos
−
V
Vfb = 50%
V9 = 1 V
1.4 − Vos
1.5 − Vos
1.6 − Vos
V
Vfb = 80%
V9 = 1.6 V
−
2.1 − Vos
−
V
2.4 − Vos
−
2.6 − Vos
V
tPLH
response time pulse width
modulation pin 5 to pin 2
LOW-to-HIGH
note 2
−
−
700
ns
tPHL
response time pulse width
modulation pin 5 to pin 2
HIGH-to-LOW
note 2
−
−
1
µs
0.7 − Vos
0.8 − Vos
V
−
1
µA
clamp
V9 = 2.25 V
Feed forward
V5
threshold for switching output
(Vfo)
V4 = 0.5 V; V13 = 0 V; 0.6 − Vos
V7 = V9 = 3 V;
I2 = 2 mA; V11 = 1 V
I13
input bias current
V13 = 0 V
March 1994
−
14
Philips Semiconductors
Preliminary specification
Control circuit for a Self-Oscillating
Power Supply (SOPS)
SYMBOL
PARAMETER
TDA8385
CONDITIONS
MIN.
TYP.
MAX.
UNIT
Slow-start
I7/I3
charge current ratio
I7
quick discharge current
V7 = 0.5 V
0.22
0.24
0.26
V7 = 1 V
20
−
−
mA
V7 = 100 mV
50
−
−
µA
2.8
3.0
3.2
V
1.5 − Vos
1.6 − Vos
V
−
300
mV
V7
clamping level
I7 = 100 µA
V5
threshold for switching output
(Vss)
V4 = 0.5 V; V13 = 0 V; 1.4 − Vos
V7 = 1 V; I2 = 2 mA;
V9 = 2 V
Output stage
V2(sat)
saturation voltage
I2 = 2 mA
I2
source current
V2 = 2 V
V2
−
operating
4.8
5.3
6.3
mA
initialization phase
−
−
50
µA
12
−
−
V
open output voltage HIGH
I2 = 5 mA
Current simulation
I5/I12
current ratio
V5 = 1 V; I12 = 0.5 mA 0.19
0.2
0.21
V12
simulation input voltage
I12 = 0.5 mA
−
−
1.1
V
V5(sat)
saturation voltage
V15 = V6 = 0 V;
I5 = 1 mA
−
−
300
mV
V15 = V6 = 0 V;
I5 = 200 µA
−
−
200
mV
100
140
mV
∆V
threshold for switching output;
voltage difference between pins 5
and 11; offset simulation voltage
(Vos)
V4 = 0.5 V; V13 = 0 V; 60
V7 = V9 = 3 V;
I2 = 2 mA;
V11 = 0.5 V
Demagnetization input
tdemLH
delay from pin 15 to pin 5
LOW-to-HIGH
see Fig.15;
pin 6 not connected
−
−
500
ns
tdemHL
delay from pin 15 to pin 5
HIGH-to-LOW
see Fig.15
−
−
1
µs
V15
clamping level
I15 = 10 mA
positive
−
−
1.2
V
negative
−
−
−1
V
90
115
140
mV
V15
demagnetization threshold
voltage
C15
input capacitance
I15
input bias current
March 1994
V15 = 60 mV
15
−
−
10
pF
−
−
0.5
µA
Philips Semiconductors
Preliminary specification
Control circuit for a Self-Oscillating
Power Supply (SOPS)
SYMBOL
PARAMETER
TDA8385
CONDITIONS
MIN.
TYP.
MAX.
UNIT
Delay setting
I6/I3
charge current ratio
V6 = 1 V
1.1
1.2
1.3
I6
charge current initialization phase V6 = 1 V; V16 = 5 V
2
−
−
mA
V6
clamping level
2.8
−
3.2
V
V6(sat)
saturation voltage
V15 = 140 mV
−
50
100
mV
tdLH
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;
excluding capacitive
tolerances
−
−
1.2
µs
t/c
delay setting (t = C6 × V/I)
V6 = 2.5 V;
I3 = 250 µA
−
10
−
ns/pF
Stand-by
V10H
threshold level HIGH
2.4
2.5
2.6
V
V10(hys)
hysteresis
450
500
550
mV
tdLH
delay to output pin 10 to pin 2
LOW-to-HIGH
−
−
1
µs
tdHL
delay to output pin 10 to pin 2
HIGH-to-LOW
−
−
1
µs
I10
input current
−
−
5
µA
V10 = 2.3 V
Over voltage protection
V8
threshold level
2.4
2.5
2.6
V
tdLH
delay to output pin 8 to pin 2
LOW-to-HIGH
−
−
1
µs
tdHL
delay to output pin 8 to pin 2
HIGH-to-LOW
−
−
1
µs
V7
reset level
90
−
140
mV
I7/I3
slow discharge current ratio
V7 = 1 V
0.12
0.23
0.31
I8
input current
V8 = 3 V
−
−
1
µA
Regulation indicator output
V1
saturation voltage
I1 = 1 mA
−
−
300
mV
I1
leakage current
V1 = V16
−
−
1
µA
Notes
1. Vos = Voffset.
2. V5 pulse = 1 V; V4 = 0.5 V; V9 = V7 = 3 V; V11 = 0.5 V; V13 = 0 V; I2 = 2 mA.
March 1994
16
Philips Semiconductors
Preliminary specification
Control circuit for a Self-Oscillating
Power Supply (SOPS)
TDA8385
VP
Vdiff
(pin 11)
15 V
t
~
~ 3V
2V
t
MCD412
Frequency = 50 kHz.
Slew rate = 0.2 µs.
Frequency = 50 kHz.
Slew rate = 0.2 µs.
Fig.13 Supply voltage ripple rejection;
VP as a function of time.
Fig.14 Supply voltage ripple rejection;
Vdiff as a function of time.
Table 1 Condition of test circuit used for Figs 13 and 14.
PINS
1, 2, 4 to 6, 12, 13
STATUS
not connected
8 to 10, 14, 15
ground
3
Rref = 2.7 kΩ
7
Css = 4.7 µF
16
VP; see Fig.13
11
Vdiff; see Fig.14
March 1994
MCD413
17
Philips Semiconductors
Preliminary specification
Control circuit for a Self-Oscillating
Power Supply (SOPS)
TDA8385
115 mV
handbook, full pagewidth
~
~ + 0.8 V
demagnetization input
(pin 15)
0V
~
~ – 0.8 V
1V
90%
peak-current setting input
(pin 5)
10%
t demLH
t demHL
Fig.15 Timing diagram; demagnetization delay time.
March 1994
18
0V
MCD414
VI
(mains)
1/2 CNR50
March 1994
Ic
T1
nh
TH1
R12
19
CP
VP
RC
V stab
Co
R15
12
14
16
10
15
9
5
C
6
Cdelay
4
TDA8385
11
1
2
R ref
13
3
R Ton(min)
C ss
7
8
VO
MCD415
1/2 CNR50
Control circuit for a Self-Oscillating
Power Supply (SOPS)
handbook, full pagewidth
Fig.16 Application circuit of SOPS with stand-by facility.
A
A
np
ns
Vf
Philips Semiconductors
Preliminary specification
TDA8385
APPLICATION INFORMATION
Philips Semiconductors
Preliminary specification
Control circuit for a Self-Oscillating
Power Supply (SOPS)
TDA8385
VO
handbook, full pagewidth
Vf
Ton
ns
V
np I
Toff
storage time and delay
(SOPS)
Ic
output sub-section 11
RESET
(sub-section 13)
output sub-section 12
DEMAGNETIZATION
delay
Vc
V r (output sub-section 7)
Vsim
comparator (18)
level = 1 V
Vsim (output sub-section 10)
output sub-section 8
COMPARATOR
SET
(sub-section 13)
output sub-section 13
Q
output sub-section 16
DEMAGNETIZATION
output sub-section 14
LED driver
t
Fig.17 Application timing diagram.
March 1994
20
MCD416
Philips Semiconductors
Preliminary specification
Control circuit for a Self-Oscillating
Power Supply (SOPS)
TDA8385
PACKAGE OUTLINE
seating plane
22.00
21.35
8.25
7.80
5.1
max
1.2 min
3.9
3.4
2.2
max
2.54
(14x)
0.53
max
0.254 M
0.32 max
7.62
1.4 max
9.5
8.3
MSA349
16
9
6.48
6.14
8
1
Dimensions in mm.
Fig.18 16-lead dual in-line; plastic with internal heat spreader; opposite bent leads (SOT38WBE).
March 1994
21
Philips Semiconductors
Preliminary specification
Control circuit for a Self-Oscillating
Power Supply (SOPS)
SOLDERING
Plastic dual in-line packages
BY DIP OR WAVE
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.
TDA8385
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.
REPAIRING 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.
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.
March 1994
22