Datasheet TDA4700A, TDA4718A Datasheet (Siemens)

Control IC for Single-Ended and Push-Pull
Switched-Mode Power Supplies (SMPS)

Features

● Feed-forward control (line hum suppression)

● Symmetry inputs for push-pull converter

(TDA 4700)

● Push-pull outputs

● Dynamic output current limitation

● Overvoltage protection

● Undervoltage protection

● Soft start

● Double pulse suppression

Type Ordering Code Package Temp.-Range

TDA 4700
TDA 4718

P-DIP-24-1

TDA 4700 A Q67000-Y594 P-DIP-24-1 – 0 to 70 °C
TDA 4718 A Q67000-Y639 P-DIP-18-1 – 0 to 70 °C

■

■ Not for new design

These versatile SMPS control ICs comprise digital and
analog functions which are required to design high­quality flyback, single-ended and push-pull converters
in normal, half-bridge and full-bridge configurations.
The component can also be used in single-ended
voltage multipliers and speed-controlled motors.
Malfunctions in electrical operation are recognized by
the integrated operational amplifiers, which activate
protective functions.

P-DIP-18-1

1)

Is now available for temperature range – 25 to 85 °C.

Semiconductor Group 1 05.95

Pin Configuration (TDA 4700)

(top view)

TDA 4700
TDA 4718

Semiconductor Group 2

Pin Definitions and Functions (TDA 4700)
Pin Symbol Function

1 GND Ground 0 V

TDA 4700
TDA 4718

2
3

4
5

6
7
8

9
10
11

12
13

14
15

16

+

V

REF

+ V

S

Q2
Q1

I SYM Q2
Q SYNC

C

soft start

R

T

C

filter

C

T

R

R

C

R

I COMP
Q Op Amp

– I Op Amp

Reference voltage
Supply voltage

Output Q2
Output Q1

Symmetry Q2
Sync. output
Soft start

VCO R

T

Capacitance
VCO

Ramp generator R
Ramp generator C

C

T

R

R

Comparator input
Operational amplifier output

Operational amplifier input (–)
17
18

+ I Op Amp
I SYNC

Operational amplifier input (+)

Sync. input
19 ON/OFF/IUV ON/OFF, undervoltage
20

21
22

23

QOV
IOV

–

I

DYN

+ I

DYN

Overvoltage output

Overvoltage input

Dynamic current limitation (–)

Dynamic current limitation (+)
24 I SYM Q1 Symmetry

Semiconductor Group 3

Pin Configuration (TDA 4718)

(top view)

TDA 4700
TDA 4718

Semiconductor Group 4

Pin Definitions and Functions (TDA 4718)
Pin Symbol Function

1 GND Ground 0 V

TDA 4700
TDA 4718

2
3

4
5

6
7

8
9

10
11

12
13

14
15

R

R

C

R

I COMP
I SYNC

IUV
IOV

–

I

DYN

+ I

DYN

+

V

REF

+ V

S

Q 2
Q 1

Q SYNC

C

soft start

Ramp generator R
Ramp generator C

R

R

+ Input comparator K2
Sync. input

Input undervoltage, ON/OFF
Input overvoltage

Input dynamic current limitation (–)
Input dynamic current limitation (+)

Reference voltage
Supply voltage

Output Q2
Output Q1

Sync. output
Soft start

16
17
18

R
C
C

T

filter
T

VCO R

T

Capacitance
VCO

C

T

Circuit Description
Voltage Controlled Oscillator (VCO)

The VCO generates a sawtooth voltage. The duration of the falling edge is determined
by the value of
approximately the frequency, is determined by the value of

C

, the oscillator frequency can be changed by its rated value. During the fall time, the

filter

C

. The duration of the rising edge of the waveform and, therefore,

T

R

. By varying the voltage at

T

VCO provides a trigger signal for the ramp generator, as well as an L signal for a number
of IC parts to be controlled.

Semiconductor Group 5

TDA 4700
TDA 4718

Ramp Generator

The ramp generator is triggered by the VCO and oscillates at the same frequency. The
duration of the falling edge of the ramp generator waveform is to be shorter than the fall
time of the VCO. To control the pulse width at the output, the voltage of the rising edge
of the ramp generator signal is compared with a DC voltage at comparator K2. The slope
of the rising edge of the ramp generator signal is controlled by the current through
This offers the possibility of an additional, superimposed control of the output duty cycle.
This additional control capability, called “feed-forward control”, is utilized to compensate
for known interference such as ripple on the input voltage.

Phase Comparator

If the component is operated without external synchronization, the sync input must be
connected to the sync output for the phase comparator to set the rated voltage at
The VCO then oscillates with rated frequency. In the case of external synchronization,
other components can be synchronized with the sync output. The component can be
frequency-synchronized, but not phase-synchronized, with the sync input. The duty
cycle of the squarewave voltage at the sync input is arbitrary. The best stability as to
small phase and frequency interference deviation is achieved with a duty cycle as
offered by the sync output.

C

R

filter

R

.

.

Push-Pull Flipflop

The push-pull flipflop is switched by the falling edge of the VCO. This ensures that only
one output of the two push-pull outputs is enabled at a time.

Comparator K2

The two plus inputs of the comparator are switched such that the lower plus level is
always compared with the level of the minus input. As soon as the voltage of the rising
sawtooth edge exceeds the lower of the two plus levels, both outputs are disabled via
the pulse turn-off flipflop. The period during which the respective, active outputs is low
can be infinitely varied. As the frequency remains constant, this process corresponds to
a change in duty cycle.

Operational Amplifier K1 (TDA 4700; A)

The K1 op amp is a high-quality amplifier. Fluctuations in the output voltage of the power
supply are amplified by K1 and applied to the free + input of comparator K2. Variations
in output voltage are, in this way, converted to a corresponding change in output duty
cycle. K1 has a common-mode input voltage range between 0 V and + 5 V.

Semiconductor Group 6

TDA 4700
TDA 4718

Pulse-Turn-OFF Flipflop

The pulse turn-OFF flipflop enables the outputs at the start of each half cycle. If an error
signal from comparator K7 or a turn-off signal from K2 is present, the outputs will
immediately be switched off.

Comparator K3

Comparator K3 limits the voltage at capacitance

C

soft start

(and also at K2) to a maximum
of + 5 V. The voltage at the ramp generator output may, however rise to 5.5 V. With a
corresponding slope of the rising ramp generator edge, the duty cycle can be limited to
a desired maximum value.

Comparator K4

The comparator has its switching threshold at 1.5 V and sets the error flipflop with its
output if the voltage at capacitance

C

soft start

is below 1.5 V. However, the error flipflop
accepts the set signal only if no reset pulse (error) is applied. In this way the outputs
cannot be turned on again as long as an error signal is present.

Soft Start

The lower one of the two voltages at the plus inputs of K2 is a measure for the duty cycle
at the output. At the instant of turning on the component, the voltage at capacitor

C

soft start

equals 0 V. As long as no error is present, this capacitor is charged with a current of 6 µA
to the maximum value of 5 V. In case of an error,

C

soft start

is discharged with a current of
2 µA. A set signal is pending at the error flipflop below a charge of 1.5 V and the outputs
are enabled if no reset signal is pending simultaneously. As the minimum ramp
generator voltage, however, is 1.8 V, the duty cycle at the outputs is actually increased
slowly and continuously not before the voltage at

C

soft start

exceeds 1.8 V.

Error Flipflop

Error signals, which are led to input

R of the error flipflop cause an immediate disabling
of the outputs, and after the error has been eliminated, cause the component to switch
on again by the soft start.

Comparator K5, K6, K8, V

Overcurrent Load

REF

These are error detectors which cause immediate disabling of the outputs via the error
flipflop when an error occurs. After elimination of the error, the component switches on
again using the soft start. The output of K5 can be fed back to the input. This causes the
IC output stage to remain disabled even after elimination of the overvoltage. However, it
requires high-ohmic overvoltage coupling.

Semiconductor Group 7

TDA 4700
TDA 4718

Comparator K7

K7 serves to recognize overcurrents. This is the reason why both inputs of the op amp
have been brought out. Turning on is resumed after error recovery at the beginning of
the next half period but without using the soft start.

K7 has a common-mode range covers 0 V and + 4 V. The delay time between
occurrence of an error and disabling of the outputs is only 250 ns.

Symmetry (TDA 4700; A)

In push-pull converters, a saturation of the transformer core must be prevented. The
degree of saturation of the transformer can be determined with an external circuit, thus
the active periods of the outputs can be decreased unsymmetrically at the symmetry
inputs.

Outputs

Both outputs are transistors with open collectors and operate in a push-pull
arrangement. They are active low. The time in which only one of the two outputs is
conductive can be varied infinitely. The length of the falling edge at VCO is equal to the
minimum time during which both outputs are disabled simultaneously. The minimum
L voltage is 0.7 V.

Reference Voltage

The reference voltage source is a highly constant source with regard to its temperature
behavior. It can be utilized in the external wiring of the op amp, the error comparators,
the ramp generator, or other external components.

Semiconductor Group 8

TDA 4700
TDA 4718

Block Diagram (TDA 4700)

Semiconductor Group 9

TDA 4700
TDA 4718

Block Diagram (TDA 4718)

Semiconductor Group 10

TDA 4700
TDA 4718

Absolute Maximum Ratings
Parameter Symbol Limit Values Unit Test

Condition

min. max.

Supply voltage
Voltage at Q1, Q2

Current at Q1, Q2
Symmetry 1, 2 TDA 4700; A
Sync output

Sync input
Input
Input R
Input C
Input R
Input C

C

filter

T

T

R

R

Input comparator
K2, K5, K6, K7

Output K5

V

S

V

Q

I

Q

V

SYM

V

SYNC Q

I

SYNC Q

V

SYNC I

V

I Cf

V

IRT

V

ICT

V

IRR

I

ICR

V

I K

V

Q K5

– 0.3
– 0.3

33
33

70 mA Q1, Q2 low
– 0.3 33 V
– 0.3

0
– 0.3

– 0.3
– 0.3
– 0.3
– 0.3
–10

– 0.3

7

10

33

7

7

7

7

10

33
– 0.3 33 V

V
V Q1, Q2 high

V
mA

SYNC Q high
SYNC Q low

V
V
V
V
V
mA

V

Input op amp TDA 4700; A
Output op amp TDA 4700; A

Reference voltage
Input

C

soft start

Junction temperature
Storage temperature

Thermal resistance
system - air TDA 4700; A

TDA 4718
TDA 4718 A

V

I Op Amp

V

Q Op Amp

V

REF

V

I soft start

T

j

T

stg

R

th SA

R

th SA

R

th SA

– 0.3 33 V
– 0.3 VS –1

max. 7
– 0.3 V

REF

– 0.3 7 V

150
–55

125

65

70

60

V
V

V

°C
°C

K/W
K/W
K/W

Semiconductor Group 11

TDA 4700
TDA 4718

Operating Range
Parameter Symbol Limit Values Unit Test

Condition

min. max.

Supply voltage

V

S

10.5 30 V

Ambient temperature

TDA 4700
TDA 4718

T

A

–25

85

°C
TDA 4700 A
TDA 4718 A

VCO frequency
Ramp generator frequency

T

A

f
f

RG

0
40

40

70

°C

250 000
250 000HzHz

Characteristics

V

= 11 to 30 V; TA = –25to85°C

S

Parameter Symbol Limit Values Unit Test

Condition

min. typ. max.

Supply current

I

S

820mAC

= 1 nF

T

f

VCO

= 100 kHz

Reference

Reference voltage

V

REF

2.35 2.5
Reference voltage
change

∆V

REF

Reference voltage
change

∆V

REF

Reference voltage
change

∆V

REF

Temperature
coefficient

TC

Response threshold
of

I

overcurrent

REF

1)

At TA = 0 to 70 °C, this value falls to max. 5 mV

I

REF

8
15

0.25
10

2.65

1)

15

0.4

V
mV
mV
mV
mV/K
mA

0mA <

I

REF

< 5 mA

14 V ± 20 %
25 V ± 20 %

0mA <

I

REF

< 5 mA

Semiconductor Group 12

Characteristics (cont’d)

V

= 11 to 30 V; TA = –25to85°C

S

Parameter Symbol Limit Values Unit Test

Condition

min. typ. max.

Oscillator (VCO)

TDA 4700
TDA 4718

Frequency range
Frequency change
Frequency change
Tolerance
Fall time sawtooth

RC combination
VCO

Ramp Generator

Frequency range
Maximum voltage
at

C

R

Minimum voltage
at

C

R

Input current
through

R

R

Current
transformation ratio

f

VCO

∆f/f
∆f/f
∆f/f

t
t
C

T

R

T

f

V

H

V

L

I

RR

I

RR/ICR

VCO
VCO
VCO

40
–1

–7

0.82

5

40

0

0.5

1
10

5.5

1.8

1/4

100 000
1

7

47
700

100 000

400

Hz
%
%
%

µs
µs

nF
kΩ

Hz
V
V
µA

14 V ± 20 %
25 V ± 20 %

∆

R

= 0; ∆CT = 0

T

C

= 1 nF

T

C

= 10 nF

T

Synchronization

Sync output
Sync input
Input current

V
V
V
V

– I

Q H
Q L
I H
I L

4
2

I

Semiconductor Group 13

0.4

0.8
5

V
V
V
V
µA

I

= – 200 µA

Q H

I

= 1.6 mA

Q L

Characteristics (cont’d)

V

= 11 to 30 V; TA = –25to85°C

S

Parameter Symbol Limit Values Unit Test

Condition

min. typ. max.

Comparator K2

TDA 4700
TDA 4718

Input current
Turn-OFF delay
Input voltage

1)

I

–

t

D OFF

V

IK2

I K2

1.8

5
Common-mode input
voltage range

V

I C

0

Soft Start K3, K4

Charge current for

C

soft start

I

ch

6
Discharge current for

C

soft start

Upper limiting voltage
Switching voltage K4

I
V
V

dch

lim
K4

2

5

1.5

Operational Amplifier K1 (TDA 4700; TDA 4700 A)

Open-loop voltage
gain
Input offset voltage

G
V

IO

V0

60
–10

80
Temperature

coefficient of
Input current

V

IO

TC

– I

I

–30

Common-mode input
voltage range
Output current

V
I

IC

Q

0

–3
Rise time of output
voltage
Transition frequency
Phase at

f

T

Output voltage

∆V/∆t

f

T

ϕ

T

V

Q H/L

1.5

1
3
120

2
500

5.5

10
30

2
5

1.5

5.5

µA
ns

for duty cycle
V
V

D = 0

D = max.

V

µA
µA

V
V

dB
mV

µV/K
µA

V
mA

V/µs
MHz
deg.
V –3mA <

I <1.5 mA

1)

At the input: step function ∆V = – 100 mV ∆V = + 100 mV

Semiconductor Group 14

Characteristics (cont’d)

V

= 11 to 30 V; TA = –25to85°C

S

Parameter Symbol Limit Values Unit Test

Condition

min. typ. max.

Symmetry (TDA 4700; TDA 4700 A)

TDA 4700
TDA 4718

Input voltage
Input current

V
V

– I

I H
I L

I

Output Stages Q1, Q2

Output voltage

V
V

Q H
Q L

Output leakage
current

I

Q

ON, OFF, Undervoltage K6

Switching voltage
Input current
Turn-OFF delay time
Error detection time

V

– I

t

D OFF

t

I

1)

1)

Dynamic Current Limitation K7

Common-mode input
voltage range
Input offset voltage
Input current
Turn-OFF delay time
Error detection time

V

IC

V

IO

– I

t

D OFF

t

I

2)

2)

2.0

V

REF

0
–10

–0.03

250
50

250
50

0.8
2

30

1.1
2

V

+0.032V

REF

4
10
2

V
V
µA

V
V

µA

µA

ns
ns

V
mV
µA
ns
ns

I

= 20 mA

Q

V

= 30 V

Q H

Overvoltage K5

Switching voltage
Input current
Output current
Turn-OFF delay time
Error detection time

1)

At the input: step function ∆V = V

2)

At the input: step function ∆V = – 100 mV ∆V = + 100 mV

V

– I

I

– I

t

D OFF

t

Q

REF

1)

1)

–0.03

V

REF

0

250
50

– 100 mV V

REF

Semiconductor Group 15

V

+0.03

REF

2
200

+ 100 mV

V

µA
µA

ns
ns

V

QH min

= 5 V

Characteristics (cont’d)

V

= 11 to 30 V; TA = –25to85°C

S

Parameter Symbol Limit Values Unit Test

Condition

min. typ. max.

Supply Undervoltage

TDA 4700
TDA 4718

Turn-ON threshold for

V

rising

S

Turn-OFF threshold
for

V

falling

S

Input

C

filter

Rated voltage for
rated frequency
Frequency approx.
proportional to voltage
within the range
Voltage at open
sync input

V

V

V

V

V

S

S

R

R

C filter

8.8

8.5

3

4

1.6

11

10.5

10.5
10

5

V
V
V
V

V

V
V

0 °C <

0 °C <

T

<70 °C

A

T

<70 °C

A

Semiconductor Group 16

TDA 4700
TDA 4718

Dimensioning Notes for RC Network

1. Determination of the minimum time during which both outputs must be disabled

C

→ selection of

2. Determination of the VCO frequency = 2 x output frequency
→ selection of

3. Determination of the rated slope of the rising ramp generator voltage, which the

maximum possible turn-on period per half wave depends on

→ selection of

4. Duration of the soft start process
→ selection of

5. In the case of a free-running VCO: connect sync output with sync input.

6. Wiring of the op amp according to the dynamic requirements and

connection of its output with the free input of K2. (TDA 4700; TDA 4700 A)

; selection of CR ≤ CT.

T

R

.

T

R

.

R

C

soft start

.

C

7. Capacitance

is not required in the free-running operation (sync input connected

filter

with sync output).
In the case of external synchronization, that value depends on the selected operating

frequency and the required maximum phase interference deviation.
Rated VCO frequency: 100 kHz 50 Hz

C

favourable: 10 nF 1µF

filter

Semiconductor Group 17

TDA 4700
TDA 4718

Pulse Diagram

Semiconductor Group 18

TDA 4700
TDA 4718

VCO Frequency versus RT and C

T

Semiconductor Group 19

VCO Temperature Response

V

= 12 V; D = max.

S

∆

f

VCO

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

f

K×

K

1 K⁄[]

with

C

as parameter

T

TDA 4700
TDA 4718

Semiconductor Group 20

TDA 4700
TDA 4718

Current Consumption
versus Temperature

Output Current versus
Output Voltage

Semiconductor Group 21