TSM1013

START UP AND SHORT CIRCUIT CONDITIONS

6/8

The

voltage-control

trans-conductance

operational amplifier can be fully compensated.

Both of its output and negative input are directly

accessible

for

external

compensation

components.

An example of a suitable compensation network is

shown in Fig.2. It consists of a capacitor

Cvc1=2.2nF and a resistor Rcv1=22K

Ω in series.

The

current-control

trans-conductance

operational amplifier can be fully compensated.

Both of its output and negative input are directly

accessible

for

external

compensation

components.

An example of a suitable compensation network is

shown in Fig.2. It consists of a capacitor

Cic1=2.2nF and a resistor Ric1=22K

Ω in series.

5

START UP AND SHORT CIRCUIT

CONDITIONS

Under start-up or short-circuit conditions the

TSM1013 is not provided with a high enough

supply voltage. This is due to the fact that the chip

has its power supply line in common with the

power supply line of the system.

Therefore, the current limitation can only be

ensured by the primary PWM module, which

should be chosen accordingly.

If the primary current limitation is considered not

to be precise enough for the application, then a

sufficient supply for the TSM1013 has to be

ensured under any condition.

It would then be

necessary to add some circuitry to supply the chip

with a separate power line. This can be achieved

in numerous ways, including an additional winding

on the transformer.

6

VOLTAGE CLAMP

The following schematic shows how to realise a

low-cost power supply for the TSM1013 (with no

additional windings).Please pay attention to the

fact that in the particular case presented here, this

low-cost power supply can reach voltages as high

as twice the voltage of the regulated line. Since

the Absolute Maximum Rating of the TSM1013

supply voltage is 28V. In the aim to protect he

TSM1013 against such how voltage values a

internal zener clamp is integrated.

Rlimit = (Vcc-Vz)Ivz

Fig. 4: Clamp voltage

Fig. 5:

Vz

28V

Vcc

Rlimit

cc

Ivz

TSM1013

+

CS

DS

D

R2

R1

Rsense

Rvc1

22K

Cvc1

2.2nF

Ric1

22K

OUT+

OUT-

+

Cic1

2.2nF

IL

Ric2

1K

R5

10K

R4

100K

R3

100

IL

Vsense

+

Rlimit

Vcc

28V

Vcc

Cv-

CV Out

Gnd

Cc-

Cc+

Vref

1

4

5

3

7

CV

CC

CC Out

TSM1013