TSM1051 STMicroelectronics, TSM1051 Datasheet - Page 7

• Manufacturer Part Number: TSM1051
• Description: CONSTANT VOLTAGE AND CONSTANT CURRENT CONTROLLER FOR BATTERY CHARGERS AND ADAPTORS
• Manufacturer: STMicroelectronics

TSM1051
connected in parallel with another capacitor
Cvc2=22pF.
The current-control trans-conductance operation-
al 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 in series.
When the Vcc voltage reaches 12V it could be in-
teresting to limit the current coming through the
output in the aim to reduce the dissipation of the
device and increase the stability performances of
the whole application.
An example of a suitable Rout value could be
330
Vcc=12V.
3. Start Up and Short Circuit Conditions
Under start-up or short-circuit conditions the
TSM1051 is not provided with a high enough sup-
ply voltage. This is due to the fact that the chip has
Figure 10 :
7/9
Rs
DS
in series with the opto-coupler in case
Vcc
CS
+
+
1.210V
200mV
Ictrl
Vsense
Rsense
Vsense
+
+
-
-
IL
TSM105
Vcc
Gnd
Ric2
500
Out
its power supply line in common with the power
supply line of the system.
Therefore, the current limitation can only be en-
sured 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 suffi-
cient supply for the TSM1051 has to be ensured
under any condition. It would then be necessary
to add some circuitry to supply the chip with a sep-
arate power line. This can be achieved in numer-
ous ways, including an additional winding on the
transformer.
The following schematic shows how to realize a
low-cost power supply for the TSM1051 (with no
additional windings).
Please pay attention to the fact that in the particu-
lar case presented here, this low-cost power sup-
ply can reach voltages as high as twice the volt-
age of the regulated line. Since the Absolute Max-
imum Rating of the TSM1051 supply voltage is 14
V, this low-cost auxiliary power supply can only be
used in applications where the regulated line volt-
age does not exceed 7 V.
Rout
Ric1
22K
Cic1
2.2nF
To primary
Cvc2
22pF
Rvc1
470K
D
Cvc1
2.2nF
R2
R1
+
IL
OUT+
OUT-