TSM1052 Datasheet, PDF (8/15 Pages) STMicroelectronics – Constant voltage and constant current controller for battery chargers and adapters

Application information
4
Application information
TSM1052
4.1
Typical application schematic
Figure 15. Typical adapter or battery charger application using the device
TSM1052
1.210 V
+
Vcc
6
+
3 OUT
-
R1
Rled
Rvc1
Cvc1
200 mV
4
Ictrl
+
-
5
Vsense
1 Vctrl
Cic1
2 GND
Ric1
R2
Vout
Ric2
Rsense
Iout
In the above application schematic, the device is used on the secondary side of a flyback
adapter (or battery charger) to provide an accurate control of voltage and current. The
above feedback loop is made with an optocoupler.
4.2
4.2.1
Voltage and current control
Voltage control
The voltage loop is controlled via a first transconductance operational amplifier, the voltage
divider R₁, R₂, and the optocoupler which is directly connected to the output. Its possible to
choose the values of R1 and R2 resistors using Equation 1:
Equation 1
a)
V_out
= V_ref
⋅ ^{(R1 + R2 )}
R₂
b)
R₁
=
R₂
⋅
(V_out + V_ref
V_ref
)
where Vout is the desired output voltage.
As an example, with R1 = 100KΩ and R2 = 27KΩ, V_OUT = 5.7V
8/15