TSM101A STMicroelectronics, TSM101A Datasheet - Page 6

• Manufacturer Part Number: TSM101A
• Description: VOLTAGE AND CURRENT CONTROLLER
• Manufacturer: STMicroelectronics

TSM101/A
Figure 2 : SMPS Using a TL431 as Voltage Controller
The optocoupler current increases and tends to
reduce the output voltage by the way of the PWM
controller.
By enabling the TSM101 current source (pin 2) it is
possible to offset the current sensing by a voltage
equal to :
This offset lowers the output charge current and
this function can be used to charge two types of
batteries having different capacities. The current
source is enabled by connecting pin 2 to ground
3 - CALCULATION OF THE ELEMENTS
The charge current is regulated at 700mA (if the
charge control input is left open) or 200mA (if the
charge control input is put to ground ), allowing the
charge of two different types of batteries.
3.1 - Voltage limitation
The end-of- charge voltage is limited at 1.45V/cell,
this is the recommended voltage for an ambient
temperature at 25
A diode is generally inserted at the output of the
charger to avoid the discharge of the battery if the
charger is not powered. This diode is sometimes
directly integrated in the battery pack. The influ-
6/15
V
off
# R4 * Io with I
o
C.
o
= 1.4mA
ence of this diode on the charge is negligible if the
voltage drop (0.7V) is taken into account during the
design of the charger.
The voltage at the output of the charger is :
P1, which is a part of R6 and R7 is not considered
in this equation.
The following values are used on the application
board :
3.2 - Current regulation
R5 is the sense resistor used for current measure-
ment.
and regarding R6 and R7 :
V
R6
R7 = 12k
R6 = 1k
P1 = 220 , adjust for V
battery replaced by a 1k resistor
R10 = short circuit
C3 = 100nF
out
V
R6 R7
out
R6
V
ref
V
xV
ref
r
x R7
output
= 15.2V with the