TSM101 STMicroelectronics, TSM101 Datasheet - Page 9

• Manufacturer Part Number: TSM101
• Description: VOLTAGE AND CURRENT CONTROLLER
• Manufacturer: STMicroelectronics

5.4. An example of application where the
charging current is different according to the
charging phase.
The following application includes a specific rec-
ommendation which requires that the charging
current should be fixed to Ich1 = 800mA in normal
charging conditions, and Ich2 = 200mA when the
cell voltage is below Vl=2.5V to optimize the cell
life-time.
Moreover, an Charging Status LED should be
switched off when the cell voltage is above
Vh=6.5V.
Figure 6 shows how this can easily be achieved
using an additional dual comparator (type LM393)
where the first operator (C1) is used to activate the
TSM101 internal current generator to offset the
current measurement thanks to R4, and the sec-
ond (C2) is used to switch the status LED off. On
figure 6, the status signal is determined by voltage
measurement, this could as well be achieved by
current measurement.
If V5 = 100mV is the maximum tolerable voltage
drop through the sense resistor R5 during normal
charging conditions, then the following calcula-
tions apply :
Figure 6 : Optimized Charging Conditions
Current Control :
R5 = V5 / Ich1 = 0.1 / 0.8 = 0.125
R5 = 125m
V5 = V
and V
R3 = 1k , R2 = 11.4k
V5 = R4 x Io + R5 x Ich2, therefore, R4 = (V5 - R5
x Ich2) / Io with Io = 1.4mA
R4 = 53.6
Vref = Vl x R15 / (R14 + R15) with Vl = 2.5V and
R14 + R15 ~ 20k
R15 = R14 = 10k
Voltage Control :
Vref = Vh x R6 / (R6 + R7) with Vh = 6.5V and
R6 + R7 ~ 12kW
R6 = 2.36kW, R7 = 10kW
Vref = Vh R17 / (R16 + R17)
R17 = 10kW, R16 = 42kW
Voltage Control :
Vref = Vh x R6 / (R6 + R7) with Vh = 6.5V and
R6 + R7 ~ 12kW
R6 = 2.36kW, R7 = 10kW
Vref = Vh R17 / (R16 + R17)
R17 = 10kW, R16 = 42kW
ref
ref
= 1.24V
x R3 / (R2 + R3) with R2 + R3 ~ 12k
TSM101/A
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