TSM101C STMICROELECTRONICS [STMicroelectronics], TSM101C Datasheet - Page 9

• Manufacturer Part Number: TSM101C
• Description: VOLTAGE AND CURRENT CONTROLLER
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

5.3. Higher Precision for the Voltage Control
The voltage drop through the sense resistor R5
offsets the voltage measurement. In most battery
charging applications, this offset is not taken into
account because the error is negligeable com-
pared to the end-of-charge voltage due to the fact
that the charging current value decreases drasti-
cally during the final phase of the battery charging.
But in other applications needing highest possible
precision in voltage control, another connecting
5.4. An example of application where the
charging current is different according to the
charging phase.
The following application includes a specific recom-
mendation which requires that the charging current
should be fixed to Ich1 = 800mAin normal charging
conditions, and Ich2 = 200mA when the cell volt-
age 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 5 : Precise Output Voltage Control
schematic is possible for TSM101 as shown on
figure 5.
In this schematic, the 0V reference is defined as
the common point between the sense resistor, the
0V Output Voltage, the foot of the resistor bridge
R6/R7, and the ground (pin 4) of the TSM101.
TSM101A(1% internal voltage referenceprecision)
is required in such applications.
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 second
(C2) is used to switch the status LED off. On figure
6, the status signal is determined by voltage meas-
urement, 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
TSM101/A
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