TSM102 Datasheet, PDF (8/10 Pages) STMicroelectronics – DUAL OPERATIONAL AMPLIFIER - DUAL COMPARATOR AND ADJUSTABLE VOLTAGE REFERENCE

TSM102
= 2.5 / [ 56 / (131.5 + 56 + 0.68 ) ]
= 8.400V
Vout = 8.400V
Low Battery signal :
If R5 = 0Ω and R6 = open :
Vout(LoBatt) = Vref / [ R19 / ( R17 + R19 ) ]
= 2.5 / [ 10 / (12.4 + 10) ]
= 5.6V
Vout(LoBatt) = 5.6V
End of Charge signal :
Vout(EOC) = Vref / [ (R2 + R3 ) / (R1 + R2 + R3) ]
= 2.5 / [ (56 + 0.68) / (131.5 + 56 + 0.68) ]
= 8.300V
Vout (EOC)= 8.300V
Notes:
The current control values must be chosen in ac-
cordancewith the elements of the primary side. The
performances of the battery charger in their global-
ity are highly dependent on the adequation of the
primary and the secondary elements.
The addition of the diode D9 is necessary to avoid
dramatic discharge of the battery cells in case of
the charger disconnection from the mains voltage,
and therefore, the voltage measurement is to be
operated on the cathode side of the diode not to
take its voltage drop into account. The total bridge
value of R1, R2, R3 must ensure low battery dis-
charge if the charger is disconnected from main,
but remains connected to the battery by mistake.
The chosen values impose a 44µA discharge cur-
rent max.
R12 and R13 are the equivalentresistors seen from
the opamp and from the comparator.
A hysteresis resistor can be connected to the ”End
Of Charge” comparator to ensureproper hysteresis
to this signal, but this resistor must be chosen
carefully not to degrade the output voltage preci-
sion. It might be needed to impose unidirectionnal
hysteresis (by inserting a diode on the positive
feedback of the comparator).
Figure 3 shows how to use the integrated Voltage
Reference to build a precise Power Supply for the
Figure 3 : A precise power supply for the TSM102A and other components
Vaux
Vcc
+
Vaux
+
9
8
13
TSM102 Vref
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