TSM101A STMicroelectronics, TSM101A Datasheet - Page 8

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

TSM101/A
5 - IMPROVEMENT
5.1. High frequency compensation
Two R-C devices (R9 + C2 & R10 + C3) are used
to stabilize the regulation at high frequencies.
The calculation of these values is not easy and is
a function of the transfer function of the SMPS.
A guess value for the capacitors C2 and C3 is
100nF.
winding is added at the secondary side of the
transformer.
This winding is forward coupled to the primary
winding, the voltage across it is directly proportional
to the mains rectified voltage, even if the flyback
voltage is close to zero.
As this auxiliary winding is a voltage source, it is
necessary to add a resistor (R11) on the cathode
of the rectifier (D3) to limit the current.
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Figure 4 : An Auxiliary Winding for TSM101 Power Supply
5.2. Power supply for TSM101
In applications requiring low voltage battery charge
or when the charger is in current regulation mode,
the outputvoltage can be too low to supply correctly
the TSM101.
The same problem occurs when the output is short-
circuited.
A solution to provide a quasi constant supply volt-
age to the TSM101 is shown at figure 4 : an auxiliary
A low cost regulator (Q2 and Zener diode D4) is
used to power the TSM101. This is necessary with
autoranging SMPS with wide input voltages, for
example 90 to 240V without switching. In standard
SMPS with voltage range from 200 to 240VAC or
100 to 130VAC, this regulator can be removed and
replaced by the small power supply shown on
figure 5 (Raux, Caux, D2).