viper22as13tr STMicroelectronics, viper22as13tr Datasheet - Page 8

• Manufacturer Part Number: viper22as13tr
• Description: Low Power Off Line Smps Primary Switcher
• Manufacturer: STMicroelectronics

VIPer22ADIP / VIPer22AS
Figure 8 : Rectangular U-I output characteristics for battery charger
RECTANGULAR U-I OUTPUT
CHARACTERISTIC
A complete regulation scheme can achieve
combined and accurate output characteristics.
Figure 8 presents a secondary feedback through
an optocoupler driven by a TSM101. This device
offers two operational amplifiers and a voltage
reference, thus allowing the regulation of both
output voltage and current. An integrated OR
function performs the combination of the two
resulting error signals, leading to a dual voltage
and current limitation, known as a rectangular
output characteristic.
This type of power supply is especially useful for
battery chargers where the output is mainly used in
current mode, in order to deliver a defined charging
rate. The accurate voltage regulation is also
convenient for Li-ion batteries which require both
modes of operation.
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AC IN
F1
C3
T2
D4
C4
C5
C10
ISO1
C6
R5
R7
R10
WIDE RANGE OF V
The V
This feature offers a great flexibility in design to
achieve various behaviors. In figure 8 a forward
configuration has been chosen to supply the
device with two benefits:
– as soon as the device starts switching, it
– the output current characteristic
FB
U1
VIPerX2A
immediately receives some energy from the
auxiliary winding. C5 can be therefore reduced
and a small ceramic chip (100 nF) is sufficient to
insure the filtering function. The total start up
time from the switch on of input voltage to output
voltage presence is dramatically decreased.
maintained even with very low or zero output
voltage. Since the TSM101 is also supplied in
forward mode, it keeps the current regulation up
whatever the output voltage is.The V
voltage may vary as much as the input voltage,
that is to say with a ratio of about 4 for a wide
range application.
VDD
R2
CONTROL
R3
C8
R8
R1
DD
TSM101
U2
pin voltage range extends from 9V to 38V.
C2
D3
SOURCE
-
GND
Vref
+
DRAIN
Vcc
D1
D5
DD
+
-
T1
VOLTAGE
C7
R4
C9
D2
C1
R6
R9
can be
DD
DCOUT
GND
pin