VIPER53-E STMicroelectronics, VIPER53-E Datasheet - Page 15

• Manufacturer Part Number: VIPER53-E
• Description: Fixed frequency off line converter
• Manufacturer: STMicroelectronics

VIPer53 - E
5
Primary regulation configuration example
Figure 18. Off line power supply with auxiliary supply feedback
The schematic on
amplifier of the device in a primary feedback configuration. The primary auxiliary winding
provides a voltage to the V
error amplifier connected to this pin. The secondary voltage has to be adjusted through the
turn ratio of the transformer between auxiliary and secondary.
The error amplifier of the VIPer53 is a transconductance type: its output is a current
proportional to the difference of voltage between the V
reference (i.e., the error voltage). As the transconductance value is set at a relatively low
value to control the overall loop gain and ensure stability, this current has to be integrated by
a capacitor (C7 in
blocks any DC current from the COMP pin and imposes a “nil” error voltage. Therefore, the
V
This results in a good load regulation, which depends only on transformer coupling and
output diodes impedance. The current mode structure takes care of all incoming voltage
changes, thus providing at the same time an excellent line regulation.
DD
AC IN
voltage is accurately regulated to 15V.
R1
F1
C1
C4
R3
C5
Figure
Figure 18
OSC
T1
VIPer73
U1
15V
18). When the steady state operation is reached, this capacitor
DD
TOVL
delivers a fixed output voltage by using the internal error
VDD
R6
1k
pin, and is automatically regulated at 15V, due to the internal
C6
D1
COMP
10nF
C11
R4
SOURCE
R5
C7
C2
DRAIN
Primary regulation configuration example
C3
DD
D2
D3
pin and the internally trimmed 15V
R2
T2
D4
C10
C8
L1
C9
15/36
DC OUT