VIPER20A-22-E STMicroelectronics, VIPER20A-22-E Datasheet - Page 13

• Manufacturer Part Number: VIPER20A-22-E
• Description: IC SWIT SMPS CM OTP PENTAWATT5
• Manufacturer: STMicroelectronics
• Series: VIPER™r

Specifications of VIPER20A-22-E

• Output Isolation: Isolated
• Frequency Range: 90 ~ 200kHz
• Voltage - Input: 8 ~ 15 V
• Voltage - Output: 700V
• Power (watts): 57W
• Operating Temperature: 25°C ~ 125°C
• Package / Case: Pentawatt-5 HV (Bent and Staggered Leads)
• Number Of Outputs: 1
• Output Voltage: 700 V
• Output Current: 500 mA
• Mounting Style: Through Hole
• Switching Frequency: 200 KHz
• Fall Time: 100 ns
• Rise Time: 50 ns
• Synchronous Pin: No
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 497-6795-5; VIPER20A-22-E

VIPer20A-E
5.4
The soft start feature can be implemented on the COMP pin through a simple capacitor which
will be also used as the compensation network. In this case, the regulation loop bandwidth is
rather low, because of the large value of this capacitor. In case a large regulation loop
bandwidth is mandatory, the schematics of
performance compensation network together with a separate high value soft start capacitor.
Both soft start time and regulation loop bandwidth can be adjusted separately.
If the device is intentionally shut down by tying the COMP pin to ground, the device is also
performing start-up cycles, and the V
This voltage can be used for supplying external functions, provided that their consumption does
not exceed 0.5mA.
shutdown. Once the "Shutdown" signal has been activated, the device remains in the Off state
until the input voltage is removed.
Transconductance error amplifier
The VIPer20A-E includes a transconductance error amplifier. Transconductance Gm is the
change in output current (I
The output impedance Z
This last equation shows that the open loop gain A
A
where G
G
An impedance Z can be connected between the COMP pin and ground in order to define the
transfer function F of the error amplifier more accurately, according to the following equation
(very similar to the one above):
F
The error amplifier frequency response is reported in for different values of a simple resistance
connected on the COMP pin. The unloaded transconductance error amplifier shows an internal
Z
achieve different compensation level. A capacitor will provide an integrator function, thus
eliminating the DC static error, and a resistance in series leads to a flat gain at higher
frequency, insuring a correct phase margin. This configuration is illustrated in
As shown in
avoid any high frequency interference.
Is also possible to implement a slope compensation when working in continuous mode with
duty cycle higher than 50%.
classical compensation network, and Q1 is injecting the slope compensation with the correct
polarity from the oscillator sawtooth.
VOL
(S)
COMP
m
is defined by specification, but Z
= Gm x Z(S)
G
Z
= G
COMP
m
of about 330K . More complex impedance can be connected on the COMP pin to
m
=
m
value for VIPer20A-E is 1.5 mA/V typically.
------------------ -
x Z
l
=
Figure 19
COMP
V
COMP
DD
--------------------
V
I
COMP
COMP
(see Figure 18)
=
an additional noise filtering capacitor of 2.2nF is generally needed to
------- -
G
COMP
1
m
COMP
Figure 21
------------------------
at the output of this amplifier (COMP pin) can be defined as:
V
) versus change in input voltage (V
COMP
V
DD
shows a typical application of this function, with a latched
COMP
DD
shows such a configuration. Note: R1 and C2 build the
voltage is oscillating between V
and therefore A
(see Figure 17)
VOL
can be related to G
VOL
can be used. It mixes a high
are subject to large tolerances.
DD
). Thus:
DDon
m
Operation description
and Z
and V
Figure 20
COMP
DDoff
:
.
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