VIPER53SP STMicroelectronics, VIPER53SP Datasheet - Page 18

• Manufacturer Part Number: VIPER53SP
• Description: IC OFFLINE SWIT PWM CM POWERSO10
• Manufacturer: STMicroelectronics
• Series: VIPER™r

Specifications of VIPER53SP

• Output Isolation: Isolated
• Frequency Range: 93 ~ 300kHz
• Voltage - Input: 8.4 ~ 19 V
• Voltage - Output: 620V
• Power (watts): 40W
• Operating Temperature: 25°C ~ 125°C
• Package / Case: PowerSO-10 Exposed Bottom Pad
• For Use With: 497-8435 - BOARD EVAL FOR VIPER53 28W497-6458 - BOARD EVAL BASED ON VIPER53-E497-6262 - BOARD REF SGL VIPER53 90-264VAC497-5866 - EVAL BOARD 24W NEG OUT VIPER53E497-4933 - BOARD PWR SUPPLY 24W OUTPUT VIPE
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 497-3289-5

VIPer53DIP / VIPer53SP
Figure 20: Complete Converter Transfer Function
in the current mode section. A zero due to the
R
the maximum load R
The total transfer function is shown as F(s).G(s) at
the bottom of figure 20. For maximum load (plain
line), the load pole is exactly compensated by the
zero of the error amplifier, and the result is a
18/24
3.2
3.2
Gm R
COMP
F(
------------------- -
P
------------------- -
P
P
P
C O M P
OU T 2
O U T1
M A X
M AX
S
).G(
1
1
1
-C
G(
F(
S
S
COMP
S
)
)
)
--------------------------------------- -
R
L1
1
network is set at the same value as
C
O UT
--------------------------------------- -
L2
R
--------------------------------------------------------------- -
2
L2
pole.
1
C
F
R
O UT
BW
C O M P
1
1
C
CO M P
F
BW
2
----------------------------------------------- -
2
ES R C
F
1
C
O UT
F
F
F
perfect first order decreasing slope until it reaches
the zero of the output capacitor ESR. The error
amplifier cut off then prevents definitely any further
spurious noise or resonance from disturbing the
regulation loop.
The point where the complete transfer function has
a unity gain is known as the regulation bandwidth
and has a double interest:
– The higher it is the faster will be the reaction to
– The phase shift in the complete system at this
In figure 20, the unity gain is reached in a first order
slope, so the stability is ensured.
The dynamic load regulation is improved by
increasing the regulation bandwidth, but some
limitations have to be respected: As the transfer
function above the zero due the capacitor ESR is
not reliable (The ESR itself is not well specified,
and other parasitic effects may take place), the
bandwidth should always be lower than the
minimum of F
As the highest bandwidth is obtained with the
highest output power (Plain line with R
figure 20), the above criteria will be checked for
this condition and allows to define the value of
R
on this value for this frequency range. The
following formula can be derived:
With:
And:
The lowest load gives another condition for
stability: The frequency F
the second order slope generated by the load pole
and the integrator part of the error amplifier. This
condition can be met by adjusting the C
value:
With:
The above formula gives a minimum value for
C
natural soft start function as this capacitor is
charged by the error amplifier current capacity
I
COMPhi
C
R
COMP
COMP
an eventual load change, and the smaller will be
the output voltage change.
point has to be less than 135 ° to ensure a good
stability. Generally, a first order gives 90 ° of
phase shift, and 180 ° for a second order.
COMP
COMP
P
, as the error amplifier gain depends only
. It can be then increased to provide a
P
P
M AX
at start-up.
=
OUT2
OUT1
-------------------------------------------- -
6.3 Gm R
P
-----------------
R
P
=
OUT2
L1
C
M AX
=
=
1
-- - L
2
and ESR zero.
V
--------------
V
--------------
C
R
R
2
OUT
2
OUT
OUT
L2
P
L1
2
COMP
F
------------------------------------------------
BW 2
I
2
LIM
BW1
R
Gm
F
L2
P
-----------------
SW
P
OUT1
M AX
must not encounter
C
OUT
:
L2
load in
COMP