VIPER20A-E STMicroelectronics, VIPER20A-E Datasheet - Page 11

IC SWIT SMPS CM OTP PENTAWATT5

VIPER20A-E

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

Specifications of VIPER20A-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 (Min)
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
497-6796-5
VIPER20A-E
VIPer20A-E
5
5.1
5.2
Operation description
Current mode topology:
The current mode control method, like the one integrated in the devices, uses two control loops
- an inner current control loop and an outer loop for voltage control. When the Power MOSFET
output transistor is on, the inductor current (primary side of the transformer) is monitored with a
SenseFET technique and converted into a voltage V
reaches V
outer voltage control loop defines the level at which the inner loop regulates peak current
through the power switch and the primary winding of the transformer.
Excellent open loop D.C. and dynamic line regulation is ensured due to the inherent input
voltage feedforward characteristic of the current mode control. This results in improved line
regulation, instantaneous correction to line changes, and better stability for the voltage
regulation loop.
Current mode topology also ensures good limitation in case there is a short circuit. During the
first phase the output current increases slowly following the dynamic of the regulation loop.
Then it reaches the maximum limitation current internally set and finally stops because the
power supply on V
internally set can be overridden by externally limiting the voltage excursion on the COMP pin.
An integrated blanking filter inhibits the PWM comparator output for a short time after the
integrated Power MOSFET is switched on. This function prevents anomalous or premature
termination of the switching pulse in case there are current spikes caused by primary side
capacitance or secondary side rectifier reverse recovery time.
Stand-by mode
Stand-by operation in nearly open load conditions automatically leads to a burst mode
operation allowing voltage regulation on the secondary side. The transition from normal
operation to burst mode operation happens for a power P
Where:
L
I
device is able to provide in normal operation. This current can be computed as :
t
and comparator, and represents roughly the minimum on time of the device. Note: that P
may be affected by the efficiency of the converter at low load, and must include the power
drawn on the primary auxiliary voltage.
STBY
b
P
+ t
is the primary inductance of the transformer. F
d
is the minimum controllable current, corresponding to the minimum on time that the
is the sum of the blanking time and of the propagation time of the internal current sense
COMP
P
I
STBY
STBY
(the amplified output voltage error) the power switch is switched off. Thus, the
=
=
DD
-----------------------------
1
-- - L
2
t
b
is no longer correct. For specific applications the maximum peak current
+
P
I
L
t
2
d
p
STBY
V
IN
F
SW
SW
S
is the normal switching frequency.
proportional to this current. When V
STBY
given by :
Operation description
STBY
11/34
S

Related parts for VIPER20A-E