VIPER100A STMicroelectronics, VIPER100A Datasheet - Page 13

• Manufacturer Part Number: VIPER100A
• Description: IC SWIT PWM SMPS CM PENTAWATT5
• Manufacturer: STMicroelectronics
• Series: VIPER™r

Specifications of VIPER100A

• Output Isolation: Isolated
• Frequency Range: 90 ~ 200kHz
• Voltage - Input: 8 ~ 15 V
• Voltage - Output: 700V
• Power (watts): 82W
• 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: 3000 mA
• Mounting Style: Through Hole
• Switching Frequency: 90 KHz to 110 KHz
• Operating Supply Voltage: 0 V to 15 V
• Fall Time: 100 ns
• Rise Time: 50 ns
• Synchronous Pin: No
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: 497-2712-5

VIPer100/SP - VIPer100A/ASP
Operation Description:
Current Mode Topology:
The current mode control method, like the one integrated in the VIPer100/100A, 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
amplified output voltage error) the power switch is switched off. Thus, the 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
correct. For specific applications the maximum peak current 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
to provide in normal operation. This current can be computed as :
t
comparator, and represents roughly the minimum on time of the device. Note: that PSTBY may be
affected by the efficiency of the converter at low load, and must include the power drawn on the primary
auxiliary voltage.
As soon as the power goes below this limit, the auxiliary secondary voltage starts to increase above the
13V regulation level, forcing the output voltage of the transconductance amplifier to low state (V
V
state, resulting in missing cycles and zero duty cycle. As soon as V
and the V
providing a burst mode of which the effective duty cycle is much lower than the minimum one when in
normal operation. The equivalent switching frequency is also lower than the normal one, leading to a
reduced consumption on the input main supply lines. This mode of operation allows the VIPer100/100A
to meet the new German "Blue Angel" Norm with less than 1W total power consumption for the system
when working in stand-by mode. The output voltage remains regulated around the normal level, with a
low frequency ripple corresponding to the burst mode. The amplitude of this ripple is low, because of the
output capacitors and low output current drawn in such conditions.The normal operation resumes
automatically when the power gets back to higher levels than P
STBY
b
P
COMPth
+ t
is the primary inductance of the transformer. F
d
is the minimum controllable current, corresponding to the minimum on time that the device is able
is the sum of the blanking time and of the propagation time of the internal current sense and
). This situation leads to the shutdown mode where the power switch is maintained in the Off
COMPth
threshold is reached, the device operates again. The above cycle repeats indefinitely,
STBY
given by :
S
proportional to this current. When V
SW
is the normal switching frequency.
STBY
P
I
STBY
STBY
.
DD
=
gets back to the regulation level
=
1
-- - L
2
(
-----------------------------
t
b
P
+
I
2
L
t
STBY
d
p
)V
S
IN
reaches V
F
SW
DD
is no longer
COMP
COMP
13/24
(the
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