viper100bsp STMicroelectronics, viper100bsp Datasheet - Page 3

• Manufacturer Part Number: viper100bsp
• Description: Smps Primary I.c.
• Manufacturer: STMicroelectronics

ORDERING NUMBERS
PINS FUNCTIONAL DESCRIPTION
DRAIN PIN:
Integrated power MOSFET drain pin. It provides
internal bias current during start-up via an
integrated high voltage current source which is
switched off during normal operation. The device
is able to handle an unclamped current during its
normal operation, assuring self protection against
voltage surges, PCB stray inductance, and
allowing a snubberless operation for low output
power.
SOURCE PIN:
Power MOSFET source pin. Primary side circuit
common ground connection.
VDD PIN :
This pin provides two functions :
-
-
It corresponds to the low voltage supply of the
control part of the circuit. If V
the start-up current source is activated and the
output power MOSFET is switched off until the
V
the internal current consumption is reduced,
the V
and the COMP pin is shorted to ground. After
that, the current source is shut down, and the
device tries to start up by switching again.
This pin is also connected to the error amplifier,
in order to allow primary as well as secondary
regulation configurations. In case of primary
regulation, an internal 13V trimmed reference
voltage is used to maintain V
secondary regulation, a voltage between 8.5V
and 12.5V will be put on V
transformer design, in order to stuck the output
of the transconductance amplifier to the high
state. The COMP pin behaves as a constant
DD
voltage reaches 11V. During this phase,
DD
PENT AW ATT HV
pin is sourcing a current of about 2mA
VIPer100B
DD
DD
goes below 8V,
at 13V. For
DD
PENTAWATT HV (022Y)
pin by
VIPer100B (022Y)
COMP PIN :
This pin provides two functions :
-
-
OSC PIN :
An R
to define the switching frequency. Note that
despite the connection of R
significant frequency change occurs for V
varying from 8V to 15V. It provides also a
synchronisation capability, when connected to an
external frequency source.
current source, and can easily be connected to
the output of an optocoupler. Note that any
overvoltage due to regulation loop failure is still
detected by the error amplifier through the V
voltage, which cannot overpass 13V. The
output voltage will be somewhat higher than
the nominal one, but still under control.
It is the output of the error transconductance
amplifier, and allows for the connection of a
compensation network to provide the desired
transfer function of the regulation loop. Its
bandwidth can be easily adjusted to the
needed value with usual components value. As
stated
configurations are also implemented through
the COMP pin.
When the COMP voltage is going below 0.5V,
the shut-down of the circuit occurs, with a zero
duty cycle for the power MOSFET. This feature
can be used to switch off the converter, and is
automatically activated by the regulation loop
(whatever is the configuration) to provide a
burst mode operation in case of negligible
output power or open load condition.
T
-C
T
network must be connected on that pin
above,
secondary
VIPer100BSP
Pow erSO -10
VIPER100B/BSP
T
to V
regulation
DD
, no
3/20
DD
DD